I Can Work This Thing!

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5 K2 Operation manual

Submitted by Jerry Neufeld VE3QSO
E-mail: ve3qso@rac.ca
Phone: 613-828-0959

Note: I have placed qq numbers in the Table of Contents to facilitate location of specific sections of the Elecraft manual. This manual contains comprehensive information on kit construction and alignment as well as other matters that may not be of immediate interest to the end user. As a result, you may be a bit frustrated when searching for specific information as normally appears in user-friendly format in more standard manuals. Consult the K2 you can work this thing.txt file for basic help.

Table of Contents

qq001 Introduction
qq002 Specifications
qq003 Preparation for Assembly
qq004 Control Board
qq005 Front Panel Board
qq006 RF Board
qq007 Assembly, Part I
qq008 Alignment and Test, Part 1
qq009 Assembly, Part 2
qq010 Alignment and Test, Part 2
qq011 Assembly, Part 3
qq012 Alignment and Test, Part 3
qq013 Final Assembly
qq014 Operation
qq015 connections
qq016 Controls and Display
qq017 Calibration Functions
qq018 Basic K2 Operation
qq019 CW Operation
qq020 SSB Operation
qq021 Advanced Operating Features
qq022 Secondary Menu Functions
qq023 Circuit Details
qq024 Front Panel Board
qq025 Control Board
qq026 RF Board
qq027 Options
qq028 Appendix E, Troubleshooting
qq029 Signal Tracing

qq001 Introduction

The Elecraft K2 is a high-performance, synthesized, CW/SSB
transceiver that covers all HF bands. It is a true dual-purpose
transceiver, combining the operating features you’d expect in a
home-station rig with the small size and weight of a rugged,
go-anywhere portable.
The basic K2 operates on 80-10 meter CW, and provides over 10
watts of RF output. If you prefer a full-power station, you can
complete your K2 as a K2/100 at any time by adding the internal
100-watt final stage (KPA100 option). Assembly of the KPA100
is covered in Appendix G, a separate manual supplied with the
KPA100 kit.
You can customize your K2 by choosing from a wide range of
additional options:
- SSB adapter with optimized 7-pole crystal filter
- Automatic antenna tuner (20 W internal or 150 W external)
- 160-m adapter with receive antenna switch
- 60-m adapter with low-level transverter interface
- Computer control interface (RS232)
- Noise blanker
- Digital or analog audio filter, each with real-time clock
- Internal 2.9-Ah rechargeable battery
- Programmable band decoder
- High-Performance VHF and UHF transverters

For a complete description of available options, see page 113. In
addition to the options, a companion enclosure the same size and
style as the K2 is available for those who wish to build their own
matching station accessories (model EC2).

The K2 is an intermediate-level kit, yet you’ll be pleasantly surprised
at how uncomplicated it is to build. All of the RF (radio-frequency)
circuitry is contained on a single board, while two plug-in modules
provide front panel and control functions. Wiring is minimal, unlike
traditional kits which depend on complex wiring harnesses.

A unique feature of the K2 is that it provides its own built-in test
equipment, including a digital voltmeter, ammeter, wattmeter,
complete RF probe, and frequency counter. These circuits are
completed early in assembly, so they're ready to be used when you
begin construction and alignment of the RF board. We also provide
complete troubleshooting and signal-tracing information.

In addition to this owner’s manual, you’ll find extensive support for
the K2 on our website, www.elecraft.com. Among the available
materials are manual updates, application notes, photographs, and
information on new products. There’s also an e-mail forum; sign-up
is available from the web page. It’s a great way to seek advice from
the K2’s designers and your fellow builders, or to tell us about your
first QSO using the K2.

We’d like to thank you for choosing the K2 transceiver, and hope it
meets your expectations for operation both at home and in the field.

Pre-Wound Toroids Available
You can obtain a set of pre-wound toroids for the K2 if you prefer
not to wind them yourself. Refer to our web site for details.

Customer Service Information

Technical Assistance

If you have difficulty with kit construction, operation, or
troubleshooting, we’re here to help. You may be able to save time
by first consulting our web site, www.elecraft.com, or by posting
your question on our e-mail forum, elecraft@mailman.qth.net.
Telephone assistance is available from 9 A.M. to 5 P.M. Pacific
time (weekdays) at 831-662-8345. Via e-mail, use
support@elecraft.com for support and parts@elecraft.com to
request replacement parts. Please use e-mail when possible; this
gives us a written record of the details of your problem.
Repair Service

If necessary, you may return your completed kit to us for repair.
Contact Elecraft before mailing your kit to obtain current
information on repair fees. (Kits that have been soldered using
acid core solder, water-soluble flux solder, or other corrosive or
conductive fluxes or solvents cannot be accepted for repair.)
The following information should be provided to expedite repair:
your name, address, and phone number; your e-mail address (if
applicable); and a complete description of the problem.
Shipping: First, seal the unit in a plastic bag to protect the finish
from dust and abrasion. Use a sturdy packing carton with 3" or
more of foam or shredded paper on all sides. Seal the package with
reinforced tape. (Neither Elecraft nor the carrier will accept
liability for damage due to improper packaging.) Cover the "to"
address label with clear tape so it will be weatherproof. Finally,
call or send e-mail to obtain the proper shipping address.

Elecraft’s 1-Year Limited Warranty

This warranty is effective as of the date of first consumer purchase.
Before requesting warranty service, you should complete the
assembly, carefully following all instructions in the manual.

What is covered: During the first year after date of purchase,
Elecraft will replace defective parts free of charge (post-paid). We
will also correct any malfunction caused by defective parts and
materials. You must send the unit at your expense to Elecraft, but we
will pay return shipping.

What is not covered: This warranty does not cover correction of
assembly errors or misalignment; repair of damage caused by misuse,
negligence, or builder modifications; or any performance
malfunctions involving non-Elecraft accessory equipment. The use of
acid-core solder, water-soluble flux solder, or any corrosive or
conductive flux or solvent will void this warranty in its entirety. Also
not covered is reimbursement for loss of use, inconvenience,
customer assembly or alignment time, or cost of unauthorized

Limitation of incidental or consequential damages: This
warranty does not extend to non-Elecraft equipment or components
used in conjunction with our products. Any such repair or
replacement is the responsibility of the customer. Elecraft will not be
liable for any special, indirect, incidental or consequential damages,
including but not limited to any loss of business or profits.

qq002 Specifications

All measurements were made using a 14.0 V supply and 50-ohm
load unless otherwise indicated. Values are typical; your results will
be somewhat different. Specifications are subject to change without
notice. (See option manuals for additional specifications.)


Cabinet 3.0" H x 7.9" W x 8.3" D
(7.5 x 20 x 21 cm)
Overall 3.4" H x 7.9" W x 9.9" D
(8.5 x 20 x 25 cm)
Weight 3.3 lbs. (1.5 kg), excluding options
Supply voltage 9 to 15 VDC;
reverse-polarity protection;
internal self-resetting fuse
Current drain,
Receive 120-150 mA in minimum-current
configuration; 180-250 mA typical
Transmit1 2.0 A typical at 10 watts;
programmable current limiting
Frequency control PLL synthesizer w/single VCO
covering 6.7-24 MHz in 10 bands;
fine steps via DAC-tuned reference
Frequency ranges,2 MHz
Basic kit 3.5-4.0, 7.0-7.3,
10.0-10.2, 14.0-14.5, 18.0-18.2,
21.0-21.6, 24.8-25.0, 28.0-28.8
160 m (opt.) 1.8-2.0
60 m (opt.) 5.0-5.5
Stability < 100 Hz total drift typ. from
cold start at 25° C
Accuracy3 +/- 30 Hz over a 500 kHz range
(typ) when calibrated
Resolution 10 Hz
Tuning steps 10 Hz, 50 Hz, and 1000 Hz nominal
(other step sizes available via menu)
Memories 20 (10 assigned to 160-10 m
Bands; 10 general-purpose)
RIT/XIT range +/- 0.6 to +/- 4.8 kHz (selectable);
10-40 Hz steps depending on range.
Fine RIT mode steps 2-3 Hz typ.


Power output range <0.5 W to >10 W (typ.);
power setting resolution 0.1 W,
accuracy 10% @ 5 W
Min. supply voltage 9.0 V min for 2 watts out
recommended4 9.5 V min for 5 watts out
10.0 V min for 7 watts out
10.5 V min for 10 watts out
Duty cycle 5 W, 100%; 10 W, 50%
Spurious products -40 dB or better @ 10 W (-50 typ)
Harmonic content -45 dB or better @ 10 W (-55 typ)
Load tolerance 2:1 or better SWR recommended;
will survive operation
into high SWR
T-R delay approx. 10 ms-2.5 sec, adjustable
External keying 70 WPM max.
CW sidetone 400-800 Hz in 10 Hz steps


Keying modes Iambic A and B; adjustable weight
Speed range 9 - 50 WPM
Message memory 9 buffers of 250 bytes each; 1-level
chaining; auto-repeat (0 - 255 s)


Preamp On Preamp Off
Sensitivity (MDS) -135 dBm -130 dBm
3rd-order intercept 0 to +7.55 +10
2nd-order intercept +70 +70
Dynamic range,
Blocking 125 dB 133 dB
Two-tone 96 97
I.F. 4.915 MHz (single conversion)
CW 7-pole variable-bandwidth crystal
filter, approx. 200-2000 Hz
SSB6 7-pole fixed-bandwidth crystal
filter, 2.2 kHz typ.
Audio output 1 watt max. into 4-ohm load
Speaker internal: 4 ohm, 3 W;
Rear-panel jack for external speaker
Headphones 4 - 32 ohms, stereo or mono

qq003 Preparation for Assembly

Overview of the Kit
The K2 uses modular construction, both physically and electrically.
This concept extends to the chassis (Figure 3-1). Any chassis
element can be removed during assembly or troubleshooting. (Also
see photos in Appendix D.) If the KPA100 is installed, it takes the
place of the original top cover.

As shown in Figure 3-2, there are three printed circuit boards
(PCBs) in the basic K2 kit: the Front Panel board, Control Board,
and RF board. Option modules plug into the RF or Control board,
but are not shown here.

Board-to-board Connectors
The circuit boards in the K2 are interconnected using board-to-board connectors, which eliminates nearly all hand wiring. Gold-plated contacts
are used on these connectors for reliability and corrosion resistance.
Figure 3-3 shows a side view of the PC boards and board-to-board connectors. As can be seen in the drawing, the Front Panel board has a
connector J1 which mates with right-angle connector P1 on the RF board. Similarly, right-angle connector P1 on the Control Board mates
with J6 on the RF board. (Not shown in this drawing are two additional right-angle connectors on the Control board, P2 and P3, which mate
with J7 and J8 on the RF board.)
These multi-pin connectors are very difficult to remove once soldered in place. Refer to Figure 3-3 during assembly to make
sure you have each connector placed correctly before soldering.

There are six steps in the K2 assembly process:

  1. Control Board assembly
  2. Front Panel Board assembly
  3. RF Board assembly and test, part I (control circuits)
  4. RF Board assembly and test, part II (receiver and synthesizer)
  5. RF Board assembly and test, part III (transmitter)
  6. Final assembly

This assembly sequence is important because later steps build on the
previous ones. For example, in step 3 you’ll put the modules
together for the first time, allowing you to try out the K2’s built-in
frequency counter. The counter will then be used in step 4 to align
and test the receiver and synthesizer on 40 meters. In step 5 all the
pieces will come together when you complete the transmitter and
filters, then align the K2 on all bands. The last few
details—speaker, tilt stand, etc.—will be wrapped up in step 6.

Unpacking and Inventory
When you open the kit you should find the following items:
- six chassis pieces (Figure 3-1)
- three printed circuit boards (Figure 3-2)
- FRONT PANEL board components bag
- CONTROL board components bag
- RF board components in two bags
- MISCELLANEOUS components bag (includes hardware)
- WIRE bag
- 4-ohm Speaker, 5 small knobs, and large tuning knob
- plastic tube containing the latching relays
- an envelope containing the LCD bezel, green LED bargraph
filter, serial number label, thermal insulators, and other items

We strongly recommend that you do an inventory of parts before
beginning to assemble the kit. It is not necessary to inventory the
resistors, which are supplied attached to tape in assembly order.
Even if you don’t do an inventory, it is helpful to familiarize
yourself with the parts list, Appendix A. Additional information on
identifying capacitor, chokes, and resistors is provided below.

Identifying Capacitors
Small-value fixed capacitors are usually marked with one, two, or
three digits and no decimal point. If one or two digits are used, that
is always the value in picofarads (pF). If there are three digits, the
third digit is a multiplier. For example, a capacitor marked "151"
would be 150 pF (15 with a multiplier of 101). Similarly, "330"
would be 33 pF, and "102" would be 1000 pF (or .001 µF). In rare
cases a capacitor manufacturer may use "0" as a decimal
placeholder. For example, "820" might mean 820 pF rather than
the usual 82 pF. Such exceptions are usually covered in the parts
lists. To be safe, measure the values of all capacitors below 1000 pF
(most DMMs include capacitance measurement capability).
Fixed capacitors with values of 1000 pF or higher generally use a
decimal point in the value, such as .001 or .02. This is the value in
microfarads (µF). Capacitors also may have a suffix after the value,
such as ".001J." In some cases the suffixes or other supplemental
markings may be useful in identifying capacitors.
Hard-to-identify capacitor values:
3.3 pF: These capacitors may have pillow-shaped, dark-green
bodies about 1/8" (3 mm) square, with a black mark on the top. The
"3.3" label may be difficult to read without a magnifying glass.
150 pF: These are correctly marked "151" on one side, but the
other side may be marked #21 ASD, where "#21" looks like "821."

Resistors, Chokes, and the Color Code
All resistor and RF choke color bands are provided in the text along
with their values. However, it is helpful to familiarize yourself with
the color code to allow you to identify these components without
having to refer to the text or parts list each time.
The color-code chart, Figure 3-4, shows how to read the four color
bands on 5% resistors. 1% resistors are similar, except that they use
five bands (three significant digits, multiplier, and tolerance). For
example, a 1,500 ohm (1.5 k) 5% resistor has color bands
BROWN, GREEN, and RED. A 1.5 k, 1% resistor has color bands
BROWN, GREEN, BLACK, BROWN. The multiplier value is 1
rather than 2 in the 1% case because of the third significant digit.
Because 1% resistors have color bands that are sometimes hard to
distinguish clearly, you should always check their resistance using
an ohmmeter.
The markings on RF chokes reflect their value in microhenries
(µH). Like 5% resistors, chokes use two significant digits and a
multiplier. Example: an RF choke with color bands RED, VIOLET,
BLACK would have a value of 27 µH.

The following specialized tools are supplied with the K2:
- .050" (1.3 mm) Allen Wrench, short handle
- 5/64" (2 mm) Allen Wrench, long handle
- Double-ended plastic inductor alignment tool

In addition to the tools supplied, you will need these standard tools:
- Fine-tip soldering iron, 20-40 watt (temperature-controlled
preferred, with 700 or 800°F tip [370-430°C]
- IC-grade, small-diameter (.031") solder (DO NOT use acidcore
solder, water-soluble flux solder, additional flux, or
solvents of any kind, which will void your warranty)
- Desoldering tools (wick, solder-sucker, etc.)
- Needle-nose pliers
- Small-point diagonal cutters, preferably flush-cutting
- Small Phillips screwdriver
- Jeweler’s flat-blade screwdriver
While not required, the following items are recommended:
- DMM (digital multimeter) for doing resistance and voltage
checks. A DMM with capacitance measurement capability is
strongly recommended (see Identifying Capacitors).
- Magnifying glass
- Conductive wrist strap

Assembly Notes

Step-by-Step Assembly
Each step in the assembly process is accompanied by a check-box:

In some steps you will actually be installing multiple components of
a particular type. In this case the instructions will be followed by a
table listing all of the components to be installed, so you won’t
need to refer to the parts list during assembly. The order that the
components are installed corresponds to their PCB locations.
Do not skip any assembly steps; you may find that you’ve
installed one component that hinders the installation of

Forming component leads: In a few cases you’ll find that the
space provided for a component on the PC board is larger than the
distance between the leads on the part itself. In such cases, you’ll
need to carefully bend the leads out and then down to fit the given
space. Always use needle-nose pliers to accomplish this task, and
bend the leads–don’t tug on them. This is especially important
with capacitor leads, which are fragile.

Bottom-Mounted Components

A number of components in the K2 are mounted on the bottom of
the PC boards to improve component spacing or for electrical
reasons. Component outline symbols are provided on both sides of
each board, so it will always be clear which side a particular
component goes on. You’ll be able to tell the top of the board from
the bottom easily: the top side has far more parts. Bottommounted
parts are identified on the schematic by this symbol:

Top/bottom interference: In a few cases, top-mounted parts may
interfere with the trimming and soldering of a bottom-mounted
part. In this case, pre-trim the leads of the bottom-mounted part
before final placement, and solder it on the bottom rather than on
the top. (Since all holes are plated-through, you can solder on
either side.)

Integrated Circuits and ESD

The K2 transceiver uses integrated circuits and transistors that can
be damaged by electrostatic discharge (ESD). Problems caused by
ESD can often be difficult to troubleshoot because components may
only be degraded, at first, rather than fail completely.
To avoid such problems, simply touch an unpainted, grounded
metal surface before handling any components, and occasionally as
you build. We also recommend that you take the following antistatic
precautions (in order of importance):
- Leave ESD-sensitive parts in their anti-static packaging until
you install them
- Ground yourself using a wrist strap with a series 1 megohm
resistor (do NOT ground yourself directly, as this poses a shock
- Make sure your soldering iron has a grounded tip
- Use an anti-static mat on your work bench

IC Sockets

Sockets are used for only the largest ICs. You should not use
sockets for the other ICs because they tend to be unreliable and can
cause problems due to added lead length. Since sockets are not used
in most cases, you must double-check the part number and
orientation of each IC before soldering.
Soldering, Desoldering, and Plated-Through Holes
CAUTION: Solder contains lead, and its residue can be
toxic. Always wash your hands after handling solder.
The printed circuit boards used in the K2 have circuitry on both
sides ("double-sided"). Boards of this type require plated-through

When you solder components on these boards, the solder fills the
plated holes, making excellent contact. This means that you do not
need to leave a large "fillet" or build-up of solder on top of the pads
themselves. A small amount of solder will do for all connections.

Unfortunately, removing components from double-sided PC boards
can be difficult, since you must get all of the solder back out of the
hole before a lead can be removed. To do this, you'll need solder
wick and a vacuum desoldering tool (see techniques below).

The best strategy for avoiding de-soldering is to place all
components properly the first time. Double-check values and
orientations, and avoid damaging parts via ESD.
holes to complete electrical connections between the two sides.

When removing components:
- Don't pull a lead or pin out of a hole unless the solder has been
removed, or you are applying heat. Otherwise, you can literally
pull out the plating on the plated-through hole.
- Limit soldering iron contact to a few seconds at a time.
- Use small-size solder-wick, about 0.1" or 2.5 mm wide. Use the
wick on both the top and bottom pads when possible. This
helps get all of the solder out of the hole.
- Buy and learn how to use a large hand-operated vacuum
desoldering tool, such as the "Soldapullt," model DS017LS.
Small solder suckers are not effective.
- With ICs and connectors, clip all of the pins at the body first,
then remove all of the pins slowly, one at a time. You may
damage pads and traces by trying to remove a component
intact, possibly leaving a PC board very difficult to repair.
- Invest in a PC board vice with a heavy base if possible. This
makes parts removal easier because it frees up both hands.
- If in doubt about a particular repair, ask for advice from
Elecraft or from a someone else with PCB repair experience.
Our e-mail reflector is also an excellent source for help.

qq004 Control Board

The Control board is the "brain" of the K2. It monitors all signals
during receive and transmit, and handles display and control
functions via the Front Panel board. The microcontroller, analog
and digital control circuits, automatic gain control (AGC), and audio
amplifier are located on this board.

- Review the precautions described in the previous section
before handling any IC’s or transistors. These components can be
damaged by static discharge, and the resulting problems are often
difficult to troubleshoot.
- Open the bag of components labeled CONTROL and sort the
parts into groups (resistors, diodes, capacitors, etc.). If any of the
components are unfamiliar, identify them using the illustrations in
the parts list, Appendix A.
- Locate the Control board. It is the smallest of the three K2
PC boards, labeled "K2 CONTROL" on the front side, in the lower
right-hand corner. The lower left-hand corner is notched.
- Open the bag labeled MISCELLANEOUS and empty the
contents into a shallow box or pan. This will prevent loss of any of
the small hardware while allowing you to locate items as needed.
- The Allen wrenches are located in a small bag with the
MISCELLANEOUS items. These wrenches may have been oiled
during manufacturing. Remove the wrenches and wipe off the oil, if
any, then discard the bag.
- There are five sizes of 4-40 machine screws provided with
the kit. The relative sizes of the screws are shown below for
identification purposes (not to scale). All of the screws are black
anodized except for the 7/16" (11 mm) screws. The 3/16" (4.8
mm) pan-head screws are the most numerous, and will be referred to
as chassis screws throughout the manual. There is only one flathead,
3/16" screw.


The side of the Control board with most of the components is
the top side. With the top side of the Control board facing you and
the notch at the lower left, locate the position of resistor R5, near
the left edge. The label "R5" appears just below the resistor’s

Install a 33-k resistor (orange-orange-orange) at R5, with the
orange bands at the top and the gold band (indicating 5% tolerance)
at the bottom. Make sure it is seated flush with the board, then bend
the leads on the bottom to hold it in place. Do not solder this
resistor until the remaining fixed resistors have been installed in the
next step.

Install the remaining fixed resistors, which are listed below in
left-to-right PC board order. The resistors should all be oriented
with their first significant-digit band toward the left or top. This
will make the color codes easier to read if you need to re-check the
values after installation. Check 1% resistors with an ohmmeter.

Note: When multiple items appear on one line in a component list
such as the one below, complete all items on one line before
moving on to the next, as indicated by the small arrow. (In other
words, install R5 first, then R2, then go to the second line.)
__ R5, 33 k (ORG-ORG-ORG) to __ R2, 3.3 M (ORG-ORG-GRN)
__ R3, 10 k (BRN-BLK-ORG) __ R4, 5.6 k (GRN-BLU-RED)
__ R6, 100 (BRN-BLK-BRN)
__ R7, 1.78 k, 1% (BRN-VIO-GRY-BRN)
__ R8, 100, 1% (BRN-BLK-BLK-BLK)
__ R9, 806 k, 1% (GRY-BLK-BLU-ORG)
__ R10, 196 k, 1% (BRN-WHT-BLU-ORG)
__ R16, 10 (BRN-BLK-BLK) ? __ R17, 3.3 M (ORG-ORG-GRN)
__ R21, 270 k (RED-VIO-YEL) __ R20, 2.7 ohms (RED-VIO-GLD)

- Solder all of the resistors, then trim the leads as close as
possible to the solder joints. Some builders prefer to trim the
leads before soldering. Either method can be used.
- Locate RP6, a 5.1 k, 10-pin resistor network. ("RP" means
"resistor pack," another name for resistor networks.) RP6 is usually
labeled "770103512." Check the parts list for alternative resistor
network labels if necessary. Pin 1 of RP6 is indicated by a dot.
- Locate the component outline for RP6 at the left end of the
PC board. Install the resistor network so that the end with the dot
is lined up with the "1" label.
- Make sure the resistor network is seated firmly on the board,
then bend the leads at the far ends in opposite directions to hold it
in place. (Do not trim the leads.) Do not solder RP6 yet.
- Components with many leads are difficult to remove once
soldered. Double-check the part numbers and orientation.
- Install the remaining resistor networks in the order listed
below. Do not solder them until the next step.
__ RP1, 3.9 k, 10 pins (770103392) __ RP7, 33 k, 8 pins (8A3.333G)
__ RP2, 82 k, 8 pins (77083823) __ RP3, 47 k, 10 pins (10A3.473G)
__ RP5, 470, 10 pins (10A3.471G) __ RP4, 82 k, 8 pins (77083823)
- Solder the resistor networks. (No need to trim the leads.)
- Install potentiometer R1 (50 k), located at the left side of the
board. R1 will sit above the board due to the shoulders on its pins.
Hold it in place (flat, not tilted) while soldering.
- Install the 82 mH shielded inductor (L1) as shown by its
component outline. Make sure the L1 is pressed down onto the PC
board as far as it can go, then bend the leads slightly to hold it in
place while soldering.
- Install the 1N4148 diodes listed below. D1 is in the upper lefthand
corner of the PC board. If a diode has only one band, the end
with the band (the cathode) should be oriented toward the banded
end of the corresponding PC board outline. If a diode has multiple
bands, the widest band indicates the cathode end.
__ D1, 1N4148 __ D2, 1N4148
- Double-check the orientation of the diodes, then solder.
- Find the component outline for diode D3, near the top edge of
the board (right end). Install and solder resistor R22 at this location
(82 k, gray-red-orange).
- Install the small fixed capacitors listed below, beginning with
C2 in the upper left-hand corner of the board. (This list includes all
of the fixed capacitors on the Control board except the tall,
cylindrical electrolytic types, which will be installed later.) The list
shows both the value and the capacitor labels, using notation
explained in the previous section. After installing each capacitor,
bend the leads outward to hold it in place, but do not solder.

Note: Remember to complete all items in each line before moving
on to the next. (Install C2, C3, and C4, then C7, etc.)
__ C2, .001 (102) ? __ C3, .01 (103) ? __ C4, 0.47 (474)
__ C7, 330 (331) __ C6, .047 (473) __ C8, 39 (39)
__ C9, .01 (103) __ C10, .01 (103) __ C12, .0027 (272)
__ C5, .01 (103) __ C14, .047 (473) __ C17, .01 (103)
__ C42, 0.1 (104) __ C16, .047 (473) __ C11, .01 (103)
__ C19, .047 (473) __ C21, 33 (33)
__ C23, .01 (103) __ C20, .001 (102) __ C18, .01 (103)
__ C43, .001 (102) __ C27, .022 (223) __ C25, 0.1 (104)
__ C26, 0.1 (104) __ C24, .0027 (272) __ C31, .01 (103)
__ C34, .001 (102) __ C30, .047 (473) __ C40, .01 (103)
__ C35, .01 (103) __ C36, .0027 (272) __ C39, .01 (103)
__ C41, .01 (103) __ C37, .01 (103) __ C38, 680 (681)
- Solder all of the small fixed capacitors.
Install and solder the electrolytic capacitors listed below,
which are polarized. Be sure that the (+) lead is installed in the hole
marked with a "+" symbol. The (+) lead is usually longer than the
(–) lead, and the (–) lead is identified by a black stripe (Figure 4-1).
C1, 2.2 µF ? __ C13, 22 µF ? __ C15, 100 µF
__ C28, 220 µF __ C29, 220 µF __ C33, 2.2 µF
__ C32, 22 µF
- Install and solder ceramic trimmer capacitor C22. Orient the
flat side of this trimmer as shown on its PC board outline.
- Using a small flat-blade screwdriver, set C22 so that its
screwdriver slot is parallel to the outline of nearby crystal X2.
- Locate Q12 (type PN2222A), which is a small, black TO-92
package transistor. Q12 and other TO-92 transistors may have
either of the two shapes shown in Figure 4-2. The large flat side
of the device must be aligned with the flat side of the
component outline. The part number may be found on either
- Install Q12 near the upper left-hand corner of the PC board.
Align the large flat side of Q12 with its PC board outline as in
Figure 4-2. The body of the transistor should be about 1/8" (3 mm)
above the board; don’t force it down too far or you may break the
leads. Bend the leads of the transistor outward slightly on the
bottom to hold it in place. Solder Q12.
- Install the remaining TO-92 package transistors in the order
listed below.
__ Q11, PN2222A ? __ Q1, 2N3906 ? __ Q2, 2N3906
__ Q3, 2N7000 __ Q4, 2N7000 __ Q5, 2N7000
__ Q6, J310 __ Q7, J310 __ Q8, PN2222A
__ Q9, MPS5179 __ Q10, MPS5179
- Solder and trim the leads of these transistors.
- Install crystals X1 and X2 so that they are flat against the
board. X1 is 5.068 MHz and is located near the notch in the lower
left-hand corner. X2 is 4.000 MHz, and is located near the center
of the board.
- Solder the crystals.
- Prepare two 3/4" (19 mm) jumpers wires from discarded
component leads. These short jumpers will be used to ground the
crystal cans in the next step.
- Grounding the crystal cans in the following step is required
to ensure proper crystal oscillator performance.
- Referring to Figure 4-3, insert the jumper wires into the
grounding holes provided near X1 and X2. Fold each wire over the
top of the crystal and solder it to the top of the can. (Only a small
amount of solder is required.) Then solder and trim the wire on the
bottom of the board.
- The voltage regulators, U4 and U5, will be installed in the
following steps. These regulators have different voltages and must
not be interchanged. Check the labels before soldering.
- Install U4 (LM2930T-8) and U5 (78M05, 7805T, L7805,
etc.), forming the leads as indicated (Figure 4-4). Fold the pins over
the shaft of a small screwdriver to create smooth bends. After
inserting the leads into the proper holes, secure each IC with a 4-40
x 3/8" (9.5 mm) machine screw, #4 lock washer, and 4-40 nut.
(These regulators may have either plastic or metal mounting tabs.)
- Solder the voltage regulator ICs.
- Trim the IC leads as close to the PC board as possible.
- Install a 40-pin IC socket at U6. (The microcontroller will be
inserted into the socket in a later step.) Orient the notched end of
the socket to the left as shown on the PC board outline. Bend two
of the socket’s diagonal corner leads slightly to hold the socket in
place, then solder only these two pins. If the socket does not
appear to be seated flat on the PC board, reheat the solder joints
one at a time while pressing on the socket.
- Solder the remaining pins of the 40-pin socket.
- The connectors used in the following steps have plastic
bodies that can may melt if too much heat is applied during
soldering, causing the pins to be mis-positioned. Limit soldering
time for each pin to 3 seconds maximum (1 to 2 seconds should be
- Install the 2-pin male connectors, P5 and P6. As shown in
Figure 4-5, the polarizing tab on each connector should be closest
to the top edge of the board. P5, the voltmeter input connector,
can be found near the upper left-hand corner of the board. P6 is
used for frequency counter input, which is in the upper right-hand
- Install the 10-pin, dual-row connector, P4 (to the left of P5).
The short ends of the 10 pins are inserted into the board. P5 must
be seated flat on the board before soldering.
- Install P7, a 3-pin male connector (to the right of P5). The
short ends of the 3 pins are inserted into the board.
- Install a shorting jumper onto the two right-hand pins of P7.
At the upper left and right corners of the board are short
jumpers, labeled with ground symbols ( ). Use discarded
component leads to make 3/4" (19 mm) long U-shaped wires for
each jumper (Figure 4-6). Solder the jumpers on the bottom of the
board, with the top of the U-shape approx. 1/4" (6 mm) above the
- Locate the outlines for resistors R18 and R19 on the bottom
side of the Control board.
- The pads used for R18 and R19 are shared with connectors
J1 and J2, which are labeled on the top side of the board. These
connectors are provided with the KAF2 and KDSP2 audio filter
options. You should not install J1 and J2, or an audio filter option,
until after K2 assembly and checkout have been completed.
- Install short wire jumpers at R18 and R19. Make the jumpers
from discarded component leads as you did above, but keep them
flat against the board. Solder the jumpers on the top side.
- Install the following resistors on the bottom side of the board
(solder on the top side):
__ R12, 820 (GRY-RED-BRN) __ R11, 47 k (YEL-VIO-ORG)
- The connectors along the bottom edge of the board (P1,
P2 and P3) will be installed next. It is very difficult to remove them
once they are soldered. Follow all instructions carefully.
- Hold the Control board vertically as shown in the side view
below (Figure 4-7). The top side of the board--the side with most of
the components--should be to the right.
- Turn to page 8 and review Figure 3-3, which shows how the
Control board plugs into the RF board. P1, P2, and P3 will all be
installed on the top side of the Control board as shown.
- Position 6-pin right-angle connector P1 as shown in the side
view below (Figure 4-7). Do not solder P1 until the next step.
The plastic part of the connector must be seated flat against the PC
board, and the pins must be parallel to the board. Do not bend or
trim the pins on the bottom of the board.
- Solder just the two end pins of P1, then examine the placement
of the connector. If P1 is not flat against the board, re-heat the
solder on the end pins one at a time while pressing firmly on the
connector. Once it is in the right position, solder all pins. Do not
trim the leads.
- Install P3, the 20-pin, dual-row right-angle connector (Figure
4-8). Use the same method you used for P1. Do not solder P3 until
you are sure that it is seated properly.
- Install P2, the 36-pin, dual-row, right-angle connector. Use the
same method you used for P1 and P3.
- When you install ICs in the following steps, always
straighten the leads of each IC first as shown in Figure 4-9. The two
rows of pins must be straight and parallel to each other to establish
the proper pin spacing for insertion into the PC board or socket.
- To straighten the pins, rest one entire row of pins against a hard,
flat surface. Press down gently on the other row of pins and rock
the IC forward to bend the pins into position as shown below.
- Before handling any IC, touch an unpainted,
grounded metal surface or put on a conductive wrist-strap.
- Locate U2, an 8-pin IC, part number LM833. (LM833 is the
basic part number. There may be an additional prefix or suffix or
other markings.) This and all remaining ICs on the Control board
are Dual-Inline Packages, or DIPs. Referring to Figure 4-10,
identify the notched or dimpled end of the IC. IC pins are counted
starting from pin 1 (as shown below) and going counter-clockwise.
- Straighten the leads of U2 (see Figure 4-9).
- Install U2 in the orientation shown by its PC board outline,
near the upper left-hand corner of the PC board, but do not solder
it yet. Make sure the notched or dimpled end is lined up with the
notched end of the PC board outline. Even though the outline is
covered when the IC is installed, you can still verify that the IC is
installed correctly by looking at pin 1. The PC board pad
corresponding to pin 1 will be either oval or round.
- You may overheat the IC pins or PC pads if you take an
excessive length of time to solder. After a few tries, you should be
able to solder an IC pin in about 1 or 2 seconds.
Bend two of U2’s corner pins out slightly on the bottom of
the board to hold the IC firmly in place, flat against the top of the
board. Find pin 1 and verify that its pad is either round or oval.
Once U2 is properly seated, solder all eight pins, using a minimum
of solder.
- Install the ICs listed below. Bend the pins to hold each IC in
place as you did with U2, but do not solder until the next step. The
notched or dimpled end of each IC must be aligned with the notched
end of its PC board outline.
- Note: For U1, the IC type supplied may be either NE602 or SA602.
__ U1, NE602 __ U3, LM6482 __ U7, 25LC320
__ U8, MAX534 __ U9, LM380 __ U10, LMC660
- Check the orientation of pin 1 on each IC by looking at the
associated PC board pads, as before. Then solder all of the ICs.
- Locate the microcontroller, U6.
- Straighten the pins of U6 (see Figure 4-9). With a large IC such
as this, you can hold the IC body at both ends as you re-form each
row of pins.
- When the microcontroller is pressed in its socket, you must
be careful to avoid jamming its pins. Make sure that all pins are
lined up with the associated holes in the socket before pressing
down on the IC. Watch the pins on both rows as you press down,
re-aligning them with the socket holes individually if necessary.
- Insert the microcontroller, U6, into its socket. Make sure that
pin 1 on the IC itself is lined up with the pin 1 label near the lower
left-hand corner of the PCB outline. Note: The revision label on
the IC (usually white) may not be oriented the same direction as the
text printed on the IC. Do not use the label as a guide--use the
notch or dimple to identify pin 1.

Key Shaping Components (Required)
Your K2 kit includes recent changes that provide an optimized keying envelope shape (sigmoidal, or S-shaped leading and
trailing edges). The result is completely click-free CW transmission. Two of the parts for this change must be installed on the
back of the Control board as described below.
- Locate the green insulated hookup wire. Strip two 1/4" (6.4 mm) lengths of insulation from one end of the wire. These will be used to
insulate the leads of C46 in the following steps.
- Slip the two lengths of insulation over the leads of a .01 µf capacitor ("103"). This is a new component (C46), not present on the board.
- On the bottom side of the Control board, solder C46 between R21 and the base lead of Q8 as shown below. Keep lead length short.
- A 22-µF electrolytic capacitor has also been added (C45). Solder C45 as indicated above, between U8 pin 2 (+ lead) and U8 pin 14 (- lead).
- Carefully compare your installation of C46 and C45 to Figure 4-11. Make sure the leads of these capacitors are soldered to the indicated
pads. Verify the orientation of the (+) and (-) leads on C45.

Option Components

All component locations on the Control board should now be filled
except for the following:
• C44 (top side of the board near the microcontroller, U6). This
capacitor will not be used.
• J1 and J2 (bottom side). These two connectors are provided for
an audio filter option (KAF2 or KDSP2). An audio filter should
not be installed until the K2 has been completed and tested.

Visual Inspection

Nearly all problems with kits are due to incorrectly installed
components or poor solder joints. You can avoid these problems by
doing a simple visual inspection. A few minutes spent here may
save you hours of troubleshooting time.
Make sure there are no components installed backwards. Check
all diodes, resistor networks, electrolytic capacitors, and ICs. (The
parts placement drawings in Appendix F will be helpful when
checking diode orientation.)
Examine the bottom of the PC board carefully for the
following (use a magnifying glass if available):
- cold solder joints
- solder bridges
- unsoldered pins

Resistance Checks

In the table below, "<" means "less than," and ">" means "greater
than." When measuring resistances that show a minimum value in
the table (such as > 100 k), your resistance reading may be much
higher or even infinite. This is typical when using a DMM (digital
multimeter). If you use an analog meter you may find that some or
all resistance measurements are too low. Note: Some digital
multimeters will flash their display to indicate an infinite resistance.

Perform the resistance checks listed below to ensure that there
are no shorts in the most critical control circuits. (The Control
board will be fully tested in a later section.)

Test Point: P2 pin 1
Signal Name: 12V
Res. to GND: > 10 k

Test Point: U5, OUT ("5V" pin)
Signal Name: 5A
Res. to GND: > 2 k

Test Point: U4, OUT ("8V" pin)
Signal Name: 8A
Res. to GND: 3 - 7 k

Test Point: Q1 collector
Signal Name: 8 T
Res. to GND: > 1 M

Test Point: Q2 collector
Signal Name: 8R
Res. to GND: > 1 M

Test Point: U3 pin 8
Signal Name: 12V IN
Res. to GND: > 10 k

Test Point: U6 pin 13
Signal Name: OSC1
Res. to GND: > 100 k

Test Point: U6 pin 14
Signal Name: OSC2
Res. to GND: > 100 k

Test Point: U6 pin 29
Signal Name: DASH
Res. to GND: 70 - 90 k

Test Point: U6 pin 30
Signal Name: DOT/PTT
Res. to GND: 70 - 90 k

Test Point: U8 pin 2
Signal Name: VPWR
Res. to GND: > 100 k

Test Point: U8 pin 15
Signal Name: VBIAS-XFIL
Res. to GND: > 100 k

Test Point: U8 pin 16
Signal Name: VBFO
Res. to GND: > 100 k

qq005 Front Panel Board

The Front Panel board includes all of the control and display
devices that you’ll use when operating the K2, including the liquidcrystal
display (LCD), LED bargraph, push-button switches, and
potentiometers. See Appendix D for photos of the completed front
panel assembly.

- Open the bag labeled FRONT PANEL and sort the parts into
groups (resistors, diodes, capacitors, etc.). Observe anti-static
precautions when handling ICs and transistors.
- Locate the front panel PC board, which is just a bit larger than
the Control board. It is labeled "K2 FP" on the top side, in the
lower right-hand corner.

- Your K2’s appearance and operation will be adversely
affected if the controls or display are not mounted correctly, and in
the indicated sequence. There are also special instructions for
installing components on the bottom of the board.
- Locate the Spacer Set PC board (Figure 5-1). Using long-nose
pliers, carefully break out the pushbutton switch spacing tool and
the four backlight LED spacers. Break the material only at the four
indicated points. Note: The switch spacing tool doubles as the PC
board for the RF probe, which will be assembled later.

Position pushbutton switches S1 and S2 as shown in Figure 5-2,
using the switch spacing tool to set the switch height. Make sure all
four legs of each switch are centered in their holes, then gently
push each switch until it is resting flush against the switch-spacing
tool. (Caution: switch pins are fragile.) Do not solder yet.

Figure 5-3 shows a side view of a switch that is properly mounted
(spacing tool not shown). The leads of the switches will just be
visible on the bottom of the board. Proper switch height is
important for maintaining an even appearance.
- Once you’re satisfied that S1 and S2 are seated correctly,
solder the leads (on the bottom side of the board). Leave the
spacing tool in place until you’ve finished soldering both switches.
- Install the remaining switches, S3-S16, using the same
technique. When you get to S8 through S16, you may install three
switches at a time using the spacing tool.
- Install the following 1/4-watt fixed resistors, which are listed
in left-to-right PC board order. Solder the resistors after all have
been installed. (R13 and a few other parts are part of the SSB
adapter option, and are not included in the basic K2 kit. A checklist
of these components is provided at the end of this section.)
__ R12, 120 (BRN-RED-BRN) ? __ R10, 33 (ORG-ORG-BLK)
__ R9, 220 (RED-RED-BRN) __ R11, 470 (YEL-VIO-BRN)
__ R6, 4.7 k (YEL-VIO-RED) __ R7, 4.7 k (YEL-VIO-RED)
__ R14, 100 k (BRN-BLK-YEL)
- Install the following resistors on the bottom of the board.
Solder them on the bottom side. Keep your iron tip away from the
bodies of the resistors.
__ R16, 15 k (BRN-GRN-ORG) __ R15, 10 k (BRN-BLK-ORG)
- When you install the resistor networks in the next
step, you must align the dotted end of the network with the
pin 1 label on the PC board outline.
- Install the resistor networks listed below (top side of the
board). Double-check pin 1 orientation and values before soldering.
__ RP2, 120, 10 pins (770101121) (dotted end should be near "RP2" label)
__ RP1, 100 k, 10 pins (10A1.104G) (dotted end near "RP1" label)
- Install and solder the diodes listed below, observing proper
orientation as described in the previous section.
__ D4, 1N5817 __ D5, 1N5817 __ D6, 1N5817
- Install and solder the following capacitors. C9 is located on the
bottom of the board and must be soldered on the top side.
__ C1, .047 (473) __ C2, .01 (103) __ C3, .047 (473)
__ C9, .01 (103), on bottom
- Install PN2222A transistors at Q1 and Q2, near the middle of
the board, and solder. These transistors must be mounted so the lead
length above the PC board is less than 1/8" (3 mm) to prevent
them from hitting the front panel.
- There are two ground jumpers on the Front Panel board, one
at the far left and the other at the lower right, labeled with a
symbol. Use discarded component leads to make 3/4" (19 mm) long
U-shaped wires for each jumper. Solder them on the bottom side.
- Install a 40-pin IC socket at U1, on the bottom of the board.
(The IC will be inserted into this socket later.) Orient the notched
end of the socket to the left as shown on the PC board outline.
- The ICs to be installed in the next step are very
sensitive to static discharge. Touch a grounded surface
before handling each IC. Also note that U4's label will read
upside-down (pin 1 at the right) when properly installed.
- Install the following ICs. Before soldering, verify that the ICs
are oriented correctly (pin 1 associated with a round or oval pad).
__ U4, A6B595KA or TPIC6B595
__ U3, A6B595KA or TPIC6B595
__ U2, 74HC165
- The bargraph LED will be installed in the following two
steps. This component must be seated flat on the PC board or it
will interfere with final front panel assembly. Also, any
misalignment will be visible from the front of the K2.
- Locate the bargraph LED, DS2. The bargraph has a beveled
corner or edge that indicates pin 1. Install DS2 as shown by its PC
board outline, just to the left of the LCD. Bend two opposite corner
pins slightly to hold it to the board, then solder only these two
- If the bargraph is not perfectly flat against the PC board, reheat
the solder on the corner pins alternately while pressing it
down. Once it is in the correct position, solder the remaining pins.
- Remove any hardware supplied with the microphone jack, J2.
The nut and washer will not be used.
- Install the microphone jack (J2) in the lower left-hand corner
of the board, with its polarizing nub at the top (Figure 5-4). Press
the jack down until it is completely flat against the PC board. Recheck
the orientation of the polarizing nub before soldering.
- Install two 3/16" (4.8 mm) diameter x 1/4" (6.4 mm) long
round standoffs on the top of the board, adjacent to the
microphone jack (Figure 5-5). Use two #4 lock washers between
each standoff and the PC board as shown. Secure the standoffs from
the bottom side with chassis screws. Recall that "chassis screw" is
short-hand for 3/16" (4.8 mm) long pan-head machine screws.
- Install another 3/16" (4.8 mm) diameter x 1/4" (6.4 mm) long
round standoff on the top of the PC board, on the left side of the
large square hole in the middle of the board. The standoff mounting
hole is below C2. Use the same hardware as indicated in Figure 5-5,
including two #4 lock washers and one chassis screw.
- Install two 1/4" (6.4 mm) diameter x 1/2" (12.7 mm) long hex
standoffs on the bottom of the board (Figure 5-6). The holes for
these standoffs are indicated by large pads on the top and bottom of
the board. Use one lock washer and a chassis screw for each
standoff. Insert the lock washer between the standoff and PC board.
- Identify the two different types of panel-mount
potentiometers. Four of them are 5-kohm linear-taper types,
labeled "B5K". The fifth is an audio-taper type, labeled "A5K".
They may be physically identical or have slightly different shafts,
body colors, etc.
- When you install the panel-mount potentiometers
in the next two steps, do not push on the shafts, which may
damage the part. Push only on the metal frame.
- Install the audio-taper potentiometer, R3, in the lower lefthand
corner. (The PCB is labeled "AUDIO" at R3.) Push only
on the frame, not the shaft. Make sure that the potentiometer body
is parallel to the PC board and is pressed against the board as far as
it will go before soldering.
- Install the four 5-k linear-taper potentiometers at R1, R2, R4,
and R5. (The PC board is labeled "LINEAR" at each pot.) Verify
correct positioning as you did in the previous step.
- Before installing J1 in the following step, review
Figure 3-3 (page 8) to be sure you have J1 on the correct
side of the board.
- The front panel attaches to the RF board via J1, a 20-pin
single-row female connector. Install J1 on the bottom side of
the board (Figure 5-7). Solder just two pins, one at either end.
- Re-heat the two end pins and press the connector down until J1
is seated flat against the board, then solder the remaining pins.
- Install rectangular gray key caps on S1 and S3 so the key caps
are parallel to the long axis of the PC board (Figure 5-8). The caps
are installed simply by pressing them onto the switch plungers.
- Install a square black key cap on S7 as shown above.
- Install rectangular black key caps on the remaining switches.
- Before handling U1, touch an unpainted, grounded
metal surface or put on a conductive wrist-strap.
- Straighten the pins of U1, the LCD driver (PCF8566), as you
did with the microcontroller on the Control board.
- Insert U1 into its socket on the bottom of the board. (This
must be done before continuing with LCD installation, since the
LCD’s presence will make pressing U1 into its socket much more
difficult.) Be sure that U1 is completely seated with no bent pins.
- Locate the LCD backlight assembly, which is about 3" (7.5 cm)
long. It includes the diffuser and two small LEDs, one at each end.
Do not remove the backing from either side of the diffuser.
- Make sure the LEDs in the LCD backlight assembly are pressed
into the diffuser and are not mis-aligned or loose.
- Place two 3/4" (19 mm) long spacers over the leads of each
backlight LED as shown in Figure 5-9.
- Position the backlight assembly between the mounting holes
labeled D2 and D3 as shown in Figure 5-10. The diffuser must be
parallel to and 1/8" (3 mm) above the PC board. To hold the LED
spacers and backlight assembly in place, use a rubber band or bend
the LED leads out slightly on either end.
- Examine the backlight assembly closely to ensure that it is
parallel to the Front Panel board and seated as far down on the
board as it will go (exactly 1/8" [3 mm] above the board).
- Solder D2 and D3. If the backlight assembly is not flat against
the PC board, re-heat the LED pins one at a time and press it into
- CAUTION: The LCD and its pins are fragile—handle
carefully. Do not drop the LCD on a hard surface, as it is made
of glass and may break. Do not remove the protective plastic
film from the front surface of the LCD until later in this section
when the front panel assembly is completed.
- Carefully remove the LCD from its packing materials.
- CAUTION: Do not peel off the thick plastic material
on either side of the LCD, or the LCD will have to be
replaced (not covered under warranty).
- Hold the LCD up to a bright light and look at both sides for the
presence of a very thin, clear protective film (like transparent tape).
All LCDs have such film on the front surface of the LCD, which
will be removed in a later step. But the back of some LCDs (not all)
may also have such film, with faintly visible yellow or gray diagonal
lines. If protective film is found on the back side, use a fingernail
at one corner of the LCD to dislodge it, then peel it away.
- The LCD has six pins along its lower edge (three on each side),
and 24 pins along the upper edge. Place the LCD in its proper
position on the board but do not solder yet.
- The LCD must be seated flat against the diffuser as shown in
the edge view (Figure 5-11). If the LCD does not appear to be
seated correctly, it may be because the backlight LEDs or spacers
are mis-aligned. When the assembly is installed correctly, the
LCD’s pins will all protrude the same distance from the bottom of
the board. (Some units may be supplied with shorter pins that do
not protrude at all.)
- Solder the four corner pins of the LCD, then re-check the
alignment of the LCD assembly. If everything looks correct, solder
the remaining pins. LCD pins can be soldered on the top of the
board if they do not protrude from the bottom.
- Attach two thin, 1/4" (6.4 mm) self-adhesive rubber pads to
the bottom side of the Front Panel board in the positions indicated
in Figure 5-12. The pads should be placed as close as possible to the
corners, but should not hang over on either edge. These pads
establish the correct spacing for the Front Panel board.

Uninstalled Components

- Check off each of the components in the list below, verifying
that they are not yet installed.
__ C4, .01 (103) __ C5, .01 (103) __ C6, .01 (103)
__ C7, .01 (103) __ C8, .01 (103) __ R13, 68 k, 1%
__ RP3, 10 k resistor network
__ Q3, 2N3906
__ P1 (Mic. Configuration connector, on the bottom of the board)
- The unfilled locations (above) are for parts that are provided
with the SSB adapter (model KSB2). If you have the SSB adapter
kit, you should install them now. Follow the third and fourth
assembly steps under Front Panel Board Components in the
KSB2 manual.

Visual Inspection

- Make sure there are no components installed backwards. Check
all diodes, resistor networks, electrolytic capacitors, and ICs. The
parts placement drawings in Appendix F will be helpful in verifying
the orientation of diodes.
- Examine the bottom of the PC board for solder bridges, cold
solder joints, or unsoldered components.

Resistance Checks

- Set all potentiometers to their mid-points (approx.).
Perform the resistance checks (to ground) listed below. U1 is
on the back of the board.

Front Panel Final Assembly
- Locate the front panel chassis piece. Place it on a soft cloth
to protect the finish and labeling.
- In the following step, the paint masking material
will be removed from the inside of the front panel. The
masking material is usually green, but may appear gray
because of paint overspray. DO NOT remove the masking
material from the other chassis pieces at this time.
- Some holes in the front panel were masked on the inside
surface during painting. If masking tape (usually green in color) is
still present, you'll need to remove it. The holes that are masked
are in the four corners, along the top and bottom edges.
- Masking tape should be removed as follows:
- Using a blunt instrument such as a ball-point pen, push on the
tape through a hole until the tape begins to lift away from the
- Peel the tape completely off, using a sharp tool if necessary. Be
careful not to nick or scratch the outer surface of the panel.
- After removing any masking tape, place the front panel
chassis piece face-down, with the large, round microphone jack hole
on the right.
- Locate the green plastic bargraph filter and two pieces of
double-backed tape. These items will be found in a small bag with
the serial number label.
- Caution: The adhesive on the double-backed tape is
very strong. Once you position the tape on the green filter,
you will not be able to remove it. Be very careful to align
the tape with the long edges of the filter as explained below.
- Remove the white paper backing from one side of each piece
of tape. Attach the tape to the long edges of the green filter
(Figure 5-13). Be careful not to get any adhesive on the center
portion of the filter, since it might be visible after installation.
- Remove the brown paper backing from the other side of each
piece of tape, then turn the filter/tape assembly adhesive-side down.
Carefully center the green plastic filter over the inside of the
bargraph LED hole
- Turn the front panel face up.
- Position the clear plastic LCD bezel over the LCD and
bargraph holes as shown in Figure 5-15. The bezel goes on the
outside of the panel.
- Secure the bezel with four 2-56 screws (stainless steel) as
shown in Figure 5-15. Tighten the 2-56 screws only the
amount needed to hold the bezel to the front panel. Overtightening
may crack the bezel or strip the threaded holes
in the panel.
- Remove the insulation from four 1.5" (38 mm) lengths of
green hookup wire.
- Install the bare wires on the bottom of the front panel PC
board, using the four pads below the large rectangular hole (Figure
- Solder and trim the wires on the top side of the board. The
wires will be connected to the optical encoder, Z1, in a later step.
- Remove the protective plastic film from the face of the LCD.
Be careful not to scratch the glass. Caution: Do not peel off the
LCD glass, just the thin protective film. The LCD will not be
usable if you lift the glass itself.
- Insert the front panel PC board assembly into the front panel.
The pushbutton switch caps on both sides of the LCD should
protrude slightly as shown in the side view, Figure 5-17a.
- Note: the board/panel assembly will not be rigidly held in place
until it is mated with the RF and Control boards in a later section.
- A 1/4" (6.4 mm) standoff on the PC board should now be
visible through the hole just to the left of the encoder mounting
hole. Secure the panel to this standoff using the 4-40 x 3/16"
(4.8 mm) flat-head screw as shown in Figure 5-17b.
- Remove the hardware from the shaft of the encoder, Z1, and
discard the lock washer, which will not be used. Insert the encoder
through the hole in the Front Panel board (Figure 5-18a).
- Cut 1/8" (3 mm) off the end of each of the encoder's four
connector pins.
- Attach the encoder to the inside of the front panel using the
nut and flat washer only. Figure 5-18 shows the side view (a) and
front view (b) with encoder properly installed. The encoder has a
small metal tab near the shaft that will only allow it to be installed
one way. Do not over-tighten the nut. (Note: the green encoder
bushing is metal, not plastic.)
- Attach the four encoder wires you installed earlier to the
matching pins on the back of the encoder. Each wire should be
wrapped securely around the base of its matching pin, with no slack
in the wire. Trim and solder the wires, making sure they aren't
shorting to each other or to the encoder body, which is conductive.
- Set all potentiometers to midway in their rotation.
- In the next step, a small knob may fit too tightly onto its
potentiometer shaft. If so, rotate the shaft until it bumps up against
one of its stops, place the knob at the top of the shaft, and rotate
it slowly in the same direction while gently pressing it down.
- Attach small knobs to the potentiometer shafts, starting with
the KEYER and POWER controls. Each knob's two set screws can
be tightened using the small Allen wrench (.050", 1.3 mm). The
knobs should be mounted as close as possible to the panel without
touching it. Align the pointers per panel labeling.
- Locate the 1" (25 mm) dia. by 1/16" (1.6 mm) thick felt
washer, and place it over the encoder nut (Figure 5-19). The washer
should be seated on the front panel, with the nut inside it.
- Place the large knob on the encoder shaft. Push the knob on
until it just touches the felt washer. If the knob does not spin
freely, move it out slightly. If the knob is not contacting the felt
washer at all, it may "drift" slightly once it stops spinning.
- Using the larger Allen wrench (5/64", 2 mm), tighten the two
set screws alternately, in small increments.
- At this point, the pushbutton switches may not all protrude
an equal distance. The switch height will become equalized once the
front panel assembly is mated to the RF board in a later step.

qq006 RF Board

Most of the K2’s receiver and transmitter circuits are located on
the RF board, including filters, oscillators, and RF amplifiers. The
front panel and Control boards plug into the RF board, and the
chassis pieces are designed to form a tight enclosure around it (see
photos in Appendix D). In addition, many option boards plug
directly into the RF board to minimize wiring.
Assembly and testing of the RF board is broken into three parts:
Part I: The DC and control circuits are installed so that the front
panel and Control boards can be plugged in and tested. The I/O
controller (U1 on the RF board) is also installed and tested at this
time. Once this phase of assembly is completed, you’ll have the
K2’s built-in test equipment available for testing and aligning the
remaining circuits.
Part II: Synthesizer and receiver components are installed and
tested. By the end of Part II you’ll have the K2 receiving on 40
Part III. Transmitter components and all remaining filter
components are installed. The K2 is then aligned on all bands.


- Review anti-static precautions before handling transistors
or ICs.
- Open the bags labeled RF and sort the components into related
groups. In later steps you’ll sort some of the components according
to value to reduce the likelihood of assembly errors.
- Locate the RF board and place it in front of you with the
component side up (the side with most of the parts), and the front
edge facing you (the edge with the irregular cutouts). Throughout
this section we’ll refer to the different areas of the board in terms
of their proximity to you. For example, "front-left" means the
corner closest to you on the left.
- Take a moment to familiarize yourself with the RF board using
Figure 6-1 to identify the major sections. If you flip the board over
you’ll see that there are a few components on the bottom of the
board, primarily in the transmitter section.

qq007 Assembly, Part I

- Locate a 2-D fastener and hold it vertically as shown in Figure
6-2. Looking at a side with two holes, note that the holes are offset
from the center. When you install the fasteners in the following
step, be sure to position them so that the holes in the fastener are
shifted in the same direction as the holes in the PC board outlines
on the bottom of the board.
- Install 2-D fasteners at 5 locations on the bottom of the board
as shown in Figure 6-3. Secure each fastener from the top side of
the board using two chassis screws (black, 3/16" [4.7 mm]) and two
#4 lock washers. The washers go on the top side of the board.
- Make sure that the 2-D fasteners on the edges line up with the
edge of the PC board and do not hang over. If they hang over or do
not match their component outlines, they are installed backwards.
- Install two 3/16" (4.8 mm) diameter by 1/4" (6.4 mm) long
round standoffs on the bottom of the board at the locations
identified in Figure 6-3. Secure these standoffs from the top side
with chassis screws and #4 lock washers. Do not put lock washers
between the bottom of the board and the standoffs.
- Turn the board back over to the top side. Install the 28-pin IC
socket at U1, near the middle of the board (Figure 6-1). The
notched end of the socket should be at the left. Make sure the
socket is flat against the PC board before soldering. (U1 itself will
be installed in a later step.)
- In the following steps you will install the latching relays
(K1-K17). Relay pins must not be bent or trimmed, even after
placement on the PC board, as this may cause unreliable mechanical
operation. Since the pins cannot be bent to hold the relays on the
board, an alternative assembly technique using a flat surface must be
used. For this technique to work, the relays must be installed before
any of the taller components.
- Place relays K1-K17 on the top side of the RF board. One end
of each relay has a heavy line printed across the top to indicate the
pin 1 end. This end must be matched with the same end of the
relay’s PC board outline. Do not solder the relays yet.
- When all of the relays have been placed on the board, lay a
flat object such as a book or piece of cardboard on top of the relays
to keep them in place, then flip the board over.
- Solder only two pins (at opposite corners) on each relay. Do
not bend or trim relay leads.
- Turn the board back over and verify that all of the relays are
in the correct orientation and are seated flat on the board.
- Solder all of the remaining relay pins.
- Install R1 and R2 (220 ohms, RED-RED-BRN), near the back
left corner of the board.
- To avoid stray signal coupling, all capacitors on the RF
board must be mounted as close to the PC board as possible (without
damaging the leads or their epoxy coating).
- Install C1 and C2 (.001 µF, "102"), which are on the left edge.
- Install electrolytic capacitors C105 and C106 (2.2 µF), located
near the front-left corner.
Install R35 and R36 (82, GRY-RED-BLK) just to the right of
- Install R115 (.05 ohms, 3 watts) at the front right corner of
the board. Form the leads as indicated by the component outline.
- Install the following components to the left of R115.
__ C111, 2.2 µF electrolytic ("+" lead goes into the square pad)
__ R113, 82 (GRY-RED-BLK)
- Install the internal speaker connector, P5, which is a 2-pin
connector like that shown in Figure 4-5. P5 is mounted near the
on-off switch (S1). Position the connector as shown by its
component outline, with the vertical locking ramp toward S1.
- Install high-current diodes D10 and D12 (large black body),
located near the right edge of the board:
__ D10, 95SQ015
__ D12, SB530 (a 1N5821 may be substituted for D12)
- Install the following components near D10:
__ C77, .001 (102) __ C196, .047 (473)
__ R69, 100 k (BRN-BLK-YEL) __ R66, 2.7 k (RED-VIO-RED)
- Install the self-resetting fuse, F1, near D10. F1 is yellow and
looks like a square-bodied capacitor. One side is labeled "G300".
- Install the key jack, J1, at the back-left corner of the board.
Before soldering, make sure that the jack is aligned with its PC
board outline.
- Install the headphone jack, J2, on the small board extension
near the front left corner. The pins on J2 are not very long, so
they will be nearly flush with the bottom of the board. Solder the
pin closest to the front edge first (ground), then verify that the
jack is seated flat on its plastic nubs before soldering the remaining
- Install the power switch, S1, at the right front corner. (S1's
key cap will be installed later.)
Install the DC input jack, J3, at the back right corner. The 3
leads on the jack must be lined up with the slot-shaped holes in the
component outline. If the holes are a tight fit, press firmly until
the connector snaps into position.
- Install the antenna jack, J4 (BNC), just to the left of J3.
- Install the following components near U1 (at the middle of
the board). You may need to confirm the part number of U2
(78L06), since it is easy to confuse it with U8 (78L05). Use a
magnifying glass if necessary.
__ U2 (78L06) __ C139, 0.1 (104)
__ C140, .001 (102) __ R64, 100 (BRN-BLK-BRN)
- Install the ceramic resonator, Z5, near U1. (Z5 looks like a
capacitor with 3 pins.) It can be installed in either orientation.
- Install R65 (10 k, BRN-BLK-ORG) on the bottom of the
board, near U1.
- Install D8 and D18 (1N4148), on the bottom of the board,
toward the right edge. Make sure the banded end of each diode is
aligned with the band on its component outline.
- In the steps that follow you’ll install the connectors that
mate with the control and Front Panel boards. These connectors
must be installed properly to ensure reliable mechanical connection.
They are very difficult to remove once installed, so follow all
instructions carefully. Review Figure 3-3 (page 8) for correct
- Install the 6-pin, single-row female connector, J6, which is just
left of the power switch. It must be seated vertically on the board
and must not be tilted (Figure 6-4). Solder just one pin near the
center of J6.
- If J6 does not appear to be completely flush with the board,
re-heat the soldered pin and press down. Once it is installed
correctly, solder the remaining pins.
- Install the 20-pin, dual-row female connector, J8, near the
front left corner of the board. Use the same technique you used for
J6. This connector must be seated flush with the board before
- Install 36-pin dual-row female connector J7 in the same
manner as J6 and J8.
- Position 20-pin male right-angle connector P1 on the bottom
of the board (Figure 6-5), but do not solder P1 yet. Review Figure
3-3 (page 8) for correct placement. The short ends of the bent
pins are inserted into the holes, and the long ends must be parallel
with the board.
- Solder just the two end pins of P1.
- Look closely at P1 to make sure that its plastic support is
pressed down as far as it will go, and that the pins are parallel to the
board. If not, re-heat the soldered ends while pressing it into place.
Once it is seated properly, solder the remaining pins.
- To the left and right of the I/O controller, U1, you’ll find two
short jumpers labeled " " or "GND" (on the top side of the
board). Form 3/4" (19 mm) long U-shaped ground jumpers and
install them at these locations as you did on the control and Front
Panel boards. Use discarded component leads.
- On the bottom of the board you’ll find two additional ground
jumpers, one near the middle and the other near the back edge.
Install U-shaped ground jumpers in these two locations.
- Before handling U1, touch an unpainted, grounded
metal surface or put on a conductive wrist-strap.
- Install the I/O controller, U1 (PIC16F872 or 16F872A), in its
socket (near the middle of the board). Be sure to align the notched
or dimpled end of U1 with the notched end of the socked (to the
left). Make sure U1 is seated as far down in the socket as it will go
and that none of its pins are bent. Note: The revision label on U1
may not be oriented in the same direction as the text printed on
the IC. Use only the notch or dimple to identify the pin 1 end.

Visual Inspection

- Examine the RF board carefully for unsoldered pins, solder
bridges, or cold solder joints.
- Set switch S1 on the RF board to the "OFF" position. (Plunger
OUT is OFF, plunger IN is ON.)

Resistance Checks

- Perform the following resistance checks.

- When working with the side panels in the following steps,
place a soft cloth on your work surface to protect the paint.
- Locate the two side panels. Remove any masking tape from
the panels using the same technique described in the Front Panel
section, taking care not to scratch the outer surfaces.
- Arrange the two panels as shown in Figure 6-6, and verify that
they are mirror images of each other. The 2-D fasteners to be
attached in the next step go on the inside surface, which has bare
aluminum areas that were masked during painting. (Note: the actual
size and shape of masked areas may vary.)
- Install two 2-D fasteners on each side panel at the locations
indicated by small rectangles in Figure 6-6. Use one chassis screw to
hold each fastener to the side panel (see Figure 6-7). The two
unused holes on each fastener must be offset away from the side
- Locate the tilt stand, which can be found in the
MISCELLANEOUS component bag. It has three parts: two oval
feet and a tilt bail (Figure 6-9). Note: the screws that will be used to
hold the tilt bail in place are not the black anodized type. They are
standard steel/zinc plated screws, 7/16" (11 mm) long, so you won’t
confuse them with the 3/8" (9.5 mm) or 1/2" (12 mm) black
- Remove any masking tape from the bottom cover chassis
- Each oval foot has a notch into which the bail will be inserted.
Install one of the oval feet on the bottom cover using two 7/16"
(11 mm) 4-40 screws, #4 lock washers, and 4-40 nuts. The notch in
the foot should be facing inwards (toward the other foot). The nuts
and lock washers go on the inside of the bottom cover.
- Install the tilt bail, then the second oval foot. The bail should
be compressed firmly between the two feet. You may need to adjust
the positions of the feet slightly before tightening the hardware.
- Make sure the two feet are at exactly the same distance from
the front edge of the bottom cover. If they are not equally spaced,
the tilt stand may "rock" when in use.
- Turn the RF board/side panel assembly upside down. Check for
any untrimmed component leads on the bottom of the board.
- Position the bottom cover as shown in Figure 6-10, then secure
it using six chassis screws. (The heat sink and rear feet will not be
installed until Part III when the transmitter is assembled.)
- With the entire assembly still upside down or resting on one
side panel, plug the front panel assembly into the RF board (Figure
6-10). Align the two assemblies so that connector J1 on the bottom
of the front panel PC board mates with P1 on the bottom of the
RF board. The arrow in Figure 6-10 shows the approximate
location of P1 on the RF board.
- Once the front panel assembly is in place, the headphone jack
(on the RF board) should be just flush with the front panel. The
small rubber pads in the upper corners of the Front Panel board
should be just touching the 2-D fasteners on the RF board. If this is
not the case, the front panel must be pushed farther in.
- Secure the front panel to the side panels and RF board using 4
chassis screws. (Refer to the photos in Appendix D.) You may need
to make slight adjustments to the 2-D fasteners at the top edge.
- Plug the Control board assembly into the RF board, with the
component side of the Control board facing backwards. (Refer to
the photos in Appendix D.) All three connectors on the Control
board must be lined up with the three connectors on the RF board at
all pins.
- Make sure the Control board is pushed as far down as it will go;
it should be flat against the RF board along its entire edge, with all
three connectors properly mated.
- If the Control board does not plug in easily, you may have
one or more connectors installed incorrectly.
- The long-handled Allen wrench can be used to extract the
Control board (Figure 6-11). To the left of J7 on the RF board
you’ll find the label "LIFT" near a hole at the base of the Control
board. Insert the Allen wrench into this hole, then rest the knee of
the wrench on the nearby screw head. Pry the board up with the
wrench while guiding the board out at the top.
- Once you have tried the Control board extraction technique
described above, plug the Control board back in for the tests that
- Secure the front panel and Control boards together using two
chassis screws (Figure 6-12). The upper left and right corners of the
Control board may be touching the 2-D fasteners, or there may be a
small gap.
- Push the black keycap onto S1’s plunger until it snaps into
place. Test S1’s action (push on, push-off). Leave the switch in the
OFF position (out).

qq008 Alignment and Test, Part 1

In this section you’ll test most of the circuits on the Control board
and front panel. Along the way you’ll become familiar with basic
operation of the K2, including use of the front panel switches,
display, and menu.

Before proceeding with initial test, turn to the first page of the
Operation section of the manual to familiarize yourself with the
K2’s front panel layout. Do not turn on power to the K2 at this

The Tap/Hold Rule
Each of the push-button switches on the front panel has two
functions, one activated by a TAP (short press) and the other
activated by a HOLD (long press, about 1/2 second). The upper
label on each switch shows the TAP function (white lettering), and
the lower label shows the HOLD function (yellow lettering). To
highlight this in the text, we use two different typographical styles
to identify switches: TAP and HOLD.

Initial Test
- If any test or alignment step fails, refer to the
Troubleshooting section (Appendix E).
Set the controls on the front panel as follows:
AF GAIN: midway (12 o’clock)
RF GAIN: maximum (clockwise)
KEYER: midway
POWER: minimum (counter-clockwise)
OFFSET: midway

- Locate P7 on the Control board. A shorting jumper should be
installed onto the two pins of P7 nearest the "P7" label.
- For the remaining test and alignment steps, you’ll need a wellregulated
12-14 V power supply or a battery. A power supply rated
at 300 mA or more of output current will suffice for the tests in
Parts I and II, but higher currents (3-3.5 A) will be needed for
transmitter tests in Part III.
- If your power supply or battery does not already have a plug
that mates with the power jack (J3), use the supplied mating plug
and prepare a suitable power cable. The center lead of the plug is
positive (+).
- Make sure the K2 is turned OFF (power switch S1 out). Plug
your power supply or battery into J3 on the rear panel.
Fold the tilt stand out to improve the viewing angle if desired.
- If you see or smell smoke when you turn the K2 on for the
first time, turn off power and disconnect the power supply
immediately. Normally, you should hear the relays being reset by
the I/O controller. Next, nonvolatile configuration memory
(EEPROM) will be initialized. This process takes approximately 10
seconds. During this period, you should see INFO 201 on the
LCD. Displays of this kind are referred to as "INFO messages," and
are used to alert you to possible problems. In this case, the info
message is just a reminder that EEPROM has been initialized.
- Turn on the K2 using S1. After about 10 seconds, you should
see the default K2 frequency display for 40 meters: 7100.00c .
The letter C indicates CW mode. The annunciator for VFO A will
also be turned on. (If you see any other INFO messages or the
display does not come on, refer to Troubleshooting.)
- Turn the K2 off and wait for a few seconds, then turn it back
on. The display should now show ELECRAFT for about two
seconds, followed by the frequency display. Now that the EEPROM
is initialized, this is the display you should always see on power-up.
The "R" and "T" in "ELECRAFT" appear in lower-case letters due
to the limitations of the seven-segment LCD characters.
- Tap the DISPLAY switch once to select voltage/current
display. The display should now show something similar to this:
E12 .0i0 . 08
This would indicate that the power supply voltage (E) is about 12.0
V, and the supply current (I) is about 80-100 mA

Optical Encoder Test

- Tap the DISPLAY switch to return to the frequency display.
Turn the VFO knob in both directions and verify that the
displayed frequency changes accordingly.
- Tap the RATE switch to the right of the knob to change the
tuning rate, and repeat the VFO test at each rate.

Relay Test
- Tap BAND+ . After a short delay the K2 will switch to the
next band. At the same time, you’ll hear one or more relays.
- Tap the BAND+ switch 7 more times to verify that you hear
relays being switched with each band change. Note: The 1.8 MHz
(160 m) and 5 MHz (60 m) bands will not appear in the band list
unless the associated options are installed. This can be done only
after assembly and alignment have been completed.
- Tap the PRE/ATTN switch three times. You should hear relays
switch each time.

RF Probe Assembly
The Switch Spacing Tool used during Front Panel can now be used
as the PC board for the RF probe. All parts for the probe, including
a ground alligator clip, 2 feet of RG174 coax, and banana plugs for
a DMM, are supplied with the kit. You can assemble the probe at
any time, using the instructions on page 9 of Appendix E.

Voltmeter Probe Assembly
- If you do not have a DMM (digital multimeter), you can use the
simple DC voltage probe shown below in conjunction with the builtin
voltmeter. The crimp pin and 2-pin housing can be found in the
MISCELLANEOUS components bag.
- Assemble the voltage probe as shown in Figure 6-13 using
green-insulated hookup wire. No ground connection is needed since
you will be measuring voltages inside the K2.
- Plug the voltage probe assembly into P5 on the Control board.
The probe should be oriented so that the hookup wire is connected
to the (+) side of P5.
- Move the voltage select jumper (Control board, P7) toward
P5. Select voltage/current display mode using the D I S P L A Y switch.
The voltage reading on the LCD should go to 0 0 . 0 .
- To test the voltage probe, touch the tinned end of the hookup
wire to pin 1 of the I/O controller, U1 (RF board). The voltage
displayed on the LCD should be approximately 6 V.
- Return the voltage select jumper to the "12 V" position.
- Note: Always disconnect the voltage probe when it is not in use.
It may cause shorts or noise pickup if left inside the K2 during
normal operation

Menu Tutorial
- We’ll present a brief tutorial on using the menu here. A complete
list of menu functions can be found in the Operation section.
Tap the MENU switch on the K2. The first entry will be displayed:
- This is the sidetone level menu entry. 040 is the associated
parameter, in this case the sidetone volume setting. The row of
annunciators under S T L serves as an underline, indicating that
turning the VFO knob will change the menu entries.
- Tap the MENU switch again and you’ll return to the frequency or
voltage/current display, depending on what display mode was
selected when you entered the menu.
- Tap MENU again to bring up the menu. Turn the VFO knob now,
and you’ll see the other menu entries and their parameters scroll
by. (You can also tap the BAND+ or BAND- switches to scroll
through menu entries.) Scroll the menu until you see
- This menu entry is used to select the keying device. HAND means
that the key jack is configured for a hand key or external keyer.
- Press and hold the EDIT switch for 1/2 second to activate the EDIT
function. (Remember the TAP/HOLD rule: when you HOLD a
switch in, you activate the function indicated by the lower label on
the switch.) The display should now show:
- Notice that the underline has moved to the parameter (HAND ).
This tells you that you’re in EDIT mode, and that turning the VFO
knob will now change the parameter for the current menu entry.
You can also change the parameter using BAND+ and BAND- .
- Turn the VFO knob now to see the various keying input selections.
PDLn and PDLr configure the key jack for a keyer paddle, wired
for either normal (tip = dot) or reverse (tip = dash) operation.
- Tap the MENU switch again to exit EDIT mode. The underline
should return to the menu entry.

Using the Calibration Functions

- Scroll the menu until you see CAL OFF . This is the entry point
into the calibration sub-menu, which you’ll be using during
- Enter EDIT mode by holding EDIT as before, moving the underline
to the OFF parameter. Then turn the VFO knob to see the various
CAL functions, including FCTR (frequency counter), CUR
(transmit current limiting), t P A (KPA100 temperature
calibration), SLO/SHI (S-meter calibration), FIL (crystal
filter configuration), and PLL (VFO calibration).
- Once you select a CAL function, holding EDIT again activates the
function. The selected CAL function remains active until you tap
MENU again, which returns you to the menu. Another tap of MENU
returns you to the normal K2 display.
- In the following section you’ll activate the CALFCTR
(frequency counter) function. For now, just tap M E N U once or
twice to return to the normal display.

Frequency Counter Probe Assembly

- In the bag labeled MISCELLANEOUS you’ll find the
components for the frequency counter probe (Figure 6-14). These
components include a 10 pF axial-lead capacitor, two crimp pins, a
2-pin housing, and a 1-pin male connector (probe tip).
- Cut a 7" (18 cm) length of RG-174 cable and carefully remove
1/2" (13 mm) of the coax jacket from each end. Be careful not to
nick the braid.
- Separate the braid from the center conductor at both ends.
Remove 1/4" (6 mm) of insulation from each center conductor. At
one end, cut the braid off completely right at the coax jacket (a
ground connection will not be needed for frequency measurements).
The braid should be twisted into a fine bundle at the other end.
- Solder crimp pins onto the center conductor and shield at the
housing end of the cable. Solder quickly, so that the heat from
soldering does not melt the center insulator of the coax and cause a
shield-to-center short.
- Insert the pins into the crimp housing as shown in Figure 6-14.
They should snap into place. Each crimp pin has a small tab on the
back that latches into a hole in the housing.
- Trim the leads of the 10 pF axial-lead capacitor down to 1/4"
(6 mm). Solder one end to the center conductor of the coax cable.
- Solder the probe tip to the other end of the 10 pF capacitor.
- Slip a 1" (2.5 cm) length of the larger size heatshrink tubing
onto the probe tip components. Shrink the tubing using a heat gun.
(You can also use a soldering iron, but avoid melting the tubing.)
- Add a second, identical length of heatshrink tubing on top of
the first, then shrink it. This strengthens the assembly.
- Plug the frequency counter probe assembly into P6, which is at
the far left end of the Control board (as viewed from the front of
the transceiver). The connector can only be plugged in one way.
- Turn on the K2 and tap M E N U to bring up the menu, then
scroll to the C A L menu entry. Hold E D I T , then scroll the C A L
parameter until the display shows C A L F C T R . Hold E D I T again
to activate the frequency counter function of the C A L sub-menu.
The LCD should show 0 0 0 0 0 . 0 0 . (The frequency counter
circuitry is sensitive, so it may pick up a stray signal and show it on
the display.)
- To test the counter, you can read the frequency of the 4 MHz
oscillator on the Control board. Touch the counter probe tip to the
left side of trimmer capacitor C22, which is just below U1, the
microcontroller. The LCD should now read within +/- .02 kHz of
- Remove the frequency counter probe.

Audio Amplifier and Tone Generator Test

- Plug in a pair of low-impedance (4 to 32 ohm) headphones,
stereo or mono.
- Tap MENU and scroll to the sidetone level menu entry
(STL). Hold EDIT to activate the sidetone. You should now hear a
clean 600-Hz audio tone. Turning the VFO knob should vary the
- Notice that turning the AF GAIN control does not affect the
sidetone volume. The sidetone is injected into the AF amplifier
after the volume control, so AF GAIN affects only the receiver
- Tap MENU to turn off the sidetone, then scroll up to the
sidetone pitch menu entry (ST P) using the VFO knob or by
tapping the BAND + switch. The display will show
- This indicates that the sidetone pitch is set for 0 . 6 0 kHz (600 Hz).
Hold EDIT to turn on the sidetone, then vary the VFO knob. The
pitch of the sidetone should change to match the display.


- In the following steps you’ll test the keyer (audio tone generation
only). This tests the keyer jack, speed control, and potentiometer
read circuits, including the A-to-D converter on the
- Tap MODE until C is displayed at the right end of the LCD,
indicating CW mode.
- Plug a keyer paddle into the key jack. The plug must be stereo
(2 circuit). A mono plug will key the transmitter continuously. (A
mating stereo plug for the keyer jack is supplied with the kit.)
- Using the menu’s I N P entry, set up the keyer input for either
PDLN or PDLR as described previously.
- Adjust the KEYER control. As soon as you turn it, the display
should show the keying speed (approx. 9-50 WPM).
- While listening with headphones, test the keyer paddle to
verify that both dot and dash are working.
- Note: No sidetone will be generated when LSB or USB mode is
selected (L or U).

Setting the AGC Threshold

- Make sure the RF GAIN control is rotated fully clockwise.
- Locate potentiometer R1 on the Control board (right side, as
viewed from the front of the K2).
- Set your DMM for DC volts. Connect the (-) lead of the
DMM to one of the ground jumpers or to the K2 chassis ground.
- Touch the (+) lead to pin 5 of U2 on the Control board. (U2 is
located just above trimmer R1. Pin 5 is the pin nearest diode D1.)
- Adjust R1 for a reading of 3.80 volts on the DMM. This is the
suggested setting, but it can be adjusted later to suite the operator.
- The S-meter must be realigned anytime the AGC
threshold setting is changed. S-meter alignment is covered
in the following steps.

S-Meter Alignment

- Using the menu, select the CALSLO function (S-meter
zero). Hold EDIT a second time to activate it.
- Turn the VFO knob until you see only the left-most segment
of the LED bargraph lit. Then turn the knob a bit more clockwise
until this LED just turns off.
- Exit the CALSLO function by tapping MENU. Enter the
menu again and select CALSHI (S-meter full-scale sensitivity).
- Turn RF GAIN fully counter-clockwise. Adjust the VFO knob
until bargraph segment 9 lights, then turn it a bit more counterclockwise
until segment 10 just turns on (right-most segment).
- Turn the RF GAIN control back to its full clockwise position.
- Exit the CALSHI function by tapping MENU .
- If you have an Elecraft XG1 receiver test oscillator or other
calibrated signal source, set it for 50 microvolts (-73 dBm) and
verify that the S-meter indicates S-9. If not, adjust CALSHI.

Bargraph Current Test

- In the following steps, you’ll test the current measurement circuit
by using the bargraph LEDs to establish a known current drain.
- Enter the menu and verify that G R P H (LED bargraph mode)
is set to DOT, not to BAR or OFF.
- Set the RF GAIN control for minimum gain. Segment 10 of
the LED bargraph should now be on if you have done the S-meter
adjustment as described above.
- Using the menu, select the LCD menu entry. Change the
parameter from NITE to DAY. At this point you’ll see the LCD
backlight turn off, and segment 10 of the LED bargraph will
become much brighter.
- Exit the menu and tap DISPLAY to switch to voltage/current
mode. Write down the voltage and current readings.
- Use the menu to change the GRPH mode to BAR. All 10
segments of the LED should now be on.
- Exit the menu and check the current. It should now be about
0.16 to 0.18 amps higher.
- Use the menu to change GRAPH to DOT, and LCD to NITE.
- The combination of LCD DAY and GRAPH BAR can
result in high peak current drain on receive. DOT or OFF are
preferred for battery operation. See Advanced Operating Features.

qq009 Assembly, Part 2

- In this section you’ll install the components for the synthesizer
and receiver circuits. Most of the components to be installed are on
the front half of the board (see Figure 6-1). After all of the parts
are installed, individual stages will be aligned and tested. Detailed
troubleshooting procedures are provided in the Troubleshooting
section should you need them (Appendix E). The supplied RF probe
will be very useful if you need to do signal tracing. RF probe
assembly instructions start on page 9 of Appendix E.
- In some steps a large number of components will be installed, then
soldered as a group. Check for unsoldered leads after completing
each group. A final complete check will be done later.
- Remove the screws holding the Control board to the Front
Panel board, then unplug the Control board. To avoid damaging any
Control board components, use the long-handled Allen wrench as
described in Part I.
- Remove the bottom cover (six screws).
- Remove the screws from the front panel assembly and unplug it
from the RF board. Pull it straight out from the bottom edge, near
the middle of the panel. This may be easier to do with the
transceiver sitting on its right side so that you can steady it with
one hand and pull with the other.
- Remove the side panels by taking out the two screws along the
bottom edge of each panel.
- Install the following 1/4-watt resistors, orienting them so that
the first band is at the left or toward the back of the board. The
resistors are listed in the order they appear on the RF board,
starting with R9 (near the left edge, about halfway back).
- Note: Remember to complete each line of resistors before
proceeding to the next line (i.e., install R9, then R16, then R10).

__ R9, 100 k (BRN-BLK-YEL) ?__ R16, 100 k (BRN-BLK-YEL)
__ R10, 470 (YEL-VIO-BRN) __ R31, 10 k (BRN-BLK-ORG)
__ R32, 10 k (BRN-BLK-ORG) __ R33, 15 k (BRN-GRN-ORG)
__ R30, 120 (BRN-RED-BRN) __ R28, 27 k (RED-VIO-ORG)
__ R20, 270 (RED-VIO-BRN) __ R21, 100 k (BRN-BLK-YEL)
__ R22, 3.3 M (ORG-ORG-GRN)
__ R25, 2.7 k (RED-VIO-RED) __ R24, 2.7 k (RED-VIO-RED)
__ R15, 33 (ORG-ORG-BLK) __ R14, 10 k (BRN-BLK-ORG)
__ R13, 10 k (BRN-BLK-ORG) __ R12, 560 (GRN-BLU-BRN)
__ R17, 100 k (BRN-BLK-YEL) __ R11, 560 (GRN-BLU-BRN)
__ R5, 2.7 k (RED-VIO-RED) __ R78, 22 (RED-RED-BLK)
__ R6, 100 (BRN-BLK-BRN) __ R7, 68 (BLU-GRY-BLK)
__ R8, 100 (BRN-BLK-BRN)
__ R92, 33 (ORG-ORG-BLK) __ R91, 820 (GRY-RED-BRN)
__ R93, 820 (GRY-RED-BRN)
__ R72, 470 (YEL-VIO-BRN) __ R95, 2.7 k (RED-VIO-RED)
__ R96, 2.7 k (RED-VIO-RED) __ R74, 47 (YEL-VIO-BLK)
__ R73, 2.7 k (RED-VIO-RED) __ R97, 33 (ORG-ORG-BLK)
__ R80, 680 (BLU-GRY-BRN) __ R81, 1.8 k (BRN-GRY-RED)
__ R79, 1.8 k (BRN-GRY-RED)
__ R82, 18 (BRN-GRY-BLK) __ R101, 10 k (BRN-BLK-ORG)
__ R107,100 k (BRN-BLK-YEL) __ R111 5.6 k (GRN-BLU-RED)
__ R112, 22 (RED-RED-BLK) __ R90, 470 (YEL-VIO-BRN)
__ R89, 100 (BRN-BLK-BRN) __ R88, 470 (YEL-VIO-BRN)
__ R84, 18 (BRN-GRY-BLK) __ R85, 150 (BRN-GRN-BRN)
__ R83, 4.7 ohms (YEL-VIO-GLD

- Install the resistor networks. Start with RP2, which is in the
front left-hand corner. Align the pin 1 mark on each resistor
network with the pin 1 end of its component outline.
__ RP2, 10 k, 8 pins (8A3.103G)
__ RP6, 100 k, 8 pins (8A3.104G)
__ RP4, 100 k, 6 pins (6A3.104G)
__ RP5, 100 k, 6 pins (6A3.104G)
- NOTE: RP3 is not used. The Thermistor PC board will be installed at
this location as described on the next page.

- Locate the PLL Upgrade kit, which should include the
Thermistor PC board and all other parts listed below.

Description:33K 1/4W Resistor (org-org-org)
QTY: 1

Ref: RB
Description: 12K 1/8W Resistor (brn-red-org)
QTY: 1

Description: 2.2K 1/8W Resistor (red-red-red)
QTY: 1

Ref: RD
Description: 1.8K 1/8W Resistor (brn-gray-red)
QTY: 1

Ref: RE, RF
Description: 10K 1/8W Resistor (brn-blk-org)
QTY: 2

Ref: THM
Description: Thermistor, 10K, 3% (small orange body
with black and brown stripes near leads)
QTY: 1

Description: Thermistor PC Board
QTY: 1

Description: #24 Green Wire, Insulated, solid conductor
QTY: 1 ft.
(30 cm)

- Locate the thermistor printed circuit board. One side will be
labeled with THM and the letters A through F. All components will
be installed on the labeled side, and soldered on the other side.
- Install 1/8th-watt resistors RB, RC, RD, RE, and RF in their
respective positions as shown on the board. (Color codes are listed
above; be sure to check them carefully.) Do not pull on the resistor
leads, as they may be fragile. Bend the leads outward.
- Solder all of the leads. Trim off excess lead length.
- Install resistor RA (33 k, 1/4 watt). Solder and trim its leads.
- Locate the thermistor, which has an orange body with black
and brown stripes. The thermistor is fragile, so avoid bending its
leads any more than necessary. Insert the thermistor at THM.
(The part is symmetrical and can be installed in either orientation.)
Po sition the thermistor body so that it is just touching the circuit
board. Solder and trim its leads.
- Remove the insulation from a 6” (15 cm) length of green
hookup wire. Cut the bare wire into 8 pieces of about 0.75” (2 cm)
in length.
- The remaining 8 holes on one edge of the board are used as
leads to insert into the pads provided for the original resistor
network, RP3. Solder one wire into each of the holes, with most of
the lead protruding from the component side.
- On the component side, bend each lead at a 90-degree angle so
that it points away from the board (but parallel to it).
- Locate the position for resistor network RP3 (near the frontleft
corner, adjacent to U6). Slide each of the 8 leads of the
thermistor board through the corresponding holes at RP3. The
components on the thermistor board should be facing U6, and the
thermistor should be oriented toward the location of crystal X1.
- Once all of the leads are inserted, slide the board down until it
is flush against the RF Board. It may be necessary to bend the
thermistor board toward U6 slightly so that the solder joints on the
bottom of the thermistor board can clear C87 on the RF board. The
thermistor board and its parts should not be touching U6 or its pads.
- Make sure the edge of the thermistor board is contacting the
RF Board along its full length. Then solder the eight connections
on the bottom side of the RF Board.
- Examine the area closely. There should be no shorts between
the thermistor board and nearby components.
- Locate all of the small glass-bodied diodes. You should have a
number of 1N4148 diodes, and one 1N5711, which will be similar in
size but should have different markings. Use a piece of masking
tape to identify the 1N5711 as "D9, 1N5711."
- Install the following diodes, located near the outline for
toroidal transformer T5, in the synthesizer area. Be sure to orient
the diodes according to their outlines.
__ D11, 1N4148 __ D13, 1N4148
__ D6, 1N4007 __ D7, 1N4007
- Varactor diodes have a small plastic package, like a TO-92
transistor, but with only two leads. Sort the varactor diodes into
groups: type MV209 and type 1SV149. (1SV149 diodes are labeled
"V149" and may have a center lead that has been cut flush with the
body of the device.) The K2 will not function correctly if the
varactor diode types are interchanged.
- Install the MV209 diodes listed below. The flat side of each
diode must match the flat side of its PC board outline. These diodes
must be pushed all the way down on the board to prevent stray
signal coupling. Bend the leads slightly to hold them in place. D16
and D23-D26 are in the front-left corner. D39 is to the right of J7
(Control board).
__ D16 __ D23 __ D24
__ D25 __ D26 __ D39
- Note: Do not install D19 and D20. These are supplied with the
K60XV option, which should not be installed until the K2 has been
aligned and tested.
- Install type 1SV149 diodes at D37 and D38, near the SSB
option connector. Keep them flat against the PC board, with no
excess lead length.
- Install the remaining 1SV149 diodes listed below, keeping them
flat against the PC board, with no excess lead length. D17, D21 and
D22 are in the front-left corner. D29 through D34 are on the right
side near the crystal filter.
__ D17 __ D21 __ D22
__ D29 __ D30 __ D31
__ D32 __ D33 __ D34
- Install the TO-92 package transistors listed below. Start with
Q17, near the middle-left edge.
__ Q17, 2N7000 __ Q16, PN2222A __ Q18, J310
__ Q19, J310 __ Q20, 2N7000 __ Q24, J310
__ Q25, PN2222A
- Install Q21 (2N5109), which is located near U1 in the middle
of the board. Align the small tab on the transistor’s case with the
tab on its component outline. Bend the leads on the bottom to hold
Q21 in place, then solder.
- Install Q22 (2N5109), which is to the right of the
"ELECRAFT" label. Make sure Q22 is flat against the board before
- Carefully press a 3/4" (19 mm) dia. by 0.25" (6.4 mm) high
star heat sink onto Q22. The heat sink should be pressed down as
far as it will go, and should not touch the components around the
transistor. The heat sink is fragile. If you need to spread it
slightly, use a blunted wooden pencil or a plastic wire nut.
- Install Q12 (2N7000), which is to the right of Q22.
- Install Q23 (2N7000), near the right-front edge of the board.
- Install C167 (.001 µF, "102"), which is near J11, the connector
for the SSB adapter. The leads on this capacitor should be formed
to match its PC board outline.
- Sort all of the remaining capacitors by value to reduce the
possibility of assembly errors in the next step. If you are unsure of
any capacitor’s value and do not have a capacitance meter, the
pictures in the parts list (Appendix A) may help.
- Install the following capacitors, starting with C86 in the frontleft
corner. Integer values are in pF and fractional values are in µF.
__ C86, 0.1 (104) ? __ C84, 120 (121) ? __ C85, 120 (121)
__ C100, .001 (102) __ C95, .01 (103) __ C96, 1 µF (105)
__ C71, 82 (82) __ C72, 270 (271) __ C73, 47 (47)
__ C74, 20 (20)
__ C82, .001 (102) __ C80, .001 (102) __ C81, .001 (102)
__ C79, .001 (102) __ C59, 0.1 (104) __ C38, .001 (102)
__ C55, .01 (103) __ C61, .01 (103) __ C58, .01 (103)
__ C65, 0.1 (104) __ C54, .01 (103)
__ C68, 10 pF (10) __ C64, .001 (102) __ C67, 0.1 (104)
__ C63, .01 (103) __ C92, .022 (223) __ C94, 0.047 (473)
__ C89, .001 (102) __ C87, .01 (103) __ C175, .01 (103)
__ C62, .01 (103) __ C154, 100 (101) __ C144, 100 (101)
__ C156, .047 (473) __ C158, .01 (103) __ C53, .01 (103)
__ C52, .01 (103) __ C141, .01 (103) __ C57, .001 (102)
__ C146, .01 (103) __ C151, 0.1 (104) __ C145, .01 (103)
__ C153, 68 (68) __ C155, .01 (103) __ C172, .01 (103)
__ C177, .022 (223) __ C174, 82 (82) __ C173, 220 (221)
__ C178, 0.1 (104) __ C176, 0.1 (104) __ C165, .01 (103)
__ C169, 390 (391) __ C168, .01 (103) __ C160, .01 (103)
__ C159, .01 (103) __ C143, .01 (103) __ C142, .01 (103)
__ C163, .01 (103) __ C162, .047 (473) __ C164, .01 (103)
__ C170, .047 (473) __ C166, .047 (473) __ C179, 100 (101)
__ C182, 180 (181) __ C184, .01 (103)
__ C185, 0.1 (104) __ C181, .01 (103)

- Install the following ICs, aligning the notched end of each IC
with the notch on its component outline. U6 is at the front-left.
__ U6, LMC662 ? __ U5, LTC1451 ? __ U4, MC145170
__ U3, LT1252 __ U10, NE602 __ U9, LT1252
__ U11, NE602 __ U12, MC1350
- Install U8 (78L05), which has a plastic TO-92 package like a
transistor. U8 is located near the front left corner of the board.
Option-bypass jumpers W5, W2 and W3 are located on the
right side of the board, near the crystal filter. Use component leads
to make these jumpers, or remove the insulation from appropriate
lengths of green hookup wire. These jumpers should be formed so
that they lie flat on the board, and should not touch any adjacent
- Test points TP1, TP2, and TP3 are round, yellow, single-pin
female connectors. TP1 and TP3 can be found in the synthesizer
area of the board. TP2 is near the SSB option connector, J11.
- Install and solder all three test points.
- Install RF choke RFC13 (100 µH, BRN-BLK-BRN), near the middle of
the board. Orient the first color band to the left.
- Install the receive mixer, Z6 (TUF-1 or TOP-1), below the
"ELECRAFT" label at the middle of the board. Make sure that Z6
is lined up with its component outline and is flush with the board
before soldering.
- Install the electrolytic capacitors in the order listed below,
starting with C60 near the far left-hand edge. Insert the (+) lead of
each capacitor into the hole with the (+) symbol.
__ C60, 100 µF __ C93, 10 µF __ C103, 220 µF
- Looking at the bottom of the RF board, locate U4
(MC145170, near C90). As shown by the "X" in Figure 6-14b, the
short trace from pin 16 of U4 to C89 (on the top side) has been cut
at the factory.
- Solder C91 (.001 µF, "102") to the two pads shown in Figure
6-14c. Use short leads.
- Solder C88 (68 pF, "68" or "680") between pins 12 and 13 of
U4 as shown above. Use short leads.
- Locate the miniature 100 µH RF choke, RFC15 (tan body,
brown-black-brown; much smaller than the other 100-µH RF
chokes in the kit). RFC15's leads are fragile—do not pull on
- Solder RFC15 to the pads indicated above. Use short leads.
- Examine C88, C91 and RFC15 closely. Their leads should not
contact adjacent pads or traces.
- Locate the crystals used on the RF board: 12.096 MHz (1),
4.9152 MHz for BFO (2) and 4.9136 MHz for crystal filters (7).
Do not mix the BFO and filter crystals, which have different
- The bag of 7 filter crystals should have a number written on it.
Record the number here:

frequency of the crystals, and can be used in aligning filters.)
- Install the 12.096 MHz crystal, X1, at the lower left. The
crystal should be seated flat on the board before soldering (it is OK
to bend the pins to hold it to the board). X2 is not used.
- To the left of X1 (along the edge of the board) you’ll find a
pad for grounding the crystal case. Use short lengths of bare wire to
ground the crystal on at the top of the can.
- Install the BFO crystals at X3 and X4 (near J7). Important:
trim X3's leads, and fold them down flat against their pads, before
soldering. Then use a minimal amount of solder. This is necessary to
avoid interference between X3 and L33 in a later step.
- Ground the cases of X3 and X4. The ground pads are to the left
of the crystals.
- Install the 4.9136 MHz filter crystals at X5 through X11.
- Ground the cases of X5 and X6. The ground pads are near
where the two crystals meet.
- A special grounding technique is required for X7-X11.
- There are two ground pads for each of these crystals, one on either
side. Use bare wires (10 total) for grounding the crystals as you did
in previous steps, but do not solder the wires to the tops of the
crystals. The wires must be soldered to the sides of the crystals,
instead, about 1/4" (6 mm) up from the surface of the PC board.
- Be very careful not to overheat the crystals. Use a
temperature-controlled iron, and limit soldering time to
about 3 seconds per soldering attempt.
- In the following steps you’ll install several toroidal
inductors. Use the number of turns indicated. Do not attempt
to alter the turns to match inductances specified in the parts list.
- Sort the black and dark gray toroidal cores into three groups to
avoid mis-identifying them in later steps. You should have eight
FT37-43 ferrite cores (3/8", 9.5 mm); four T44-10 iron powder
cores (0.44", 11 mm); and one FT50-43 ferrite core (0.5", 12.7
mm). Ferrite cores are dark gray; T44-10 cores are black.
- Locate a 3/8" (9.5 mm) diameter ferrite toroidal core (type
FT37-43) as described above.
- Find RFC14’s component outline on the RF board, near the
front left-hand corner. Compare this component outline to Figure
6-15, which shows two views of a typical toroidal inductor. RFC14
will be mounted vertically as shown at the right side of the drawing,
with one wire exiting at the core’s upper left, and the other at the
lower right. There are pads on the PC board in these two locations.
- To wind RFC14, cut a 9" (23 cm) length of #26 red enamelcoated
wire, then "sew" the long end of the wire through the core
exactly 10 times. Each pass through the core counts as one turn.
The finished winding should look very similar to Figure 6-15, but
with 10 turns rather than 14.
- Verify that the turns of RFC14 are not bunched together.
They should be evenly-spaced and occupy about 85% of the core’s
circumference. If the turns are all bunched together, RFC14’s
inductance value will not be correct. (Unless otherwise specified,
about 80 to 90% of the core should always be used.)

Stripping Toroid Leads

- The enamel wire supplied with the kit can be heat-stripped. One
way to do this is to place a small amount of solder (a "blob") on the
end of your soldering iron, then insert the wire into the hot solder
for a few seconds. Another possibility is to burn the insulation off
by heating it with a match or small butane lighter for a few seconds,
then use fine-grain sandpaper to remove the enamel residue. Avoid
scraping insulation off with a razor blade, as this may nick the wire.
- Strip and tin the leads of the toroid before you mount it on the
board. As shown in Figure 6-15, you should remove the enamel
from the leads up to about 1/8" (3 mm) from the core. You should
see only bare wire (no insulation) on the side to be soldered.
- Install RFC14 vertically as shown by its component outline,
near the front left-hand corner of the board, then pull the leads taut
on the bottom of the board.
- Solder the leads of RFC14. When soldering, make sure that the
- solder binds well to the leads. If the lead appears to be an "island" in
a small pool of solder, chances are it is not making good contact.
Measure from pad to pad (not wire to wire) using an ohmmeter to
be sure the leads are making contact.
- Do not use adhesives or fixatives of any kind to
secure toroids to the PC board. Toroids will be adequately held
to the board by their leads alone. (T5 is the only exception.)
- RFC16 is wound on an FT37-43 core (dark gray) using 16
turns of red enamel wire (12", 30 cm). Wind this inductor in the
same manner as RFC14. Install RFC16 vertically, to the right of
- RFC11 is wound on an FT37-43 core using 20 turns of red
enamel wire (16", 40 cm). Wind this inductor and prepare its leads
in the same manner as RFC14.
- Install RFC11 horizontally, on the bottom side of the board, as
shown by its component outline (near the center of the board). The
pads for RFC11 are the two that just touch the outline. Pull the
leads taut on the top to keep the toroid secured to the board, then
- T5 is a toroidal transformer, with two numbered windings.
These numbers are printed next to each pad on the PC board. T5’s
windings are 1–2 and 3–4.
- Locate the large yellow core (T50-6) for use at T5. The core
is 1/2" (12.7 mm) in diameter.
- Wind the first winding, 1-2, using 16 turns of red enamel wire
(15", 38 cm). This winding must occupy 85% of the core, and will
look very similar to Figure 6-15. Remember that each pass through
the core counts as one turn.
- Carefully strip and tin the leads of T5’s 1-2 winding.
- T5’s other winding, 3–4, uses 4 turns of green enamel wire
(7", 18 cm). Wind the 3–4 winding on top of the 1–2 winding,
interleaving the turns as shown in Figure 6-16. The turns should be
secure, not loose. Strip and tin the leads of the 3–4 winding.
- Install T5 as shown by its component outline in the
synthesizer area of the board. Figure 6-17 shows how the 1–2 and
3–4 windings are oriented with the numbered pads. (Also shown are
the nylon washer and screw, which will be installed in the next
step.) Pull T5’s leads taut on the bottom of the board, but do not
solder yet.
- Secure T5 to the board as shown in Figure 6-17 using a 3/8"
(9.5 mm) diameter nylon washer, 1/2" (12.7 mm) long nylon 4-40
screw, and a #4 nylon nut. Tighten the nylon nut just enough to
hold the assembly in place. Do not over-tighten as this will strip
the threads. Solder T5, checking for good solder joints as before.
- T7 is a toroidal transformer wound on a 3/8" (9.5 mm)
diameter ferrite core (dark gray, FT37-43). T7’s orientation and
windings will appear similar to Figure 6-18. Wind T7’s 3–4 winding
first, using 20 turns of red enamel wire (20", 51 cm). (The drawing
shows 14 turns.)
- Wind T7's 1–2 winding using 5 turns of green enamel wire (6",
15 cm). Strip and tin the leads of both windings.
- Install T7 as shown by its component outline near the frontright
corner of the board, with the windings oriented as shown in
Figure 6-18. Pull the leads taut on the bottom and solder.
- Transformer T6 is mounted vertically, near the middle of the
board. It uses a different winding technique where the wires for the
two windings are twisted together before winding ("bi-filar"). Cut
two 12" (30 cm) lengths of enamel wire, one red and one green.
Twist them together over their entire length. The wires should
cross over each other about once every 1/2" or 12 mm.
- Wind the twisted wires onto a 3/8" (9.5 mm) ferrite core
(FT37-43), using exactly 10 turns. Use the same method you used
when winding non-twisted wires, covering about 85% of the core.
Figure 6-19 shows how the winding should look from two views
(your turns count will be 10 rather than 8 as in the drawing).
- Clip and untwist the ends of the red/green pairs so that the
leads of the transformer look like those in Figure 6-19 (b). The pin
numbers shown match the component outline, with the red wires
numbered 1-3 and the green wires numbered 2-4.
- Strip and tin all four wires. Be careful not to strip the leads so
close to the core that the red/green wire pairs might short together.
- Install T6 vertically, with the wires inserted as indicated in
Figure 6-19 (b). Pull the leads taut on the bottom, then solder.
- Sort the slug-tuned shielded inductors into two groups: 1 µH
("T1050", quantity 4) and 4.7 µH ("T1005", quantity 8).
- Install 4.7 µH inductors at L30 and L34 ("T1005"). Press
these inductors down as far as they’ll go before soldering.
- Install the components listed below, starting with C39 in the
back left corner (near the key jack).
__ C39, .001 (102) __ C4, 820 (821)
__ C5, 100 (101) __ C9, .001 (102)
__ C7, 100 (101)
__ C8, 820 (821) __ C108, .01 (103)
__ W6 (option bypass jumper) __ D1, 1N4007
__ R38, 1 k (BRN-BLK-RED) __ D2, 1N4007
__ RFC1, 100 µH (BRN-BLK-BRN)
__ C107, .01 (103) __ C109, .01 (103)
__ C110, .01 (103) __ D3, 1N4007
__ D5, 1N4007 __ D4, 1N4007
__ R37, 100 k (BRN-BLK-YEL) __ R39, 1 k (BRN-BLK-RED)
__ C113, .01 (103) __ C114, .01 (103)
__ W1 (option bypass jumper)
- Review Figure 4-2 before installing Q2 in the next step.
Q2 is a ZVN4424A transistor, which has a slightly modified TO-92
package. It is flat on both sides, and the labeling may be on the
smaller flat side. The wider flat side must be aligned with the flat
side of the component outline.
- Install Q2, which is near C113 (just installed). Be sure to
orient Q2 as shown in Figure 4-2.
RFC3 is wound on an FT37-43 core (dark gray) using 16 turns
of red enamel wire (12", 30 cm). Wind this inductor in the same
manner as RFC14. Install RFC3 vertically, just to the left of W1.
- Install 4.7 µH slug-tuned shielded inductors (marked "T1005")
at L1 and L2, near the back-left edge of the board.
Install the 40-meter low-pass filter components, which are
listed below. These components are located near Q22 (2N5109
transistor with heat sink).
__ C225, 390 (391) __ C228, 56 (56) __ C227, 330 (331)
__ C226, 680 (681) __ C229, 220 (221)
__ L25, T44-2 (red), 14 turns #26 red enamel wire, 14" (35 cm)
__ L26, T44-2 (red), 12 turns #26 red enamel wire, 13" (33 cm)
- The leads of some bottom-mounted components may need
to be pre-trimmed before mounting and soldering. See Page 11.
- Install the following components on the bottom side of the
board, starting with C207 at the back left. Once all components
have been installed, solder them on the top side, being careful not
to damage any adjacent top-mounted components.
__ C207, .001 (102) __ C216, .001 (102) __ C223, .001 (102)
__ C224, .047 (473) (bend body down before soldering)
__ C204, .001 (102) __ C208, .001 (102) __ C195, .001 (102)
__ C133, 0.1 (104) (bend body down before soldering)
__ C135, .01 (103) __ C122, 56 (56) __ C119, .01 (103)
__ C17, .001 (102) __ C27, .001 (102) __ C104, 68 (68)
__ C29, 12 (12) __ C28, 12 (12)
__ R34, 2.7 k (RED-VIO-RED)
__ RFC2, 100 µH (BRN-BLK-BRN) __ RFC7, 15 µH (BRN-GRN-BLK)
- Find the "C6" label, along the back edge. The three pads near
C6 are labeled "J15" on the top side (for use with the K60XV
option). Install C6 (4.7 pF) into the outer two of the three pads.
- Locate L31, a 12 µH shielded solenoidal inductor (black case;
may not be color coded). L31 is mounted on the bottom of the
board, near the right edge.
- Install the group of components listed below on the bottom of
the board. C183 is near the front left corner.
__ C183, .01 (103) __ C186, .01 (103)
__ C161, .01 (103) __ C150, 330 (331)
__ C90, .047 (473) (bend body down before soldering)
__ C157, .047 (473) (bend body down before soldering)
__ R77, 220 (RED-RED-BRN) __ R76, 10 (BRN-BLK-BLK)
__ R75, 680 (BLU-GRY-BRN) __ R94, 82 (GRY-RED-BLK)
__ R99, 270 (RED-VIO-BRN) __ R98, 270 (RED-VIO-BRN)
__ R100, 820 (GRY-RED-BRN) __ R110, 5.6 k (GRN-BLU-RED)
__ R114, 3.9k (ORG-WHT-RED) __ R18, 1 M (BRN-BLK-GRN)
__ R29, 10 k (BRN-BLK-ORG)
__ R19, 2.7 k (RED-VIO-RED)
__ RFC12, 100 µH (BRN-BLK-BRN)
__ D36, 5082-3081 (fragile glass diode; orient banded end as shown)
__ RFC10, 1 mH (BRN-BLK-RED)
- The BFO toroid, L33, is supplied pre-wound due to
the large number of turns and very small gauge wire
required. When handling L33, be very careful not to
damage the leads.
- Locate the rubber stem bumper. Clip off about one-half of the
tip of the stem using diagonal cutters.
- L33 is located on the bottom of the board, near the front
center. Place the rubber stem bumper directly on top of L33's
component outline. Flush-trim the leads of all parts under or
near L33 so the stem bumper can sit flat on the PC board.
- Locate the pre-wound BFO inductor, L33 (41 µH, 5%). It may
be supplied in a small envelope or bag labeled "L33".
- Press L33 down onto the stem bumper as far as it will go.
- Position L33 and the stem bumper as shown in Figure 6-20.
- Locate resistor R116 (1/8th watt, 5.1 megohm, green-browngreen).
- Bend the leads of R116 down at 90-degree angles to match
the spacing of L33's pads (Figure 6-20).
- Insert R116's leads into L33's pads, then press the resistor
down directly on top of L33. The resistor's body should be partially
recessed into the "well" left in the center of the toroid.
Use the leads of R116 to hold L33 firmly to the board (Figure
6-21), bending them outward on the top side. Solder R116.
- Solder L33's leads to the leads of the resistor points as shown
in Figure 6-22. Keep L33's leads as short as possible, and away from
any nearby component pads.
- Trim off the excess portion of L33's leads. Note: Trimming
fine wire may be difficult with worn or poor-quality diagonal
cutters. Be careful not to stress L33's leads in the process. Use a
magnifying glass if necessary.
- To ensure that R116 cannot short to the bottom cover, attach
a thin self-adhesive insulator to the bottom cover in the area
directly beneath L33. Electrical or other types of tape may be used.
- D40 and D41 were added to the receiver I.F. circuit to
prevent saturation when a station a few feet away transmits on
your frequency. These diodes will be installed in the steps below.
- On the bottom of the RF board, locate resistor R114, which is
near the power switch. Near R114 you'll find the 8 pads for I.F
amp U12, which is on the top side of the board (Figure 6-23).
- Solder D40 and D41 to the two round pads just to the right of
R114 (pads #3 and #4 of T7, which is on the top side). The
banded ends of the diodes go in opposite directions.

Visual Inspection

- Examine the bottom side of the RF board carefully for
unsoldered pins, solder bridges, or cold solder joints. Since this is a
large board, you should break the examination up into three parts:
__ perimeter of the board __ front half __ back half
- Examine the top side in the same manner.
- Set S1 on the RF board to OFF position. (Plunger OUT).

Resistance Checks

Perform the following resistance checks:

Test Point: R115, right end (near S1)
Signal Name: 12V IN
Res. (to GND): > 500 ohms

Test Point: U6 pin 8
Signal Name: 8B
Res. (to GND): > 100 ohms

Test Point: U4 pin 16
Signal Name: 5B
Res. (to GND): > 1 k

Test Point: U11 pin 8
Signal Name: 8A
Res. (to GND): > 250 ohms

Test Point: U10 pin 8
Signal Name: 8 T
Res. (to GND): > 500 ohms

Test Point: U12 pin 1
Signal Name: 8R
Res. (to GND): > 500 ohms

- It's very important to re-assemble the chassis as described
below before attempting the alignment steps in the next section. If
you don’t put the chassis together, some results will not be
- Install the side panels and secure with two chassis screws each.
- Plug in the front panel assembly. Secure with two chassis
- Plug in the Control board.
- Secure the front panel and Control boards together using two
chassis screws.
- Before installing the bottom cove in the next step, verify
that all components on the bottom of the RF board have an
installed height of 1/4" (6 mm) or less. Capacitors or other parts
that stand above this height must be bent downward at an angle to
prevent them from hitting the bottom cover.
- Install the bottom cover and secure it temporarily using six
chassis screws.

qq010 Alignment and Test, Part 2

- In this section you’ll test and align the PLL (phase-locked-loop)
synthesizer and receiver circuits. Once this is completed you’ll be
able to test the receiver using all modes on 40 meters.
- Connect your power supply or battery and turn on the K2.

4 MHz Oscillator Calibration

- Plug the frequency counter probe into P6 (Control board).
- Connect the probe tip to the PLL reference oscillator test
point, TP3 (left-front corner of the RF board, near U4).
- Using the menu, select CALFCTR, then hold
EDIT a second time to enable the frequency counter. The counter
should show a frequency of 12090 kHz +/- 30 kHz. If it is 0000.00,
changing rapidly, or out of range, you could have a problem with
the counter probe or the PLL Reference Oscillator.
- Use one of the following methods to adjust C22 on the
Control board (listed in order of preference):
- Connect a calibrated external frequency counter probe to TP3,
without removing the K2's internal counter probe. Adjust C22
until the K2's reading matches the external counter's reading.
- Alternatively, you can use a calibrated short-wave or ham-band
receiver. Set the receiver for LSB or USB mode. Connect a
short length of wire to the receiver's antenna jack, and lay the
end near the 4 MHz crystal on the K2 Control board. Find the
oscillator signal on the receiver. Tune the receiver to 4.000
MHz, and adjust C22 until you hear a zero-beat (pitch = 0 Hz).
- If you don't have a counter or receiver, leave C22 set at its
mid-point for now. You can improve the calibration later using
a calibrated signal generator or an on-air signal, such as WWV
(at 10.000 MHz).

PLL Reference Oscillator Range Test

- Set up the K2 internal counter as described for 4 MHz
Oscillator Calibration (at left, first three steps).
- If you have an external frequency counter probe connected to
TP3 along with the K2's internal counter probe, disconnect it.
- When you’re in frequency counter mode, the BAND + and BAND - switches can be used to check the range of the PLL
reference oscillator. First, tap BAND + and write down the frequency
reading below (typically about 12100 kHz). Then tap B A N D - and
write down this frequency reading (typically 12080-12090 kHz).
Ref. High Freq. Ref. Low Freq. Range (kHz)
- Subtract the lower frequency reading from the higher reading.
The range must be between 9.8 and 15 kHz (if not, see
Troubleshooting). Tap MENU to exit CALFCTR

VCO (Voltage-Controlled Oscillator) Test

- Use BAND + or BAND - to select the 80-meter band, and set the
VFO for a frequency of about 4000.10 kHz.
- Connect the frequency counter probe to the VCO test point,
TP1. Activate the frequency counter using CALFCTR as before.
- You should now see a frequency counter reading in the 8 to 10
MHz range. It may or may not be stable at this time (i.e., the
frequency may be changing). If the reading is 0000 kHz or is
changing rapidly, you probably don’t have the counter cable
connected to the VCO test point. If the reading is fairly stable but
not between 8 and 10 MHz, refer to Troubleshooting.
- Tap MENU to exit CALFCTR.

VCO Alignment

- In the following steps you’ll adjust the VCO inductor (L30) so that
the VCO control voltage is in the proper range.
- Disconnect the internal frequency counter probe and remove
it completely from the K2.
- Select 80 meters, and set the VFO for about 4000 kHz.
- Connect a DMM (digital multimeter) to the left end of resistor
R30 (near the center of the synthesizer area of the RF board) and
ground. Use a small alligator clip to ensure a good connection. (You
can also use the built-in voltmeter to measure the VCO control
voltage. Refer to Voltmeter Probe Assembly in Part I.)
- It is possible to damage the slugs in slug-tuned inductors if
you use a metal tool or if you tune the slug too far in or out. The
tuning tool provided will not damage the slugs.
- Using the wide end of the plastic tuning tool, adjust the slug in
inductor L30 until the voltage at R30 reads 6.0 V. If the voltmeter
reading does not change at all as you tune L30 through its full
range, refer to Troubleshooting. If the voltage changes but you
cannot get to 6.0 V, you have probably wound the VCO inductor
(T5) incorrectly or have installed the wrong value at L30 or C72.
- Set the VFO for approximately 3500 kHz.
- Measure and write down the VCO control voltage at this
frequency in Table 6-1 (using pencil).
- For each remaining band, set the VFO to the low and high
frequencies listed in Table 6-1 and write down the VCO control
voltages.9 (You can tune quickly to the approximate frequencies in
the table by selecting the 1-kHz tuning rate.)

Band: 80 m
Low Frequency: 3500
High Frequency: 4000

Band: 40 m
Low Frequency: 7000
High Frequency: 7300

Band: 30 m
Low Frequency: 10000
High Frequency: 10150

Band: 20 m
Low Frequency: 14000
High Frequency: 15000

Band: 17 m
Low Frequency: 18000
High Frequency: 18200

Band: 15 m
Low Frequency: 21000
High Frequency: 21450

Band: 12 m
Low Frequency: 24800
High Frequency: 25000

Band: 10 m
Low Frequency: 28000
High Frequency: 28800

- If some VCO control voltage readings above are < 1.5 V, or
some of them are > 7.5 V, you may be able to shift the entire set of
readings so that they are all within the 1.5 to 7.5 V range. Switch to
the band (and frequency) that had the highest or lowest voltage,
then adjust L30 to bring that reading into range. Then re-measure
all of the voltages to make sure they're in range.
- If you have some voltages that are < 1.5 V and others that
are > 7.5 V, you have probably installed the wrong value at one or
more of the VCO capacitors (C71-C74) or varactor diodes (D21-
D26). Another possibility is that T5 has the wrong number of turns
or that you installed the wrong type of slug-tuned inductor at L30.
- If you change any of these components, repeat the VCO alignment
- Disconnect the DMM from R30.
- Connect the internal frequency counter probe to the BFO test
point, TP2 (right side of the RF board, near the crystal filter).

BFO Test

- The BFO (beat-frequency oscillator) will be tested in the following
- Switch to the 40-m band.
- Connect the frequency counter to the BFO test point (TP2),
which is on the right side of the RF board near the crystal filter.
Using the menu, select CALFCTR. The counter should show
a frequency between 4908 and 4918 kHz.
- If you see a reading of 0000.00 kHz, or one that is
changing rapidly, you may not have the frequency counter probe
connected properly, or the BFO may not be working (see
Troubleshooting). If you see a stable frequency reading that is
nowhere near 4908-4918 kHz, you may have installed the wrong
crystals in the BFO (X3/X4).
- When you’re in frequency counter mode, the BAND + and
BAND - switches can be used to check the range of the BFO. First,
tap BAND + and write down the frequency reading below (typically
about 4916-4917 kHz). Then tap BAND - and write down this
frequency reading (usually about 4909-4912 kHz). Finally, calculate
the BFO range (high - low) in kHz. Typical range is 4 to 6 kHz.
BFO High Freq. (must be >= 4916.3 kHz)
BFO Low Freq. (must be <= 4912.7 kHz)
Range (High - Low) (must be >= 3.6 kHz)
- If your BFO range is less than 3.6 kHz, you may have the wrong
varactor diodes installed at D37 or D38, or the wrong crystals
installed at X3 or X4.
- If the BFO frequencies are shifted too high or too low, it may be
due to one of the following:
-If you didn't calibrate the K2's internal frequency counter using
an external counter, it may not be reading accurately. If
possible, borrow an accurate counter and re-do the 4 MHz
Oscillator Calibration.
- The BFO range shift could be due to the inductance of L33
being too high or too low. However, since L33 is supplied prewound
and tested, this is unlikely.
- The leads of R116 may have been heated excessively during
soldering, shorting out a portion of L33's turns.
- One of L33's leads could be broken. Look closely at the leads
using a magnifying glass.
- One or more of the capacitors or varactor diodes in the BFO
circuit could be of the wrong value.

BFO Alignment

- The K2 uses a variable-bandwidth crystal filter, allowing the
operator to set up as many as four filter bandwidths for each
operating mode. Each of these filter configurations requires an
appropriate BFO setting, which determines the pitch you hear.
- Filter and BFO set up is done with the CALFIL calibration
function. CALFIL is described in detail in the Operation section
of the manual, under Calibration Functions. Rather than duplicate
this information here, we'll refer you to the instructions and
example in the Operation section.
- Make sure the bottom cover is securely attached.
- Tap PRE/ATT until the PRE annunciator is turned on.
(Turning the preamp on will provide some background noise so you
can hear the effect of changing filter bandwidths.)
- Follow all instructions on page 88 to become familiar with the
CALFIL function.
- Perform the steps in the example on page 89 to set up all
filters. You'll use the filter and BFO data from Table 8-1 (for a
CW-only K2), since the SSB adapter is not installed. If you later
install the SSB adapter, you can easily change the settings to take
advantage of the optimized, fixed-bandwidth SSB filter.

VFO Linearization

- Make sure the bottom cover is securely attached.
- Allow the K2 to stabilize for at least 10 minutes at room
temperature (approx. 20-25°C). (Note: Avoid using a high-wattage
work lamp direct above the K2 during calibration. With the top
cover removed, this could heat the RF board to a higher
temperature than would ever be seen during normal operation.)
Connect the internal frequency counter cable to the VCO
output test point (TP1).
- Use the procedure listed below to linearize the VFO. If you see
any INFO messages, refer to Troubleshooting.
1. Use BAND + or BAND - to select 40 meters. Select CW normal
mode and filter FL1.
2. Set the VFO to anywhere in the range 7000-7100 kHz.
3. Enter the menu and select CALPLL, then hold EDIT a
second time to start the VFO linearization sequence.
4. The frequency counter will show the VCO frequency as it
decreases through a range of about 10-13 kHz. (The letter "d "
will flash each time a calibration data point is stored.)
5. When calibration is completed (4-8 minutes), you'll see the
message End on the LCD. You can then tap any switch to
return to normal operation. If you see an INFO message rather
than End , refer to Troubleshooting (Appendix E).

I.F. Amplifier Alignment

- L34, located near the right front corner of the RF board, is used to
peak the output of the I.F. amplifier.
- Using the wide end of the plastic tuning tool, adjust the slug in
L34 until it is near the top of the can. Stop turning the slug
when it appears to be at the top or when you feel resistance.
- Turn L34’s slug one full turn clockwise (down into the can).
- Set the band to 40 meters using BAND + or BAND - . Select CW
Normal and FL2 (700 Hz nominal bandwidth).
- Make sure the RF GAIN control is fully clockwise (max. gain).
- Disconnect the antenna from J4, if one was connected.
- Tap PRE/ATTN until the PRE annunciator turns on.
- Connect a pair of headphones (stereo or mono) to the front
panel jack, and turn the AF GAIN control to about midway.
- Slowly tune the VFO to locate the weak internally-generated
signal near 7000 kHz. If you can't hear the signal at all, you may
have a receiver problem. Try the 40-meter Band Pass Filter
Alignment, below, then refer to Troubleshooting if necessary.
While listening to the signal at 7000 kHz, adjust L34 for best
signal strength and lowest noise. This setting occurs at about 1 to
1.5 turns below the top of the can. (You can use your DMM on AC
volts, at the speaker jack, to obtain a more sensitive indication.)

40-Meter Band Pass Filter Alignment

- Connect an antenna or a signal generator to the antenna jack
on the rear panel. If you use a signal generator, set it for approx.
7150 kHz at an output level of about -100 dBm, or strong enough
to activate the S-meter. If you're using an antenna, tune in a signal
in the range of 7100-7200 kHz. If you cannot find a signal, you
can use atmospheric noise from the antenna to peak the filter.
- Using the plastic tuning tool, adjust both L1 and L2 (back left
corner) for peak signal strength. You may be able to use the
bargraph if the signal is strong enough. If you do not hear any
signals or noise, see Troubleshooting.
- In CW mode, the frequency shown on the display takes into
account an offset equal to your sidetone pitch. This allows you to
determine a station's actual carrier frequency by matching their
pitch to your sidetone, rather than by zero-beating the signal. The
SPOT switch can be used for this purpose.
- This completes 40-meter receiver alignment. You may wish to
become familiar with the K2’s receiver features before proceeding
(see Operation). In Part III you’ll install the remaining band-pass
filters and align the transmitter and receiver on all bands.

qq011 Assembly, Part 3

- In this final RF board assembly section you’ll install the transmitter
components, as well as the remaining band-pass and low-pass filters.
- This will allow you to align and test the K2 on all bands.
- Turn off the K2 and disconnect the power supply.
- Remove the two screws holding the Front Panel board to the
Control board, then unplug the Control board. Use the long-handled
Allen wrench as described in Part I.
- Remove the bottom cover.
- Remove the screws from the front panel assembly and unplug
it from the RF board.
- Remove the side panels by taking out the two screws along the
bottom edge of each panel.
- Install the following 1/4-watt resistors, starting with R46
which is just to the left of I/O controller U1.
__ R46, 270 (RED-VIO-BRN) to __ R45, 47 (YEL-VIO-BLK)
__ R59, 4.7 k (YEL-VIO-RED) __ R61, 120 (BRN-RED-BRN)
__ R49, 120 (BRN-RED-BRN) __ R40, 470 (YEL-VIO-BRN)
__ R41, 560 (GRN-BLU-BRN) __ R55, 33 (ORG-ORG-BLK)
__ R53, 4.7 ohms (YEL-VIO-GLD)
__ R56, 33 (ORG-ORG-BLK)
__ R54, 4.7 ohms (YEL-VIO-GLD)
__ R60, 100 ohms (BRN-BLK-BRN)
__ R62, 2.7 k (RED-VIO-RED)
__ R67, 1.5 k, 1% (BRN-GRN-BLK-BRN)
__ R68, 226 ohms, 1% (RED-RED-BLU-BLK)
- The 150 pF and 3.3 pF capacitors to be installed below
may be hard to identify. See capacitor information on page 9.
- Install the capacitors listed below. C12 is near the back left
corner. Note: C13 and C14 will not be installed; they are included
with the 160 m/RX Antenna option (K160RX).
__ C12, 560 (561) to __ C11, 1800 (182) to __ C26, .001 (102)
__ C16, 1800 (182) __ C15, 560 (561) __ C22, 3.3 pF (3.3)
__ C20, 47 (47) __ C19, 330 (331) __ C30, 470 (471)
__ C24, 47 (47) __ C25, 330 (331) __ C35, 56 (56)
__ C37, .001 (102) __ C36, 470 (471) __ C33, 2.2 pF (2.2)
__ C49, .001 (102) __ C31, 56 (56) __ C42, 330 (331)
__ C43, 33 (33) __ C48, 330 (331) __ C47, 33 (33)
__ C45, 1 pF (1) __ C115, .01 (103) __ C117, .047 (473)
__ C118, .01 (103) __ C116, 33 (33) __ C121, 0.01 (103)
__ C120, .01 (103) __ C131, 0.1 (104)
__ C124, 0.1 (104) __ C130, 0.1 (104) __ C128, 680 (681)
__ C129, .01 (103) __ C127, 680 (681) __ C191, 1800 (182)
__ C190, 1200 (122) __ C197, 100 (101) __ C198, 27 (27)
__ C210, 82 (82) __ C211, 10 (10) __ C218, 150 (151)
__ C219, 12 (12) __ C138, .047 (473) __ C222, 100 (101)
__ C221, 39 (39) __ C220, 220 (221) __ C214, 68 (68)
__ C213, 33 (33) __ C212, 150 (151) __ C203, 47 (47)
__ C199, 220 (221) __ C200, 150 (151) __ C202, 120 (121)
__ C201, 220 (221) __ C192, 1200 (122)

- There are two types of ceramic trimmer capacitors used in
the band-pass filters: 30 pF and 50 pF. These may look identical.
- They will either be bagged separately, or the 50-pF trimmers will
have a red marking.
- Install the trimmers listed below, starting with C21 near the
back-left corner. Orient the flat side of each trimmer capacitor
with the flat side of its component outline. This orientation is
required to prevent RF pickup during alignment.
__ C21, 50 pF __ C23, 50 pF
__ C32, 30 pF __ C34, 30 pF
__ C44, 30 pF __ C46, 30 pF
- Set all of the trimmer capacitors just installed to their mid-way
points. Use a small flat-blade screwdriver.
- Install L5, a 33 µH RF choke (ORG-ORG-BLK), near the
back-left corner.
- Install the following transistors, which are located near the I/O
Controller (U1).
__ Q10, 2N7000 __ Q11, PN2222A __ Q13, PN2222A
- Ferrite-bead assemblies Z1 and Z2 will be installed vertically
near transformer T3 as indicated by their component outlines. To
make these assemblies, string two ferrite beads onto a 1" (25 mm)
length of bare hookup wire (or discarded component leads)
- Install Z1 and Z2, bending the leads on the bottom of the
board to hold them in place. Make sure that the beads are seated
flat against the PC board, then solder.
- Locate D9, the 1N5711 diode which you identified and set
aside earlier. Install D9 near the right edge of the board.
- Install electrolytic capacitors C126 (47 µF) and C137
(100 µF), Near the "ELECRAFT" label at the center of the board.
- Insert the (+) lead of each capacitor into the hole marked (+).
- Install electrolytic capacitor C125 (22 µF) which is near U1.
- Install Q5 (2N5109). Be sure Q5 is firmly seated on the board
and has its tab oriented as shown by the component outline before
- Install the following components on the bottom of the board,
working from left to right.
__ R63, 220 (RED-RED-BRN)
- Note: bend the leads of R58 exactly as shown by its component outline.
__ R58, 180 ohms, 1/2 watt (BRN-GRY-BRN)
__ RFC8, __ RFC9, __ RFC4, 10 µH (BRN-BLK-BLK)
__ RFC6, 0.68 µH (BLU-GRY-SILVER)
__ RFC5, 10 µH (BRN-BLK-BLK)
__ R50, 1.5 ohms, 1/2-watt (BRN-GRN-GLD)
__ R48, 120 (BRN-RED-BRN) __ R47, 47 (YEL-VIO-BLK)
__ R43, 22 (RED-RED-BLK)
__ R42, 4.7 ohms (YEL-VIO-GLD)
__ R44, 2.7 k (RED-VIO-RED)
- Make sure you have separated the remaining slug-tuned
shielded inductors into 1 µH and 4.7 µH types. Install these
inductors in the order indicated below, on the top of the board.
These inductors are difficult to remove once soldered, so doublecheck
the part numbers. The 4.7 µH inductors are labeled "T1005,"
and the 1 µH inductors are labeled "T1050."
__ L3, 4.7 µH ("T1005") __ L4, 4.7 µH
__ L8, 4.7 µH __ L9, 4.7 µH
__ L10, 1 µH ("T1050") __ L11, 1 µH
__ L12, 1 µH __ L13, 1 µH
- TO-220 package transistors Q6, 7, and 8 look identical, but
Q6 is different. Locate the two 2SC1969’s (labeled "C1969"), Q7
and Q8, and set them to one side. The 2SC2166 transistor, Q6
("C2166"), will be installed first.
- Attach a self-adhesive thermal pad to the PC board on top of
the component outline for Q6. The hole in the thermal pad must
be aligned precisely with Q6's mounting hole on the board.
Prepare the leads of Q6 as you did with the voltage regulators
on the Control board (Figure 4-4, page 16), using gradual bends to
avoid lead breakage. Insert Q6 as shown by its component outline.
- Secure Q6 to the board using a 4-40 x 3/8" (9.5 mm) screw, #4
lock washer and 4-40 nut. The screw should be inserted from the
bottom side of the RF board; the washer and nut go on the top.
- Verify that the body of Q6 is not touching the leads of any
adjacent components, then solder.
- Wind and install each of the low-pass filter inductors listed
below, starting at the back-right with L16 and L17 (80 meters).
- Wind each of the toroids using the core type and number of turns
indicated (use red enamel wire). Review the toroid winding
instructions and illustrations for RFC14 (Page 53).
__ L16 T44-2 (red), 21 turns 19" (48 cm)
__ L17 T44-2 (red), 21 turns 19" (48 cm)
__ L18 T44-2 (red), 9 turns 10" (25 cm)
__ L19 T44-2 (red), 8 turns 9" (23 cm)
__ L20 T44-2 (red), 7 turns 8" (18 cm)
- Note: The black cores below are all of the powdered-iron (ceramic)
type, not ferrite. If necessary you can identify them by measuring
their diameter, which is 0.44" (11 mm), not 3/8" (9.5 mm).
__ L21 T44-10 (black), 9 turns 10" (25 cm)
__ L22 T44-10 (black), 8 turns 9" (23 cm)
__ L23 T44-10 (black), 11 turns 11" (28 cm)
__ L24 T44-10 (black), 10 turns 10" (25 cm)
- It is very important to wind and install toroidal
transformers T1 through T4 exactly as described in the following
steps. Remember that transformer windings are identified by
numbered pairs of leads, which correspond to the PC board and
- T1 is wound on an FT37-43 ferrite core (dark gray) and has
windings similar to those shown in Figure 6-25. The 1–2 winding is
9 turns of red enamel wire (10", 25 cm). The 3–4 winding is 3 turns
of green enamel wire (5", 13 cm). (The drawing shows more than 9
turns on the larger winding.)
- Prepare T1’s leads as in Part II. Completely remove the
insulation to within about 1/8" (3 mm) of the core, then tin the
- Install T1 horizontally near Q5, inserting the leads into the
matching numbered holes as indicated by the above illustration and
by the component outline.
- T2 is wound on the same core type as T1 (FT37-43). Its
windings must be spaced as shown in Figure 6-26(a), with the 3-4
winding occupying about half the diameter of the core. T2’s 1–2
winding is 12 turns of red enamel wire (13", 33 cm), and its 3–4
winding is 8 turns of green (9", 23 cm).
- Prepare T2’s leads, but leave an extra 1/2" of insulation on
leads 3 and 4 (green) as shown in Figure 6-26(a).
Fold the leads of T2's green winding (3-4) down and under the
core as shown in Figure 6-26(b).
- Install T2 horizontally, just to the right of Q6. To ensure that
the leads do not contact any adjacent pads or components, T2
should be mounted so that it is elevated slightly above the board
(about 1/16" [1.5 mm]).
- Transformer T3 is mounted vertically, to the right of T2. The
wires for the two windings must be twisted together before winding
(bi-filar). First, cut two 10" (25 cm) lengths of enamel wire, one
red, and one green. Then twist the wires together over their entire
length. The wires should cross each other once every 1/2" or 1 cm.
- Wind the twisted wires onto a 1/2" (12.7 mm) dia. ferrite core
(FT50-43), using exactly 5 turns and covering about 85% of the
core. Figure 6-27 shows how the winding should look. The leads of
T3 are labeled with letters A through D on the PC board to avoid
confusing them with the numbered leads of T2 and T4.
- Separate T3’s leads as shown in Figure 6-27. Strip and tin the
leads, being careful not to let the red/green wire pairs short
- Install T3 vertically as shown by its component outline. T3
must be seated flat against the PC board, with its leads pulled tight
on the bottom side.
- Locate the "binocular" (2-hole) ferrite core for T4. Wind 2
turns of green-insulated hookup wire (5", 13 cm) through the
core as shown in Figure 6-28. This forms the 1–2 winding. (Do not
use enamel-coated wire.)
- Cut and strip the two leads using the lengths shown. Be careful
not to nick the wire.
- Wind a 3-turn winding (3–4) on top of the 1-2 winding, but
with the wire starting and ending on the opposite side (Figure 6-29).
Use 7" (18 cm) of white-insulated hookup wire (not enamelcoated
wire). Prepare the leads in the same manner as above.
- Before installing T4, verify that the screws holding the 2-D
fastener beneath it are tightened, and that #4 internal-tooth lock
washers were used. It is important that these screws not come loose
sometime after T4 has been installed.
- Install T4 to the right of T3, inserting leads for the 1–2 and
3–4 windings into their matching numbered holes. T4 should rest
directly on top of the screws that secure the 2-D fastener beneath
it. T4 should also be parallel to the board, not tilted to one side.
Pull the leads taut on the bottom and bend them to hold the
transformer in place. Do not solder T4 yet.
- Use two 2" (5 cm) lengths of bare hookup wire to form the
5–6 and 7–8 windings on T4 (Figure 6-30). (These are more
accurately described as links, each being just a single turn.) Route
the bare wires through the core first, then bend them down and
insert them into their numbered holes. Do not solder yet.
- Adjust all of the windings of T4 as needed so that the
transformer is positioned directly above its component outline. Pull
the leads tight on the bottom, then solder.
- Inspect all four transformers in the transmitter area closely,
on both top and bottom, for shorts or cold solder joints.
- PA transistors Q7 and Q8 (2SC1969) must be installed on
the bottom of the PC board, with their metal tabs facing away from
the board, as explained in the following steps. Locate the
component outlines on the bottom of the board before proceeding.
- Prepare the leads of Q7 as shown in Figure 6-31. Bend the
leads upward, away from the tab--the opposite of the way you bent
the leads of Q6. Form the leads using the shaft of a small
screwdriver to create gradual bends. Do not install Q7 yet.
- Insert a 4-40 x 1/2" (12.7 mm) screw through the PC board
hole for Q7’s tab (see Figure 6-31). Then slip the hardware listed
below onto this mounting screw from the bottom side. (The
shoulder washer can be found with the MISCELLANEOUS
__ #4 fibre washer (black)
__ 1/4" (6.4 mm) dia., 1/8" (3 mm) long phenolic standoff (brown)
__ #4 nylon shoulder washer (black)
- Do not use any hardware other than that supplied. The
height of the PA transistor assembly is critical for maintaining
good heat dissipation.
- Place Q7 on the bottom of the board so that the leads are
inserted into the PC board as indicated by Q7’s component outline.
The mounting screw and hardware should appear as shown in Figure
6-31. Do not solder yet.
- Make sure the smaller part of the shoulder washer is visible
through the hole in Q7’s metal tab.
- Secure Q7 and its hardware temporarily using a 4-40 nut and
#4 lock washer. Tighten the nut only finger-tight.
- Once Q7 and its hardware appears to be parallel to the PC
board as shown in Figure 6-31, solder Q7 on the top of the board.
Repeat the steps above for the other PA transistor, Q8.

Uninstalled Components

- Check off the components in the list below, verifying that
they are not yet installed. All of these components are on the top
side of the board. Note: Most of these components are provided
with option kits, as indicated in the list. Some of the connectors
can be pre-installed, as will be explained on the next page.
__ J14 (near antenna jack); supplied with K160RX
__ C13 and __ C14 (in 160 m band-pass filter); supplied with K160RX
__ C75 (synthesizer area); supplied with K160RX
__ J15 (3-pin connector in 40 m band-pass filter); supplied with K60XV
__ J13 (transverter conn., near 40 m band-pass filter); supplied with K60XV
__ D19 and D20 (synthesizer area); supplied with K60XV
__ P6 (near DC input jack); supplied with KAT2 or KPA100
__ P3 (near crystal filter); supplied with KBT2 or KPA100
__ J9, __ J10, and J11 (near crystal filter); supplied with KSB2
__ J12 (near crystal filter); supplied with KNB2
__ J5 (near BFO crystals); reserved for future use
__ X2 (front left corner); not used
- If you have already purchased option kits, you may install
selected option components now, as explained in the following
steps. This will simplify installation of the options after K2
alignment and test have been completed.
- Do not remove the option bypass jumpers (W1, W2, etc.).
The K2 must be aligned and tested before the jumpers are
removed and option modules installed.

K160RX Component Installation (optional)

- Locate the Installation section of the K160RX kit manual.
Cross out the first three steps (turning off the K2, removing
hardware, etc.), which are not applicable since the K2 is already
disassembled. Skip the next two steps. Do not remove W1.
- Complete the steps for J14 through C13 and C14.
Cross out the next two steps (examination of Q7 and Q8).
The remaining steps should be completed after K2 alignment.

KSB2 Component Installation (optional)

- Locate KSB2 Module Installation in the KSB2 manual.
- Complete only the steps required to install J11, J9, and J10,
and the standoff. Do not remove W2, W3, or C167 at this
time. Complete the remaining steps after alignment.

Other Option Component Installation (optional)

- If you have the KAT2 (ATU) or KPA100 (Amplifier) option,
install 2-pin connector P6. Use the option manual's instructions.
- If you have the KBT2 (Battery) or KPA100 option, install
2-pin connector P3. Use the option manual's instructions.
- If you have the KNB2 (Noise Blanker) option, locate the
Installation section of the KNB2 manual. Complete only the
installation of J12 and the standoff. Do not remove W5, R88,
R89 or R90 at this time.
- Do not attempt to pre-install parts supplied with the
K60XV option. The K2 must be completed and tested first.

Visual Inspection

- Examine the bottom (solder side) of the RF board carefully for
unsoldered pins, solder bridges, or cold solder joints. Since this is a
large board, you should break the examination up into three parts:
__ perimeter area __ front half __ back half
- Examine the top (component side) of the RF board for
unsoldered pins, solder bridges, or cold solder joints. This step is
necessary because some components are installed on the bottom of
the board and soldered on top.
- Make sure switch S1 on the RF board is in the OFF position.
(Plunger OUT is OFF.)

Resistance Checks

- Perform the following resistance checks

Test Point: Q7 collector
Signal Name: 12V
Res. (to GND): > 500 ohms

Test Point: Q6 base
Signal Name: Driver bias
Res. (to GND): 100-140 ohms

Test Point: Q7 base
Signal Name: PA bias
Res. (to GND): 2.5 - 3.0 k

Test Point: U11 pin 8
Signal Name: 8A
Res. (to GND): > 250 ohms

Test Point: U10 pin 8
Signal Name: 8T
Res. (to GND): > 500 ohms

Test Point: U12 pin 1
Signal Name: 8R
Res. (to GND): > 500 ohms

- Install the two side panels and secure with two chassis screws
each as you did in Part I and Part II.
- Plug in the front panel assembly and make sure the connectors
are completely mated. Secure the front panel with four chassis
- Verify that all components on the bottom of the RF board
have an installed height of 1/4" (6 mm) or less. Capacitors that
stand above this height must be bent downward so that they won’t
hit the bottom cover or heat sink.
- Install the bottom cover and secure it using six chassis screws.
Plug in the Control board. Make sure that all three connectors
are completely mated.
- Secure the front panel and Control boards together using two
chassis screws.
- Locate the heat sink panel. You'll need to remove all of the
masking tape from this panel except that covering the "RCV ANT"
and "XVTR IN/OUT" holes. Use a sharp tool to cut though the
tape, leaving a 1/2" (12 mm) border around these holes. Then peel
the tape off, leaving these holes covered.
- Attach two round rubber feet to the heat sink using 4-40 x
7/16" (11 mm) screws, #4 lock washers, and 4-40 nuts. The screws
are standard steel/zinc-plated, not black anodized. The nuts go on
the inside surface of the heat sink. (The rubber feet can be found
with the MISCELLANEOUS items.)
- Remove the finishing nuts and washers from the shafts of the
antenna and key jacks. They will be re-installed later.
- Turn the K2 up on its left side. This will keep the PA
transistor screws from slipping out during the following steps.
- Remove the 4-40 nuts and #4 lock washers from the mounting
screws for Q7 and Q8, but do not pull the screws out. (If you pull
these screws out, the associated hardware will fall off and will have
to be re-installed.)
- In the next step you'll install thermal insulation pads on
the power amplifier transistors, Q7 and Q8. These pads must be
positioned correctly to keep the collectors of the transistors from
shorting to ground. Proper positioning is also required to guarantee
good heat conduction.
- Place self-adhesive thermal pads on top of Q7 and Q8 as
shown in Figure 6-32, with the hole in the pad centered over the
hole in the transistor tab. The adhesive side must be in contact with
the transistor.
- Back out the mounting screws for Q7 and Q8 until the ends of
the screws protrude only slightly from the transistor tabs. Keep the
K2 on its left side so the screws don’t slip out further.
- Make sure that the thermal pads on Q7 and Q8 are centered,
and that you can see the shoulder washers inside the tab holes. If
the shoulder washers have come out of the tab holes, re-align the
PA transistor hardware as needed.
- Keeping the K2 on its left side, slip the heat sink over the
rear-panel connectors and into position (Figure 6-33). Figure 6-34
shows how the heat sink and associated hardware appear in crosssection.
- Make sure that the four small holes in the heat sink line up
with Q7/Q8 and the 2-D block between them.
- Press the Q7/Q8 mounting screws all the way back in so that
they protrude from the heat sink.
- Use two chassis screws and two #4 lock washers to secure the
heat sink firmly to the 2-D fastener.
- Secure Q7 and Q8 on the bottom of the heat sink using 4-40
nuts and #4 lock washers. Do not over-tighten the nuts, as this may
cause the thermal pads to scrape against the heat sink, possibly
causing a short to ground.
- Using an ohmmeter on a low resistance scale, check for a
short from Q7 or Q8 collector to ground. (This test should also be
performed any time the heat sink is removed and re-installed.) If a
short is measured, remove the heat sink and investigate the cause.
The most likely reason for a short is mis-alignment of a shoulder
washer or thermal pad. If a thermal pad or shoulder washer is
damaged, it must be replaced.
- There are four more #4 holes in the heat sink: two on the
bottom and two on the back panel. Use four chassis screws to secure
the heat sink to the side panels and RF board at these locations.
You may need to adjust the positions of the 2-D fasteners on the
side panels slightly.
- Install the washers and finishing nuts that you removed earlier
from the antenna and key jacks. (The antenna jack hardware is
shown installed in Figure 6-34.)

qq012 Alignment and Test, Part 3

- In this section you’ll complete alignment and test of the K2 on all
- Make sure the power switch, S1, is in the OFF position (out).
- Connect your power supply or battery. For transmitter tests, a
battery or well-regulated power supply that can handle at least 2
amps is recommended. Avoid using a switching power supply unless
it is well shielded and includes EMI filtering. A linear-mode supply
will typically generate much less noise in the HF bands. (See any
recent ARRL Handbook for examples of both types.)
- Connect a 50-ohm dummy load such as the Elecraft DL1 to
the antenna jack. The dummy load should be rated at 10 watts or
higher. (The DL1 is rated at 20 watts.)
- Connect a pair of headphones and a key or keyer paddle.
Set the POWER control fully counter-clockwise (minimum
power output).
- Turn on the K2. You should see ELECRAFT on the LCD,
followed by the frequency display.
- Select voltage/current display mode by tapping DISPLAY to
make sure the receiver is not drawing excess current. (Typical
current drain will be 180-250 mA depending on menu settings.)
Return to frequency display mode.
- Switch to CW and select FL1 using XFIL.
Use the menu to set up the desired CW sidetone volume and
pitch if you have not already done so, using S T L and S T P . The
pitch can be set from 400 to 800 Hz, although 500-600 Hz is
recommended. The sidetone volume and tone will vary a small
amount as the pitch is changed, but it should have a pleasant
sinewave sound at any setting.
- Set up the desired keying device using INP. If you’re using a
hand key or external keyer, use INPHAND. To use the internal
keyer, select PDLn or PDLr (normal or reverse paddle). You can
also connect a computer or external keyer along with the keyer
paddle. Refer to the Operation section for details on this "autodetect"
- To verify that the sidetone is functioning, hold the
SPOT switch. Tap any switch to turn the SPOT tone off.

40-Meter Transmitter Alignment

- To align the transmitter you’ll need some means for
monitoring power output as you adjust the band-pass filters. An
analog wattmeter or oscilloscope is ideal. However, in the
instructions that follow we’ll assume that you’re using the K2’s
built-in digital wattmeter, which will also provide satisfactory
- Set the POWER control for 2.0 watts.
- Switch to the 40 meter band and set the VFO for about 7100
- Locate the 40-meter band-pass filter inductors, L1 and L2, and
be prepared to adjust them using the wide end of the tuning tool.
- In the following steps you’ll place the K2 into "TUNE"
mode by holding TUNE. You should limit key-down periods to about
5 or 10 seconds during tune-up for safety reasons. If you see or
smell smoke turn the K2 off and refer to Troubleshooting.
- Note: While in tune mode, it is normal to see power drift upward
several tenths of a watt. You may also see a sudden jump in power
during alignment. The output will quickly be reduced to about 2.0 W
by the firmware if this happens.
- Put the K2 into tune mode and activate the built-in wattmeter
by holding TUNE . Using the alignment tool, adjust L1 for maximum
output. Tap any switch to exit TUNE mode.
- Enter tune mode again and adjust L2 for maximum output.
- Tap any switch to exit.
- If necessary, repeat the adjustment of L1 and L2 two or three
times to be sure that you have the inductors peaked correctly. If
you cannot get power output to 2.0 watts or higher, see
- Make sure the bar graph is set for DOT mode using the
GRPH menu entry.
- Set power output to 5.0 W using the POWER control.
- Tap DISPLAY to enter voltage/current display mode. When
this display is selected, you can use TUNE to check your voltage and
current in transmit mode.
- Enter tune mode and note the change in voltage and current.
- Current drain at 5 watts is typically 1.3 to 1.6 amps.10 If the
current reading is much higher than this, or if the voltage drops
more than 1 V, you may have a problem in the transmitter, load, or
power supply (see Troubleshooting).
- Return to frequency display using the DISPLAY switch.
Set the POWER control for 10.0 watts.
- Enter tune mode just long enough to verify that the wattmeter
reads approximately 10 watts. If you then switch to voltage/current
display and hold TUNE again, you should see a current drain of
typically 1.8 to 2 amps. If you see a "HI CUR" warning message
(high current), use CAL CUR to set your transmit current limit
higher. If current is much higher than 2 A, see Troubleshooting.
This completes transmitter alignment and test on 40 meters.

Receiver Pre-Alignment

- Since the same filters are used on both receive and transmit, it is
possible to align all the remaining bands on transmit only.
- However, you can pre-align the filters on receive by using a signal
or noise generator (such as the Elecraft N-Gen), separate ham
transceiver, or on-air signals and atmospheric noise. This prealignment
on receive will make transmitter alignment easier, since
the filter adjustments will already be at or close to their final values.
Switch to 80 meters and set the VFO for about 3750 kHz
(mid-band). Turn on the RF preamp by tapping PRE/ATTN until
you see the PRE annunciator turn on.
- Use a signal generator or an antenna to inject a signal or noise
at this frequency.
Adjust L3 and L4 for maximum signal strength.
- Since some inductors are shared between two bands, you
must always align the remaining bands in the order indicated.
Always use this procedure if you re-align the filters later.
- Switch to 20 meters (14100 kHz) and turn on the preamp. Set
C21 and C23 to their mid-points. Adjust L8 and L9 for maximum
signal strength. (This step pre-sets C21, C23, L8, and L9 before
final adjustment in the next two steps.)
- Switch to 30 meters (10100 kHz) and turn on the preamp.
- Adjust L8 and L9 for maximum signal strength.
- Switch back to 20 meters (14100 kHz). Adjust C21 and C23
for maximum signal strength.
- Switch to 15 meters (21100 kHz) and turn on the preamp.
- Adjust L10 and L11 for maximum signal strength.
- Switch to 17 meters (18100 kHz) and turn on the preamp.
- Adjust C32 and C34 for maximum signal strength.
- Switch to 10 meters (28200 kHz) and turn on the preamp.
- Adjust L12 and L13 for maximum signal strength.
- Switch to 12 meters (24900 kHz) and turn on the preamp.
- Adjust C44 and C46 for maximum signal strength.
- This completes receiver alignment.
- During receiver alignment, you may have noticed that
signal strength is somewhat lower in volume when you select the
narrowest filter (100 Hz setting, FL4). This is because the K2's
crystal filter is optimized for wider bandwidths (250-800 Hz).
Despite the slightly greater attenuation, the narrower settings are
very useful in reducing QRM (interference) from strong, nearby
signals. (Any of the filter settings can be changed, and FL2-FL4 can
even be turned OFF.

Transmitter Alignment

- If you did the receiver alignment, above, you may find that little or
no transmit adjustment is required on most bands.
- Set the POWER control for 2.0 watts.
- Switch to 80 meters and set the VFO for about 3750 kHz
- Enter tune mode and adjust L3 and L4 for maximum power as
indicated on the internal wattmeter. (Use a more sensitive analog
instrument if available.) Limit tune-up time to 5 or 10 seconds.
- Since some inductors are shared between two bands, you
must always align the remaining bands in the order indicated.
- Always use this procedure if you re-align the filters later.
- Switch to 20 meters (14100 kHz). Set C21 and C23 to their
mid-points. Adjust L8 and L9 for maximum power output. (This
step pre-sets C21, C23, L8, and L9 before final adjustment in the
next two steps.)
- Switch to 30 meters (10100 kHz) and adjust L8 and L9 for
maximum power output.
- Switch to 20 meters (14100 kHz) and adjust C21 and C23 for
maximum power output.
- Switch to 15 meters (21100 kHz) and adjust L10 and L11 for
maximum power output.
- Switch to 17 meters (18100 kHz) and adjust C32 and C34 for
maximum power output.
- Switch to 10 meters (28200 kHz) and adjust L12 and L13 for
maximum power output.
- Switch to 12 meters (24900 kHz) and adjust C44 and C46 for
maximum power output.
- This completes transmitter alignment.

qq013 Final Assembly

- Place the top cover upside down as shown in Figure 7-1, with
its rear panel facing away from you. The illustration shows how the
speaker, 2-conductor cable, external speaker jack and other
hardware will be attached to the top cover.
Trim the supplied grille cloth to the size of the speaker frame.
- Place #4 fibre washers (black) at each of the top cover's four
speaker mounting holes. Trim the corners of the grille
cloth so it just fits between the fibre washers, not touching them.
- Place the speaker on top of the fibre washers and grille cloth.
Secure it with four 3/8" (9.5 mm) screws, #4 lock washers, and 4-40
nuts (Figure 7-2). Do not over-tighten the nuts.
- Locate the two holes marked A in Figure 7-1. Use two 4-40 x
3/8" (9.5 mm) screws to fill these holes, securing them with #4 lock
washers and 4-40 nuts. (The holes are for the battery option.)
- Install 2-D fasteners at the two locations marked B in Figure
7-1. The 2-D fasteners should line up exactly with the edges. Use
two chassis screws per 2-D fastener.
- Using a sharp tool, cut through and peel off about 1/2" x 1/2"
(12 x 12 mm) of the masking material covering the EXT SPKR
hole. Note: Leave the other holes covered with masking material
until the associated options are installed.
- Install the external speaker jack in the EXT SPKR hole.
Orient the jack as shown in Figure 7-1 and Figure 7-4, with the
"AF" tab nearest the inside of the top cover. (Caution: Misidentification
of the three tabs could result in a ground short.)
- 24" (61 cm) of 2-conductor speaker cable is supplied. Cut it
into two pieces, 15" (38 cm) and 9" (23 cm) long.
- Solder crimp pins to the two wires at one end of the 15" (38
cm) length of speaker cable (Figure 7-3).
- When you insert crimp pins into the housing in the next
step, they should snap into place. Each pin has a small tab on the
back that latches into a hole in the housing when inserted.
- Insert the copper wire into the pin 1 position of a two-pin
housing as shown. Insert the other wire into the pin 2 position.
- Connect the other end of this cable to the external speaker
jack as shown in Figure 7-4. The copper wire must be connected to
the "AF" lug of the speaker jack. Solder only the copper wire.
- Connect one end of the 9" (23 cm) speaker cable to the
speaker terminals. The copper wire should be connected to the lug
marked (+) on the speaker. Solder both wires.
- Connect the other end of this cable to the external speaker
jack as shown in Figure 7-5. The copper wire must be connected to
the lug marked "SP" below. Solder all three lugs.
- Use three cable ties at the points shown in Figure 7-1 to hold
the speaker cables in place. (Save the fourth cable tie for use with
the supplied RF probe.) The ties should be pulled tight. Trim any
excess cable tie length.

Finishing Touches

- Examine the Control board one last time to be sure that it is
correctly plugged into the RF board. All three connectors must be
mated completely.
- Leave the frequency counter test cable connected to the BFO
test point (TP2). This will allow you to modify your filter and BFO
settings if necessary during normal operation.
- If there are any missing chassis screws in the bottom cover,
heat sink, side panels, or front panel, install them now.
- Plug the internal speaker cable into P5 on the RF board, just
behind the on-off switch, S1. The connector is keyed and can only
be plugged in one way.
- Even if you have purchased some K2 options, you should
not assemble and install them yet. The option manuals assume that
you are familiar with basic K2 operation.
- Remove the masking material from the two top-cover
mounting holes marked C in Figure 7-1.
- Cut through and peel off about 1/2" x 1/2" (12 x 12 mm) of
masking material from around the top-cover mounting holes
marked D in Figure 7-1. These holes are in the far corners of the
top cover's rear panel, corresponding to screws 1 and 2
- Place the top cover onto the chassis and secure it using six
chassis screws
- When removing the top cover in the future, take out only
the six screws
- Attach the self-adhesive serial number label to the rear panel
of the heat sink in the space provided.
- Write the serial number on the inside cover of your manual.
- This completes assembly of your K2. Please read the Operation
section, which follows, and try each of the K2's features.
- If you did not have access to a frequency counter or
calibrated receiver when aligning the 4-MHz oscillator, you may
wish to use the one of the alternative VFO calibration techniques
described in the Operation section (page 101). You can use an onair
signal, such as WWV at 10 MHz, to obtain better than +/- 50 Hz
VFO dial calibration on all bands.

qq014 Operation

This section of the manual explains how to set up and operate the
K2. Refer to the illustrations on the previous pages for control
locations. A comprehensive "mini-manual" is also
available for the K2; see our web site for details.

qq015 connections

Power Supply

You can power the basic K2 (without the KPA100 amplifier)
from any 9-15 V DC power supply. A mating connector for the
DC input jack is provided with the kit. Current drain is typically
1.5-2 A on transmit, but can be over 3 A at the highest power
settings or with high SWR. (See Current Limiting, below.)
Internal Battery: An optional 12 V, 2.9-Ah rechargeable
battery can be installed inside the K2 (model KBT2). A 14.0 V
power supply can then be used to recharge the battery and power
the transceiver. If an external battery is connected, the internal
battery must be disabled using the INT BATTERY switch.
Low Battery Warning: If the supply voltage drops below about
11 V, you’ll see a brief LO BATT message flashed on the LCD
once every 8 minutes (approx.). If this happens, reduce power and
recharge your battery. For tips on battery operation, see page
Self-Resetting Fuse: If the K2's internal 12 V line is shorted to
ground, fuse F1 will temporarily open, limiting current drain to
about 100 mA. The display will remain blank. If this happens,
turn power off until the problem is located and corrected.
Current Limiting: You can specify the maximum transmit
current. You'll see HICUR on the
LCD if the programmed limit is reached.
50/60-Hz Interference: Do not place the K2 beside, or on top
of, any equipment that uses a large AC power transformer. This
could result in modulation of the K2's low-level signal sources.


A well-matched antenna (50 O) or an antenna tuner should be used
with the K2. Some high SWR conditions may result in excessive
current drain unless power is reduced. If you have the KAT2 antenna
tuner option installed, the K2's power control and power output
display will be much more accurate under all SWR conditions.

Keying Devices

Any type of hand key, bug, or external keyer can be plugged into the
KEY jack, or you can use the K2's built-in memory keyer. In all
cases, you must use a stereo plug with the keying device (a suitable
plug is provided with the kit). Also see CW Operation.


A standard 8-pin microphone jack is provided on the front panel. A
jumper block on the front panel PCB is used to configure the mic
jack for specific microphones. Refer to the SSB adapter manual.


Any type of mono or stereo headphones at nearly any impedance
will work with the K2. However, for best results we recommend highquality
stereo headphones with full ear covers and 1/8" (3 mm) plug.

External Speaker

The K2 has a built-in, high-sensitivity 4-ohm speaker. You can also
plug in an external 4 or 8-ohm speaker at the "EXT. SPKR" jack.

Option Connectors

A number of mounting holes are provided on the back panel of the
K2 for specific option connectors. See Options. Two new
holes were recently added to the lower rear panel to provide more
convenient low-level transverter I/O. Refer to the K60XV manual.

qq016 Controls and Display

LCD and Bargraph Meter

The LCD shows the operating frequency and other information
depending on selected display mode. The LED bargraph functions
as an S-meter on receive, and RF out or ALC meter on transmit.
Power-Up Messages: The LCD will display ELECRAFT for
two seconds on power-up. If a problem is detected, the display will
show INFO 100 or a similar message. The number shown
corresponds to a paragraph in the Troubleshooting section.
Mode Indicator: A letter at the right end of the display tells you
the operating mode: C (CW), L (LSB), or U (USB). A fourth
mode, RTTY/data, can also be enabled, and uses the letter r (page
104). If a small bar appears above the C or r , it means that the
CW sideband is inverted (CW reverse or DATA reverse). The mode
indicator will also flash slowly in two cases: CW TEST mode and SPEECH (VOX) mode.
Annunciators: The LCD provides eight Chevron-shaped
annunciators, or status indicators:
NB noise blanker on (flashes if Low Threshold setting is selected using LEVEL)
ANT2 ant. 2 selected (requires ATU)
PRE pre-amp on (approx. +14 dB)
ATTN attenuator in (-10 dB)
A VFO A selected (flashes in SPLIT mode)
B VFO B selected (flashes in SPLIT mode)
RIT RIT turned on (flashes if wide range selected)
XIT XIT turned on (flashes if wide range selected)
Decimal Points: The decimal point to the right of the 1 kHz
digit will flash slowly if the VFO is locked by holding LOCK. See
Advanced Operating Features for other cases where decimal points


You can install an LED on the front panel that will turn on
whenever SPLIT, RIT, or XIT is in effect. See the associated
application note, Adding a SPLIT/RIT/XIT LED to the K2.


AF GAIN receiver audio level
RF GAIN receiver RF level11
Turning this control CCW (counter-clockwise) decreases receiver RF
sensitivity. At the same time it increases the bargraph S-meter
indication to remind you that you’re not at full receive sensitivity.
The farther CCW the control is set, the stronger a signal must be
before it results in a meter deflection.
KEYER keyer speed control
When you turn this control, keyer speed in words per minute (WPM)
will be displayed, e.g. SPD 18 . The speed can be set from about 9 to
50 WPM.
POWER power output control
When you turn this control, power output will be displayed in watts,
e.g. P5.0. The range is 0.1 to 15 W for the basic K2, and 1 to
100 W if you have the KPA100 amplifier installed. See Basic K2
Operation for details on controlling power output (page 93).
This control provides a default range of +/- 0.6 kHz in 10 Hz steps
when RIT and/or XIT are enabled. You can also select a wider
RIT/XIT range.

Switch Functions

Each pushbutton switch as two primary functions, indicated by the
upper and lower labels. TAP a switch to access its upper function;
HOLD a switch for over 1/2 second to access its lower function.
Numeric Keypad: In addition to their tap/hold functions, ten of
the switches are labeled with digits 0 through 9. A digit can be
entered using either a TAP or HOLD (e.g. 5 , or 5 ). In some cases
the difference between the two is significant, as indicated below.

Tap and Hold Functions

BAND+ select next higher band
RCL recall memory #0 -9 (to start scan, use #0 -9 )

BAND - select next lower band
STORE store memory #0 -9 (to start scan, use #0 -9 )

MENU enter the menu
EDIT edit current menu parameter

DISPLAY show voltage/current, time*, DSP parameters
RF/ALC select SSB transmit bargraph mode (RF or ALC)

ANT1/2 toggle between ATU antenna jacks 1 and 2
TUNE key transmitter; activates ATU if installed

NB select noise blanker mode (OFF/NB1/NB2)
LEVEL toggle noise blanker threshold (low or high)

RATE select VFO tuning rate (see RATES menu entry)
LOCK lock/unlock VFO (DP flashes)

MODE select operating mode (CW/LSB/USB)
VOX CW: oper/test; SSB*: PTT/SPEECH (0.2-1.0)

PRE/ATT turn on preamp or attenuator
SPOT CW audio spot signal on/off

RIT turn on RIT
PF1 activate programmable function 1

A/B select A or B VFO
REV temporary A/B VFO swap (used in SPLIT)

CWRV toggle between CW norm/reverse or USB/LSB

XIT turn on XIT
PF2 activate programmable function 2

A=B set both VFO’s to current VFO frequency
SPLIT toggle between SPLIT and NORMAL transceive

XFIL select next crystal filter (FL1-4)
AFIL audio filter mode (OFF, AF1-2, CF1-4, SF1-4)

MSG play or chain CW msg #0 -8 (to repeat, use #0 -8 )
REC record CW message #0 -8 (M S G cancels record)

Two-Switch Combinations (hold both switches)

BAND+ + BAND-: direct frequency entry (e.g., #7 0 4 0 )

PRE/ATT + AGC: AGC on/off (mode letter dec. pt. flashes)

XFIL + AGC: display crystal filter # and bandwidth
(plus audio filter setting, if applicable)

AFIL + SPLIT DSP notch filtering on/off

AFIL + REC: DSP noise reduction on/off

DISPLAY + TUNE: override ATU TUNE power limit

RIT + XFIL: turn FINE RIT on/off

Using the Menu

There are two menus: primary and secondary. You'll use the
primary menu far more often; see list at right.
To access the menu: Tap MENU. The display will show the
menu entry last used, with an underline. For example, you might
see: LCD DA , indicating that the LCD is in "day" mode (i.e.,
backlight off). You can scroll to a desired menu entry by turning
the VFO knob or by tapping the BAND + and BAND - switches.
To modify a menu entry's parameter: Hold EDIT to move the
underline to the parameter, rather than the menu entry name. In
the case of LCD , the parameter can be DAY or NITE . Change
the parameter using the VFO knob or BAND+ / BAND- . When
you’re finished, tap MENU to return to scrolling. Another tap of
MENU will return you to normal operation.
DISPLAY Switch Usage in EDIT Mode: The DISPLAY switch
is used to access supplemental parameters when editing certain
menu entries (marked "*" at right). You will normally not need to
change these settings. Entries which use DISPLAY include:
Entry DISPLAY witch Usage in EDIT mode
STL Selects the sidetone source, U6 - 25 or U8 - 4 . Use
U8 - 4 (default).
T - R Specifies "8R" behavior, 8r hold or 8 r nor .
"Hold" mode (default) holds the 8R line low during
the user-programmed QSK delay.
INP Selects auto-detect mode, ADETOn (default) or
EDIT Shortcut: If the menu entry you want to change is the last
one used, you don't need to tap MENU; just hold EDIT. Change the
parameter as usual, then exit by holding EDIT once more.

Primary Menu Functions

All primary menu functions are listed below. Supplemental parameters accessed
with DIPLAY are marked (*); see explanation at left.

STL: sidetone level (volume): 0-255 (Tone Source*)
ST P: sidetone pitch: 0.40 to 0.80 kHz in 10 Hz steps
T-R: QSK delay: 0.00 to 2.55 sec. (8R Mode*)
RPT: CW message repeat interval: 0 to 255 seconds
INP: CW input selection (Auto-detect on/off*): PDLn (internal keyer/norm. w/auto-detect12) PDLr (internal keyer/reversed w/auto-detect) HAND (hand key or external keying device)
IAB: iambic mode: A or B
SSBA: SSB audio level (mic gain): 1 , 2 , 3 , or BAL
SSBC: SSB speech compression level: 1 - 1 through 4-1 ; in RTTY/data mode, a separate compression level is provided, and the menu entry is SSBCr
LCD: DAY (backlight off, bargraph bright) or NITE (backlight on, bargraph normal)
GRPH: LED bargraph selection: OFF , DOT , BAR (OPT BATT overrides GRPH BAR , forcing DOT mode)
OPT: receiver optimization: PERFormance or BATTery
ATU: ATU operating mode
RANT: RX antenna: OFF or ON , per-band (page 100)
CAL: calibration submenu
PF1/PF2: programmable functions; can be assigned to any menu function, SCAN , or FPon (Fast-Play)

qq017 Calibration Functions

The C A L menu provides the following functions:

FCTR: Frequency counter
CUR: Programmable transmit current limit
TPA: PA temperature set (see KPA100 manual)
SLO: S-meter zero set
S HI: S-meter full-scale sensitivity set
PLL: VFO linearization
FIL: Filter settings (see next page)

After selecting a C A L function, hold EDIT to activate it.

Frequency Counter (CAL FCTR)

CALFCTR displays the frequency of the signal at P6 on the
Control board during alignment.

Transmit Current Limit (CAL CUR)

CALCUR allows you to set a safe maximum transmit current.
The recommended setting is 3.50 A. A lower setting may be
appropriate if you're using 5 watts or less, or if your power supply
has a lower current rating.

S-meter Calibration (CAL S LO, CAL S HI)
To set the S-meter zero level:

  1. Disconnect the antenna.
  2. Make sure the RF GAIN control is fully clockwise (max gain).
  3. Select CALSLO in the menu.
  4. Turn the VFO knob until the left-most bargraph segment is

just barely turned off.
5. Exit CAL mode by tapping MENU.
To set S-meter sensitivity:

  1. Disconnect the antenna.
  2. Turn the RF GAIN control fully counter-clockwise (minimum

3. Select CALSHI in the menu.
4. Turn the VFO knob until the right-most bargraph segment is just
barely turned off.
5. Exit CAL mode by tapping MENU .
Note: The S-meter must be recalibrated anytime the AGC threshold
is changed.

VFO Linearization (CAL PLL)

The CALPLL function automatically calibrates VFO fine-tuning13.
You can repeat CALPLL at any time, although this should not
normally be necessary. One reason you might re-run CALPLL is
after calibrating the frequency counter. In general, you'll need to re-run CALPLL and
CALFIL anytime you change the setting of C22 (Control board),
which is used to align the 4 MHz crystal oscillator.
To Linearize the VFO:

  1. Remove the top cover. The bottom cover must be installed.
  2. Allow a 10-minute warm-up period at room temperature.
  3. Connect the internal frequency counter cable to TP1 (VCO).
  4. Exit the menu if you were using it.
  5. Switch to 40 meters and set the VFO anywhere in the 7000-7100

kHz range.
6. Use the menu to activate CALPLL.
7. When calibration is completed (4-8 minutes), you'll hear a short
alert tone and see E n d on the LCD. You can then tap any
switch to return to normal operation.

Filter Settings (CAL FIL)

This section explains how to use CALFIL to select the
bandwidth and BFO settings. An example appears on the next
page. The Elecraft web site provides information on other filter
setup methods, including a method that uses a personal computer
sound card. For a discussion of how the crystal filter and BFO
settings are related.

Basic CAL FIL Setup

  1. Connect the frequency counter test cable to TP2 (BFO).
  2. Set AF GAIN high enough to hear some background noise.
  3. Switch to a band between 160 m and 17 m. (The sideband is

inverted on 15 m and above, which may be confusing during
filter setup.)
4. Select CW mode using MODE . If a bar appears above the C,
the K2 is in CW Reverse mode; hold CWRV to select CW
Normal mode.
5. Tap XFIL until FL1 is selected.
6. Tap MENU and scroll to CAL . Hold EDIT to move the
underline to OFF , then scroll until you see CALFIL .
Finally, hold EDIT again to activate the filter display.

Filter Bandwidth Display
The initial CALFIL display shows the present filter bandwidth
and the operating mode, e.g. FL 11.50c. The number 1.50
indicates a bandwidth of roughly 1.50 kHz.14 This parameter has
a range of 0.00 TO 2.49. Above 2.49 , the parameter changes to
OP1 TO OP5 , which can be used to select optional filters. For
example, the filter on the SSB adapter (KSB2) is OP1 .
Note the present bandwidth setting, then try using the VFO knob
to change it. You'll hear the "shape" (or pitch) of the noise
change. (Return to the original bandwidth after experimenting.)

BFO Displays
Tap BAND- to display the BFO setting for filter FL1, which will be
similar to BF1t110c. The 3-digit number is the BFO control
parameter. This number can be changed using the VFO knob, but
you'll use a different BFO-setting method described below. The letter
t after BF1 is a reminder that the B F 1 BFO frequency is always used
on transmit, which is important for SSB operation.
Whenever the BFO control parameter is displayed, you can tap
DISPLAY to show the actual BFO frequency in kHz. The VFO knob
can then be used to set the BFO directly. This method is used in the
filter-setup example.
Note: After changing the BFO setting, you can tap AGC to remeasure
and save the BFO information without switching filters. This
is useful if you want to try various BFO settings for a particular filter
to find the one with the best audio peak.

Other CAL FIL Operations
When you're in CALFIL you can always tap XFIL to change to the
next filter, tap MODE to change modes, and hold CWRV to switch
from CW normal to CW reverse. Whenever you switch modes or
filters, the K2 will first record your new settings, if they have been
BAND+ switches to the filter bandwidth display, and BAND- switches
to the BFO display. Tapping M E N U exits CALFIL and returns to
the normal display. (On exit from CALFIL , changes are saved.)
Turning Selected Filters Off
FL2, 3, or 4 can be individually disabled. To turn off a filter, display
the filter bandwidth using CALFIL , then set the bandwidth number
to OFF . (To get to OFF , go to 0.00 first, then turn the VFO knob
a bit farther counter-clockwise.)

CAL FIL Example (setting up all filters):
Table 8-1 shows the recommended filer settings for a CW-only
K2. If you already have the SSB adapter installed, use the SSB
settings from the KSB2 manual.
1. Read the CAL FIL instructions on the previous page if you
haven't already. You'll need to be familiar with CAL FIL
displays and controls before proceeding.
2. Do the Basic CAL FIL Setup from the previous page
exactly as described. You should then see a display similar to
3. Using the VFO knob, set FL1 to the value shown for CW
Normal (1.50). Tap XFIL to save the new value and move to
FL2 . (The CW Reverse bandwidth will also be updated.)
4. Set up FL2, FL3 , and FL4 in the same manner.
5. Use XFIL to return to FL1. Tap BAND- to show BF1.
6. Tap DISPLAY to show the actual BFO frequency. Use the VFO
knob to select the value shown in the table. Typically you'll be
able to get to within +/- 20 Hz of the target frequency.
7. Tap XFIL to save the new value and move to BF2. Repeat steps
6 and 7 to set up BF2, BF3, and BF4 .
8. Switch to CW Reverse by holding CWRV . Then repeat steps 6
and 7 for each CW Reverse BFO setting (BF1 -BF4 ).
9. Tap BAND+ to return to the filter bandwidth display. Use the
MODE switch to select LSB, and return to FL1 using XFIL.
10. Set up each LSB filter bandwidth according to the table. (This
also updates the USB filter bandwidths.)
11. Tap BAND- and set up each LSB BFO as you did for CW.
12. Tap MODE to select USB, and set up each USB BFO.
13. If you use settings that differ from the defaults, record them in
Table 8-2. Use pencil, since you may change them later.

Table 8-1. Recommended Filter and BFO Settings, CW-only K2

Mode: CW Norm
FL1: 1.50 BF1: 4913.6 FL2: 0.70 BF2: 4913.2 FL3: 0.40 BF3: 4913.1 FL4: 0.20 BF4: 4913.1

Mode: CW Rev.
FL1: 1.50 BF1: 4915.0 FL2: 0.70 BF2: 4914.4 FL3: 0.40 BF3: 4914.4 FL4: 0.20 BF4: 4914.4

Mode: LSB
FL1: 2.20 BF1: 4913.7 FL2: 2.00 BF2: 4913.5 FL3: 1.80 BF3: 4913.5 FL4: 1.60 BF4: 4913.5

Mode: USB
FL1: 2.20 BF1: 4916.0 FL2: 2.00 BF2: 4915.6 FL3: 1.80 BF3: 4915.6 FL4: 1.60 BF4: 4915.3

qq018 Basic K2 Operation

Mode Selection
Tap MODE to cycle through the operating modes, noting the
change in the mode indicator letter (C = CW, L = lower sideband,
U = upper sideband). If RTTY/data mode is enabled, r = RTTY/data
will also appear in the mode list.
Sideband Inversion: The K2 inverts the sideband on 15 meters
and above due to the frequency mixing scheme (the upper and lower
sidebands of the signal become reversed). In CW Normal mode, the
pitch of CW signals goes up with frequency on the lower bands; on
15 m and up, the pitch goes down with frequency.

Receiver Configuration
Gain Controls: The RF GAIN control should normally be set
fully clockwise. Adjust the AF GAIN control for comfortable
volume. Sidetone volume is set using STL.

Crystal Filter Selection: Each operating mode provides up to
four filter settings, FL1-FL4. Bandwidth and BFO settings can be
customized using CALFIL. Tapping XFIL cycles
through the filters. FL2, 3, or 4 can also be turned OFF.

Filters and Operating Modes: The CW Normal and CW Reverse
crystal filter selections are tied together. For example, if you switch
to FL2 when in CW Normal mode, CW Reverse also switches to
FL2. The same applies to the LSB and USB modes.

Checking Filter Status: You can check the current filter number
and its bandwidth without changing filters by holding
XFIL + AGC . For example, you might see FL20.80c . If a KAF2
or KDSP2 audio filter is installed and enabled, you'll see audio filter
info after the crystal filter display (e.g. AF1, CF1, SF1 ).

Audio Filter Control: If you have a KAF2 or KDSP2 option
(audio filter and real-time clock) installed, A F I L will control audio
filter selection. Tap DISPLAY to activate other features.

Preamp: The preamp provides about 14 dB gain. If you experience
strong in-band interference, you may want to turn the preamp off.
Attenuator: If necessary, 10 dB of attenuation can be switched in
by turning on the attenuator. This is more effective than using the
RF GAIN control in the case of strong-signal overload.

Scanning: See Advanced Operating Features

Antenna Selection: If you're using a KAT2 or KAT100
automatic antenna tuner, the ANT1/2 switch will toggle between
the two ATU antenna jacks. This also instantly recalls the ATU's
stored L-C parameters for each antenna. Refer to the relevant
ATU manual.

Noise Blanker Controls: The KNB2 option is required to use
these controls. The noise blanker is always turned OFF on powerup,
and you should leave it off unless needed. When it is turned on,
the receiver will be more susceptible to interference from strong
signals. To turn on the noise blanker, tap the N B switch. You’ll see
NB1, NB2, and OFF in that order. The NB1 and NB2 modes
provide short or wide pulse blanking intervals, respectively. One
may be more effective than the other, depending on the type of
noise. In either mode, the NB annunciator will turn on.
The noise blanker provides two thresholds of noise detection: high
and low. If you hold LEVEL the noise blanker will toggle between
these two modes, with the display showing HITHR or LOTHR.
High threshold is the default and should be used in most cases. If
you select low threshold, the noise blanker may be more effective
on certain types of noise, but it will also leave the receiver more
vulnerable to strong in-band signals. When LOTHR is selected,
the NB annunciator flashes as a reminder.

LCD and Bargraph Configuration

Day/Night Selection: For daytime outdoor operation, use the
menu to select LCD DAY (LCD backlight off, and high-brightness
LED bargraph). Indoors or at night, use LCD NITE (backlight on,
reduced bargraph brightness).

Bargraph Modes: You have a choice of OFF, DOT, or BAR for
the LED bargraph. If you select D O T , just one bargraph segment
representing the current meter level will be illuminated. If you
select BAR, all LED segments to the left of the current level will
also be illuminated, resulting in a more visible display. OFF mode
turns off the bargraph completely during receive but uses DOT
mode on transmit (see Advanced Operating Features).

Display Modes: Tapping DISPLAY alternates between frequency
display mode and voltage/current display mode. If you have the
KAF2 or KDSP2 option installed (audio filter and real-time-clock),
a time/date display will also be accessible (plus DSP settings in the
case of the KDSP2).

In frequency display mode, the LCD will show the operating
frequency, mode indicator, and any annunciators that are enabled,
e.g. 24945.04C. This is the display you’ll use most often.
In voltage/current display mode, the LCD will show supply voltage
(E) in 0.1 V increments and supply current (I) in 0.02 A
increments, e.g. E13.8I1.40. This is useful for monitoring battery
condition. It can also be used with a simple voltage probe to check
DC voltages inside the K2. Jumper P7, on the Control board,
selects either 12 V monitoring or the voltage probe (P5). If the
display shows 0.0 volts, P7 may be in the probe position.
In time/date/DSP display mode, the LCD will show either time (e.g.
08.05.00) or date (e.g. 11-28-02) or DSP settings. You can
toggle between time and date by holding BAND+ and BAND-
together. Refer to the KAF2 or KDSP2 manual for details on
setting the time and date as well as other features.

Frequency and Band Selection

The basic K2 covers 80-10 meters, and you can also tune well
above and below the ham bands.16 160 meters can be added with
the K160RX option, and 60 meters with the K60XV. 60-meter
users will probably want to set up channel hopping (see page 99).
Transverter Bands: The K2 provides up to six programmable
transverter band displays for use with external transverters. Refer
to the TRNx menu entry (page 105).
Transmit Limits: Some countries require transmit to be disabled
outside of specified amateur bands. If you key the transmitter with
the VFO set outside fixed limits, you’ll see E n d on the LCD.
You can change bands in one of three ways:

  • tap BAND+ or BAND-
  • hold RCL (memory recall); see below
  • use Direct Frequency Entry (described later)

Whenever you change bands or recall a frequency memory, a
number of parameters are saved in nonvolatile memory
(EEPROM). This update also occurs periodically if you’ve moved
the VFO (see Backup Timer). The parameters that are saved on a
per-band basis include:

  • A and B VFO frequencies and VFO tuning rate
  • Current VFO (A or B)
  • Operating mode (CW, USB, LSB) and CW Normal/reverse
  • AGC slow/fast
  • Preamp and attenuator on/off
  • Noise blanker on/off (requires noise blanker option)
  • ANT1/2 selection (ATU option)
  • Receive antenna on/off (160 m/RX ant. option)

Default Frequency Memories: When you first turn on the K2,
each band memory is preset as follows:
• VFO A is set to the first multiple of 100 kHz above the band
edge (e.g. 7100, 24900).

  • VFO B is set to the U.S. CW QRP frequency for that band
  • Other defaults include: CW mode; VFO A; fast AGC; preamp

ON above 40 meters and OFF on 40 m and below; noise blanker
OFF and high threshold; antenna 2 OFF (antenna 1 selected);
receive antenna OFF (normal receive operation)
Memories #1-8 are preset to the same values as the 160-10 meter
band memories, respectively.

Store and Recall: Ten memories are provided, numbered 0
through 9. Each memory stores the same information that is stored
To store the current setup in a frequency memory, hold STORE
until you see ENTO-9, then tap one of the numeric keypad
switches. To recall a stored setup, hold RCL until you see ENT0-9, then tap the number of the memory you wish to recall. In both
cases you can cancel the operation by tapping any non-numeric
Note: If you hold rather than tap a numeric keypad digit when
doing either a store or recall, you will initiate scanning.

Direct Frequency Entry: To do direct frequency entry, hold both
BAND+ and BAND- simultaneously. When you see "

LCD, release the two switches, then enter the target frequency
using the numeric keypad. To enter a frequency in the 160 meter
band, you must enter 5 digits, starting with a leading 0, e.g. 01835. For other bands below 10 MHz, you need only enter 4 digits
(e.g., 7040). On transverter bands, direct frequency entry can
only be used to go to a new frequency within the present band.
There are three possible results from using direct frequency entry:
• If you enter a frequency within the current band, only the
current VFO will be updated.
• If you enter a frequency that is in a different band, a band
change results, and the entire configuration for the target band
will be loaded, except that the current VFO will now be at the
frequency you just entered.
• If you enter a frequency that is too far outside any available
band, you’ll be switched to the closest available band, and the
frequency will be set to the one last used on that band. For
example, if you try to switch to 8400 kHz--which is typically
outside the range of the synthesizer--the K2 will switch to 40
meters and setup the VFOs as they last were on this band.

Tuning Rates: The VFO tuning rate is selected by tapping RATE.
Default tuning rates include 10 Hz, 50 Hz, and 1 kHz per step,
resulting in 1 kHz, 5 kHz, and 100 kHz per VFO knob turn. Other
tuning rates can be selected; see the RATES menu entry
The frequency display changes to remind you of the current tuning
rate. At 10 Hz/step, two decimal places are shown (100 Hz and 10
Hz). When you select 50 Hz/step, the 10 Hz digit is blank. When
you select 1 kHz/step, both decimal places are blank.

VFO Lock: The current VFO frequency can be locked by holding
the LOCK switch until LOC is displayed. The decimal point will
then flash slowly as a reminder. Split Operation: Lock applies
only to the current (receive) VFO. So, while you are holding the
REV switch (temporary VFO reverse), you can change the
frequency of the other VFO (transmit), overriding lock. This is
very useful when operating SPLIT, since it allows you to check and
modify your transmit frequency without unlocking the receive
Holding the switch again cancels lock and displays NOR (normal).

Power Control

Turn the POWER control to set the power output directly in watts
(e.g., P5.0). The normal range of the control is 0.1 to 15 watts.
If you have the KPA100 option installed and enabled, the range is
0.1 to 110 watts, with the amplifier module disabled at 10 watts or
lower. In CW mode, you must send a few CW characters or press
TUNE to allow the ALC (automatic level control) to lock-in the
new power level.

Requested vs. Actual Power: The POWER control sets the
requested power, which may exceed the actual power that the
transmitter can achieve. To see actual power output, use TUNE (see
below). In tune mode, the display always shows the actual power
output (except when the display is showing voltage and current, or
when the ATU is doing an autotune). The power displayed will be
accurate to within about 10% if the load at the antenna is matched
(50 ohms).

Using TUNE: Hold TUNE to key the transmitter. You’ll hear one
beep when you start tune, and another when you terminate tune by
tapping any switch or hitting the keyer paddle.

ATU: If you're using a KAT2 or KAT100 automatic antenna tuner,
pressing TUNE will drop power to either 2 or 20 watts maximum
(depending on whether the KPA100 is in use), and may trigger a retune
of the antenna matching network. You can also override
power reduction by holding TUNE + DISPLAY.

Transverter Bands: Maximum power output on each transverter
band can be set in watts or milliwatts (the latter requires the K60XV

Current Limiting: To protect the transmitter and power
supply/battery from excess current drain, you can program a
transmit current limit using CALCUR (see Calibration

VFO Selection

To select the A or B VFO, tap A/B . To set the unused VFO equal in
frequency to the current VFO, tap A = B . The currently-selected
VFO will determine both the transmit and receive frequencies unless
you’re running SPLIT (see below). A and B VFO frequencies are
saved in EEPROM on a per-band basis, and are updated periodically
(see Backup Timer at the end of this section).

Split and Reverse Operation

Split operation means transmitting and receiving on different
frequencies. This is useful for DX work, since many DX stations
will ask you to call them above or below their carrier frequency to
avoid interference. To enter split mode, hold SPLIT until the
message SPLIT appears on the LCD. Holding SPLIT in again will
display NOR (normal). The active VFO annunciator (A or B) will
flash slowly when you’re in SPLIT mode to remind you that this
feature is enabled and that your receive and transmit frequencies are
different. Also, each time you transmit when in SPLIT mode, the
transmit frequency is displayed for a minimum of 1/2 second.
When you're using split, you can switch between your transmit and
receive frequencies by tapping A / B . However, there are times when
you only want to quickly listen on your transmit frequency, not
switch VFOs. In this case you can hold in the R E V switch (reverse),
which temporarily swaps the VFOs. When you release REV, the
LCD will return immediately to the receive frequency. When using
split, experienced operators can simultaneously hold in the REV
switch and adjust the VFO knob--all with one hand--to quickly find
a clear spot to transmit. (REV overrides VFO lock as described
You can install an LED on the front panel that will turn on
whenever SPLIT, RIT, or XIT is in effect. See the associated
application note, Adding a SPLIT/RIT/XIT LED to the K2.


You can turn on RIT (receive incremental tuning) by tapping RIT.
The RIT annunciator then turns on. It flashes slowly if you have
selected a wide-range RIT/XIT offset (see RIT menu entry, page
104). The OFFSET knob controls the receive offset.
The +1 and -1 kHz marks on the offset control apply only if the
RIT/XIT range is set to +/- 1.2 kHz using the RIT menu entry.
Regardless of the range used, the exact offset can be determined by
comparing the VFO frequencies with RIT on and off.17
When XIT is turned on, it works similarly to RIT, except that the
transmit frequency is varied with the OFFSET control. This can be
useful for small-split operation (for example, when a DX station
you're listening to says to call "UP 1" kHz), or to adjust your
transmitted frequency at the request of another station. The
transmitted frequency is not displayed during receive mode, so if
you need to determine the exact setting of the offset control when
using XIT, you can briefly turn on RIT.
It's OK to have both XIT and RIT on at the same time. In this case
the OFFSET control can be thought of as an extension to the main
tuning knob, but covering only a small frequency range.
As with SPLIT, if you have RIT or XIT enabled, the transmit
frequency will be displayed when you transmit, and the receive
frequency will be restored a minimum of 1/2 second later.
FINE RIT: In some cases you may want to control the VFO in
smaller steps to fine-tune signals on receive. This can be done using
the FINE RIT feature.

Automatic Antenna Tuner (ATU)

Both the low-power internal automatic antenna tuner (model
KAT2) and high-power external antenna tuner (KAT100) can
match nearly any coax-fed or random-length antenna on multiple
bands. ATU functions will be covered briefly here; refer to the
specific ATU manual for details.
The operating mode of the KAT2 or KAT100 is selected using the
ATU menu entry, and is normally set to AUTO. The menu entry
also allows you to see the L and C selection, step through ATU
relays, etc. Note: If you have both a KAT2 and a KAT100
connected to your K2, the ATU menu entry will control only the
KAT100. The KAT2 will be placed in through mode (L and C = 0),
and will be set to antenna 1.
The ATU is activated whenever you press TUNE. The K2 display
will show SWR or forward/reflected power, depending on the tuner's
mode. If a KPA100 is installed, its T U N E display will be used. Power
is reduced to 2 watts during TUNE mode (20 watts if the KPA100
is enabled). This power reduction can be overridden by holding
TUNE+DISPLAY. In this case, no auto-tune will be attempted.
Two antenna jacks are provided on both ATUs, with the matching
network data for both antennas stored on a per-band basis. You can
tap ANT1/2 to switch antennas. Since the relays take only a small
fraction of a second to switch, it becomes practical to quickly try
both antennas anytime the distant station is weak. This is
particularly useful for Field-Day and similar contests, where you
might use two end-fed random wires running in different directions.

Backup Timer

While you're moving the VFO, a 30-second data backup timer is
being continuously re-started. Once you have completely stopped
tuning the VFO for at least 30 seconds, the K2 will then save your
current operating frequency in EEPROM. As long as you stay on a
particular frequency, no further updates will be done.

qq019 CW Operation

The K2 provides a number of features for the CW operator:
- fast I.F.-derived AGC with fast/slow/off control
- full break-in operation with no relays
- accurate control of sidetone volume and sidetone pitch/offset
- memory keyer with Iambic modes A and B,
- nine programmable message buffers; chaining and auto-repeat
- software-selectable paddle selection (normal or reverse)
- multiple crystal filter bandwidths and opposite-sideband CW
- dedicated S P O T switch for accurate signal pitch matching.
- optional analog or digital audio filter
Several advanced CW features are covered in later sections:
- Fast-Play ("one touch") message buffers
- Adjustable keying weight
- "smart" CW signal scanning
- FINE RIT for fine-tuning CW signals

Keying Device Selection

A single connector in the back is provided for your keyer paddle,
hand key, keyer, or computer. It is also possible to connect both a
paddle and an external keyer or computer at the same time (see
External Keying Auto-Detect, below).
You must use a stereo (2-circuit) plug, even if you use only a hand
key or external keyer. This should not affect the use of the keying
device with other equipment, since the middle contact on the plug
(often called the "ring" contact) is only used with keyer paddles.

Hand key or External Keying Device: To use a hand key or
external keying device, select INPHAND using the menu. Use the
"tip" contact (DOT) of the key jack with a hand key or external
keying device. You can key the K2 externally at up to 70 WPM.

Internal Keyer: To use a keyer paddle, use the menu to choose
INPPDLn or INPPDLr (normal or reverse paddle). With
PDLn selected, the "tip" contact on the stereo key jack is DOT
and "ring" (the middle contact) is DASH. PDLr is the reverse.

External Keying Auto-Detect: If you wish to connect a
handkey, external keyer or computer along with a keyer paddle,
you can use the K2’s "auto-detect" feature. Simply connect your
external keying device to the DOT and DASH lines through two
diodes as shown in Figure 8-1, along with the keyer paddle. Be sure
you have selected INPPDLn or INPPDLR in the menu.

When you connect the keying devices in this way, you can
continue to use the paddle as usual. But if the external keying
device is keyed, both the DOT and DASH lines will be pulled low
simultaneously via the diodes. The K2 firmware interprets this as
direct external keying rather than as DOT or DASH triggers.
Auto Detect can be turned off if desired. Find the I N P menu entry,
EDIT the parameter, then tap DISPLAY to select ADE OFF.

Basic CW Setup

Mode Selection: To place the rig in CW mode, tap the MODE
switch until the mode indicator changes to C.

Filter Selection: Select a crystal filter using the XFIL switch. FL1
is usually configured as the widest filter. Similarly, use AFIL to
select an audio filter (requires KAF2 or KDSP2). Note: If you have
the KSB2 installed, you can use CALFIL to configure FL1 as OP1
(SSB option filter) in CW and CW reverse modes, and leave FL2-4
at the narrower factory defaults (0.7, 0.4, and 0.2). Details on how
to do this setup can be found in the SSB adapter manual.

CW Frequency Display: In CW mode, the frequency shown on
the LCD takes into account an offset equal to your sidetone pitch.
This allows you to determine a station's actual carrier frequency by
matching their pitch to your sidetone, rather than by zero-beating
the signal. The SPOT switch can be used for this purpose.

Operate vs. Test mode: If you want to try out the keying
without actually transmitting, hold the VOX switch until the display
shows TEST. The mode letter C on the LCD will flash to remind
you that you have disabled transmit. Holding the VOX switch in
again returns to OPERATE.

Sidetone Setup: Key the rig in TEST mode and listen to the
sidetone volume and pitch. To change the volume, use the menu’s
STL entry (sidetone level). The pitch can be changed using the
S T P entry (sidetone pitch). STL is used often, so you might
want to assign it to PF1 or PF2 (see Advanced Operating Features).

Break-in (QSK) delay: The QSK delay is set using the T-R menu
option. A setting of 0.00 is fastest, although you may prefer the
break-in sound with 0.01 selected, especially when using
headphones. 0.05 is about right for casual operation. You can
select a longer delay (up to 2.5 seconds) for slower CW work or to
prevent un-muting when sending a repeating beacon message.

The SPOT Switch

The SPOT switch can be used to zero-in on received signals or to
test your sidetone pitch quickly, without having to key the
transmitter or enter the menu. It’s important to use SPOT before
using CW reverse. Once a signal has been SPOTted, you’ll only
hear a slight change in pitch when you use the CWRV switch.
When you use SPOT, receiver audio will not be muted. This allows
you to listen to another station and turn the VFO knob until the
pitch of the received signal matches that of the sidetone. Once the
two match, you’ll be very close to the station’s frequency if you
call. (Exception: If you’re using RIT, XIT, or SPLIT, your transmit
and receive frequencies will differ by more than just the normal
transmit/receive offset. Turn off these features when using SPOT.)
Matching audio pitch may be difficult for some operators.
Basically, you’ll need to tune the VFO up and down until the station
you’re hearing seems to "disappear" under the sidetone--that is,
until you can’t hear any difference between the two. When this
happens, you’ll know the two pitches are matched.

Using the Internal Keyer

Two menu entries are provided to set up the keyer:
- IAB allows you to select Iambic mode A or B . (Mode A is
similar to Curtis mode A; mode B is similar to Super CMOS
Keyer III mode B. If you aren't sure which to use, start with
mode A, which has less critical timing requirements.)
- INP selects paddle normal (PDLn ), paddle reverse (PDLr ), or
hand key/ext. keyer (HAND )
These settings are stored in EEPROM, so you won’t lose them
when you turn power off.
Use the KEYER control to select the desired CW speed. The
display shows the speed in WPM as soon as you start turning the
knob. You can adjust the keyer speed even while transmitting.

Message Memories

The K2 provides nine CW message memories of 250 bytes each.
Playback features include message repeat and 1-level chaining. CW
messages can only be recorded using a keyer paddle connected
directly to the K2's key jack. Set INP to PDLn or PDLr.
To record a message: Hold REC, and when prompted tap a
numbered switch (#0 -8 ) to select one of the nine message buffers.
The display will then show REC 250, indicating that 250 bytes of
storage are available in this message buffer. This number will count
down toward 0 as long as you are sending. Whenever you stop
sending, up to two standard-length word spaces will be inserted. To
stop recording, tap MSG. If you do this before starting to send, the
original message contents will not be lost.
To play back a message: Tap MSG, then select a message buffer
(#0 -8 ). Message play can be canceled at any time by hitting M S G
again or by tapping the keyer paddle. To listen to a message
without transmitting, use TEST mode (VOX switch).
Auto-Repeat: Any message memory can be auto-repeated when
played. To auto-repeat, tap M S G as usual, then hold the desired
numbered switch (#0 -8 ). The message will then play back
continuously until you tap M S G again or hit your key or paddle.
The buffer # will flash at the end of each transmission (e.g., B 6 ).
Note: You cannot change the frequency with the VFO knob during
a repeating message, but you can use RIT (if enabled) to listen
above and below your receive frequency between calls.
Setting the Auto-Repeat Interval: The length of the pause
between messages during auto-repeat can be programmed using the
RPT menu entry (0-255 sec.). Long delays are useful for beacons.
Message Chaining and chain/repeat: While a message is
playing, you can tap #0 -8 to chain a message onto the end of the
current one. The buffer number will be displayed twice: once when
you hit the numbered switch, and again when the chained message
starts. To chain a repeating message onto the current message,
HOLD rather than TAP the numbered switch (i.e., use #0 -8 ).
Chaining is useful during contests. For example, you might set up
message 5 as "QSL 73" and message 6 as "CQ TEST DE N6KR."
You could then hit M S G 5 6 at the end of a QSO to sign with the
previous contact, then begin a repeating CQ.

CW Reverse

CW Reverse allows you to listen to CW using the opposite
sideband. Sometimes this can eliminate or reduce interference from
a strong station without reducing the strength of the desired signal.
To switch to the opposite sideband, hold the CWRV (CW reverse)
switch. A bar will appear above the mode letter C on the LCD. (Use
SPOT first to stay on frequency when you switch to CW reverse.)

Sidetone Pitch and Receive Offset

When you change the sidetone pitch using the STP menu entry,
you’re also changing the CW receive offset. The two always match
within approximately 10 Hz. This ensures that when you listen to
other stations at same pitch as the sidetone, your transmitted signal
will be right on that station’s frequency.
To see how the receive offset tracks the sidetone pitch: Use SPOT
to tune in a station at your current sidetone pitch as described
earlier. Then use STP to change the pitch. As soon as you exit
the menu, you’ll notice that the station you were listening to has
also been shifted to the new sidetone pitch.
Changing the sidetone pitch does not automatically re-adjust the
BFO frequencies in relation to the crystal filter passband. So if you
change your sidetone pitch, you should use CALFIL to manually
optimize the BFO settings.

qq020 SSB Operation

You can receive SSB and data-mode signals with a basic K2, but
transmitting in these modes requires a KSB2 SSB adapter. For
complete details on SSB transmit, refer to the KSB2 manual.

SSB Controls

Operating Mode: Use MODE to select L (LSB) or U (USB). To
alternate directly between USB and LSB, use CWRV. LSB is usually
used on 40 meters and below, and USB is used on the higher bands.

Crystal Filter Selection: If the SSB adapter is installed, you'll be
able to take advantage of its 7-pole fixed-bandwidth filter,
designated OP1 in CALFIL. This filter can be used in all modes.

DSP Filtering, Notch, and Noise Reduction: Refer to the
KDSP2 option manual for details on these features.

SSB Menu Entries: SSBA is used to set the mic audio level (mic
gain), from 1 to 3 . An additional setting, B A L , is used during SSB
adapter alignment. SSBC is used to set the speech compression
level, from 1 - 1 to 4 - 1 . Higher settings add "punch" and are
especially useful at low power levels.

PTT/VOX Selection: By default the K2 uses PTT (push-to-talk)
via your mic's PTT switch. To use VOX (voice-operated transmit),
hold the VOX switch until you see SPCH0.2 ,0.4 , or 1.0 on the
LCD. The number 0.2 - 1.0 is the VOX delay time in seconds.
Holding V O X again restores the setting to PTT.

Power/ALC Metering: If you have the SSB adapter installed,
you’ll be able to switch between RF and ALC bargraph meter modes
by holding RF/ALC. ALC metering is used only in SSB modes, and
may help in setting the mic gain and speech compression level. The
ALC reading starts from the right end of the bargraph rather than
the left, using BAR mode, so you won’t confuse it with the RF
display. Use RF meter mode except when checking ALC level.

Microphone Configuration

You’ll need to configure the MIC CONFIG header on the Front
Panel board in order to transmit SSB on the K2. Most microphones
with standard 8-pin connectors can be used. All Elecraft
microphones include 8 small jumper blocks to simply installation.
On many mics, the Up and Down buttons can be configured to
switch between VFO A and B. You'll hear one beep on switching to
VFO A, and two beeps when switching to VFO B.

RTTY/Data Operation

RTTY/data operation can be accomplished in SSB modes by using
AFSK (audio frequency shift keying) or other modulation modes.
Audio must be fed into the mic jack from a computer or modem,
and the K2’s audio output routed to the computer or modem from
either the headphone or speaker jack. Either LSB or USB can be
used; this will probably be determined by your software. You can use
either the SSB adapter's fixed filter (OP1) or the variablebandwidth
crystal filter for receive purposes. On transmit, OP1 is
always used.
Since some RTTY/data mode duty cycles approach 100%, you
should reduce power to about 5W or avoid transmitting at 10W for
longer than 1-2 minutes at a time. (Power levels above 10 W are
not recommended.) You can key the transmitter via either the key
jack or the mic jack, since the DOT line is also the PTT line.
RTTY/Data Mode (mode letter r ): This is a special fourth mode
of operation that provides independent crystal filter selections for
use with RTTY, PSK31, etc. For details on configuring and using
RTTY/data mode, see page 104.
FINE RIT: Fine RIT allows you to vary the receive frequency in
increments smaller than 10 Hz. This is especially useful with
PSK31 and other narrow-band data modes.

qq021 Advanced Operating Features

A number of specialized operating techniques are described in this
- Scanning and channel hopping (see below)
- Reducing current drain for portable operation
- Using a separate receive antenna
- Programming the PF1/PF2 functions
- AGC on/off control
- VFO frequency calibration techniques
- Checking firmware revision numbers
- Resetting to factory defaults
- Using computer control of the K2
- FINE RIT mode

Scanning and Channel Hopping

The K2's scanning features let the K2 tune any band segment
continuously, or channel-hop among two or more memories, with
or without the receiver squelched. Scanning when squelched allows
the K2 to ignore stable carriers (key-down signals with no
modulation), stopping only when "interesting" signals are found.
Scanning with the receiver "live" (unsquelched) is especially useful
when listening for weak signals on very quiet bands.
60-Meter Channels: Channel-hopping (manually or using scan) is
intended primarily for use on 60 meters. The present U.S. 60-meter
channel designations are 5330.5, 5346.5, 5366.5, 5371.5, and
5403.5 kHz (USB only). Typically these would be programmed
into memories 1-5. See channel hopping details at right.
Scan Resume: Scan-mode users may wish to use the menu to
program P F 2 (or P F 1 ) as SCAN RESUME. Holding that switch will
then re-start scan without having to use the RCL/STORE method.

To use continuous scanning (from VFO A to VFO B):
- Setup VFOs A and B for the two ends of the band of interest.
VFO A must be set for a frequency lower than VFO B.
- Select the operating mode, preamp/attenuator setting, and
tuning rate (RATE ). Select a narrow filter if the band is noisy.
- Store this setting in any memory (using the STORE switch), but
instead of tapping the switch for the desired memory, hold the
numbered switch (0 -9 ) until you see SCAN on the display. You
can also initiate scanning when you recall a stored memory.
Just hold RCL, then hold the numbered switch, as with STORE.
The memories can store up to 10 scan ranges for instant recall.
- To scan with the receiver live (unsquelched), continue to hold
the numbered button until you see AFON. If the tuning rate is
set for 10 Hz steps, live scanning proceeds at 50 kHz/minute.
- During squelched scanning, when a station is found, the receiver
will un-squelch and will stay on that frequency for about 25
seconds or until the signal fades.
- You can stop scanning by tapping any switch, key, or PTT.
- Use SCAN RESUME (PF1 or PF2 , see at left) to restart scan.
To resume "live" scanning, hold until you see AFON.

To use channel hopping (manually or with scanning):
- Set up and STORE two or more memories for the target band
(using VFO A only). Then choose one memory as the
"initializer" to be used when starting channel scan, and RCL it.
- Edit the RATES secondary menu parameter; tap
DISPLAY to select CHSC (channel scan) or CHSC-TN
(channel scan plus manual hopping); exit the menu; STORE
this memory. If manual hopping is enabled, you can now use
the VFO to hop among memories assigned to this band.
- Scanning can be initiated via RCL or STORE. The scan rate is
0.2 seconds per channel (0.5 seconds per channel for "live"
scanning). Note: VFO B can be set up differently on a perchannel
basis for split operation, if desired, or you can fine-tune
channels when necessary by turning on both RIT and XIT.

Reducing Current Drain for Portable Operation
You can use any of the methods listed below to reduce receivemode
current drain and thus extend battery life. These techniques
will have only a small effect on transmit current drain, however.
Reduce power output to the lowest effective level if you're
transmitting frequently on a weak battery.
- Use headphones or reduce speaker volume.
- Turn off the RF preamp.
- Set GRPH to DOT mode. There's also an OFF mode, which
completely disables the S-meter and forces DOT mode for
transmit power display.
- Set OPT (Optimization) to BATT (battery); this reduces the
I.F. post-mixer amplifier current by about 40 mA and
automatically forces the bargraph to use DOT mode if set for
BAR. Receive performance is minimally affected by this
setting unless you have very strong in-band stations nearby.
- Set LCD to DAY to turn off the LCD backlight. This is most
effective if you also set GRPH to OFF , since each bargraph
LED segment that is turned on in DAY mode uses about 18
mA. (Each segment uses only 6 mA in NITE mode.)
Note: Voltage/current display mode can be used to verify the effect
of each setting.

Using a Separate Receive Antenna
The 160 m/RXANT option (K160RX) provides a separate receive
antenna which can be enabled on a pre-band basis.
To enable the receive antenna: Switch to the desired band. Use
the menu to change the RANT option to ON. The preamp and
attenuator settings with RANTON can be set independently from
of their normal settings. If you switch between the normal and
receive antennas often, you can program PF1 or PF2 as RANT,
and it will switch immediately (one switch press).

Programmable Function Switches (PF1/PF2)
The PF1 and PF2 switches (below RIT and XIT, respectively) can
be programmed as direct edit shortcuts to any two menu entries of
your choice, including secondary menu entries. Two
special functions can also be assigned to PF1 or PF2: Fast Play and SCAN RESUME.
To program PF1 or PF2: Enter the menu and scroll to PF1 or
PF2, then change the parameter to the desired entry. Exit the
To use PF1 or PF2: HOLD one of these switches to activate the
selected menu shortcut, then change the menu parameter (which
will be underlined) using the VFO knob or BAND+/BAND-. To
return to normal operation, tap any switch or the keyer paddle.
Exceptions: the FPon, SCAN and RANT functions take effect
Using PF1 or PF2 as secondary menu shortcuts: Enter the
menu and scroll to PF1 or PF2. To switch to the secondary menu
entries, tap DISPLAY. (Tapping DISPLAY again will return to the
primary menu entries.) Select the desired parameter, then exit the

AGC On/Off Control
Some operators prefer to turn AGC off and use manual RF GAIN
control under certain weak-signal conditions.
To turn off AGC: Hold both the PRE/ATT and AGC switches
simultaneously. Release the switches when you see OFF flashed on
the LCD. To remind you that AGC is off, the decimal point to the
left of the mode indicator will flash slowly. Received signals will no
longer affect the S-meter level. Turning the RF GAIN control
counter-clockwise will increase the S-meter reading.

Frequency Calibration Techniques
The VFO is only as accurate as the 4.000 MHz oscillator on the
Control board, which is calibrated using C22. C22 can be fine-tuned

using one of the following methods:

Using an External Counter or Ham-Band Receiver:
These methods are described in detail in Alignment, Part II (4 MHz
Oscillator Calibration). After setting C22 using either
technique, you must re-run CALPLL (with the counter probe on
TP1). You'll also need to use CALFIL (with the probe on TP2)
to re-adjust each BFO setting, which will allow the K2 to store new,
more accurate BFO frequency measurements.

Using a Calibrated Signal Source:
You can calibrate C22 using a signal generator, ham transmitter, or
strong AM carrier such as WWV at 10 MHz. The K2’s receiver is
used to zero-beat this signal to determine how far off the VFO is,
then C22 is adjusted to compensate. Here's the procedure:

  1. Select LSB or USB mode on the K2.
  2. Zero-beat the calibrated signal source on the K2, then note the

VFO dial error. For example, 10 MHz WWV might zero-beat at
10000.20 kHz. The error is then 10000.20 - 10000.00 =
+0.20. Do not move the VFO from this position.
3. Connect the K2's internal counter to the VCO test point
4. Select and activate CALFCTR using the menu.
5. Note the displayed VCO frequency. (In this example, 14913.88
kHz. Your VCO frequency will be somewhat different.)
6. Subtract the VFO dial error from the VCO to obtain a target
VCO frequency. (In our example, 14913.88 - 0.20 =
7. Adjust C22 until the VCO is at the target frequency.
8. Re-run CALPLL (see Calibration Functions). Tap MENU to
exit CALPLL when "End" appears.
9. Move the counter probe to TP2 (BFO). Using CALFIL,
change the BFO control parameter for the filter presently
being used by at least one count, then return it to the original
setting. Tap MENU to exit without switching filters. This will
force the K2 to re-measure the BFO frequency.
10. Repeat step 2. If the VFO dial is still off, repeat steps 3 - 9.
11. Modify all BFO settings using CALFIL (as in step 9).

Firmware Revision Numbers
You can check the K2's main microcontroller and I/O
controller firmware revisions by holding in any switch on powerup.
Two numbers will then be displayed briefly. For example, you
might see 2.04 P1.09. The first number is the main
microcontroller's firmware revision and letter suffix. The second
number is the I/O controller's firmware revision.
The KAT2 or KAT100 firmware revision is one of the parameters
in the ATU submenu, e.g. F1.00. The KPA100 firmware revision
can be found in the P A submenu. The KSB2 firmware revision can
be obtained by first setting the SSBA menu entry to BAL, then
holding the VOX switch. (Return the SSBA menu entry to its
normal setting after checking the firmware revision.)
The firmware revisions for other options may also be accessible;
refer to the individual option manuals.

Resetting the Configuration to Factory Defaults
You should reset configuration data to defaults only if the K2’s
EEPROM is accidentally corrupted. (This is extremely unlikely to
happen.) The most likely symptom that this has occurred would be
an unexpected frequency setting showing up on a particular band, or
strange characters appearing on the LCD. Before resetting the
configuration to defaults, try simply re-entering the correct
frequency and storing it in the affected memory.
If you find it necessary to reset to defaults, record the following data

  • filter and BFO settings for all modes/filters (using CAL FIL)
  • other CAL parameters, e.g. S-meter HI/LO, current limiting
  • primary menu parameters
  • secondary menu parameters, if applicable

To reset to defaults: Turn the K2 off, then hold down the 4,5,
and 6 switches, and turn power back on. The EEPROM will be
rewritten with factory defaults. You can then re-enter the data
saved above using the menu functions. Re-doing CAL PLL is also

Computer Control of the K2
If you have the RS232 interface adapter installed (model KIO2), or
the 100-watt stage (KPA100), you’ll be able to use a computer to
control the K2. Both the KIO2 and KPA100 provide true RS232
levels (at 4800 baud), with no need for a level converter.
The K2's computer-control capabilities are compatible with nearly
all contesting, logging, and remote-control software, including
Elecraft's k2remote and k2voice programs. Control over the
internet is also possible. You can write your own programs as well
(see the KIO2 Programmer's Reference, on our web site).
Refer to the KIO2 or KPA100 manuals for additional details.

Fine RIT Mode
The K2's FINE RIT feature provides receiver tuning in steps
smaller than 10 Hz. The primary use of FINE RIT is for data
modes such as PSK31, which can benefit from a reduction in T/R
frequency shift between FL1 and one other filter18. FINE RIT mode
is only effective for this if FL1 is configured as O P 1 (SSB crystal
filter). FINE RIT can also be used to accurately zero-beat AM
stations, or to fine-tune CW signals when a narrow filter is used.
Limitations: Entering FINE RIT mode turns off SPLIT, RIT, and
XIT, which cannot be used in combination with FINE RIT. If you
move the VFO while using FINE RIT, you may need to readjust the
OFFSET control due to small differences in linearity over the
VFO's tuning range.
To use FINE RIT: Select a narrow data-mode filter (FL2 - FL4)
using XFIL. Next, hold RIT and XFIL together; the display will
show FINE ON, and the RIT and XIT annunciators will alternate
on/off slowly. Only FL1 and the selected narrow filter will now be
available; the other two will be temporarily disabled. You can then
use the OFFSET knob to fine-adjust the signal pitch of the narrow
filter without affecting the pitch of FL1. Turning the OFFSET
knob will display the filter selection and the FINE RIT offset, from
-15 to +15 units (e.g., FL3 - 12). One unit is about 1 to 3 Hz
(finer on lower bands). When you transmit (always through OP1),
you will be closer to the received station's carrier frequency, and on
receive, switching filters will result in few if any lost characters.

To cancel FINE RIT: Hold RIT + XFIL, or change modes or bands.
FINE OFF will be displayed.

qq022 Secondary Menu Functions

To access the secondary menu, tap MENU, then tap DISPLAY.
You'll see SEC. All secondary menu functions are listed and
described here. Additional parameters accessed with DISPLAY
during EDIT mode are marked (*); see below.

SLCH Squelch level
RATES RATE switch selections
DOT Dot/space ratio (keying weight)
FPLY Fast Play switch selections
PORT RS232 interface on/off (Port Test*)
SPLT SPLIT, RIT, XIT configuration
Po2810/12 meter SSB power output limit
RTTY RTTY (data) mode control
RTC Real-time clock control
RIT RIT/XIT offset range (up to +/- 4.8 kHz)
ACC Accessory output control
D19 Leave at default (n ) unless K60XV option installed
PAK2/100 final stage mode selection (Fan Mode*)
TRN1-3/4-6 Transverter band setup (Parameter*)

DISPLAY Switch Usage in EDIT Mode: The DISPLAY switch is
used to access supplemental parameters when editing certain menu
entries (marked "*" above). You will normally not need to change
these settings. Entries which use DISPLAY include:

Menu Entry DISPLAY Usage
PORT Sends an RS232 test message if PORT is ON
PA Selects PA fan mode (see KPA100 manual)
TRN1-6 Selects transverter parameter
D19 Selects PA low-pass filter to use on 60 meters.
PA60 = 80 (80 m filter) or PA60 = 40 (40/30 m
filter). See instructions in K60XV manual.

Squelch (SLCH)
Squelch defaults to OFF. You can set the threshold to 1-10,
corresponding to the S-meter's bargraph segments. Transmitting
holds squelch open for about 10 seconds.

Tuning Rate Selection (RATES)
The RATES menu entry lets you specify how the RATE switch
works. The four options are:
3N3 rates, normal order (10/50/1000 Hz steps)
3R3 rates, reverse order (1000/50/10 Hz steps)
3C3 rates, CW optimized (10/20/1000 Hz steps)
22 rates (10/50 Hz steps only)

Keying Weight (DOT)
DOT sets the internal keyer's dot/space ratio (keying weight). The
range is 0.90-1.40, roughly 90% to 140% of "normal" weighting.
The default is 1.1

Fast-Play CW Messages (FPLY)
CW messages are normally played by tapping MSG, then 0-8 .
During contests, some operators prefer to have one-touch access,
which we refer to as Fast-Play.
To use Fast-Play: First, program PF1 or PF2 as FPon for use in
turning Fast-Play mode on/off. Next, use the FPLY menu entry to
select a switch group. For example, if you have FPLY2-5
selected, you can use 2,3,4, and 5 for Fast-Play. (The TAP
functions of these switches won't be available in CW mode; HOLD
functions are unaffected.) When Fast-Play is on, the letter F will
replace the mode letter c once every few seconds as a reminder.
A tap of any Fast-Play switch will play its message buffer one time.
To auto-repeat, you must still use MSG.

RS232 Interface Setup (PORT)
Use the PORT menu entry to turn on 4800-baud RS232
communication. When PORT is ON , tapping DISPLAY sends an
"FA" command (VFO A frequency) for test purposes. Refer to the
KIO2 or KPA100 manual for details.

SPLIT/RIT/XIT Configuration (SPLT)
Normally, the K2's SPLIT, RIT, and XIT selections stay the same
as you switch from one band to the next. To have these selections
stored on a per-band basis and retained when power is off, set
SPLT to PER(per-band).

10 and 12 m Power Limit in SSB/RTTY Modes (Po28)
The highest distortion-free single-sideband power output level may
be less than 15 watts, especially on 10 and 12 m. We recommend
leaving Po28 at 10.0 watts. (Does not apply to CW mode.)

RTTY/Data Mode (RTTY)
RTTY/Data mode (mode letter lower-case r ), if enabled, provides
four independent crystal filter settings for use with data modes. To
enable RTTY/Data mode, set the RTTY menu parameter to ON.
The MODE list will then include C,L,U and r. r-NORMAL mode
uses lower sideband, and r -REVERSE (with a "bar" over the r ) uses
upper sideband. To select r -REVERSE, hold the CWRV switch.
(FINE RIT is also very useful in data modes).
Filter configuration (CALFIL): r mode defaults to the same
settings as LSB and USB. Use CALFIL (on 17 meters or below) to
modify the r -mode filter bandwidths or BFO settings as needed.
Speech compression (SSBCr): The SSBC menu entry will
change to SSBCr when r mode is selected. A setting of 1-1 (1:1,
or speech compression off) is recommended for RTTY/data.

Real-Time Clock (RTC)
If RTC is set to ON and a KAF2 or KDSP2 option is installed, the
DISPLAY switch can access a time or date display. (The KDSP2
also provides DSP features which are accessible via the DISPLAY
switch.) Refer to the KAF2 or KDSP2 manual.

RIT/XIT Range Selection (RIT)
RIT is used to select one of four RIT/XIT OFFSET ranges. If the
selected range is +/- 1 . 2 kHz or higher, the RIT/XIT annunciators
flash whenever RIT or XIT are turned on.

Accessory Outputs (ACC)
This menu entry can be used in conjunction with the Elecraft KRC2
programmable band decoder to control equipment external to the
K2. Refer to the KRC2 manual for details.

Extended VFO Range (D19)
Leave D 1 9 set to the default, n (no), unless you have installed
varactor diodes D19 and D20 in conjunction with the K60XV
option (60 meters plus low-level transverter I/O). At that time the
parameter should be set to Y .
Note: Do not install D19 and D20 until the K60XV option is

K2/100 Mode Selection (PA)
If you have the KPA100 option installed, the P A menu entry
shows the 100-watt stage's operating mode. While editing the P A
parameter, tapping DISPLAY selects the fan mode (nor, LoHi,
Hi). For more details, refer to the KPA100 manual (Appendix G of
the K2 owner's manual, which is supplied with the KPA100 kit).

Transverter Bands (TRN1-TRN6)
Six user-definable bands are provided for use with transverters. Once
enabled individually using the TRN1-3/4-6 menu entries, these
bands will appear in the band rotation following 10 meters. You can
use Elecraft XV-Series transverters and most other transverter
types with the K2.
Transverter switching: Up to six Elecraft XV-Series transverters
can be controlled automatically using the K60XV option (60 meter
adapter and low-level transverter I/O). Refer to the K60XV manual
for further details.
Transverter configuration: These bands are set up using the
TRN1-3/4-6 menu entries. First, tap MENU, select the secondary
menu (SEC) using DISPLAY, and scroll to TRN1,2, or 3.
(Tapping ANT1/2 switches to TRN4-6.) Next, hold EDIT to
highlight the first parameter. You can then tap DISPLAY to rotate
through the parameters. Finally, change parameters as needed using
the VFO knob or BAND+/BAND-. Changes take effect when you
exit EDIT mode.
ON/OFF Set to ON to enable this transverter band
RF Transverter operating frequency (0-999
MHz; GHz digits not used)
IF K2 band to use as the I.F. (7, 14, 21, or 28
OFS Display offset (+/- 9.99 kHz); calibrate
based on transverter oscillator offset, if any
OUT Power output limit, L0.01-L1. 27 mW
(requires K60XV) or H00.0-H12.7 watts;
can reduce setting using POWER control
ADR Elecraft XV-Series transverter selection
address (see K60XV manual)
Using transverter bands: When you switch to a transverter band
(using BAND+/BAND-), the message TRN1, 2 or 3 is flashed.
The LCD shows up to 999 MHz by shifting one place to the right.
Note: If you select 10 Hz tuning steps with RATE, the hundreds of
MHz digit will briefly disappear so you can see the 10-Hz digit.
Direct Frequency Entry on transverter bands is in-band only. For
bands over 99 MHz, the first digit is made part of the prompt. For
example, on a transverter band in the 430 MHz range, you'd see
- - - - 4 when you hold BAND+ and BAND- together to initiate
Direct Frequency Entry. To get to 432.100 MHz, you'd then enter
Controlling transverter relays: The 8R HOLD feature can
prevent excessive transverter relay switching in CW mode. To
change the 8R HOLD setting, locate the T-R menu entry (primary
menu), edit the parameter, and tap DISPLAY to select 8rhold.
(This is the default setting and is recommended for use in all
operating modes, whether or not transverters are used.)
Using the K60XV option with transverters: In addition to 60
meter coverage, the K60XV option provides a low-level, split
RX/TX path transverter interface. This interface can be selected on
a per-transverter-band basis by adjusting the OUT field for an
output value in milliwatts (L0. 01-L1.27). In T U N E mode, power
in mW is displayed, plus LP for "low power" (e.g. P1.00LP).
The K60XV also provides a buffered relay keying output, and logic
outputs for transverter switching. Additional control capabilities are
available with the Elecraft KRC2 programmable band decoder.
(Refer to the K60XV and KRC2 manuals.)
ATU considerations: Use caution when connecting both a
transverter and an HF antenna to the KAT2: you could
accidentally transmit at high power into the transverter. For
example, suppose that you have TRN1 set up for an I.F. of 14
MHz and a 1.0-watt power limit. If you switch the K2 to 14 MHz--
where there is no power limit--you must remember not to transmit
into the KAT2 antenna jack that is connected to the transverter.

qq023 Circuit Details

Before reading this section you should become familiar with the schematics
(Appendix C) and Block Diagram (Appendix B).

System Overview

The K2’s modular design allows flexibility in configuration and provides for
future expansion. At the core of this modular architecture are the three main
circuit boards:
Front Panel User interface, including display and controls
Control Board MCU, DC control, AGC, and AF amplifier
RF Board All RF circuitry, relays, and I/O controller (IOC)
This functional division allows related circuits to be grouped together, but
also provides a high degree of isolation between the analog and digital
sections of the transceiver. The RF board serves as a "mother board," while
the front panel and Control boards plug into the RF board at its front edge.
The front panel and Control boards are mounted back-to-back, with their
ground-plane layers forming a partial enclosure that helps minimize radiated
digital noise.
The K2’s custom enclosure is also modular. It is fabricated in six pieces,
with a unique 2-D fastener used at each joint and also for PCB support. This
design provides a rugged but light-weight enclosure that is ideal for field or
home use.
The top cover, which includes the upper portion of the rear panel, can support
a variety of built-in options such as an internal battery, automatic antenna
tuner, and RS-232 interface. The top cover can be replaced with a 100 W
power amplifier module, converting the K2 into a medium-power station.

Signal Flow

The block diagram (Appendix C) shows overall signal flow in the K2.
Transmit and receive paths are shown for sideband operation. For CW
transmit, the BFO signal is routed directly to the transmit mixer.
The K2 receiver is a single-conversion superhet, utilizing double-tuned bandpass
filters on each band and down-conversion to a low I.F (4.915 MHz).
This approach results in excellent CW and SSB performance. The low I.F. is
compatible with narrow, variable-bandwidth CW crystal filtering and allows
the use of fast I.F.-derived AGC. An I.F. of 4.915 MHz also results in nearly
no birdies across all nine bands. The BFO is microcontroller controlled to
allow upper and lower sideband reception on any band, as well as CW on
either sideband. AM signals can be received in SSB modes thanks to the
stable VFO, although AM transmit is not currently supported.
Individual (per-band) band-pass filters offer improved intermodulation
performance when compared to up-conversion designs that use only a single
low-pass filter to remove image products ahead of the receiver. Up-conversion
also requires the use of a second I.F. to obtain good CW performance,
increasing cost and producing additional spurious signals. (An alternative is
up-conversion followed directly by a product detector and audio filter. While
this results in minimal parts count, it was not considered since the resulting
CW and AGC performance would have been poor.)
On transmit signal flow is reversed, so the BFO is combined with the VCO
to generate an output at the operating frequency, which is filtered by the
band-pass and low-pass filters. A highly stable power amplifier chain up to
10-15 watts on all bands, and the output level can be set in 0.2-W increments
(0.1–W increments below 10 W). The transmit strip is conservatively rated to
provide excellent reliability and immunity to high SWR. High-isolation PINdiode
T-R switching is used to provide silent, no-relays QSK. (Please refer to
the RF Board section for further details.)
Coverage of 160-10 meters is provided by a single wide-range VCO (voltagecontrolled
oscillator). High-side and low-side injection are both used,
depending on the band, so the overall VCO range is limited to about 6 to 24
MHz. Only one VCO is needed, with a single high-Q inductor and three
small DPDT relays configured to select one or more fixed capacitors. The
VCO is driven by a PLL synthesizer. 5 kHz frequency steps are used at the
PLL, while 10 Hz increments are provided by a 12-bit DAC driving an 11
MHz VCXO (PLL reference oscillator).

Crystal Filters and BFO Settings

The signals you tune in on the K2's receiver are "shaped" by the crystal filter,
which passes only a narrow range of frequencies. The pitch of these signals is
determined by the BFO (beat-frequency oscillator). Figure 9-1 shows an
example of how these signals are related. The BFO frequency is below the
filter passband; this is the case for the CW "normal" and LSB modes on the
K2. Two different filters are shown: FL2 (narrow, for CW), and FL1 (wide,
for LSB voice). Frequencies in the 4915 kHz range are shown because this is
the K2’s intermediate frequency, or I.F.
In this example, filter FL2’s bandwidth is set for about 1 kHz, and it is
centered at 4914.0 kHz. The BFO is set for 4913.0 kHz.
Signal 1 (4914.0 kHz) will be passed by FL2, and you’ll hear it at an audio
pitch of 1 kHz (4914-4913). Signal 2 (4915.0 kHz) will be rejected by FL2,
but passed by FL1, and heard at 2 kHz. The same BFO setting can be used
for both filters, because the lower boundary of the K2’s variable-bandwidth
crystal filter stays fixed as it is made wider. Only the upper edge moves
Figure 9-2 shows the BFO positioned above the same two filters, which will
allow the K2 to receive USB and CW Reverse (opposite-sideband CW).
Since the upper boundary of the filter moves as the filter is widened, the
BFO frequency must move the same amount. BFO2 is used with FL2, and
BFO1 is used with FL1.
The CALFIL menu function provides the means to control how wide the
filters are, and where the BFOs are located in relation to them. (The numeric
parameters you select using CALFIL are translated into voltages that
control the filter and BFO by means of voltage-variable-capacitance diodes, or

Microcontroller (MCU)

The K2’s microcontroller is an integral part of all transceiver operations.
Firmware is used to advantage to provide many functions traditionally
provided by discrete control logic. For example, the VCXO (PLL reference
oscillator) is linearized on each band by a firmware auto-calibration routine,
with resulting tables stored in EEPROM. Another example is firmware ALC,
which is used on CW to maintain the user-specified power level across all
bands. The SSB adapter, when installed, provides its own optimized
hardware ALC.
Extensive use of firmware also results in many useful operating features not
usually found on transceivers in this price class. These features include builtin
test equipment (frequency counter and digital voltmeter), auto-calibration,
dual VFOs, memories, split operation, RIT/XIT, and a versatile keyer.
Provisions have also been made in firmware to support a wide range of
option modules. (See full feature list elsewhere on the web site.)

Latching Relays

Latching relays are used for all filter, VCO, and option switching, so there is
no relay current drawn during normal operation. This, combined with careful
power control at all stages in the transceiver, results in receive-mode current
drain as low as 100 mA. The latching relays are all controlled by a single
device, the I/O Controller (see below), which also handles other
miscellaneous I/O tasks on the RF board. DPDT relays are used for all filter
switching, reducing the number of relays needed by a factor of two. 50-ohm
switching is used for all filters, and this combined with careful layout and
guard-banding of the relays results in excellent filter input/output isolation.

Co-Processors and the AuxBus

In keeping with the K2’s modular system architecture, much of the I/O
switching is handled by co-processors. There is only one co-processor in the
basic K2, the I/O Controller (IOC). Some option modules, such as the SSB
adapter, have their own co-processors. This distributed processing technique
allows future modifications to be made to option boards without changing
the transceiver itself. It also reduces cost of the basic K2, since fewer mainprocessor
control lines are needed.
The IOC, as well as all co-processors on option modules, go into "sleep"
mode with their own 4 MHz clocks suspended during normal operation. For
this reason, there is virtually no digital noise on the RF board to cause
receiver EMI.
When the operator performs an operation that changes relay states, the main
microcontroller (on the Control board) wakes up the co-processors and sends
one of them a configuration command. These commands are transmitted on a
one-wire network called the AuxBus. The AuxBus network line sits at a logic
high during normal operation, and is only activated when needed. The
receiver is muted during commands, so the operator never hears any digital
noise due to AuxBus activity.
Most AuxBus transmissions occur due to operator requests such as a band
change. However, the AuxBus may also be used during transmit to relay
numeric data such as SWR or ALC from a coprocessor to the main
microcontroller. Waking up the coprocessors during transmit has no effect on
the transmitted signal.

qq024 Front Panel Board

The front panel PC board plugs into the RF board via a 20-pin single-row
connector, P1. The Front Panel is made up of a number of user-interface
elements as detailed below.
The LCD, DS1, is an 8-digit 7-segment transflective type with three
backplanes (triplexed). Its driver, U1, receives display commands via an I2C
interface.20 The LCD backlight LEDs, D2 and D3, are used to provide
enough brightness to handle low-lighting situations ("NITE" mode in the
menu), while drawing only a small amount of current (<30 mA). However,
they can be turned off when ambient lighting is sufficient ("DAY" mode)
because the LCD is transflective, i.e. it can either reflect or transmit light.
The LCD displays the operating frequency and status messages, and also has
8 annunciators which indicate the settings of various controls.
A 10-segment LED bargraph, DS2, is used to display received and
transmitted signal strength and ALC level. Using the menu, the operator can
select OFF, DOT or BAR mode for the bargraph, with OFF or DOT modes
typically used to save current during battery operation. U3 and U4 are 8-
output MOSFET driver arrays which control the bargraph, among other
things. Q1 and Q2 form a brightness control. When the NIGHT(low) control
line is pulled to ground by U3, the bargraph supply voltage drops to 2.7 V,
resulting in about 6 mA/LED. The LCD backlight is also turned ON in this
case. When NIGHT(low) is left high for daytime use, each LED draws about
18 mA, and the LCD backlight is OFF.
A high-quality optical shaft encoder, Z1, provides 100 counts per turn. VFO
tuning steps of 10, 50, or 1000 Hz per increment are used, resulting in 1, 5
and 100 kHz per turn, respectively. The encoder is also used to modify
parameters in the menu. The encoder can be turned off by U3 to save current
under certain operating conditions.
S1-S16 are pushbutton switches. Switch data is read by U2, an 8-bit parallelto-
serial shift register. Each switch has at least two functions: the top label
corresponds to a TAP (short press) and the bottom label corresponds to a
HOLD (long press, ~0.5s). Switch combinations are also supported, although
only two are used (BAND+ and BAND- together enter direct frequency entry
mode, and AGC with PRE/ATTN turns AGC on or off).
Potentiometers R1, R2 and R5 (Keyer Speed, Power Out, and RIT/XIT
Offset) are multiplexed onto a single A-to-D input of the MCU, the
"VPOTS" line, so their position can be read. Firmware hysteresis is used for
these controls to prevent noise from interfering with the readings, with more
hysteresis on transmit. The AF GAIN control is not read by the MCU; its
leads go directly to the input of the AF amp on the Control Board. (The
entire path from product detector to AF amp is balanced to prevent commonmode
noise pickup—see Control Board for details.) As is true of most
modern transceivers, the RF GAIN control actually controls the receiver’s IF
gain; it varies the DC control voltage on pin 5 of U12 (RF Board).
The circuitry associated with J2, the mic jack, is only present if the SSB
option is installed. P1 is a configuration header that the user can wire as
needed to support any of several industry-standard microphones with an 8-pin
circular connector. Q3 and its associated resistors are used to multiplex the
UP, DOWN, and FUNCTION lines from P1 onto the VPOTS line to allow
the mic to send commands to the MCU. The PTT line from the MIC
activates the DOT-PTT line to initiate transmit. The MICAF line, mic audio
output, is amplified and processed by circuitry on the SSB adapter (see
Option Modules)

qq025 Control Board

The Control board plugs into the RF board via connectors P1, P2, and P3
(along the bottom edge of the schematic). P1 handles the AGC signals while
P2 provide miscellaneous I/O. Redundant connections are provided for
ground, supply voltages, low-impedance signals (such as audio output) and a
few other critical signals.
U6 is a PIC18C452 microcontroller (MCU), with 8 k of EPROM, 300+
bytes RAM, serial I/O, parallel I/O, and A-to-D inputs. It is self-contained
with the exception of its 4 MHz crystal oscillator, X2. Even when running at
4 MHz, the PIC processor is very efficient: it only draws a few milliamps at
5 V. Also, since the program and data memories are located on-chip, there is
very little noise radiation from the MCU.
To get the most out of the available I/O on the MCU, much of the
communication from MCU to the rest of the K2 is done via serial interfaces:
RS232: Used for communicating with a computer via P4
(Aux I/O)
I2C: Display driver data
SPI: The serial peripheral interface is used to access various
peripherals, including the PLL and DACs.
AuxBus: 1-wire data network for co-processor control
Shift registers: serial-to-parallel shift registers are used to access
MOSFET LED drivers on the front panel; a parallel-toserial
shift register on the front panel is used for reading
In addition to the microcontroller the Control board provides a number of
specialized hardware interfaces. Circuitry is described moving from left to
right, top to bottom on the schematic.
U10A and associated circuitry are used to accurately control power output as
well as provide CW waveform shaping. The keying waveform is sigmoidal
(S-shaped) on both rising and falling edges in order to provide totally clickfree
Q9 and Q10 form a two-stage amplifier, supplying a square wave signal to
the MCU when the frequency counter is enabled and a probe is connected to
P6. The counter amp is turned off at all times except when one of the
calibration routines is being used.
The four outputs from the quad DAC (U8) provide: audio tones (via U10B),
BFO frequency control (U10D), and crystal filter bandwidth control (U10C).
Audio tone pitch, amplitude, and wave shape are controlled in firmware to
yield clean sidetone from 400-800 Hz, as well as general-purpose tones. The
bandwidth control line doubles as the transmitter driver bias control on
Note: The sidetone signal is actually generated at pin 4 of U8, which is a
logic output, while sidetone volume is set by a D-to-A output of the DAC
using Q5 as a variable-drain-voltage saturated switch. The DAC cannot be
used to generate sidetone directly because the 60 dB channel-to-channel
isolation is not adequate to prevent slight modulation of the VBFO and
BVIAS lines on transmit.
U7 provides 2 kbytes of non-volatile configuration data storage. This
memory is used for VCO lookup tables, CW messages, frequency memories
and other variables that must be permanently saved. The EEPROM can be
written millions of times without loss of data. During normal operation on a
single frequency (such as when in a QSO), the EEPROM is not accessed at
all. However, whenever the VFO is moved, a 30-second timer is triggered.
Once the VFO has stopped moving for 30 seconds, the EEPROM is updated
with the latest VFO frequency. In this way, the K2 always saves the most
recent "important" frequency. (The EEPROM update also takes place any
time you change bands or operating modes, etc., so you don’t have to wait
for 30 seconds to record an important configuration change.) An alternative
strategy used by many rigs is to use battery-backed-up RAM, continuously
recording the operating frequency. We preferred to eliminate the backup
battery, which often has a high failure rate and must be periodically replaced.
The Control board provides a built-in voltmeter and ammeter. By jumpering
P7 appropriately, the operator can monitor either the internal 12 V supply
voltage or the voltage from a test probe plugged into P5. U3B buffers the DC
signal from the probe, and also is used in conjunction with Q11 to provide
supply current monitoring. The current sense resistor, which has a value of 50
milliohms, is located on the RF board (R115).
U4 is a low-dropout 8 V regulator, which is stable with a K2 input DC
voltage as low as 8.2 V. Since all signal-generating and signal monitoring
stages in the K2 run from this 8 V supply, the transceiver will function
normally even when running from very depleted batteries; most transceivers
use a higher regulated voltage for these stages and in some cases will not
operate reliably even at a battery voltage of 11 V. (Transmit power will be
scaled back and a warning message displayed if the battery voltage drops
below a critical value or if current drain is excessive.) U5 provides 5 V for
logic circuits on the front panel and Control board, but this signal does not
appear on the RF board, so noise is minimized.
8 V Switching: Q1 and Q2 provide stable +8 V sources on transmit (8T) and
receive (8R). (Q23 on the RF board is used to guarantee that 8R goes to 0 V
on receive to maintain proper reverse voltage on T-R switch diodes.)
An optional audio filter module (KAF2 or KDSP2) can be mounted on the
bottom of the Control board. These options provide analog or digital filtering
functions. The audio filter module has its own co-processor.
Q6 and Q7 disconnect the AF amplifier from the product detector on
transmit, which is necessary for clean QSK. U9 is an LM380 audio amp IC,
supplying approximately 1W of audio drive to a 4-ohm speaker in the cover
of the K2. Sidetone is injected post-volume control so that sidetone and
receiver audio volume can be controlled independently.
The AGC circuit is the only RF stage located on the Control board.
Mixer/oscillator U1 generates a low-level signal at about 5.068 MHz, then
mixes it with the 4.915 MHz I.F. signal from the RF board to produce a new
auxiliary I.F. of about 150 kHz. This auxiliary I.F. signal is then amplified
by U2B and detected by D1 to create a positive-going AGC voltage, which is
then routed back to the RF board to control the I.F. amp (U12). While it is
possible to generate the same AGC voltage by simply amplifying and
detecting the 4.915 MHz signal itself, this technique often necessitates
shielding of the AGC RF amplifier stages to prevent radiation of the I.F. or
BFO signals back into the receiver I.F. strip. We obtain all of the gain at 150
kHz instead, so the 4.915 MHz signal is not re-radiated. 150 kHz is high
enough to obtain fast AGC response—two orders of magnitude faster than is
possible when audio-derived AGC is employed.

qq026 RF Board

The RF board is the largest of the three K2 boards, and serves as a structural
element that the chassis and the other boards attach to. This board contains
all of the RF circuits (amplifiers, oscillators, filters, etc.). Refer to the RF
board schematic (Appendix B).

Sheet 1: Synthesizer

The K2 uses a PLL (phase-locked-loop) synthesizer IC (U4) in conjunction
with a wide-range, band-switched VCO (Q18). The synthesizer provides
approximately +7 dBm output from 6 to 24 MHz, which is then injected at
the transmit and receive mixers (sheet 2). Phase noise performance of the
synthesizer is very good despite its low parts count and absence of shielding.
The reference oscillator for the PLL IC is temperature-compensated by the
components on the thermistor PC board. This circuit works by applying a
variable offset voltage to varactor diodes D16 and D17 to compensate for drift
As temperature increases, the uncompensated oscillator would drift down in
frequency. The thermistor causes a slight increase in the bias voltage to these
diodes as the temperature increases. The relative values of RA-RD and the
thermistor, Rt, (see below) set the rate of gain change with temperature.
U4 provides coarse tuning (5 kHz steps). Fine steps are achieved using a 12-
bit DAC (U5) to tune a voltage-controlled crystal oscillator (Q19), which is
the PLL reference oscillator. The reference oscillator range needed on each
band varies in proportion to the VCO output frequency. To cover exactly 5
kHz in 10 Hz steps on each band, an automatic calibration routine is provided
in firmware. The DAC is swept from its highest output voltage down, and
the DAC word needed to select each 100 Hz step is recorded in EEPROM on
a per-band basis. 10 Hz steps are then interpolated based on the 100 Hz table
data. Crystal X1 in the PLL reference oscillator can be tuned by varactor
diodes D16 and D17 over a range of about 10 kHz, which is required in order
to tune the full 5 kHz on the lowest band (160 m), but still provides better
than 10 Hz resolution on the highest bands.
The synthesizer design is unique in that three inexpensive DPDT latching
relays are used to select one of eight VCO ranges, thus requiring only a
single high-Q VCO inductor (T5). The relays are optimally interconnected to
allow for maximum coverage of the nine HF bands, plus a large out-of-band
tuning range. Computer simulation was used to find a relay topology that
allowed for the use of standard 5% fixed capacitors along with the smallest
practical varactor diode capacitance. As a result, the VCO exhibits low noise
on all bands and has a low max/min tuning ratio on each band.
In order to provide some allowance for unit-to-unit variance in T5, a much
higher value slug-tuned inductor (L30) is placed across T5’s high-impedance
winding. L30 has only a small effect on the Q of T5, but provides about a
20% tuning range. The combined parallel inductance is very small (only 1
µH), resulting in a very large C/L ratio on the lowest bands.
U3 buffers the VCO signal. Q16/Q17 provide stable ALC to keep the VCO
voltage fairly constant over the entire frequency range despite variations in the
VCO transistor, Q18.
Also shown on sheet 1 is the DC input circuitry (bottom right-hand corner),
which is designed to protect the K2 and its power supply from almost any
conceivable mis-connection or short. D10 protects the K2 from reverse
polarity at the DC input, while dropping only 0.1-0.2 volt. F1 is a thermal
self-resetting fuse that goes into a high-resistance state if a short or other
high-current situation exists anywhere inside the K2. F1 resets quickly once
the source of the short is removed. D12 provides reverse-polarity protection
for the internal battery, if applicable.

Sheet 2: Receiver and Low-Level Transmitter Circuits

The receiver is a single-conversion superhet with an I.F. (intermediate
frequency) of 4.915 MHz. The preamp and attenuator are switched in using
latching relays so that no current is required except when switching them on
or off. The mixer is a diode ring type, providing good dynamic range (Z6),
and is followed by a strong post-mixer amplifier, Q22. The current drain in
Q22 can be reduced by the operator using a menu option that turns off Q12.
A 5-pole variable-bandwidth crystal filter is used on CW (X7-X11). This
filter is optimized for use at low bandwidths (~200 to 500 Hz), but can be set
both narrower and wider as needed with only a small additional loss. The
shape factor and passband ripple content are optimized at around 300 Hz. (On
SSB, a separate fixed filter is switched in; this filter is located on the SSB
AGC is derived from the output of the I.F. amp by using an auxiliary, lowfrequency
I.F. of about 150 kHz (see Control Board). The AGC signal is then
applied to pin 5 of the I.F. amp (U12).
A second crystal filter (X6/X5) follows the I.F. amp to reduce wideband
noise. This filter is also tunable. Varactor diode D39’s capacitance is
increased during CW use, but on SSB is reduced, making the response quite
broad. Q25 turns on only if the optional SSB adapter is installed and its
fixed-bandwidth "OP1" filter is selected. This pulls capacitor C179 to
ground, which interacts with L34 to shift the second crystal filter's center
frequency so that it matches that of the OP1 filter.
The product detector is a Gilbert-cell mixer/oscillator (U11). Due to the loss
in the second crystal filter, the input voltage to U11 never exceeds the range
that the device can handle.
U11 also provides the BFO signal, which is tunable over about a 4 to 5 kHz
range by varactor diodes D37 and D38. X3 and X4 have carefully-controlled
characteristics and are well matched. As in the PLL VCXO (Q19, sheet 1),
the two crystals de-Q each other to increase the tuning range of the BFO.
On transmit, the BFO buffer/attenuator (Q24) is turned on. Q24’s drain
voltage is controlled by the microcontroller, providing BFO amplitude
control. Precision PIN diode D36 provides additional reduction in low-level
signal leakage when Q24 is turned off. U10 mixes the VCO with the BFO on
transmit, and video amplifier U9 increases the signal level while providing a
low-impedance output to drive the bandpass filters (sheet 3).

Sheet 3: Filters and I/O Controller

The band-pass and low-pass filters are switched with latching relays to
minimize loss and current drain. Only five band-pass filters and seven DPDT
relays are required to cover nine bands (160-10 m). This is accomplished by
switching fixed capacitors in or out using two additional relays. For example,
on 160 meters, relay K3 places C13 and C14 across the 80 m band-pass
filter. But relay K3 also used to switch the 20 meter band-pass filter to 30
meters by shorting C21 and C23 to ground. K6 places C32/C34 across the
15 m inductors to select 17 meters, or C44/C46 across the 10 m inductors to
select 12 meters. The band-pass response is a compromise on 80 and 160
meters but on all other bands is similar to what would be obtained with
separate filters.
The low-pass filters also serve double-duty in most cases; five filters cover 8
bands (80-10 m). The 30/20 m filter uses three pi-sections to provide good
roll-off of the 20 MHz second harmonic when operating on 30 meters. Most
of the filters are elliptic, aiding attenuation of specific harmonics. But elliptic
filters are not needed on 40 and 80 meters since these each cover only one
band. The 2nd harmonic attenuation provided by the push-pull power
amplifier is quite good even pre-filter (sheet 4).
DPDT relays are used for the low-pass and band-pass filters rather than the
traditional SPDT approach which requires twice as many relays. This is
possible by virtue of careful guard-banding techniques on both top and
bottom of the PC board in the filter areas. Isolation between input and output
of each filter is excellent across the entire frequency range.
The T-R switch (D1-D5) provides very high isolation using low-cost silicon
diodes with a PIN characteristic (1N4007). Q2 is a very high-voltage
MOSFET that provides a ground path on receive for D3 and D4, but on
transmit this transistor can easily handle the high voltages present on the
power amplifier collectors.
U1, a 28-pin PIC microcontroller (16F872 or 16F872A), drives all of the
latching relays and a few other I/O lines. U1 is referred to it as the I/O
controller (IOC) because it handles nearly all I/O functions for the main
microcontroller. It also has the job of determining whether the 160
m/RXANT option board is installed by sensing the presence or absence of the
two relays on the module. Finally, the IOC contains all of the per-band and
per-memory initialization data in ROM, which is sent to the main
microcontroller as needed to initialize EEPROM data tables. A number of
different regional band plans and other customized parameters can be
accommodated in U1’s data tables.
The latching relays are wired with a single common drive line so that when
one relay needs to be turned on or off, the others are pulled in the opposite
direction. This arrangement requires no drivers of any kind. U1’s I/O lines are
protected from relay transients by its own internal shottky clamping diodes to
6 V and ground. Measured transients are well within the current rating of the
clamping diodes. Transients are reduced in amplitude by the series resistance
of the other non-switched relays and U1’s own MOSFET driver impedance.
The relays are rated at 5 V nominal (250-ohm coils). The actual impressed
voltage is in the 5 V to 6 V range, depending on ambient temperature,
reflecting the best and worst-case sink/source current limits of the 16F872.
The IOC communicates with the main microcontroller over the 1-wire
AuxBus. U1’s 4 MHz clock is turned off and the device is in sleep mode at
all times, except when it is processing an AuxBus message, so there is no
digital noise on receive. The main microcontroller runs from a 5 V supply,
while the IOC runs from 6 V. The AuxBus is designed to accommodate
devices running at both voltage levels.

Sheet 4: Transmitter Amplifier

Q5 and Q6 are class-A pre-driver and driver stages, respectively. Q5’s bias is
provided directly by the 8 V transmit line (8T), while Q6’s bias is switched
on by the 8T line but is gated by Q10. This is necessary because the DAC
output that supplies the bias voltage for the driver is used as the crystal filter
bandwidth control voltage on receive. The bias to Q6 can be varied under
firmware control to optimize efficiency for CW vs. SSB and at different
output levels. This is useful in maintaining high overall efficiency during
battery operation.
Q7 and Q8 form a conservatively-rated push-pull power amplifier that can
easily supply 10 watts or higher output on all bands. Q11 and Q13 are used
as a bias voltage regulator. The bias regulator is effectively out of the circuit
on CW because of the large size of resistor R62, resulting in approximately a
class-B bias level. On SSB, resistor R63 is grounded by the I/O controller,
causing much more current flow through Q13 and stabilizing the bias for
class AB operation.

qq027 Options

The K2 can be customized using a variety of internal and external options,
which are briefly described here. Note: If you press a switch associated with a
missing option module, you'll see NOTINST (not installed) on the LCD.
Menu parameters for missing options will be displayed as "- - ".

KSB2 SSB Adapter: The KSB2 allows the K2 to transmit and receive LSB
and USB, which enables use of voice as well as PSK31, RTTY (AFSK),
SSTV, and other data modes. VOX and PTT are supported, and power output
can be set from about 0.5 to 15 watts (PEP). The adapter's crystal filter is
optimized for SSB transmit and receive, but can also be used for CW or AM
receive. Mic gain and speech compression level can be set using the menu.
Our MH2 Heil/Elecraft hand mic is ideally suited to use with the KSB2.

KNB2 Noise Blanker: The KNB2 is effective on a wide range of noise
sources, and includes two gain settings as well as two different blanking
pulse widths. The noise blanker is controlled using two dedicated front-panel
functions, NB and LEVEL.

KAT2 Automatic Antenna Tuner (ATU): Our internal QRP ATU handles
a wide range of impedances, tunes nearly any antenna–on any band–in
seconds, and stores all data for instant band recall. Best of all, it includes an
integral dual antenna switch (controlled by ANT1/2), providing the
functionality of two antenna tuners in one. The KAT2 uses latching relays, so
current drain is nearly zero except when an antenna is being tuned.

KAT100 High-Power Automatic Antenna Tuner (ATU): The KAT100 is
a rugged, external ATU that's the ideal companion for the K2/100. It can
handle up to 150 watts, and like the KAT2, provides two antenna jacks
accessible with the ANT1/2 switch. The KAT100 offers the same matching
range, menu control features, and display capabilities of the KAT2, and in
addition offers 10 LEDs for real-time monitoring of SWR. Note: The
KAT100 can be used with the basic K2 as well as the K2/100. The basic K2
must have the KIO2 option installed to control the tuner.

K60XV 60-m Adapter and Transverter Interface: The K60XV adds 60
meter coverage and a low-level, split RX/TX transverter interface (~0 dBm).

K160RX 160 m Adapter and RX ANT Switch: The K160RX option adds
160 meters a separate receive antenna switch. The receive antenna can have a
separate preamp/attenuator setting from the normal antenna (per-band).

KBT2 Internal 12-V Battery: The rechargeable battery fits snugly into the
top cover along with the KAT2 ATU and/or KIO2. Recharging requires an
external 14-V regulated power supply, which can also power the transceiver.

KIO2 RS232 Interface: This option allows full computer control of the K2,
and uses true RS232 signal levels. It works with most transceiver control and
logging software, as well as our own k2remote and k2voice programs.

KDSP2 or KAF2 Audio Filter and Real-Time Clock: The KDSP2
provides advanced DSP filtering, auto-notch, and noise reduction. The KAF2
provides analog low-pass and narrow CW band-pass functions. Both include
time/date display and an on-board, long-life backup battery.

KPA100 Internal 100-Watt Stage with RS232 I/O: The KPA100
completes the K2 as a 100 W PEP/CW transceiver. The kit comes with its
own top cover/heat sink that replaces the K2's original top cover. The original
top cover can be re-installed in about one minute for lightweight field

KRC2 Programmable Band Decoder: The KRC2 can be used to control
antennas, amplifiers, transverters, filters, or other station equipment directly
from the K2. Custom configuration is possible using a PC.

XV-Series Transverters: Elecraft's transverters are an ideal match for the K2,
providing high-performance receive and 20-25 watts output on VHF/UHF
bands. The K2 can directly control up to six transverters.

qq028 Appendix E, Troubleshooting

If you have any difficulty with your K2:
- Closely examine all PC boards for poor solder joints and incorrect,
broken or missing components.
- Look for your problem in the Troubleshooting Tables (below).
- Follow the step-by-step receiver and transmitter Signal-Tracing
procedures at the end of this section. Also included are complete DC
Voltage Tables for all ICs and transistors.

Troubleshooting Tables
There are five troubleshooting tables (listed below). Within each table,
problems are identified by 3-digit numbers in the ranges shown. In most cases
you’ll know which table to look in based on the symptoms you observe. If in
doubt, start with the General Troubleshooting table.
General Troubleshooting 000-049
Control Circuits 050-099
Receiver 100-149
Transmitter 150-199
Operation and Alignment 200-249
When referring to components on the various K2 boards in the table, we will
sometimes use a shorthand form such as “RF-U11,” which means U11 on the
RF board.
INFO Messages
If you see a message such as INFO100 on the LCD, look up the
corresponding entry in the troubleshooting tables. Note: I N F O messages
can be cleared by pressing any switch. However, the cause of these messages
should be investigated before continuing to operate the transceiver.

General Troubleshooting (000-049)

Problem: 000 Unit appears to be completely dead when power switch is turned on (no display, no audio)
Troubleshooting Steps:
- Make sure your power supply or battery is
connected, turned on, and isn’t plugged in
- Check power supply and battery fuses if
- The K2’s internal self-resetting fuse, F1, may
have gone into a high-resistance state due to
a short from the 12-V line to ground; unplug
the power supply and check for such shorts
- Examine power cable for shorts or opens
- Verify control board is plugged in and that its
connectors are fully seated
- Check for 12 VDC at the power jack
- Make sure speaker, battery, and other internal
option connectors are not swapped or
plugged in backwards
- Measure the +5V and +8V regulated power
supplies. If either is incorrect, check the
regulators (050).
- Check the MCU (075)

Problem: 003 LCD is dim
Troubleshotting Steps:
- Check values of R16 and R15 on the front
- Check continuity from LCD driver (U1) to
LCD. Also look for bent pins on driver.

Problem: 004 Display turns on but unit still appears functionally dead or is “running slow"
Troubleshooting Steps:
- Check the MCU, Control-U6 (075)
- Verify that the control and front panel boards
are plugged in correctly
- The MCU oscillator may be shorted out due
to solder flux residue, especially if you used
water-soluble flux solder (030)

Problem: 005 No display, but audio is OK
Troubleshooting Steps:
Remove the bottom cover and verify that the
front panel connector is properly mated with
the RF board
- If the front panel is plugged in correctly but
the problem still persists, check all LCD
voltages and control lines (060)

Problem: 009 LOBATT displayed
Troubleshooting Steps:
- P7 on the control board may be jumpered for
ext. 12V. Move the jumper to the "12V" pos.
- Battery voltage may be below 10.5V.
Recharge the battery as soon as possible.

Problem: 010 Battery voltage too low for proper voltage regulation
Troubleshooting Steps:
- If you saw INFO 010 on the LCD, your
battery voltage is too low (< 8.5V). This
usually happens on transmit when your
battery is weak. Disconnect the battery from
the K2 and measure its voltage; if the battery
voltage quickly rises back to 11 or 12V, the
K2 may be loading the battery down. But if
the battery stays stabilizes at under about 10
V when measured outside of the K2, it has
become fully discharged or may be defective.
- If you suspect the K2 is pulling the voltage
down, tap any button to clear the I N F O
message then use DISPLAY to show the
voltage and current drain. If the current drain
is > 200 mA with no signal and the bargraph
OFF, something is shorting either the 12V
line or one of the regulators (050).

Problem: 011 No audio, but display is OK
Trobleshooting Steps:
- Make sure that a working antenna is
connected; check audio filter option, antenna
switch, tuner, SWR bridge, etc.
- See Receiver Troubleshooting (100)

Problem: 012 Display, VFO knob, switches, or potentiometers do not function correctly or are intermitten
Troubleshooting Steps:
- Front panel or control board may not be
plugged in correctly
- Check the MCU (075)
- Check all regulated supply voltages (050)
- RP1 or RP2 on the front panel board may be
installed backwards.

Problem: 015 Current drain excessive on receive
Troubleshooting Steps:
- Check receive-mode current drain (140)

Problem: 016 Current drain excessive on transmit
Troubleshooting Steps:
- Connect the K2 to a known 50 ohm load
(preferably a dummy load); if current drain
returns to normal, you probably have a
mismatched antenna and will have to
improve the match or reduce output power
- If you have set the power level control
significantly above the level that the
transmitter is capable of, current may increase significantly; try reducing the power
setting or use CALCUR to set up a
current limit
- Use voltage/current monitor mode to see if
the power supply voltage drops below 11V
on transmit; if so, you may be exceeding the
capability of your power supply or battery
- If the supply voltage and antenna impedance
are correct, the driver or PA transistors may
not be operating efficiently (150)

Problem: 018 Supply voltage drops when K2 is turned on
Troubleshooting Steps:
- Use voltage/current monitor mode to see if
the receive-mode current drain is too high
- If voltage drops but current drain is normal,
you probably have a power supply problem
or a battery that is not fully charged (025);
review power supply requirements

Problem: 019 Supply voltage drops too low when transmitter is keyed
Troubleshooting Steps:
- Use voltage/current monitor mode to see if
transmit-mode current drain is too high (016)
- If voltage drops but current drain on transmit
is normal, you probably have a weak battery
or inadequate power supply (025)

Problem: 025 Battery won’t charge up to the correct voltage, or discharges too quickly
Troubleshooting Steps:
- Batteries must be charged using the right
voltage or their usable life will be greatly
reduced; if you have the K2 internal battery
option, refer to the charging instructions in
the option manual
- Battery life can be extended by reducing
power output and by turning off selected
features using the menu; see Operation
- Always disable the K2’s internal battery
using the rear-panel battery on-off switch if
you plan to use an external battery or a
reduced-voltage power supply that is
inadequate for charging purposes

Problem: 029 Small error in actual vs. displayed frequency
Troubleshooting Steps:
- Make sure your 4.000-MHz oscillator
(control board, X2) is calibrated. Two
methods are provided in the Operation
section (Advanced Operating Features).
- Make sure the bottom cover is installed when
doing CALFIL and CALPLL. Also, if
you calibrate at room temperature but operate
the radio at much lower or higher
temperatures, calibration will be worse.
- Re-do CALFIL after calibrating the
4.000–MHz oscillator
- Re-do CALPLL after calibrating the
4.000-MHz oscillator
- Use CALFCTR with probe on TP1 and
tune very slowly through about 10 kHz of
VFO range; if you see any sudden jumps of >
50 Hz over this range even after doing CAL
PLL, your 12.096-MHz oscillator crystal may
be defective (RF, X1)

Problem: 030 VFO frequency jumps or drifts, or operating frequency appears to be entirely incorrect
Troubleshooting Steps:
- You must align both the VCO and BFO using
the CALPLL and CALFIL before
operating the K2; otherwise the VFO cannot
be tuned properly and the synthesizer may
not be locked (see Operation as well as RF
board Alignment and Test, Part II)
- Make sure the supply voltage is above 8.5V
at all times or the 8V regulator may not
function correctly.
- If you used solder with water-soluble flux,
you may have conductive paths all over the
PC boards. These can cause numerous
problems with the VFO, BFO, and logic
circuits (anything high impedance). Try
cleaning the entire board with hot water and a
Q-tip, or follow solder manufacturer’s
recommendations (except immersion).
- If you used CALFIL to change the BFO
settings, make sure you placed the BFO on
the correct side of the zero-pitch value for
each operating mode (see Operation, Filter
- If you tune beyond the lock range of the
VCO, the frequency will stop changing and
may “hunt” near the end of this range. If you
are in a range that the VCO should be
capable of tuning, re-check VCO alignment
(see RF board Alignment and Test, Part II)
- If the displayed frequency is “garbage,” see
Resetting the Configuration to Defaults in
Advanced Operating Features.

Control Circuits (050-099)

Problem: 050 Regulated voltage(s) incorrect
Troubleshooting Steps:
- Remove all option boards, since any one of
them might be causing a short on a regulated
supply line
- Make sure that the DC input voltage at J3 is
> 8.5 (the minimum voltage needed by the
voltage regulators)
- If +5V is too low (< 4.5V) go to 052
- If +8V is too low (< 7.5V) go to 053

Problem: 051 General problem with control circuits (switches, knobs, display, bargraph, T-R switching)
Troubleshooting Steps:
- Check all DC voltages using the voltage
tables (later in this section). Start with the
control board.
- If the problem involves the front panel,
measure those voltages next. If the problem
is with T-R switching, check the RF board
voltages next. You may have RP1 or RP2 on
the front panel board installed backwards.

Problem: 052 +5V too low (< 4.75V)
Troubleshooting Steps:
- Remove the front panel to see if it is was
pulling the 5V line low. If not, the problem is
likely to be on the control board.
- Pull the control board out and inspect the
entire 5V line looking for heat-damaged
components or shorts. The schematic can be
used to identify components on the 5V line.
- Remove the microprocessor to see if it is
loading the 5V line down.
- Unsolder the output pin of the 5V regulator
and bend it up slightly to break contact with
the PC board. If the voltage is still too low
measured at the pin, replace the regulator.

Problem: 053 +8V too low (< 7.5V)
Troubleshooting Steps:
- Inspect the entire 8V path on the RF and
control boards. Look for heat-damaged
components or solder bridges.
- Unsolder the output pin of the 8V regulator
and bend it up slightly to break contact with
the PC board. If the voltage is still too low
measured at the pin, replace the regulator.
- There are a number of places where you can
easily break the 8V line to eliminate parts of
the circuit in your search for the problem.
One example is RFC16 on the RF board. If
you lift one end of this inductor it will
disconnect the entire synthesizer from the 8V
- A number of circuits have resistors in series
with the 8V line, for example R112 in series
with the I.F. amplifier (U12). If you measure
voltage on both sides of these resistors you
may find a circuit that is drawing high
current or is shorted. Example: If you
measured 7V on one side of R112 and 3V on
the other, it would indicate that U12 had a
current drain of 180 mA, which is much too
high (I = E/R = 4/22 = 0.18).

Problem: 060 No display on LCD
- If the bar-graph is also not working, check
the 5V regulator (052)
- Remove the front panel hardware and panel
from the front panel PC board and inspect the
entire board for shorts or incorrect
components. You may have LCD driver U1
in backwards or it may have a bent pin.
- Check the values of R15 and R16 on the
bottom of the board; these resistors set the
voltage for the LCD itself.
- Re-install the front panel board and turn on
the K2. Using a voltmeter, measure the
voltages on pins 16 and 17 of front panel
connector J1 (ICLK and IDAT). These lines
should show DC voltages between 0 and 5V
due to data transmission from the
microprocessor to the LCD driver. If the
voltages are fixed at either 0 V or 5V rather
than being somewhere in-between, the MCU
may not be functioning (075)

Problem: 065 Relay Problem
- If you suspect a ground short in any relaycontrolled
circuit (LPF, BPF, VCO) you can
simplify debugging by pulling out the control
board, then turning power ON and back OFF.
This places all relays in the RESET condition
(see schematic).
- If you hear no relays on power-up, check the
IOC (080)

Problem: 075 Possible MCU problem
- Measure the voltage on pin 32 of the MCU
(U6, control board). If it is not 5V, check the
5V regulator (052).
- Remove the control board and carefully
inspect the microprocessor. Make sure it is
not installed backwards, has no bent pins, and
is seated firmly in its socket.
- Verify that the MCU oscillator components
all have the correct values and are soldered
properly, with no shorts (X2, C21, C22).
- Listen for the 4-MHz oscillator signal using
another ham-band receiver. If you can't hear
the signal, try putting a 1M resistor across X2
on the control board. Also try rotating C22.

Problem: 080 IOC Problem
- If you saw the message INFO 080, the
I/O controller (IOC, RF-U1) or other auxBus
device did not respond to messages from the
main processor (MCU). Turn power OFF and
back ON; if you hear some relays switching
on power-up, the IOC may be OK, and the
problem is likely to be with the AuxBus
- If you do not hear any relays switching on
power-up, your IOC (RF-U1) may be
defective. Inspect U1 carefully to see if you
have installed it backwards or if any pins are
- Pull U1 out, check its pins, then re-install it,
making sure all pins make good contact with
the IC socket. Check the 4-MHz oscillator
- Remove the bottom cover and verify that all
pins of U1’s socket are soldered, as well as
those of the 6V regulator (RF-U2), and U1’s
4 MHz oscillator (RF-Z5).
- With power ON, check all voltages
associated with U1. You should see 6V at
pins 1 and 20 at all times, even when the IOC
is sleeping (not being accessed by the MCU).

Problem: 081 AuxBus problem
- You may have an option board installed that
is causing a problem with the AuxBus. Try
removing each option board and turning
power off and back on.
- Verify that R64 is installed (RF board, near
- Check the voltage at pin 1 of the IOC (RF,
U1). If it isn’t approximately 6V, U2 may be
bad (6V regulators).
- Check the voltage at pin 28 of the IOC
(RF–U1). It should be between 5 and 6V. If it
is zero volts, you probably have a short
somewhere on the AuxBus line. Turn power
OFF, then measure pin 28 of U1 to ground. If
it is a short, pull the control board out to see
if the short is on that board.
- If the voltage at pin 28 is between 5V and
6V, try pressing the B A N D + button a
number of times while watching the voltage
carefully (use an oscilloscope if possible).
The voltage should drop below 5V briefly if
the MCU (CTRL-U6) is sending a message
to the IOC. If the voltage does not change at
all, the MCU itself may not be sending
AuxBus messages.
- Check the AuxBus signal at the MCU, pin 40
(CTRL-U6). If you don’t see this voltage
drop below 5V briefly when the band is
changed, the MCU may not be functioning

Problem: 090 EEPROM test #1 failed
- If you saw the message INFO 090 or
INFO 091 on the LCD, one of the
EEPROM write tests has failed.

Problem:091 EEPROM test #2 failed
- Check all voltages on the EEPROM (CTRLU7).
- Remove the control board and inspect U7 and
surrounding traces. Verify that U7 is properly

Receiver (100-149)

Problem: 100 Low (or no) audio output from receiver, or general receiver gain problem
-If you hear audio output on some bands but
not all of them, check the band-pass and lowpass
filters and T-R switch (120)
- Make sure you have headphones or speaker
connected, and AF GAIN not at minimum
- Check for missing audio filter option
(KDSP2 or KAF2) or their bypass jumpers
- Check the key jack for a short to ground
- Make sure RF GAIN is at maximum
- The AGC threshold control (R1, Control
board) may be set incorrectly. Typical
voltage at U2 pin 5 is 3.90 volts (no antenna,
RF GAIN at max). You can set R1 for a
slightly higher voltage at U5 pin 5 to increase
the no-signal I.F. gain. If R1 is adjusted,
you'll need to re-adjust CAL S HI and CAL S
LO (S-meter).
- If you have the 160 m/RXANT option board
installed, you may have menu entry RANT
turned ON but no receive antenna connected;
this may affect only one band since RANT
can be set individually for each band.
- Peak the band-pass filters if you have not
already done so
. Check for ground shorts in the LPF and BPF
by first resetting all of the relays (065)
- Turn the AF GAIN to maximum
- If you don’t hear any “hiss” at the receiver
output, troubleshoot the AF amplifier (110)
- Check the 8V regulated supply voltage and
troubleshoot if necessary (053)
- Measure the 8R line (+8V receive) at the
anode of D6 on the RF board. It should be 8V
+/- 0.5V. If not, look for a problem in the 8V
switching circuitry (control board).
- Try using signal tracing (see procedure later
in this section)

Problem: 110 AF amp not working
- Use the menu to set a sidetone level of 60
(STL 060). Hold SPOT. If you hear a
strong tone, the A.F. amplifier itself is
probably working; check the mute circuit
(CTRL-Q6 and Q7) and trace the volume
control lines back to the product detector
- Remove the control board and inspect the
entire A.F. amplifier and mute circuit for
mis-installed components, shorts, and opens

Problem: 114 AGC or S-meter not working
- If AGC appears to be working but the Smeter
isn’t, try re-calibrating the meter using
CALSHI and CALSLO. If the Smeter
is “stuck,” you may have an open,
short, or incorrect component in the area of
U2 on the control board.
- Make sure the RF gain control is at
- If the AGC and S-meter are both not
working, you may have a dead 5.068 MHz
oscillator crystal, X1 (control board). Listen
for the 2nd harmonic of X1 at about 10.136
MHz while touching a screwdriver blade to
pin 7 of U1 (NE602). If you can’t hear this
signal, try soldering a 22 k resistor from pin 7
to pin 3 on U1 (NE602).

Problem: 120 Signal loss only on some bands
- If you have the 160 m/RXANT option
installed, make sure you have menu entry
rANT set to OFF, or if it is O N that you
have a receive antenna connected
- If K60XV option connectors are installed
(J13 and J15 on RF board), but the module is
removed, install C6 and W6.
- Peak appropriate band-pass filters
- Inspect T-R switch components and voltages
- Trace signal from band-pass filters to the
antenna using an RF signal generator
- Make sure the VCO is oscillating on affected
bands by using the frequency counter

Problem: 140 Receiver current drain is too high
- If you saw the message INFO 140, your
receive-mode current drain was measured at
over 500 mA during normal operation.
Continue with the checks below.
- Use DISPLAY to show voltage and current
on the LCD. If the current shown is > 300
mA with no incoming signal or > 200 mA
with the bargraph turned OFF and no signal,
you may have a short or excessive load on
the 8V or 8R lines (053).
- You may have the speaker and/or external
speaker jack wired incorrectly. This can place
a short across the audio amp output, causing
very low audio output (if any) and current as
high as 500 to 800 mA.

Transmitter (150-199)

Problem: 150 General Transmitter problem
- If power output is too low, go to 155
- If power output slowly increases during keydown,
go to 160
- If current drain on transmit is too high for the
given power level or you see HI CUR, go to
- If the transmitter output power seems to be
unstable go to 160
- If the transmitter stops transmitting by itself
go to 170
- If the keyer isn’t working properly, go to 180
- Use the signal tracing procedure

Problem: 155 Power output is low or zero
- You may have CAL CUR (current limit) set
too low; 2.00 A recommended at 10 W
- Check power output when using a 50O
dummy load; if the output is correct on a
dummy load but not when using an antenna,
your antenna is probably not matched
- Install the bottom cover (all six screws) to
prevent RF pick-up by low-level circuits
- Check all component values in the RF
detector; you may have two resistors
swapped (R67/R68, R66/R69) or the wrong
detector diode (D9, should be 1N5711)
- You may have a short in the LPF or BPF;
reset all of the relays before trying to look for
shorts (065)
- Examine transformers T1-T4 carefully; these
must be wound as indicated in part III of the
RF board assembly section (see this section
for drawings)
- Check all DC voltages in the transmitter (RF
board, Q5/Q6/Q7/Q8) as well as the ALC
circuitry (control board, U10A and RF board,
- One component that should be checked
specifically is R50 (driver), which can open
if the driver current goes too high.
- Make an RF probe and signal-trace through
the transmitter to find where signal is lost
(see probe and procedure later in this section)
- Check for any components getting hot
- Turn the K2 OFF and remove the heat sink;
inspect all parts and check for shorts or opens

Problem: 160 Power output fluctuates
- If you stay in key-down (TUNE) mode for
several seconds, it is normal to see some
increase in power; this is due to slow junction
heating in the final amplifier transistors. It is
not indicative of a problem unless current
drain is too high for the given power output.
- If power goes up and down significantly
during normal keying, you may have a
poorly-matched antenna OR you may have
power set too high for your battery or power
supply to handle; try reducing power to see if
it stabilizes
- If you have seen a slow (10-20Hz) oscillation
superimposed on the transmitter's output
signal, it could be due to ALC modulation.
Increase the value of R98 (RF board) to the
largest size that permits full output on 10 m.
- If the transmitter is truly unstable
(oscillating) even when connected to a 50-O
load, you may have an incorrect component
value or a toroid-winding error; go through
the checks at 155
- Make sure none of the diodes in the T-R
switch circuits are in backwards

Problem: 170 Output power drops to zero suddenly
- If you have transmit power set too high for
your battery or power supply, the supply
voltage may drop so low on transmit that it
resets the MCU (CTRL-U6) or the I/O
controller (RF-U1). Reduce power.

Problem: 175 Current drain too high on transmit (or HI CUR warning)
- You may have power set higher than the final
amplifier can achieve, resulting in overdrive
of all transmitter stages. Try reducing power
to see if normal current drain is observed at
lower power levels
- Damaged PA transistors or other components
could cause inefficiency in any stage of the
transmitter. Check all DC voltages and
components; signal trace if necessarily (155)

Problem: 180 Keyer Problem
- If the keyer is stuck at a fixed speed or the
sidetone pitch won’t change, go into the
menu and see what sidetone pitch your have.
If it’s not in the range of 0.40-0.80 kHz, you
may have bad data in the EEPROM. See
“Resetting the Configuration to Defaults” in
the Advanced Operating Features section.
- If the keyer is generally erratic when
transmitting and seems to get worse as power
is increased, you probably have RF leaking
into the keyline. Try bypassing your key with
.001 µF capacitors; also try 100 µH RF
chokes in series with the paddle and ground
- If your antenna is connected directly to the
rig with no coax (i.e., internal ATU), the only
way to cure RF problems with the keyer and
other circuits may be to reduce transmit
power, seek a better antenna match, or
improve your ground system

Operation and Alignment (200-249)

Problem: 201 EEPROM initialized
- INFO 201 is an informational message
only, not a problem indication. You will see
INFO 201 one time on power-up. The
only other time you might see this message is
if you install a new version of the firmware
that requires a reformat of EEPROM. (In
most cases new firmware should not cause an
EEPROM reformat, however.)

Problem: 230 BFO not connected to frequency counter
- INFO 230 is displayed if you try to use
CALFIL without the frequency counter
connected to the BFO test point (RF-TP2)

Problem: 231 VCO not connected to frequency counter
- INFO 231 is displayed if you try to use
CALPLL without the frequency counter
connected to the VCO test point (RF-TP1)

Problem: 232 CAL PLL on wrong band
- INFO 232 is most likely to be displayed
if you use CALPLL without first
selecting 40 meters.

Problem: 235 PLL ref. oscillator range error
- INFO 235 is displayed if CALPLL
cannot complete VFO linearization due to
inadequate PLL reference oscillator range
- You may have the frequency counter probe
on the wrong test point (should be on TP1)
- Re-test the PLL reference oscillator using the
procedure described under “PLL Reference
Oscillator Test” in Part II of the RF board
Alignment and Test section.
- If the PLL reference oscillator range is found
to be inadequate, X1 may be defective. Also
check D16, D17, C84, C85, and L31 for
proper value.

qq029 Signal Tracing

Signal tracing is the primary method by which radio equipment is tested and
repaired. You can solve nearly all receiver and transmitter problems yourself
by following the steps in this section carefully.

RF Probe Assembly

Your K2 kit includes a complete RF probe, including the PC board, coax,
and connectors. The switch spacing tool, which you used in assembling the
Front Panel, doubles as the PC board for the probe. The RF probe converts RF signals to DC so they can be measured using a DMM. The DC
readings on your DMM will be approximately equal to the signal voltage in
Vrms (root-mean-square).
Assembly Instructions: Use a discarded lead from a large diode such as an
SB530 or 95SQ015 as the probe tip (E1). It should be about 1" (2.5 cm) long.
All other components for the probe can be found in the MISCELLANEOUS
bag. An insulated alligator clip is provided for ground (E2). It should be
connected to the board using 4" of black insulated hookup wire. Two banana
plugs are supplied for connecting the probe to your DMM (P1-P2). Use
RG174 coax between the probe board and the banana plugs. The coax should
be secured to the board using one cable tie. Thread the cable tie through the
two holes provided, near the coax end of the board.
To use the Probe: Connect E2 to the nearest ground test point, and plug the
banana jacks into your DMM. Set the DMM for DC volts (20 or 30 V scale).
Avoid touching the tip or discrete components while taking measurements.

Signal Generator

A simple crystal oscillator (Figure 2) can be used in lieu of a signal generator.
This oscillator takes its output from the crystal itself, resulting in fairly low
harmonic content. This results in very slight “pulling” of the oscillator
frequency as you adjust the output level, but this is of no concern for signal
tracing. The oscillator will run on voltages as low as 8 V, but 12 V or more is
recommended to guarantee enough output for all signal tracing steps. The
components are not critical, and can vary 20% with little variation in
performance. Nearly any NPN RF transistor will work in the circuit.
Any crystal frequency that falls in or near a ham band can be used, but 10
MHz is recommended since our signal tracing measurements were done using
this band. If you have only completed the K2 up through part II of the RF
board (40 m), you'll have to use a crystal in the 6.8 to 7.5 MHz range.
You may wish to build the oscillator into an enclosure fitted with a BNC
connector and level control. Use short leads for all wiring. Use very short
leads (2”) or coax to connect the signal generator to the K2’s antenna jack.

Receiver and Synthesizer

In the following steps you’ll use the RF probe and other techniques to find the
stage where the received signal is getting attenuated. (Figure 3 shows the
approximate location of the synthesizer, receiver, and other circuits on the RF
board.) You can then use voltage tables, resistance checks and close
examination to find the bad component or connection.
Perform all measurements in the order listed. In general, your measurements
can vary 20-25% from those shown and still be acceptable. Space is provided
to record your own measurements (in pencil), which will be very useful if you
need to re-test a particular circuit after repairs.

Preparation for Receiver Signal Tracing

  1. Verify that basic display and control circuits are functioning.
  2. Using your DMM, check the 5-V and 8-V regulator outputs.
  3. Measure the voltages on the anodes (right end) of D6 and D7 (on the RF

board, near the I/O controller, U1). In receive mode, D6’s anode should
be at about 8 V, and D7’s should be near 0 V.
4. Connect the RF probe’s output to your DMM’s +/- DC input jacks.
5. Select a 2 or 3-V DC range.
6. The DMM should read close to 0.000 V DC. The reading should increase
when you touch the RF probe tip with your finger.
7. Turn on the K2 and switch to 30 m (or the appropriate band for your
signal generator). Select CW Normal mode.
8. Using the menu, select OPTPERF.
9. Use CALFIL to set up CW normal filter FL1 for a bandwidth of
1 . 5 0 . If you can hear some noise on your receiver, set up the BFO for
this filter as described in the Operation section of the manual. Otherwise,
set the BFO to the factory default value.
10. Exit CALFIL, then select the 1.50-bandwidth filter using XFIL

PLL Reference Oscillator and VCO (RF board schematic, sheet 1)

1. Connect the RF probe’s ground clip to the ground jumper near the
synthesizer circuitry.
2. Reference Oscillator Output: Measure the reference oscillator signal at
pin 1 of U4 (MC145170), which is near the front-left corner of the RF
board (near the control board). Expected: 0.8-1.8 Vrms. Actual:

3. VCO Output: Measure the VCO signal at pin 3 of U3 (LT1252).
Expected: 0.30-0.40 Vrms. Actual:

may have the secondary winding of T5 reversed.
4. VCO Buffer Output: Measure the signal on pin 6 of U3. Expected:
0.60-0.75Vrms. Actual:

5. Check the VCO frequency (RF Board, Alignment and Test Part II).

BFO (RF, sheet 2)

1. BFO Output: Measure the signal on U11, pin 6 (NE602). Expected:
0.20-0.70 Vrms. Actual:

2. Use the menu to select CALFCTR. Press EDIT again to confirm; the
display will now show a frequency reading (it will depend on where you
have the frequency counter probe connected).
3. BFO Buffer Output: Measure the amplitude of the signal at TP2 using
the RF probe. Expected: 0.025-0.070 Vrms. Actual:

4. Exit CALFCTR. Check the BFO frequency (RF Board, Alignment
and Test Part II).

Low-Pass Filter, Bandpass Filter, and T-R Switch (RF, sheet 3)

  1. Turn both the attenuator and preamp OFF using PRE/ATT.
  2. Set RF GAIN to minimum.
  3. Set AF GAIN to about 10% and connect a pair of headphones.
  4. Switch to the 30 m (or the correct band for your signal generator).
  5. Connect a signal generator or test oscillator to the antenna jack. Set the

signal generator for 0.14 Vrms as indicated by the RF probe.
6. If possible, tune the VFO until you hear the signal. It may be quite strong
even if your receiver is attenuating the signal somewhere. Find the
approximate signal peak by ear. Set AF GAIN to minimum.
7. Align the band-pass filter for the current band if possible: (a) Put the RF
probe on the banded end (cathode) of D6 (to the left of the I/O controller,
U1); (b) adjust the band-pass filter for the current band for a peak
indication on the DMM (on 30 m: adjust L8 and L9).
8. Aligning the band-pass filter may have changed the input impedance of
the receiver. Put the RF probe back on the antenna input and adjust the
signal generator for 0.14 Vrms again.
9. Low-Pass Filter Output: Measure the signal at jumper W1, near the PA
transistors (Q7/Q8). Expected: 0.13 Vrms. Actual:

10. T-R Switch #1 Output: Measure the signal at W6, which is just to the
right of the transverter/60 meter option connector, J13 (near the back
edge of the board). Expected: .093 Vrms. Actual:

11. Band-Pass Filter Output: Measure the signal at the left side of D6.
Expected: .086 Vrms. Actual:

12. T-R Switch #2 Output: Measure the signal at the right side of D6.
Expected: .077 Vrms. Actual:


Mixer, I.F. Amplifiers, and Crystal Filter (sheet 2)

1. Attenuator Off Test: Measure the signal at the end of R72 closest to
Q21. Expected: .077 Vrms. Actual:

2. Preamp Off Test: Measure the signal at the end of R73 closest to Z6.
Expected: .077 Vrms. Actual:

3. Composite Mixer Output: Measure the signal at the right end of R80.
Expected: .079 Vrms. Actual:

4. Post-Mixer Amp Output: Measure the signal at the case (collector) of
Q22 (2N5109). Expected: 2.20 Vrms. Actual:

5. -5 dB Pad Output: Measure the signal at jumper W2, near the crystal
filter. Expected: 1.40 Vrms. Actual:

6. Crystal Filter Output: Touch the RF probe to jumper W3, near the
crystal filter. Adjust the VFO for a peak in the DMM reading. Expected:
0.35 Vrms. Actual:

setting of the BFO in CAL FIL. Try a different BFO setting, then
adjust the VFO for peak again and re-measure the filter loss. (Note: this
measurement exaggerates the filter loss because the input to the filter is a
composite of many signals besides the desired one.)
7. T7 Step-Up Ratio: Measure the signal at U12, pin 4 (MC1350).
Expected: 0.4-0.8 Vrms. Actual:

8. I.F. Amp Saturated Output: Measure the signal at U12, pin 8. It may
be anywhere between 0.00 and 0.30 Vrms. Adjust the signal generator
level until the DMM reads approx. 0.15 Vrms. (If your signal generator
is running from a 9-V battery you may have trouble getting the output
this high. Try running the generator from 12V or more in this case.)
9. 2nd Crystal Filter Output: Measure the signal at U11, pin 1 (NE602).
Expected: approx. 0.27 Vrms. Actual:

10. Product Detector Saturated Output: Measure the signal at U11, pin 5
(NE602). Expected: 0.58 Vrms. Actual:


AGC (Control Board)

1. Disconnect the RF probe from the DMM. Connect the DMM’s (-) lead to
chassis ground.
2. Turn the signal generator completely OFF (remove its power).
3. Set RF GAIN to maximum.
4. No-Signal AGC, Max. IF Gain: Measure the DC voltage on pin 1 of U2
(LM833). Expected: 3.6 V. Actual:

5. Set RF GAIN to minimum.
6. No-Signal AGC, Min. IF Gain: Measure the DC voltage on pin 1 of U2.
Expected: 4.6 V. Actual:

7. Turn the signal generator back on.
8. AGC @ Saturation: Measure the DC voltage on pin 1 of U2. Expected:
6.9 V. Actual:

9. I.F. Amp AGC Input: Measure the DC voltage on pin 5 of U12 (RF,
sheet 2). Expected: 5.0 V. Actual:


Product Detector and AF Amp (RF, Sheet 2)

  1. Set up the DMM to read AC volts (use a 2 or 3-V meter range).
  2. Touch the (+) lead of the DMM to pin 5 of U11 (NE602). Decrease the

signal generator level until the AC voltage at pin 5 reads .025 Vrms. (The
K2’s RF GAIN control should still be at minimum.)
3. Disconnect the headphones and speaker. Turn the AF GAIN control to
4. Measure the signal at the speaker jack, P5 pin 1 (near the on/off switch,
S1). Expected: 1.6 Vrms. Actual:


I.F. Amp Noise Gain (RF, sheet 2)

1. Turn the signal generator off and disconnect it from the antenna jack.
Connect a 50-ohm dummy load.
2. Turn off all nearby equipment (especially computers or signal sources).
3. Set AF GAIN to maximum. Set RF GAIN to minimum.
4. Make sure the preamp and attenuator are both OFF.
5. Verify that FL1 is selected (bandwidth = 1.50), as well as CW Normal
6. AF Output, Min. IF gain: Setup the DMM for its lowest AC volts
range. Measure the signal at the speaker jack, P5 (near the on/off switch,
S1). Expected: 0.000-0.001 Vrms. Actual:

7. AF Output, Max. IF gain: Set RF GAIN to maximum. Measure the
signal at P5, pin 1. Expected: 0.007-0.013 Vrms. Actual:

8. Preamp Noise Gain: Turn on the preamp. Measure the signal at P5.
Expected: 0.030-0.060 Vrms. Actual:

9. Noise Increase w/Antenna: Connect an antenna. The signal at P5 should
increase substantially even if atmospheric conditions are quiet. A typical
reading on 30 or 40 m is 0.20-0.40 Vrms. In general, the longer or higher
your antenna is, the greater the noise increase will be.

Final Steps

If you have completed receiver signal tracing and any necessary repairs, you
should then do the following:

  1. Re-install the bottom cover and heat sink.
  2. Re-do calibration of the VCO, BFO, band-pass filters, crystal filters, etc.

as needed (see RF Board Alignment and Test, parts I, II, and III). If you
peaked L8 and L9 when signal tracing through the 30-m band-pass filter,
you’ll need to re-peak C21 and C23 on 20 m.
3. Leave the frequency counter cable connected to TP2 (BFO)
4. Connect the speaker and re-install the top cover.


The following procedure can be used to isolate problems with the transmitter
(the transmitter area of the RF board is identified in Figure 3). CW mode is
used for these tests. If you’re having difficulty with the SSB adapter, make
sure the transmitter works on CW first, then proceed with the signal tracing
instructions in the SSB adapter manual.
Once you find a location where the signal appears to be much lower than
expected, stop signal tracing and check that circuit. Check all component
values and DC voltages (see DC Voltage Tables). Closely examine the PC
board for unsoldered pins and solder bridges. One of most likely causes of a
transmitter problem is a poorly-soldered toroid lead. Re-heat any suspect
leads or solder joints.

Preparation for Transmitter Signal Tracing

1. Make sure basic display and control circuits are functioning before
attempting transmitter testing.
2. Remove the SSB adapter (if installed) and install temporary jumpers at
J9 and J10. Temporarily re-install C167 (.001 µF or higher) between pins
7 and 12 of J11. (See RF board, sheet 2.)
3. 12 V supply check: Use your DMM to check the DC voltage at the
cathode (banded end) of D10 (right edge of the board). Expected: 9 to 14
V. Actual:

found on the case (collector) of Q5 and the tab (collector) of Q6 when the
K2 is turned on and is in receive mode.
4. If you don’t have an RF probe, you can build the one from Figure 1.
Note: do not use the RF probe to directly measure the transmitter’s
power output unless you have the power set for 2 W or less. The 1N34A
diode in the RF probe may be damaged at higher power levels.
5. Test Shared Circuits: Do the receiver signal tracing (above). This tests
a number of circuits that are shared by both transmitter and receiver,
including the VCO, BFO, BFO buffer, T-R switches, band-pass filters,
and low-pass filters. It’s important not to skip this step, even if the
receiver seems to be working correctly. Shared circuits that are working
marginally may affect the transmitter more than the receiver, so their
actual output levels must be measured.
6. Set up the K2 for 40 meters (about 7100 kHz), CW Normal mode.
7. Plug in a 50-ohm dummy load (10-W or higher rating).
8. Set the power level to 5 watts.
9. Connect a hand key or keyer paddle to the key jack.
10. Connect a speaker or headphones.
11. Use the menu to set STL 030, STP0.50, and T-R0.05.
12. Select hand key mode (INPHAND).
13. Set up a transmit current limit of 2.50 amps using CALCUR.

Basic voltage checks (RF schematic, sheet 2)

Note: When using TUNE to key the transmitter, be sure to tap TUNE again
within 5 seconds or less each time. This will reduce the chance of damaging
any components in the transmitter that are consuming excess power.

  1. Switch to voltage/current display mode using DISPLAY.
  2. Hold TUNE to key the transmitter, and verify that supply voltage does

not drop by more than about 0.8 V. If it drops more than this, either your
power supply is inadequate or the transmitter is drawing excess current.
Actual transmit-mode voltage:

3. Return to normal display mode using DISPLAY.
4. Measure the key-down DC voltages on the anodes (right end) of D6 and
D7 (near U1, the I/O controller). During transmit, the voltage on the
anode of D7 should be about 8 V, and on D6, near 0 V. Actual TX-mode
voltages, D6:

5. Use TUNE and note the actual power output:


Sidetone (Control Board)

Note: If the sidetone is already functioning correctly, you can skip this
1. Make sure you’re in CW mode. The sidetone will not function in SSB
2. Disconnect the headphones and speaker.
3. Use the menu to set STL to 255 (maximum sidetone level).
4. Use the VOX button to select CW TEST mode (the mode letter will then
flash). This is a safe setting for sidetone tests, since there is no power
5. Set your DMM for AC volts, 2 or 3-V range. Touch the positive lead of
the DMM to pin 25 of U6 on the control board (18C452). (This is the
source of the sidetone signal.)
6. Key the transmitter using the hand key (TUNE does not activate the
sidetone). Measure the AC voltage on pin 25 of U6. Expected: 2.5 Vrms.

7. Move the DMM probe to the drain of Q5 (control board, 2N7000). Key
the transmitter and measure the AC drain voltage. Expected: 2.4 Vrms.

voltage supply from pin 1 of U8 (MAX534, D-to-A converter).
8. Measure the AC voltage on pin 7 of U10 (LMC660). Expected: 0.5
Vrms. Actual:

9. Measure the AC voltage on pin 8 of U9 (LM380). Expected: 0.5 Vrms.

10. Measure the AC voltage on pin 6 of U9. Expected: 0.5 Vrms. Actual:

(RF board).
11. Return the S T L setting to 030.
12. Use the VOX button to put the transmitter back into OPERate mode.

ALC (control board)

1. Make sure the POWER control is set for 5 watts, and that you’re in
CW/Operate mode.
2. Set up the DMM for DC volts, 20 or 30-V range.
3. Power Control Test (VPWR line): The VPWR line, pin 2 of U8
(MAX534), is where transmit power control begins. On key-down, the
microprocessor (U6) starts increasing the voltage on VPWR until it sees
the desired power indication from the RF output detector (RF board,
sheet 3, lower right-hand corner). To test VPWR, set the DMM for DC
volts, then measure the DC voltage on pin 2 of U8 when TUNE is
pressed. Expected: 0.7-2.5 VDC. Actual:

4. If VPWR reading is high (> 4.5 V): The ALC software will set VPWR
to its highest level (about 5 V) if the transmitter cannot be driven to the
requested power level. This happens for one of two reasons: (a) the
transmitter gain is low (or transmitter isn’t working at all); (b) the RF
detector has an incorrect component. Check all component values in the
RF detector. If you can’t find a problem with the RF detector, continue
with the next signal tracing section (transmit mixer, etc.).
5. If VPWR reading is low (< 0.4V): VPWR can be too low because: (a)
the ALC software is being “fooled” by a signal from the RF detector that
says the power is higher than it really is; (b) because U8 on the control
board is defective or has a pin shorted to ground or not soldered. Check
all component values in the RF detector (RF, sheet 3). If these appear
correct, check DC voltages on U8 (control), as well as resistance to
ground on all pins

Transmit Mixer, Buffer, Band-Pass Filter, T-R Switch (RF, sheets 2-3)

Note: The measurements in this section and the next may vary widely,
especially if you do the measurements on a band other than 40 m. However,
the ratio between any two back-to-back measurements should remain fairly
constant, and is a good indication of gain or loss of a stage in the transmitter.
For example, the ratio of measurements in steps 3 and 2 below is about 12.
1. Connect the RF probe to the DMM. Set the DMM for a 2 or 3-V DC
volts range.
2. Xmit Mixer Output: Measure the key-down signal at U10, pin 4.
Expected: 0.016 Vrms. Actual:

3. Buffer Output: Measure the key-down signal at U9, pin 6 (LT1252).
Expected: 0.200 Vrms. Actual:

4. Band-Pass Filter Output: Measure the key-down signal at W6.
Expected: 0.030 Vrms. Actual:

5. T-R Switch #1 Output: Measure the key-down signal at the anode of
D1. Expected: 0.029 Vrms. Actual:


Pre-driver, Driver, and PA (RF, sheet 4)

1. Pre-Driver Output: Measure the key-down signal at the case (collector)
of Q5 (2N5109). Expected: 0.120 Vrms. Actual:

2. Driver Input: Measure the key-down signal on the base of Q6
(2SC2166; pins are labeled B, C, E). Expected: 0.026 Vrms. Actual:

3. Driver Output: Measure the key-down signal at the tab (collector) of
Q6. Expected: 1.8 Vrms. Actual:

4. PA Input (Q7): Measure the key-down signal at the base of Q7
(2SC1969 on bottom of the board; pins are labeled on the top). Expected:
0.38 Vrms. Actual:

5. PA Input (Q8): Measure the key-down signal at the base of Q8.
Expected: 0.38 Vrms. Actual:

6. RF Detector Input: Measure the key-down signal on the anode (nonbanded
end) of D9 (1N5711, middle of the right edge of the board).
Expected: 2.0 Vrms. Actual:

constant regardless of the band used.)
7. PA Transistor Tests: If the PA input voltages were higher than
expected, but the RF detector input was too low, one or both PA
transistors could be defective. After checking DC voltages and
transformer leads, turn off power to the K2 and use your DMM’s
diode/transistor test range to test the transistors. With the DMM’s
positive lead on the base of Q7, you should measure about 0.6 k to the
emitter or collector. With the DMM’s negative lead on the base of Q7,
you should measure about 1.3 k to the emitter and > 3 k to the collector.
These also apply to Q8.

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