I Can Work This Thing!

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converted to text and edited by Gary Lee kb9zuv@arrl.net


Revision C1, November 18, 2007

Copyright 2007, Elecraft, Inc.
All Rights Reserved


A Note to K3 Owners ..................................... 3
Key to Symbols and Text Styles ..................... 3
Quick-Start Guide........................................... 4
Introduction.................................................... 7
K3 Features ............................................................7
Specifications .........................................................8
Customer Service and Support ............................10
Front Panel...................................................11
Control Groups.....................................................11
Front Panel Connectors........................................13
Primary Controls..................................................13
Multi-Function Controls ......................................14
VFO Tuning Controls ..........................................14
Memory Controls .................................................16
Message Record/Play Controls............................16
RIT and XIT Controls..........................................16
Rear Panel .................................................... 17
Connector Groups ................................................17
KIO3 Module .......................................................18
Basic Operation............................................21
Receiver Setup .....................................................23
Reducing Interference and Noise ........................24
Transmitter Setup.................................................25
Voice Modes ........................................................26
CW Mode .............................................................28
Data Modes ..........................................................29
Advanced Operating Features.......................31
Text Decode And Display....................................31
Tuning Aids: CWT and SPOT.............................32
Audio Effects (AFX)............................................33
Dual Passband CW Filtering ...............................33
Receive Audio Equalization (EQ).......................33
Transmit Audio Equalization (EQ) .....................33
SPLIT Operation ..................................................34
Extended Single Sideband (ESSB)......................34
General-Coverage Receive ..................................34
VFO B Alternate Displays...................................34
Alarm and Auto Power-On..................................34
Using the Sub Receiver........................................35
Receive Antenna In/Out.......................................36

Buffered I.F. Output............................................ 36
Using Transverters .............................................. 36
Scanning .............................................................. 37
Main and Sub Receiver Antenna Routing..... 38
Basic K3 (no KAT3 or KXV3)........................... 38
K3 with KXV3 RF I/O Module.......................... 38
K3 with KAT3 ATU ........................................... 39
K3 with KAT3 and KXV3.................................. 40
Antenna Selection Controls ................................ 40
Remote Control of the K3 ............................ 41
Options ........................................................ 42
Firmware Upgrades...................................... 42
Configuration............................................... 43
Crystal Filter Setup ............................................. 43
Option Module Enables ...................................... 44
Miscellaneous Setup ........................................... 44
VFO A Knob Friction Adjustment ..................... 45
VFO B Knob Friction Adjustment ..................... 45
Real Time Clock Battery Replacement.............. 45
Calibration Procedures ................................. 46
Synthesizer .......................................................... 46
Wattmeter ............................................................ 46
Transmitter Gain ................................................. 46
Reference Oscillator............................................ 47
Front Panel Temperature Sensor ........................ 48
PA Temperature Sensor ...................................... 48
S-Meter................................................................ 48
Menu Functions ........................................... 49
MAIN Menu........................................................ 49
CONFIG Menu.................................................... 50
Troubleshooting ........................................... 55
Parameter Initialization....................................... 55
General Troubleshooting .................................... 56
Module Troubleshooting..................................... 57
Theory Of Operation.................................... 61
RF BOARD ......................................................... 61
KANT3 and KAT3.............................................. 63
KIO3 .................................................................... 63
Front Panel and DSP........................................... 63
KREF3................................................................. 64
KSYN3 ................................................................ 65
K3 Block Diagram .............................................. 66
Appendix A: Crystal Filter Installation......... 67


A Note to K3 Owners

On behalf of our entire design team, we’d like to thank you for choosing the
Elecraft K3 transceiver.

The K3—like its predecessor, the K2—reflects our desire to go beyond what other
high-performance transceivers have offered. It isn’t just a home-station rig; at
about 8 pounds, it can accompany you wherever you go, whether it’s out to your
back porch or halfway around the world. And of course it’s the only rig in its
class that you can build yourself. But above all, we want the K3 to be ready for
any operating situation you may encounter, and be more fun to use than any
desktop transceiver you’ve ever owned.


Wayne, N6KR
Eric, WA6HHQ


Quick-Start Guide

To get started using your K3 right away, please read this page and the two that
follow, trying each of the controls. The text uses braces to refer to numbered
elements in the front- and rear-panel illustrations below. For example,
{1} refers to 1 , the mic jack. Later sections provide greater detail on all
aspects of K3 operation.

The first thing you need to know about the K3 is that most switches have two
functions. Tap (press briefly) to activate the function labeled on a switch.
Hold to activate the function labeled below the switch. In the text,
tap functions are shown like this: MAIN.
An example of a hold function is CONFIG. Additional typographical conventions
are shown on the previous page.

Try tapping <MENU> {8}. This brings up the MAIN menu. Rotating <VFO B> {19}
selects menu entries, while rotating <VFO A> {22} changes their parameters.
Tap <MENU> again to exit the menu.



*Connect a power supply to the DC input jack {26} (see Specifications, pg. 8).
*On the K3/100, a circuit breaker is provided on the fan panel for the 100-W
stage {30}.
You can power an accessory device from the switched DC output jack {38} (0.5
A max).
*Connect an antenna to ANT1 {29}. If you have an ATU installed (pg. 22), you can
connect a second antenna to ANT2 {28}. If the KXV3 is installed,
you can connect a separate RX
antenna to RX ANT IN {34}. The AUX RF connector {27} is optional; see pg. 17.

The Basics

*Press <POWER> {5} to turn on the K3. If there are any error
indications, refer to pg. 58.

*TAP and HOLD Functions: Tapping briefly activates the function labeled on a
Holding for about 1/2 second activates the function labeled beneath a switch.
*Tap either end of <BAND> {7} to select a band, and tap <MODE> {6} to select the
mode. Set the AF gain using <AF> {2}. Set <RF> to max.
SUB controls are discussed on pg. 12.
*The large knob {22} controls VFO A (upper display, {10}). The medium knob {19}
controls VFO B (lower display, {11}). VFO A is main RX/TX except in SPLIT (pg.
* <CMP / PWR> is one of four multifunction controls {24}. Each has two primary
functions, indicated by green LEDs. The knob has a built-in switch; tap it to
select either CMP (compression level) or PWR (power output).
Hold the knob in to access its secondary function, MONitor level.
Tap again to restore the primary function.

Filter Controls
*Rotate the <SHIFT / LOCUT> and <HICUT / WIDTH> controls {23} to adjust the
filter passband. Crystal filters FL1-FL5 are automatically selected as you
change the bandwidth. Tap either knob to alternate between <shift/width> and
* Hold <SHIFT / LOCUT> to NOR Malize the bandwidth (e.g., 400 Hz CW, 2.8 kHz
* Hold <HICUT / WIDTH> to alternate between two filter setups, I and II
* Tap <XFIL> {13} to select crystal filters manually; this also removes any
passband shift.

Voice Modes

* Hold <METER> {8} to see CMP / ALC levels. While talking, set <MIC> {25} for
4-7 bars of ALC, and <CMP> for the desired compression. Then return to SWR /
PWR (Pg. 26).

*Optional: Hold <TEST> {6} for TX TEST mode. Allows off-air TX adjustments
(pg. 13).

*Hold <CMP / PWR> {24} to set speech MON itor level; tap to return to CMP / PWR.

*Hold <VOX> {7} to select PTT or VOX. Hold <SPEED / MIC> to set VOX DELAY.

*Additional details: VOX, pg. 27; TX EQ, pg. 33; MIC, pg. 49; SSB/AM/FM, pg. 26.

CW Mode

* <SPEED> {25} sets the CW keyer speed. Hold this knob to set
semi-break-in DELAY.
Hold <QSK> {7} to select full break-in (QSK icon on) or semi-break-in. (Pg. 28.)

*Hold <PITCH> {18} to set sidetone pitch. Hold <CMP / PWR> to set sidetone MON

*Tap <CWT> {18} to enable tuning aid {9}. With CWT on, <SPOT> auto-tunes
(pg. 28).

*To select CW text decode/display mode, hold <TEXT DEC> {18}; rotate <VFO B>
(pg. 28).

*CW keying is converted to DATA in FSK D and PSK D modes (below and pg. 32).

*Hold <DUAL PB> {13} to turn CW dual-passband filter (pg. 28).

Data Modes

*Tap <MODE> {6} until you see the DATA icon turn on (see Data Modes, pg. 29).

*Hold <DATA MD> {18}. Use <VFO B> to select from: DATA A (PSK31 & other
soundcard-based modes), AFSK A (soundcard-based RTTY), FSK D (RTTY via data
input or keyer), or PSK D (PSK via data input or keyer). <VFO A> selects
data baud rate for internal encoder/decoder, if applicable.
<DUAL PB> turns on RTTY filter (DTF, pg. 30).

*Hold <PITCH> {18} to select mark tone and shift (for encoder/decoder and RTTY

*Hold <TEXT DEC> {18} to set up text decode. CWT shows tuning aid (pg. 32).

*Connect a power supply to the DC input jack {26} (see Specifications, pg. 8).

*On the K3/100, a circuit breaker is provided on the fan panel for the 100-W
stage {30}.

*You can power an accessory device from the switched DC output jack {38} (0.5
A max).

*Connect an antenna to ANT1 {29}. If you have an ATU installed (pg. 22), you can
connect a second antenna to ANT2 {28}. If the KXV3 is installed, you can connect
a separate RX antenna to RX ANT IN {34}. The AUX RF connector {27} is
optional; see pg. 17.

The Basics

*Press <POWER> {5} to turn on the K3. If there are any error
indications, refer to pg. 58.

*TAP and HOLD Functions: Tapping briefly activates the function labeled on a
Holding for about 1/2 second activates the function labeled beneath a switch.

*Tap either end of <BAND> {7} to select a band, and tap <MODE> {6} to select the
mode. Set the AF gain using <AF> {2}. Set <RF> to max. SUB controls are
discussed on pg. 12.

*The large knob {22} controls VFO A (upper display, {10}). The medium knob {19}
controls VFO B (lower display, {11}). VFO A is main RX/TX except in SPLIT
(pg. 34).

*<CMP / PWR> is one of four multifunction controls {24}. Each has two primary
functions, indicated by green LEDs. The knob has a built-in switch; tap it to
select either CMP (compression level) or PWR (power output). Hold the knob in
to access its secondary function, MON itor level. Tap again to restore the
primary function.

Filter Controls

*Rotate the <SHIFT / LOCUT> and <HICUT / WIDTH> controls {23} to adjust the
filter passband. Crystal filters FL1-FL5 are automatically selected as you
change the bandwidth. Tap either knob to alternate between shift/width and

*Hold <SHIFT / LOCUT> to NOR Malize the bandwidth (e.g., 400 Hz CW, 2.8 kHz SSB).

*Hold <HICUT / WIDTH> to alternate between two filter setups, I and II

*Tap <XFIL> {13} to select crystal filters manually; this also removes any
passband shift.

Voice Modes

*Hold <METER> {8} to see CMP / ALC levels. While talking, set <MIC> {25} for 4-7
bars of ALC, and CMP for the desired compression. Then return to SWR / PWR (Pg.
*Optional: Hold TES T {6} for TX TEST mode. Allows off-air TX adjustments
(pg. 13).

*Hold <CMP / PWR> {24} to set speech MON itor level; tap to return
to <CMP / PWR>.

*Hold <VOX> {7} to select PTT or VOX. Hold <SPEED / MIC> to set VOX DELAY.

*Additional details: VOX, pg. 27; TX EQ, pg. 33; MIC, pg. 49; SSB/AM/FM, pg. 26.

CW Mode

*<SPEED> {25} sets the CW keyer speed. Hold this knob to set semi-break-in

*Hold <QSK> {7} to select full break-in (<QSK> icon on) or semi-break-in.
(Pg. 28.)

*Hold <PITCH> {18} to set sidetone pitch. Hold <CMP / PWR> to set sidetone MON

*Tap <CWT> {18} to enable tuning aid {9}. With <CWT> on, SPOT auto-tunes
(pg. 28).

*To select CW text decode/display mode, hold <TEXT DEC> {18}; rotate <VFO B>
(pg. 28).

*CW keying is converted to DATA in FSK D and PSK D modes (below and pg. 32).

*Hold <DUAL PB> {13} to turn CW dual-passband filter (pg. 28).

Data Modes

*Tap <MODE> {6} until you see the DATA icon turn on (see Data Modes, pg. 29).

*Hold <DATA MD> {18}. Use <VFO B> to select from: DATA A (PSK31 & other
soundcard-based modes), AFSK A (soundcard-based RTTY), FSK D (RTTY via data
input or keyer), or PSK D (PSK via data input or keyer). <VFO A> selects
data baud rate for internal encoder/decoder, if applicable.
<DUAL PB> turns on RTTY filter (DTF, pg. 30).

*Hold <PITCH> {18} to select mark tone and shift (for encoder/decoder and RTTY

*Hold <TEXT DEC> {18} to set up text decode. <CWT> shows tuning aid (pg. 32).



*<RATE> {21} selects 10 or 50 Hz VFO/RIT tuning (pg. 22). See VFO menu entries,

*<FINE> {21} selects 1-Hz steps. <COARSE> selects large tuning steps (per-mode;

*Tap <FREQ ENT> {21} to enter frequency in MHz using numeric keypad & decimal
point. Tap <return> ( ) to complete the entry, or tap <FREQ ENT> again to
cancel. (Pg. 15.)

*Hold <SCAN> to start/stop scanning. <SCAN> must be preceded by a memory recall
(pg. 37).

*The <RIT> and <XIT> offset knob {17} has LEDs that show -/0/+ offset (pg.16).
Tap <CLR> {16} to zero the offset. Hold <CLR> for > 2 sec. to add the offset
to <VFO A>, then zero it.

Transmit, ATU, and Antenna Controls

*The TX LED {4} indicates that the K3 is in transmit mode. The .f LED turns on
if the RX and TX frequencies are unequal (SPLIT, <RIT> /<XIT>,
cross-mode, etc.). (Pg. 13.)

*<XMIT> {8} is equivalent to PTT {35}. Hold <TUNE> to put out full CW power in
any mode.

*Tap <ATU> {8} to initiate antenna matching. Hold <ATU> to enable or bypass
the ATU.

*<ANT> selects ANT1 or ANT2. <RX ANT> selects main or RX antenna (KXV3).

NB, NR, and Notch

*Tap <NB> {12} to enable DSP and I.F. noise blanking. Hold <LEVEL> to set
NB levels using <VFO A> (DSP) and <VFO B> (I.F.).
Fully CCW is OFF in both cases. (Pg. 15.)

*Tap <NR> {12} to turn on noise reduction. Hold <ADJ> to tailor noise reduction
for the present band conditions (pg15).

*Tap <NTCH> {12} once to select auto-notch (NTC H icon), and a second time to
select manual notch (adds icon). Hold <MAN> to adjust manual notch frequency.
(Pg. 24.)


*Hold <SPLIT> {13} to enter split mode (RX on <VFO A>, TX on <VFO B>).
If VFOs A and B are on different frequencies in SPLIT mode, the Delta-F LED (.f)
will turn on (pg. 13).

*Hold <BSET> {13} to adjust VFO B settings independently of VFO A (pg.35).

*Tap <SUB> {20} to turn on the sub receiver (pg. 42). <VFO B> controls its
The sub receiver can use its auxiliary input or share antennas with the main
receiver. Which antennas are available to main and sub receivers depends on
installed options (pg. 42).

Memories, Messages, and DVR

*To store a frequency memory, tap <V M> {14}, then: tap <M1> -<M4> {15} to save
a per-band quick memory; or tap <0> -<9> to save a general-purpose quick memory;
or rotate <VFO A> to select from memories 0-99, then tap <V M> again to save.
Tap <M V> to recall. (Pg. 16.)

*<REC> and <M1> -<M4> {15} are also used to record & play voice/CW/DATA
messages. The KDVR3 option is required for voice messages and "AF REC"
/ "AF PLAY" (pg. 16).


*<MENU> & <CONFIG> {8} access the MAIN and CONFIG menus. <VFO B> selects
entries; <VFO A> changes parameters. In general, CONFIG menu entries are used
less often.

*Tapping <DISP> {8} within menus shows information about each entry on <VFO B>
(pg 49).

*Up to 10 menu entries can be assigned to programmable function switches. <PF1>
and <PF2> {16} are dedicated programmable functions. Any of <M1> -<M4> {15}
can be used as Tap and/or Hold programmable functions if they’re not being used
for message play (pg 49).

Other Features

*RX and TX EQ (MAIN menu) provide 8 bands of receive/transmit equalization
(pg. 33).

*Tap <AFX> {18} to enable the selected audio effect (see AFX MD menu entry.
pg. 49).

*Tap <DISP> {8} and use <VFO B> to show time, supply voltage, etc. on <VFO B>
(pg. 34).

*The ALARM function (MAIN menu) can be used to remind you about a contest, net,
or QSO schedule, and can even turn the K3 on at alarm time (pg. 34).

*The KIO3 module provides a rich set of AF {33} and digital {32} I/O (pg. 16).

*<RATE> {21} selects 10 or 50 Hz VFO/RIT tuning (pg. 22). See VFO menu entries,

*<FINE> {21} selects 1-Hz steps. <COARSE> selects large tuning steps (per-mode;

*Tap <FREQ ENT> {21} to enter frequency in MHz using numeric keypad & decimal
point. Tap return ( ) to complete the entry, or tap <FREQ ENT> again to cancel.
(Pg. 15.)

*Hold <SCAN> to start/stop scanning. <SCAN> must be preceded by a memory recall
(pg. 37).

*The <RIT> and <XIT> offset knob {17} has LEDs that show -/0/+ offset (pg.16).
Tap <CLR> {16} to zero the offset. Hold <CLR> for > 2 sec. to add the offset
to VFO A, then zero it.



This comprehensive manual covers all the features and capabilities of the
Elecraft K3 transceiver. We recommend that you begin with the Quick-Start
Guide (pg. 4). The Front Panel (pg. 11) and Rear Panel (pg. 17) sections
are for general reference, while Basic Operation (pg. 21) and Advanced
Operation (pg. 31) fill in the details.

Your K3, including any installed crystal filters and option modules,
should already be configured. Anytime you add new filters or options, refer to
Configuration (pg. 43).

K3 Features

The K3 offers a number of advanced features that simplify operation and
enhance versatility. These are listed below. Refer to the indicated pages for
further details.


* Up to five crystal roofing filters; bandwidths as narrow as 200 Hz (pg. 23)

* High-performance, fully independent sub receiver, also with up to
five crystal filters (pg. 35)

* Variable-bandwidth crystal filters that track DSP filter settings

* Narrow ham-band front-end filters, plus wider band-pass filters for
general-coverage receive (pg. 42)


* 32-bit I.F. DSP for advanced signal processing, including full stereo and
other binaural effects (pg. 33).

* Passband tuning and programmable DSP/crystal filter presets (pg. 14)

* 8-band transmit and receive EQ (graphic equalization) (pg. 33)

* Dual-passband effects for use in contest/pileup conditions (pg. 28)

* Versatile digital voice recorder (DVR) for incoming/outgoing audio streams
(pg. 27)

CW and Digital Modes

* Built-in digital-mode demodulation with text displayed on the K3’s LCD (CW,
RTTY, PSK31) (pg. 7)

* Internal CW-to-TTY or PSK31 conversion for casual digital-mode QSOs without a
computer (pg.32)

* CW text can be decoded and displayed as you send – great for improving CW
skills (pg. 31)

* Automatic CW/data signal spotting and manual fine-tuning display (pg. 28)

User Interface

* Dual VFOs with independent modes, bands, and filter settings (pg. 14)

* 100 memories with alphanumeric labels, plus 4 quick-memories per band (pg. 16)

* Dedicated message play controls for use in CW, data, and voice modes (pg. 28)

* Real-time clock/calendar with programmable alarm times and automatic
power-on (pg. 34)

* Utility displays show voltage, current drain, front panel temperature,
PA heatsink temperature, and other data

* Instructions for menu entries available with one switch tap


* Enhanced, high-speed remote control interface with many new commands and
direct DSP access

* Firmware upgradeable via the internet (pg. 41)

* Isolated PC audio input and stereo outputs (pg. 16)

* Front and rear mic and headphone jacks

* Full stereo audio drives two speakers

* Optional RX antenna in/out, transverter in/out, and buffered IF outputs (KXV3)



Some specifications apply only if the corresponding option modules are installed
(see Options, pg. 42).


Frequency Range Main and Sub Receivers, 500 kHz - 30 MHz and 48-54 MHz. (Reduced
sensitivity in region of 8.215 MHz IF.
KBPF3 required for full general-coverage receive.)

Transmitter: Amateur bands between 1.8 and 54 MHz; transmit limits vary by
Tuning Step Sizes 1, 10, 20, and 50 Hz; user-configurable coarse tuning steps
(per-mode). Direct keypad frequency entry in either MHz or kHz
Memories 100 general purpose; 4 scratchpad memories per band
Frequency Stability +/- 5 ppm (0-50 C) TCXO standard; +/- 0.5 ppm TCXO optional
Antenna Jacks 50 ohms nominal. One SO-239 supplied (2nd SO-239 jack supplied
with KAT3 <ATU>).
BNC jacks for RX antenna in/out and transverter in/out (KXV3 Option).
Modes USB, LSB, AM, FM, CW, and DATA. In DATA mode: FSK-D (Direct), AFSK-A
(Audio), PSK-D (Direct) and DATA-A (Audio; PSK, etc.). Built in PSK,RTTY, and
CW text decode/display.
VFOs Dual VFOs (A and B) with separate weighted tuning knobs
Remote Control Port EIA-232 standard DE-9F; USB adapter option. Full control of
all radio functions
Audio I/O Line-level isolated TX/RX audio interface (stereo outputs); front and
rear stereo headphone jacks; stereo speaker jack
Low Level Transverter 0 dBm typ.; BNC connectors (KXV3 Option)

Buffered IF output BNC connector (KXV3 Option); see pg. 36 for interface
Other I/O Key/Keyer/Computer, Paddle, PTT In, and KEY Out. Band information
output via binary interface and AUXBUS on ACC connector.
Real-Time Clock/Calendar Accuracy: Approx. +/- 20 ppm (+/- 2 seconds/day). U.S.
and E.U. date formats.
Battery: 3 V coin cell (see pg. 45 for replacement instructions).
Supply Voltage 13.8 V nominal (11 V min, 15 V max). 17-22 A typical in TX for
K3/100, 3-4 A
/Current typical in TX for K3/10. 0.9A typical RX (sub receiver off).
Recommended supply:
13.8VDC @ 25A, continuous duty for K3/100; 13.8VDC @ 6A for K3/10.
Weight 8.5 lbs. (3.85 kg) max., all options installed
Size Enclosure only, 4.0 x 10.7 x 10.0 in., HWD (10.2 x 27.2 x 25.4 cm); with
4.4 x 11.1 x 11.8 in. (11.2 x 28.2 x 30.0 cm)


RECEIVERS (Main and Sub)

Sensitivity -136 dBm (typical), preamp on, 500Hz b/w
IMD3 Dynamic Range >100 dB typical at 5, 10, and 20 kHz spacing.
Blocking Dynamic Range 140 dB typical at 5, 10, and 20 kHz spacing
Image Rejection > 70 dB
IF Rejection > 70 dB
S-Meter Nom. S9 = 50 µV, preamp on; user-adjustable
Noise Blanker Adjustable, multi-threshold/multi-width hardware blanker plus DSP

8-Band RX graphic EQ +/- 16 dB/octave
Filter Controls IF Shift/Width & Lo/High Cut with automatic crystal filter

* Dynamic range measurements based on 400-Hz, 8-pole filter. Other available
filters have very similar performance; see
www.elecraft.com for full list. Receive specifications are guaranteed only
within ham bands.


Output Power 200 mW –100 W (12 W, K3/10) typ., ALC controlled (reduced power in
AM mode)
Duty Cycle CW and SSB modes, 100% 10-min. 100W key-down at 25 C ambient
True RF Speech Processor Adjustable compression
8-Band TX audio graphic EQ +/- 16 dB/octave
SSB TX Bandwidth 4 kHz max (> 2.8 kHz requires 6 kHz AM filter)
SSB TX Monitor Post-DSP filtering/processing
VOX DSP-controlled, adjustable threshold, delay, and anti-VOX
Full and Semi CW Break-In Adjustable delay; diode T/R Switching
SSB Carrier Suppression > 50 dB
Harmonic and Spurious > 50 dB below carrier (100W)


CW Offset/Sidetone 300-1000 Hz, adjustable. Filter center frequency follows
Mic Front 8 pin microphone connector, rear 3.5 mm microphone connector, wide mic
gain adjustment range. PTT IN (RCA jack) usable in all modes. Switchable DC bias
voltage available for electret mics.


Customer Service and Support

Technical Assistance

You can send e-mail to k3support@elecraft.com and we will respond quickly -
typically the same day Monday through Friday. Telephone assistance is available
from 9 A.M. to 5 P.M. Pacific time (weekdays only) at 831-662-8345.
Please use e-mail rather than calling when possible since this gives us
a written record of the details of your problem and allows us to handle a
larger number of requests each day.

Repair / Alignment Service

If necessary, you may return your Elecraft product to us for repair or
alignment. (Note: We offer unlimited email
and phone support, so please try that route first as we can usually help you
find the problem quickly.)

IMPORTANT: You must contact Elecraft before mailing your product to obtain
authorization for the return, what address to ship it to and current information
on repair fees and turn around times. (Frequently we can determine the cause
of your problem and save you the trouble of shipping it back to us.)
Our repair location is different from our factory location in Aptos. We will
give you the address to ship your kit to at the time of repair authorization.
Packages shipped to Aptos without authorization will incur an additional
shipping charge for reshipment from Aptos to our repair depot.

Elecraft 1-Year Limited Warranty

This warranty is effective as of the date of first consumer purchase. It covers
both our kits and fully assembled products. For kits, before requesting warranty
service, you should fully complete the assembly, carefully following all
instructions in the manual.

What is covered: During the first year after date of purchase (or if shipped
from factory, date product is shipped to customer), Elecraft will replace
defective or missing parts free of charge (post-paid). We will also correct any
malfunction to kits or assembled units caused by defective parts and materials.
Purchaser pays inbound shipping to us for warranty repair, we pay shipping to
return the repaired equipment to you by UPS ground service or equivalent to the
continental USA and Canada. Alaska, Hawaii and outside U.S. and Canada actual
return shipping cost paid by owner.

What is not covered: This warranty does not cover correction of kit assembly
errors. It also does not cover 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.


Front Panel

This reference section describes all front panel controls, the liquid crystal
display (LCD), LEDs, and connectors.
Operating instructions are covered in later sections.

Control Groups

Primary Controls (pg 13): These controls
provide basic transceiver setup, including power
on/off, band, operating mode, <AF> and RF gain and
squelch, <ATU> and transmit controls, display modes,
and menus.

Display (pg 12): The LCD shows signal levels, <VFO A> and B frequencies, filter
bandwidth, operating mode, and the status of many controls. The <VFO B> display
is alphanumeric, so it can show decoded text from digital modes (CW, RTTY,
PSK31), as well as menus, time and date, help messages, etc.

Multi-Function Controls (pg. 14): The upper two knobs set up receiver DSP
filtering. The lower two control transmit parameters, including keyer speed, mic
gain, speech compression, and power output level. LEDs above each knob show
which function is active; tapping the knob alternates between them. Pressing
and holding these knobs (1/2 second or longer) provides access to secondary

Keypad (pg. 15): This group of switches is numbered for use during memory
store/recall and direct frequency entry, but each switch also has normal tap and
hold functions. The upper row of switches are VFO controls. The remaining rows
control receive-mode and miscellaneous functions, such as noise reduction and
text decode/display.

Memories (pg. 16): These switches control frequency memory store/recall, message
record/play, and audio record/playback (with the DVR). -<M4><M1> can also be
used as up to eight tap/hold programmable function switches.

VFOs (pg. 14): The large knob controls <VFO A>; the smaller knob controls <VFO
B>. The four switches between the VFO knobs select tuning rates and control
related functions.

<RIT>/<XIT> (pg. 16): Three switches control <RIT> and <XIT> on/off and clear
(offset zero). The knob below the <RIT> /<XIT> switches selects the offset.


(CMP) and ALC using MET ER.
Filter Graphic: This shows the approx. bandwidth and position of the
receiver’s I.F. passband. See Using DSP and Crystal Filtering (pg. 23).
Filter Icons:
Other Icons:
<CWT> CW/data tuning aid on (<CWT> , pg. 32)
DVR in use (AF <REC> / <AF> PLAY, pg. 16)
"VOX" VOX enabled (<VOX> , pg. 26)
"QSK" Full break-in CW enabled (<QSK> , pg. 28)

Multi-character displays: The 7-segment display
(upper) shows the <VFO A> frequency. The 13segment
display (lower) shows <VFO B>.

Bargraph, receive mode: The bargraph normally acts as an S-meter. If <CWT>
is turned on, the right half of the S-meter becomes a tuning aid (pg. 32).

Bargraph, transmit mode: The bargraph normally shows SWR and RF power output.
The RF scale will be either 5 and 10 (low power) or 50 and 100 (high power).
In voice and data modes, transmit scales can be changed to compression

VFO Icons: The TX icon and two arrows indicate which VFO is selected
for transmit as shown below.
In TX TEST mode, TX flashes (see TEST).
Shows that <VFO A> or B is locked (see LOCK).

<VFO A> is the transmit VFO



<VFO B> is the transmit VFO; see

NTC H Notch filtering on (<NTCH> , pg. 24)
Manual notch (<MAN> , pg. 24)
I / II Shows selected preset (I/I I, pg. 14)
<XFIL> Crystal filter selection (FL1-FL5)

Mode Icons:

Basic operating modes (LSB , USB , CW, DATA, AM, or FM) are selected by
tapping either end (Up/Down) of <MODE>

Alternate modes (CW REV, DATA REV, AM-S, FM +/-) are selected by holding ALT . T
indicates FM/tone, or CW/data text decode.

NB Noise blanker on (NB , pg. 24)
<NR> Noise reduction on (<NR> , pg. 24)

"ANT" Antenna 1 or 2 (ANT , pg. 13)
"RX" RX antenna in use (<RX ANT> , pg. 13)
"ATT" Attenuator on (ATT , pg. 24)
"PRE" Preamp on (PRE , pg. 24)
"ATU" <ATU> enabled (<ATU> , pg. 13)
"RIT" <RIT> on (<RIT> , pg. 16)
"XIT" <XIT> on (<XIT> , pg. 16)
"SUB" Sub receiver on (<SUB> , pg. 35)
"SPLT" Split mode in effect (SPLIT, pg. 34)



TX [Red] Turns on in transmit mode.

. F [Yellow] The “Delta-F” LED turns on if transmit and receive frequencies
or modes are different due to the use of SPLIT, <RIT>, or <XIT>.

[Green] Eight LEDs show which functions are
in effect for the Multifunction Controls (pg. 14).
(-) (+) <RIT>/<XIT> OFFSET If the offset control is centered, or you tap <CLR>,
the green LED turns on (offset = 0). Otherwise, the yellow (-) or (+) LED
will be on, indicating the direction of the offset. See <RIT>, <XIT>, and <CLR>.

Front Panel Connectors

PHONES: You can use either mono or stereo headphones at either the front- or
rear-panel headphone jack. Also see <AFX> (pg. 33).

MIC: An Elecraft MH2, MD2, Proset-K2, or other compatible mic can be used
(see pinout below). To select the front- or rear-panel mic, and to turn bias
on/off, use the "MAIN:MIC SRC" menu entry.

Bias must be turned on for the MH2, MD2, and Proset-K2. It must be off for
Heil mics using the HC4 or HC5 elements.

Mic jack, viewed from front of K3

  1. Mic audio, low-Z (~600 ohms)
  2. PTT
  3. DOWN button*
  4. UP button*
  5. FUNCTION button*
  6. 8V (10 mA max)

7, 8 Ground

* If applicable (not used on MH2 or MD2)

FP ACC: This connector (RJ-45, 6 pins) is located on the bottom of the
transceiver, near the <VFO B> knob. It is used with accessory devices.

Primary Controls


Tap the left / right end of this switch to move to the next lower/higher ham
band (pg. 11).

Selects voice-operated or keying-activated transmit (VOX icon on), or
PTT-controlled transmit. Also see DEL AY (pg.26).

Selects either full break-in (<QSK> icon on) or semi break-in keying, if VOX is
selected in CW mode. Also see DEL AY (pg. 26).

Tapping the left or right end of this switch selects one of the primary
operating modes. When DATA is selected, the <DATA MD> switch is used to
specify FSK-D, AFSK-A, PSK-D, and DATA-A. (pg. 29).

Selects alternate modes: CW REV, DATA REV, AM-S (pg. 26), and FM +/-
(pg. 26).

icon flashing). TX TEST allows you to test keying,
mic level, etc., without actually transmitting.


Turns the K3 on or off. Also see Alarm and Auto Power-On (pg. 34) and
forced firmware load (pg. 42).

Displays the MAIN menu. Use <VFO A> to change parameters, and <VFO B>
to move to the next entry. Tap <DISP> to get help with the current menu entry
(default value shown in parentheses). Also see Programmable Switch Functions
(pg. 21).

Displays the "CONFIG" menu.

Manually-operated transmit. Places the K3 into transmit mode (same as PTT,
pg. 24).

Keys the transmitter in CW mode at the present power level.
See Using the <ATU> (pg. 22).

Selects the receive antenna (RX, pg. 12).

Shows an alternate display on VFO B, including time, date, voltage, etc.
Use the <VFO B> knob to select the desired display (pg. 34).

Selects voice transmit bargraph modes:
SWR and RF, or CMP and ALC (pg. 26).


Places the K3 into low-power CW transmit mode and matches the antenna using the
KAT3 automatic antenna tuner (pg. 22).

Puts the ATU into normal mode (ATU icon on) or bypass mode (pg. 22).


Selects ANT 1 or 2 and recalls the last <ATU>
settings used for that antenna (saved per-band).


Dual-Concentric Potentiometers

<AF — SUB> AF gain controls for main receiver (inner, or smaller knob) and sub
receiver (outer ring, or larger knob).

<RF / SQL — SUB> RF gain (and/or squelch) controls for main and sub receiver.

Two menu entries are provided to control squelch directly: "CONFIG:SQ MAIN", and
"SQ SUB". They can also be used to reconfigure the RF gain controls as squelch
for either receiver. See the Config Menu listing for details (pg. 50).

Multi-Function Controls

The upper two multi-function controls set up receiver filtering. The lower two
controls adjust transmit settings. Each control has two primary functions (white
labels) and a secondary function (yellow). Tap a control knob to alternate
between its primary functions, indicated by two LEDs. Hold a knob (~1/2 second
or longer) to select its secondary function.

Filter Controls

The primary functions of the filter controls are:

<SHIFT>: Shift passband either direction
<LOC UT>: Adjust low-frequency response
<HICUT>: Adjust high-frequency response
<WIDTH>: Adjust width of the passband

As these settings change, so does the filter graphic. Crystal filters are
selected automatically. See Using DSP and Crystal Filtering (pg. 23).

The secondary functions of these controls are:

<NORM> Normalize passband

Normalizing the passband sets the bandwidth to a fixed, per-mode value (e.g. 400
Hz in CW mode) and centers the passband. (Also see <XFIL> , pg. 23.)

Select preset I or II (per mode) Presets I and II each hold a complete
DSP/crystal filter setup (pg. 23).

Transmit Controls

The primary functions of the transmit controls are:

Keyer speed in WPM, 8-50
Mic gain
Speech compression level, dB
RF output power in watts (pg. 25)

The present transmit mode determines which primary functions normally apply;
for example, in CW mode, the

<SPEED / MIC> control defaults to SPEED

* You can always tap a knob to override the present selection.

The secondary functions of these controls are:

<DEL AY> VOX delay (voice/data) or CW semi break-in delay, in seconds

<MON> Voice or data monitor level or CW/data sidetone level

VFO Tuning Controls

The <VFO A> knob controls the upper frequency display. This is normally the RX
and TX frequency. In SPLIT mode, <VFO B> controls the transmit frequency (pg.
34). <VFO B> also controls the sub receiver when it is installed and turned on
(pg. 35).

The controls to the right of <VFO A> include:

<FREQ ENT>: Direct frequency entry (pg. 15)

<SCAN>: Start or stop scanning (pg. 37)

<FINE>: Select 1 Hz tuning for both VFOs

<COARSE>: Select coarse tuning rate pg. 22)

and <RIT>/<XIT> offset

<RATE>: Select one of two normal tuning rates (10/50 or 10/20 Hz; pg. 22)

Lock <VFO A> (use BSET to lock B)

<SUB>: Turn sub receiver on/off (pg. 35).

<VFO A> can optionally be coarse-tuned using
the <RIT>/<XIT> offset control if both <RIT> and <XIT> are
off . See <CONFIG>:VFO OFS.


Direct Frequency Entry

To jump to any frequency within the tuning range of the K3, tap <FREQ ENT>, then
enter 1 to 3 MHz digits, a decimal point, and 0 to 3 kHz digits. Follow this
with Enter () to accept or <FREQ ENT> to cancel. The decimal point is optional
if no kHz digits are entered, making it very easy to get to the low end of most
ham bands.


1.825 MHz: <FREQ ENT> 1 . 8 2 5

1.000 MHz: <FREQ ENT> 1

50.100 MHz: <FREQ ENT> 5 0 . 1

If four or more digits are entered without a decimal point,
a value in kHz is assumed.


Each keypad switch has tap and hold functions, listed below. These switches are
also used for direct frequency entry; to select quick memories 0-9; and for
selecting fields in certain menu entries, such as time, date, filter, and
transverter setup.

VFO Controls (Upper row)

The upper row of numeric keypad switches is used to set up VFOs A and B. Their
functions are:

A / B Exchange <VFO A> and B contents
<BSET> Set up <VFO B> and sub receiver
REV Exchange <VFO A> and B temporarily
A B Copy <VFO A> to <VFO B> (also see
<SPLIT> Enable SPLIT receive/transmit

Holding BSET allows <VFO B> (and the sub
receiver, if on) to be set up directly (pg. 35). As
long as BSET is displayed, all VFO-related
controls and display elements apply to <VFO B>. An
alternative is to set up <VFO A>, then AB.

Receiver Control & Misc. (Lower Rows)

Receiver control functions normally apply to <VFO A>. If BSET is in effect,
they apply to <VFO B>. The sub receiver, when turned on, uses the <VFO B>

PRE Preamp on/off
ATT Attenuator on/off
AGC AGC slow/fast
OFF AGC off/on
<XFIL> Select next available crystal filter
(see "CONFIG:FLx O"N)
<DUAL PB> Dual-passband CW or dual-tone
RTTY filtering (pg. 28)
NB Noise blanker on/off (pg. 24)
<LEVEL> Noise blanker levels (pg. 24); use
<VFO A> knob to select DSP blanker,
and <VFO B> to setup I.F. blanker
<NR> Noise reduction on/off (pg. 24)
<ADJ> Noise reduction parameter adjust; use
<VFO B> knob (pg. 24)
<NTCH> Notch filter auto/manual/off (pg. 24)
<MAN> Manual notch frequency (pg. 24); use
<VFO B> knob
SPOT Spot tone on/off (manual), or auto-
spot (if <CWT> is on; pg. 32)
<PITCH> CW sidetone <PITCH>, PSK center
pitch, FSK / AFSK MARK tone and
shift (pg. 29), or FM tone setup (pg.
<CWT> CW/data tuning aid on/off (pg. 12);
turn on to use auto-spot
<TEXT DEC> Text decode, CW or DATA (pg. 31);
use <VFO B> knob to select mode
<AFX> Audio effects on/off (pg. 33); use
"CONFIG:<AFX MD" to set mode
<DATA MD> DATA mode selection (pg. 29); use
<VFO B> knob


Memory Controls

Frequency Memories

The K3 has 100 general-purpose memories (00-99), plus up to 80 per-band memories
(<M1>-<M4> on each of 11 regular bands and 9 transverter bands). Each
memory holds <VFO A> and B frequencies, modes, filter presets,
antenna selection, and other settings.

Memories can have a text label of up to 5 characters (A-Z, 0-9,
and various symbols). For example, you might want to label memories associated
with nets, callsigns of broadcast stations, or your favorite scanning ranges.

To store a general-purpose memory (00-99):
First tap <VM> (VFO to Memory), then locate the desired memory using the
<VFO A> knob. The VFO A frequencies stored in each memory will be shown
as you scroll through them. When you reach the desired memory number, tap <VM>
again to store, or tap <MV> to cancel the operation.

To recall a general-purpose memory:
Tap <MV>, then select memory 00-99 using <VFO A>.
Tap <MV> again to confirm, or <VM> to cancel.

Memories 00-09 are quick memories, accessible with just two switch taps.
These could be used to get to a starting point in each of 10 ham bands.
Memories M1 – M4 are per-band quick memories.
For example, you might set up M1 for each band’s CW segment, M2 for the
SSB segment, etc.

To store or recall quick memories: Tap <VM> or <MV> as before, but instead of
rotating <VFO A>, tap 0-9 or <M1> -<M4>.

To add or change a memory’s text label: First tap <MV>, then select a memory
(00-99) using <VFO A>. Next, rotate <VFO B> to select each label position in
turn as indicated by the flashing cursor. Use <VFO A> to change characters.
After editing, tap <MV> again. (Labels can be edited at any time, including when
you initially store a memory using <VM>.) An asterisk (* ) used as the first
character of a label designates a channel-hopping memory (pg. 37).

Digital Voice/Audio Recorder

Two switches are dedicated to the DVR (KDVR3 option).
See page 27 for additional information.
Start / stop audio record <AF REC>
Start / stop audio playback <AF PLAY>.

When record or playback is active, the icon appears. It flashes during playback.

The DVR is also used for message record and play in voice modes.

Message Record/Play Controls

Five switches provide record and playback of outgoing messages:
<M1>, <M2>, <M3>, <M4> and <REC> .

These switches provide single-tap play, hold-to-repeat, and other functions that
are convenient for contests and for sending often-repeated text or voice
messages during QSOs.

For details on CW message record/play, see pg. 28. The same messages can be
used with CW-to-DATA (pg. 32). For voice message record/play, see Digital Voice
Recorder (pg. 27).

<RIT> and <XIT> Controls


<RIT> (receive incremental tuning) on/off.

Programmable function switch (pg. 21)


<XIT> (transmit incremental tuning) on/off.

Programmable function switch (pg. 21)


Sets RIT/XIT offset to 0; tap again to restore offset to previous value. Hold
for 2 seconds to copy present RIT offset to VFO A before clearing.

The RIT/XIT offset control sets the offset for RIT and XIT. Three LEDs above
the control show at a glance whether an offset is in effect (pg. 11).


Rear Panel

Connector Groups

The appearance of your rear panel may vary depending upon the options installed.

Antennas: ANT1 (SO-239) is standard. ANT2 (SO-239) is supplied with the KAT3
automatic antenna tuner option, which includes an antenna switch controlled from
the front panel. Both jacks are nominally 50 ohms when the <ATU> is bypassed or
not installed. The AUX RF connector {27} is for use with the KRX3 option; see
pg. 38.

12 VDC IN jack is an Anderson PowerPole connector rated at 30 amps.
(See Specifications, pg. 8, for detailed power requirements.)

12 VDC OUT (RCA/Phono) provides up to 0.5 A (switched) for use with accessory

Ground Terminal:
A good station ground is important for safety and to minimize local RFI.

This option panel is blank in the K3/10. In the K3/100, the blank panel is
replaced with the fan panel shown, which includes a 25 A circuit breaker.

KIO3 (pg. 63):
The KIO3 is an upgradeable digital and audio I/O module providing computer and
auxiliary control signals, single or dual (stereo) speaker outputs,
line level in/out, and supplemental headphone and mic jacks.

The KXV3 provides a variety of RF I/O signals, including receive antenna in/out
(pg. 38), transverter in/out (pg. 36), and a buffered I.F. output (pg. 36).

PADDLE (1/4” phone jack) is the keyer paddle input (see "CONFIG MENU, CW PDL",
pg. 49).

KEY (1/4” phone jack) can be used with a hand key, external keyer, computer,
or other keying device.

PTT IN (RCA/Phono) is for use with a footswitch or other external transmit
control device.

KEY OUT (RCA/Phono) is the amplifier T-R relay keying output,
capable of keying up to +200VDC @ 5A.

REF IN (SMA): Input for external standard frequency reference
(KREF3-EXT option, pg. 64).


KIO3 Module

The KIO3 module provides serial communications, digital control I/O,
audio I/O for use with sound cards, dual speaker output, and auxiliary
headphone and mic jacks.


The K3 can send and receive data simultaneously at up to 38,400 baud.
You can use a standard, straight- through 9-conductor cable, or a cable wired
for an Elecraft K2 or K2/100 transceiver.

If you’re building your own cable, you can use as few as three wires (RXD, TXD,
and ground; see table below). DTR and RTS are optional.

The table uses EIA standard descriptions, which are from the perspective of the
computer. These differ from some K2 documentation, even though the connections
are functionally identical.

Pin #: Description
1,8,9: Not used
2: RXD IN (data to PC from K3)
3: TXD OUT (data to K3 from PC)
4: DTR (see PTT and Keying, below)
5: Ground (RF isolated)
6: RTS (see PTT and Keying, below)

Serial Port Setup:

Set "CONFIG:RS232" for the desired baud rate. Software should be set up at the
same rate; 8 data bits, no parity, 1 stop bit.

PTT and Keying:

The DTR and RTS signals are not used as RS232 hardware handshaking lines.
Instead, the K3 can be configured to use either of these signals as PTT IN
or KEY IN via the "CONFIG:PTT-KEY" menu entry. No external level
translation is required, since these are RS232compatible inputs.
The default for both signals is inactive (unused). Refer to your software
documentation to see if PTT or keying via RS232 lines is available.

If a PC or other device asserts RTS or DTR while you’re in the PTT-KEY menu
entry, the K3 will enter TEST mode as a precaution.


Aux I/O connector pinouts are listed below.

Aux I/O is not a VGA video connector. The
K3 does not provide video output.

Pin #: Description
1: FSK IN (see FSK Input)
2: AUXBUS IN/OUT (see KRC2 or XV-Series transverter instruction manual)
3: BAND1 OUT (see Band Outputs)
4: PTT IN (in parallel with <MIC> PTT)
5: Ground (RF isolated)
6: DIGOUT0 (see Transverter Control)
7: XVTR ON (out) or TX INH (in) (see Transverter Control, TX INH)
8: <POWER> ON (see Remote Power-On)
9: BAND2 OUT (see Band Outputs)
10: KEYOUT-LP (10 mA keying output)
11: DIGOUT1 (see DIGOUT1)
12: Ground (RF isolated)
13: BAND0 OUT (see Band Outputs)
14: BAND3 OUT (see Band Outputs)
15: EXT ALC input (0 to +5<V M>AX; see "CONFIG>:TX ALC"

FSK Input

This is a TTL input with a pull-up resistor to 5V, so it’s compatible with
TTL-level PC control outputs. When used with an RS232 control line from the PC,
a level translator is required (refer to your software manual). For use with FSK
D and PSK D modes.

Remote Power On

A remote-control system can pull this line to ground to turn the K3 ON.
To turn it OFF, the controller must send the K3 a “PS0;” command via the
RS232 interface, then deactivate the Power On signal.


DIGOUT1 is a general-purpose open-drain output controlled by the
"CONFIG:DIGOUT1" menu entry. It can be controlled from a computer; refer to the
K3 Programmer’s Reference. A 220-ohm series resistor is included to protect the
output driver.


Band Outputs (BAND0-BAND3)

The BAND0-3 pins can output HF-6 meter band data as well as transverter
selection data. The exact behavior is determined by the "CONFIG:KIO3"
menu entry. (See tables below.)

BAND0-3 are open-drain outputs. The attached device must use pull-up resistors
(typ. 2.2-10K) to its own supply voltage (24 VDC max). In the tables
below, 0 = 0 VDC, and 1 = device supply voltage.

With "CONFIG:KIO3" set to NOR , the BAND0-3 outputs are mapped based on the
selected HF-6 m band as shown below. This mapping matches that of some
third-party band decoders. On Transverter bands, BAND0-3 will all be
set to zero.

160 m: 0: 0: 0: 1
80 m: 0: 0: 1: 0
60 m: 0: 0: 0: 0
40 m: 0: 0: 1: 1
30 m: 0: 1: 0: 0
20 m: 0: 1: 0: 1
17 m: 0: 1: 1: 0
15 m: 0: 1: 1: 1
12 m: 1: 0: 0: 0
10 m: 1: 0: 0: 1
6 m: 1: 0: 1: 0

If "CONFIG:KIO3" is set to TRNS, BAND0-3 reflect the parameters of "CONFIG:XVn"
ADR as shown below. On HF-6 m they’re set to 0.

TRN 1: 0: 0: 0: 1
TRN 2: 0: 0: 1: 0
TRN 3: 0: 0: 1: 1
TRN 4: 0: 1: 0: 0
TRN 5: 0: 1: 0: 1
TRN 6: 0: 1: 1: 0
TRN 7: 0: 1: 1: 1
TRN 8: 1: 0: 0: 0
TRN 9: 1: 0: 0: 1

Transverter Control

Whenever the K3 is on a transverter band (one for which "CONFIG:XVn ON"
is set to YES), 5 volts will appear on AUX I/O pin 7 (XVTR ON).
Otherwise this pin will be at 0 V. This can be used with Elecraft XV-series
transverters as an enable signal, on pin 8 of J6 (“CONTROL”).

AUX I/O Pin 7 can alternatively be used as a transmit inhibit signal in
multi-transmitter stations. See "TX INH", below.
For transverter keying, you can use KEYOUT-LP signal (pin 10 of the AUX I/O
connector) or the KEY OUT jack (RCA).

Also, with KIO3 = TRNS or HF-TRNS, the DIGOUT0 line (AUX I/O, pin 6)
will output 0 V when low power mode is selected for the current transverter band
("CONFIG:XVn PWR"). At all other times, DIGOUT0 will be floating (Hi-Z).

The K3’s BAND0-2 outputs emulate the Elecraft K60XV’s XVTR0-2 signals when
"CONFIG:KIO3" is set to TRNS or HF-TRNS. However, BAND0-2 on the K3 are
open-drain signals, while XVTR0-2 on the K60XV are TTL.

TX INH (Transmit Inhibit Signal)

Pin 7 of the AUX I/O connector can be configured as a transmit inhibit input
signal by setting "CONFIG:TX INH" to ON. Holding pin 7 low will then prevent the
K3 from transmitting. An external 2.2 to 10 K pull-up resistor (to 5 VDC) is
required. If TX INH is set to OFF, pin 7 reverts to its default function, XVTR
ON, for which it is configured as an output. The K3 has a 220-ohm resistor in
series with this signal to minimize current in the event of a conflict with
external equipment. With "CONFIG:KIO3" set to HF-TRNS, the BAND0-3 outputs
follow the NOR table when HF6 m bands are selected, and the TRNS table when a
transverter band is selected.



STEREO or MONO; 4 to 8 ohm

Plugging in external speaker(s) cuts off the internal speaker. A stereo plug is
recommended; tip is left speaker, ring is right. If you only have a mono plug,
set "CONFIG:SPKRS" to 1 to disable right-channel audio. (Also see note below.)


STEREO or MONO; 16 O min. recommended

The front and rear-panel headphone jacks are both isolated with
series resistors. This allows you to use mono phones on one jack and stereo on
the other, if required. You’ll need stereo phones for <AFX> (audio
effects) and stereo dual receive (with sub receiver).

You can plug in headphones and speaker(s) at the same time, and hear audio in
both, if you set "CONFIG:SPKR+PH" to YES. However, if you set
"CONFIG:SPKRS" to 1, setting "SPKR+PH" to YES will force mono headphone as well
as speaker output. You can set SPKRS to 2 if you use a stereo plug at the
external speaker jack, or if no external speaker is plugged in.


MONO; hi- or low-Z

This jack accommodates an electret or dynamic mic. Use "MAIN:MIC SEL" to select
the rear panel mic (RP). Tap <1> to turn on Low or High mic gain range.
Tap <2> to turn bias on/off (see pg. 26 for recommendations based on mic type).
The mic’s PTT signal, if used, must be routed to either the PTT IN jack or
the PTT line on the Aux I/O connector (pg. 18).


MONO, transformer-isolated; 600 Ohm (nominal)

This input should be connected to your computer’s soundcard output.
The MIC gain control sets the line input level when the "MAIN:MIC SEL" menu
entry is set to LINE IN.


STEREO, transformer-isolated; 600 Ohm (nominal)

These outputs should be connected to your computer’s soundcard inputs.
The left channel is main receiver audio; the right channel is sub receiver audio
(if applicable). The outputs are post- AGC but pre-AF-gain;
use "CONFIG:LIN OUT" to set the level.

Some laptop computers have only very high- gain, high-impedance mic inputs,
not line-level inputs. This can make it difficult to adjust the K3’s LINE OUT
level, and can also worsen noise pickup. If your laptop has only a mic input,
you may want to add a resistive attenuator between the K3 and the laptop
to keep the signal-to-noise level high. Use very short leads on all components,
and place them at the laptop end of the cable.


Basic Operation

This section covers the fundamentals of K3 receive and transmit operation.
It’ll also get you started using each of the major operating modes.

Once you’re familiar with the K3, please go on to Advanced Operating Features
(pg. 31).

Using Tap/Hold Switches

Most K3 switches have two functions. Tapping (pressing for less than 1/2 second)
activates the function labeled on the switch. Holding (pressing for more than
1/2 sec.) activates the function labeled beneath the switch.

Initial Power-Up

* Connect a power supply (pg. 8); antenna or dummy load; key, if used (pg. 16);
mic, if used, and station ground (pg. 16).

* Tap <POWER> to turn the K3 on. The LCD should illuminate and show VFO A/B
frequencies. (Tapping <POWER> again turns power off.)

* The VFO B display can show a variety of useful parameters in addition to the
normal frequency display. To see these, tap <DISP> (left of the display), then
rotate the <VFO B> knob. The VFO B display will cycle through time, date,
supply voltage, current drain, etc. (pg. 12). You can use these displays to
make sure the supply voltage is in range (11-15 V), and that current drain is
about 1 amp (1.3 amps with sub receiver installed and turned on). Tap <DISP> to
return to the normal VFO B frequency display.

Using the Menus

There are two menus: "MAIN" and "CONFIG". Most entries in the "CONFIG" menu
are used for test, configuration, and alignment, and are used infrequently.

In both menus, entries appear in alphanumeric order.


* Tap <MENU> to access the main menu. (Tapping <MENU> again exits the menu.)

* Use <VFO B> to scroll through the menu entries, referring to the list
on page 49 for details.

* Change the value (or parameter) of any menu entry using <VFO A>.


* Hold <CONFIG> (hold function of the <MENU> switch) to access
the "CONFIG" menu.

* Use <VFO B> to scroll through the "CONFIG" menu entries, referring to the list
on page 50.

Menu Help

Tap <DISP> to show help information about the present menu entry.
For most entries, the default parameter value is shown in parentheses at the
start of the help text.

Programmable Functions

Menu entries that you’d like quick access to can be assigned to any of the 10
programmable function switches, <PF1> , <PF2> , and <M1> – <M4> (tap or hold).
Function menu entries can only be used via such a switch assignment.
(Examples, from the "CONFIG" menu: VFO B->A and TTY LTR.)

To set up a programmable function switch, first locate the target menu entry.
Next, hold <PF1> or <PF2> ; or, tap or hold <M1> – <M4>.
For example, if you tap <M2> , you’ll see M2T SET (T for tap),
while holding M2 would show M2H SET (H for hold). The assigned switch can then
be used as a shortcut to access that entry. <M1> – <M4> can each be assigned a
tap and/or hold programmable function.

Any <M1> – <M4> switch that is used for programmable functions will not be
available for message play. However, they will always be usable as per-band
quick-memories (pg. 16).

To cancel a programmable switch assignment and restore a previously-stored
message buffer, tap <REC> , then tap the buffer to restore (<M1> – <M4> ),
then tap <REC> again.


Band and Mode Selection

Tap either end of the <BAND> switch to select the desired ham band
(160 through 6 meters). You can also go directly to any desired frequency using
direct frequency entry (pg. 15), or recall a frequency memory (pg. 16).

Tap either end of <MODE> to select the operating mode. Hold <ALT> to select an
alternate mode, if required. This include CW REV (pg. 28), DATA REV (pg. 29),
AM-S (synchronous detection, pg. 27), and FM +/-(FM repeater split, pg. 27).

Antenna Selection and Matching

<ATU> (KAT3)

If you have the KAT3 antenna tuner installed, you can select ANT1 or ANT2
by tapping <ANT >.

If the ATU icon is on, the antenna can be matched for best SWR by tapping
<ATU TUNE> . Hold <ATU> to alternate between AUTO (autotune enabled) and BYPASS.

Holding <ANT> allows a name to be assigned to the present antenna (e.g., YAGI).
While editing the name, <VFO B> selects the character position to change;
<VFO A> cycles through available characters (A-Z, 0-9, symbols).

RX Antenna (KXV3)

With the KXV3 installed, you can tap <RX> to select a receive-only antenna
(RX ANT IN). The K3 also has an RX ANT OUT jack for use with in-line
filters, low-noise preamps, etc.; see pg. 36.

Sub Receiver Antenna (KRX3)

For sub receiver antenna selection, see Main and Sub Receiver Antenna Routing
page 38, and "CONFIG:KRX3". Sub receiver antenna sources vary depending on
installed options.

Using the VFOs

VFO A is both the main receive and transmit frequency, unless you’re
in SPLIT mode, in which case VFO B controls the transmit frequency (pg.34).
<VFO B> also controls the sub receiver (pg. 35).

Tap <RATE> to select 10 or 50 Hz per step. The fast rate can be changed using
The number of counts (or steps) per VFO knob turn can be changed
Tapping <RATE> will briefly flash either the 10-Hz or 100-Hz digit to indicate
slow or fast tuning, respectively.

For 1-Hz steps, tap <FINE>; for wider steps, use <COARSE> (see
When <FINE> is in effect, a 1-Hz digit will appear in the VFO A
display. When COARSE is in effect, the 10-Hz digit is not shown.

Tap <A->B> once to copy VFO A’s frequency to VFO B. Tap <A/B> to exchange
VFO A and B.
Pressing <REV> exchanges the VFOs for as long as you hold <REV>.
(Also see "CONFIG:VFO B->A".)

VFO B (and the sub receiver, if turned on) can be set up directly
by holding <BSET>. As long as BSET is displayed, display icons and VFO-related
controls all apply to VFO B (pg. 35).

<RIT> and <XIT>

The <RIT>/<XIT> offset control, at the far right, sets the offset for RIT
and XIT . The offset is shown on the VFO B display as you adjust the control.
Three LEDs show whether the offset is 0, (-) or (+).

Tap <CLR> to zero the RIT/XIT offset. Tapping it a second time
restores the offset.

If you wish to copy the present RIT offset to VFO A, hold <CLR> for 2 seconds
or longer. VFO A will be moved to the new frequency before the offset is zeroed.

If RIT and XIT are both turned off, the RIT offset can coarse-tune VFO A
("CONFIG: VFO CRS"). For example, you can select 5, 9, or 10 kHz
steps in AM mode.


Receiver Setup

This section explains how to use basic receiver controls. Setup for specific
operating modes is described in later sections; see Voice Modes (pg. 26),
CW Modes (pg. 28), and Data Modes (pg. 29).

Also see Text Decode and Display (pg. 28) and Audio Effects (pg. 33).

Receiver Gain Controls

Use <AF> — <SUB> (pg. 11) to set the desired main and sub receiver volume
level. There are two overall audio volume ranges, LO and HI, which can
be selected using "CONFIG:AF GAIN".

Usually, both RF — <SUB> controls will be set fully clockwise (main and
sub receiver RF gain). You may wish to reduce RF gain to optimize
receiver response to high signal levels or noise.

If either RF gain knob has been reconfigured as squelch, turn it fully
counterclockwise to hold the squelch open. See "CONFIG:SQ MAIN" and

To improve weak-signal reception, turn on the preamp using <PRE>.
In the presence of extremely strong signals, you may wish to use the attenuator
(ATT ), or reduce the RF GAIN setting.

Crystal Filter Selection

You can install as many as five crystal roofing filters in the K3’s main
receiver, and another five in the sub receiver (KRX3, pg. 35).

Bandwidths as narrow as 200 Hz and variable- bandwidth filters are available,
thanks to the K3’s low first I.F. (intermediate frequency) of 8.215 MHz.
See Appendix A for recommended crystal filter bandwidths for each mode.

To select a crystal filter manually, tap <XFIL> . The FL1-FL5 icons show the
current selection. This sets the DSP passband to match the crystal filter,
and removes any passband shift or lowcut/hicut.

The K3 will also select the most appropriate crystal filters automatically
as you adjust the <SHIFT>, <HI CUT> <LO CUT>, and <WIDTH>, controls.

Filter Passband Controls

As you rotate the filter controls (shift, width, hicut,
locut), the associated parameter value is shown on VFO B. The filter graphic
shows the width and location of the passband, as illustrated below.
In these specific examples, segments that turned off as a result of
control movement are shown in gray.

High Cut

Low Cut



Each DSP control has an integral switch. Tapping the control alternates
between the two primary functions for that control, for example HI-CUT and
WIDTH. This is indicated by the two LEDs above each control.
Holding a control activates its secondary function, e.g. I/II, described below.

Filter Presets and Per-Mode Normalization

Each operating mode provides two filter presets, I and II, which store
DSP filter settings and crystal filter selections. You can alternate between
the two by holding I/II. The presets for VFOs A and B are independent.

Whichever preset is in effect will be updated as you adjust the filter controls.
The current settings will be saved for later recall anytime you change modes,
VFOs, or bands, or recall a memory.

To get quickly to a standard per-mode bandwidth and reset any passband shift or
cut, hold <NORM> (normalize). The normalized bandwidth is 400 Hz in CW and DATA
modes, 2.8 kHz in SSB modes, and 6 kHz for AM. Presets are not used in FM mode.


Reducing Interference and Noise

The K3 provides a number of ways to cut interference, including DSP noise
reduction, manual and auto notch, and noise blanking. Also see Audio Effects
(<AFX> , pg. 33).

There are actually two noise blankers: one at the first I.F. (KNB3 module),
and the other at the 2nd I.F. (DSP).
Noise reduction, noise blanking, and notch filtering should only be used
when necessary. These signal processing techniques are extremely effective,
but can introduce side effects. In some cases, simply reducing the
crystal filter or DSP bandwidth may be the most effective interference-
reduction strategy. This is especially true in CW and DATA modes,
where the bandwidth can often be reduced to as low as 50 Hz.

Noise Blanking

First, tap <NB> to enable I.F. and/or DSP noise blanking.

Next, hold <LEVEL> to set NB levels using <VFO A> (DSP level) and
<VFO B> (I.F. level). You’ll initially see DSP OFF and IF OFF on the VFO A and B
displays. Rotating <VFO A> clockwise will turn on the DSP NB, showing DSP t1-1
through DSP t3-7. The first number shows the relative pulse integration time,
and the second shows the blanking level. The higher the numbers, the more
aggressive the DSP blanking action.

Rotating <VFO B> clockwise will turn on the IF NB, showing IF NARn, IF MEDn,
or IF WIDn, where n varies from 1-7. NAR /MED /WID refers to narrow/medium/wide
blanking pulse widths, and n is the blanking level. The higher the value of n,
the more aggressive the blanking action. Use NAR blanking pulse width
when possible to minimize strong-signal interaction effects.

Both the DSP and IF blanking settings are saved on a per-band basis.
If "CONFIG:NB SAVE" is set to YES, the on/off status of NB will also be saved
for each band.

Always try the DSP blanker first. It’s in the 2nd I.F., where it can’t be
activated by signals outside the crystal filter passband. It can be used with
high duty-cycle and complex-waveform noise generated by computers,
switching power supplies and other peripherals, light dimmers, florescent lamps,
etc. The IF blanker, in contrast, is in the 1st I.F., where it can use very
narrow blanking widths. It is most effective at blanking AC line noise,
lightning, and other very broadband noise.

Noise Reduction

Noise reduction is quite different from noise blanking. It attempts to
mathematically eliminate random background noise while preserving “meaningful”

Tap <NR> to turn on noise reduction. (Only applicable if AGC is on.)
Hold <ADJ> to tailor noise reduction for the present band conditions using
the <VFO B> knob. In general, the higher the <NR> parameter value, the more
background noise will be removed. If it is set too high, it may degrade
weak signals.

Notch Filtering

Notch filtering can remove interfering carriers while leaving the desired signal
relatively unaffected. The K3 provides automatic and manual notch tuning.

Auto notch will find and remove one carrier, and in some cases more than one;
it is available in voice modes. (AGC must also be on to use auto-notch.)

Manual notch removes one carrier at a specified pitch, and can be used
in CW and DATA modes as well as voice. Since manual notching sets up a fixed
(rather than adaptive) notch, it can even suppress a keyed carrier,
i.e. a CW signal.

Tap <NTCH> to select auto-notch (NTCH icon). Tap a second time to select
manual notch (adds icon). Tap again to turn notch filtering off.

Hold <MAN> to adjust the manual notch frequency using <VFO B>.
This also selects manual notch.


Transmitter Setup

Transmit Crystal Filter Considerations

For each operating mode, you must specify which I.F. crystal filter to use
for transmit using the "CONFIG:FLTX" menu entry. See page 44 for recommended
per-mode transmit filter bandwidths. Transmit signals are generated on the
RF board, so the set of filters installed on the RF board must meet the transmit
bandwidth requirements of all modes you plan to use. (Filters installed on the
sub receiver board are used only in receive mode.)

Transmit Status LEDs and Icons

Before putting the K3 on the air, you should be familiar with the LEDs and
LCD icons that pertain to transmit operation (identified on pages 11 and 12).
The most important of these are reviewed here.

The TX LED turns on during transmit. The .F (Delta-F) LED turns on if the
transmit and receive frequencies differ (SPLIT / RIT / XIT).

The TX LCD icon and associated arrows show which VFO is being used for transmit.
If you plan to use SPLIT mode, see page 34.

Multifunction Transmit Controls

There are two multifunction transmit controls. Their primary functions
(mode-dependent) are:

<SPEED> CW keyer speed in WPM
<MIC> Mic gain
<CMP> Speech compression level in dB
<PWR> RF output power in watts

The secondary (hold) functions of these controls are:

VOX or CW semi-break-in delay

Voice/Data monitor or CW sidetone level.

<VOX>, PTT, and <QSK>

In voice and data modes, use <VOX> to select VOX (pg. 13) or PTT (push-to-talk).
PTT can still be used even with VOX selected. Set VOX gain and anti-vox
level using "MAIN:VOX GN" and

In CW mode, use VOX to select either VOX or PTT transmit. VOX enables
“user-activated” (hit-thekey) transmit, while PTT requires the use of PTT or
<XMIT> before CW can be sent. (pg. 17)

When the VOX icon is on in CW mode, you can use <QSK> to select full
(QSK icon on) or semi break-in. For more on break-in keying, see pg. 28.

Transmit Metering

Normally, the transmit bargraph shows SWR and RF (power output). The SWR range
is 1:1 to 3:1. The RF range is 0 to 12 W in 1-W units, or 0 to 120 W in 10-W
units. The power scale changes from watts to watts x10 between 12 and 13 watts.

In voice modes, you can use <METER> to switch to compression (CMP) and automatic
level control (ALC ) metering. See page 26 for information on adjusting the MIC
and CMP controls.

If you have a KXV3 installed, you can use milliwatt-level power output. This is
intended for use with transverters, but it can also allow the K3 to act as a
very stable, very low-noise signal generator. To route RX and TX through the
XVTR jacks on all bands, set "CONFIG:KXV3" to TEST.

When milliwatt-level output is in effect, rotating <PWR> will show milliwatts
on VFO A, and dBm (dB relative to 1 milliwatt) on VFO B.

Off-Air Transmit Testing

The K3 allows you to listen to your CW keying, test your mic and compression
settings, or monitor DATA tones, without transmitting an on-air signal.

To do this, hold <TEST> (right end of the <MODE> control). While you're in
TEST mode, the TX icon will flash slowly as a reminder that you're off air.
Hold <TEST> again to return to normal operation.


Voice Modes

Mode Selection

Tap either end of <MODE> to select LSB , USB , AM, or FM mode.
Holding the left end of this control, <ALT> , selects an alternate mode.
The alternate for AM is AM-S (synchronous AM on receive, pg. 27).
In FM mode, ALT enables a per-band repeater offset.

Microphone Selection

The K3 provides both front- and rear-panel mic jacks. Some operators prefer to
use the rear-panel jack to minimize cable clutter around the front panel. Use
"MAIN:MIC SEL" to select the front panel (FP) or rear-panel (RP) jack. This
menu entry can also be used to apply a bias voltage for electret microphones.

The front-panel mic jack is compatible with the Elecraft MH2, MD2, Proset-K2,
and some other 8pin mics (see pg. 13 for pinout and bias settings).

The rear-panel mic jack accommodates a 3.5-mm (1/8") phone plug, and can be
used in conjunction with the rear-panel PTT IN jack. An 8-pin to 3.5mm
adapter cable is available (pg. 42).

Voice Monitoring

The K3’s voice monitor allows you to hear the way your voice will sound
at your selected mic gain, compression, and transmit audio EQ settings
(TX EQ, pg. 33). Headphones are recommended.

To set up voice monitoring:

* Hold <TEST> to put the K3 in TX TEST mode, so you won’t be transmitting
(pg. 13).

* Set <MIC> to 10-20 to ensure that you’ll hear your voice.
You can fine-tune this level later.

* Press your mic’s PTT switch or tap <XMIT>.

* While speaking into the mic, adjust <MON> for a comfortable listening level.

* Exit transmit (release PTT, or tap <XMIT> again).

* You can either leave the K3 in TX TEST mode or go back to normal transmit
(hold <TEST>) as you follow the instructions in the next section.

Mic Gain, Compression, and ALC

Use the following procedure to properly set up MIC gain and compression level:

* Set the monitor level as described above.

* Optionally select TEST mode (pg. 13) or set power to zero.
This will not affect your CMP/ALC bargraph readings.

* Set <CMP> to 0.

* Hold <METER> to select CMP/ALC metering.

* While speaking into the microphone in a normal voice, adjust <MIC> for a peak
ALC meter indication of about 4-7 bars (see below).

* Adjust <CMP> for the desired speech compression level while speaking.
The CMP scale shows compression level.

* Hold <METER> to return to SWR/PWR metering.

* If you were in TX TEST mode, return to normal operation by holding <TEST>.

* If you had <PWR> set to 0, set it for the desired level in watts.
Key the rig again and verify that you have about the right power output level.

Once you’ve set up the MIC and CMP levels as described, you should only need
to adjust them if you switch mics or if band conditions change.

Voice-mode power output may be slightly higher or lower than the CW power output
you see in TUNE mode. If so, you can compensate using the "CONFIG:TXG VCE"
menu entry (voice transmit gain balance).


Voice Mode VOX Setup

<VOX> selects PTT (push-to-talk) or voice-operated (VOX)
transmit (VOX icon on).

The VOX delay can be set from 0.05 seconds (50 mS) to 2.00 seconds.
The lower the setting, the faster the K3 will return to receive mode after a
pause in speech. See <DELAY> (pg 14).

The "MAIN:VOX GN" menu entry (VOX gain) should be set so that the K3 enters
transmit mode when you speak at a normal level. Setting VOX GN too high will
result in the K3 switching into transmit mode in response to incidental noise.

"MAIN:ANTIVOX" adjusts VOX immunity to signals received through the K3's speaker
or headphones. While listening to a loud received signal, and with the mic
closer to the speaker than it would be in normal operation, adjust ANTIVOX
upward until the K3 doesn’t switch to transmit mode.

Digital Voice Recorder (DVR)

If you have the KDVR3 option installed, you can record and play voice messages
as well as capture received audio. This option also provides voice annunciation
for all K3 controls.

Message Record and Playback

To start recording, tap <REC>, then tap any of <M1> - <M4>.
The remaining buffer time in seconds will be displayed as you speak. Tap <REC>
again to stop.

Tap <M1> – <M4> to play. To cancel, tap <REC>. You can also hit the
keyer paddle, key, or any switch besides <M1> – <M4> to cancel play.

To auto-repeat a message, Hold (rather than tap) <M1> – <M4>.
"MAIN:MSG RPT" sets the message repeat interval (1 to 255 seconds).

Receive Audio Recording

Hold <AF REC> to start / stop audio record. The icon will appear.
Recording starts at the beginning of available space each time it is started,
and will stop at the end if not terminated sooner.

Hold <AF PLAY> to start / stop audio playback.
During playback, the icon flashes. This serves as a reminder that you’re
hearing recorded rather than live audio.

AM Operation

A 6 kHz crystal filter is required on the RF board for AM transmit and receive
(pg. 44).

When listening to AM signals, you have a choice of synchronous or envelope
detection (AM or AM-S). You can alternate between the two using <ALT>. You can
also listen to AM using LSB or USB modes. If you have a 6-kHz filter installed,
voice as well as music will have excellent fidelity.

FM Operation

An FM-bandwidth crystal filter is required on the RF board for FM transmit and
receive (pg. 44). The filter bandwidth is fixed in this mode; presets and filter
controls are not used.

FM defaults to simplex (transmit and receive on the same frequency).
The following controls and menu entries are used for repeater setup:

* Holding <ALT> switches between simplex, TX (+), and TX (-). This is indicated
by the + and icons (near the FM icon).

* Repeater offsets can be programmed on a per-band basis. See "MAIN:RPT OFS".

* Tone encode is set up by holding <PITCH>. Rotate <VFO A> to select a CTCSS
tone frequency (or the European repeater access tone, 1750 Hz). Use <VFO B> to
turn tone encode on or off. All of the settings described above are saved in
frequency memories.


CW Mode

CW Normal and Reverse

Select CW mode by tapping either end of <MODE>.

Hold <ALT> to alternate between CW normal and CW reverse (REV icon).
CW reverse differs from CW normal only in receive mode, using the upper
rather than lower sideband.

If you SPOT (or auto-spot) a CW signal (pg. 32), then switch between CW normal
and reverse, the pitch of the received signal should stay the same.

Basic CW-Mode Controls

In CW mode, <MON> sets the sidetone volume.
Hold <PITCH> to adjust the sidetone pitch. The peak in response of all
crystal filters will track the sidetone pitch; no filter adjustments are needed.

Hold <QSK> to select full break-in (QSK icon on) or semi break-in operation.

VOX must be turned on in CW mode to enable both full and semi break-in
operation. If PTT is selected (VOX icon off), transmit must be activated
using PTT or by tapping <XMIT> .

QSK, or full break-in, allows you to better keep track of on-frequency activity
even while you’re sending. It allows others to “break” your CW
transmission by sending one or two characters.

With semi break-in selected (QSK icon off), the K3 returns to receive mode
after a time delay you set using <DELAY>. This is a compromise between
full break-in and fully manual operation using PTT or <XMIT>.

Hold <TEST> to place the K3 into TEST mode. This allows you to send CW
without transmitting a signal on the air. This is helpful for practicing your
sending or for off-the-air checking of pre-recorded CW messages.

CW-Mode Menu Entries

Configuration menu entries are provided to set up CW iambic keying mode
("CW IAMB"), paddle normal/reverse selection ("CW PADL"), and keying weight
("CW WGHT").

SPOT and Auto-Spot

When calling another station, you should try to match your frequency to theirs.
To facilitate this, the K3 provides both manual and automatic spotting for use
with CW and DATA signals. See Tuning Aids: <CWT> and SPOT (pg. 32).

CW Text Decode/Display

The K3 can decode transmitted and received CW signals, displaying the text
on VFO B (pg. 31). This feature is especially useful when you’re learning
CW, or if someone who doesn’t know CW is looking over your shoulder while you
make CW QSOs. It’s also indispensable for CW-to-DATA operation (pg. 32).

Dual Passband CW Filtering (<DUAL PB>)

Turning on <DUAL PB> in CW mode allows you to listen to a narrow filter
bandwidth (the “focus”), set within a wider, attenuated filter bandwidth (the
“context”). See page 33.

CW Message Record/Play

Messages can only be recorded using the internal keyer, not a hand key or
external keyer.

If text decode is on (pg. 31), CW text sent using the internal keyer
is shown on VFO B (pg. 31). Use TEST to check messages off-air (pg. 13).

There are 8 message buffers, arranged in two banks of 4. Buffers hold 250
characters each. To switch banks, hold <REC> .

Message Record: To start recording, tap <REC>, then <M1> -<M4>. The remaining
buffer space will be displayed as you send. Tap <REC> again to stop.

Message Play: Tap <M1> – <M4> to play. To cancel, tap <REC>. You can also hit
the keyer paddle, key, or any switch besides <M1> – <M4> to cancel play.

Auto-Repeat: To auto-repeat a message, Hold (rather than tap) <M1> – <M4>.
"MAIN:MSG RPT" sets the message repeat interval (1 to 255 seconds).

Chaining: Tapping <M1> – <M4> during playback chains another message onto the
message being played. Holding a message switch during playback chains a
repeating message.


Data Modes

You don’t necessarily need a computer to get started with data modes on the K3:
the text decode feature can decode and display received RTTY and PSK31 on the
LCD (pg. 31). You can also transmit in data modes using your keyer paddle
(see CW-to-DATA, pg. 32).

Using a computer for data modes is also very convenient on the K3, as described

Data Mode Connections

You can transmit and receive data with a computer in three ways:

* Connect your soundcard I/O to the K3. Use "MAIN:MIC SEL" to use LINE IN/OUT,
front-panel mic jack, or rear-panel mic jack. You can use VOX or PTT to control

* Use the soundcard in receive mode, but use a PC I/O line to do direct FSK
(or PSK) modulation. Connect the PC’s I/O line to the “FSK IN” line on the K3’s
AUX I/O connector. (If this signal originates from an RS232 port, it
will require RS232-to-TTL level conversion.)

* Send and receive ASCII text via the RS232 interface. To send, insert text
into a “KY” command (e.g., “KY CQ DE N6KR;”). To receive, send “TT1;”
(text-to-terminal). “TT0;” turns it off. See the K3 Programmer’s Reference,
available at www.elecraft.com.

Data Mode Selection

Soundcard-based data communications can be done using LSB or USB mode. However,
DATA mode offers several benefits not available in SSB modes.

If you prefer to use LSB or USB, you’ll need to manually set CMP to 0 to prevent
data signal distortion. Refer to your data communications software manual to
determine how to set up the VFO and computer for accurate frequency display.

To use DATA mode, tap <MODE> until the DATA icon appears. Next, hold <DATA MD>.
The present data mode is shown on VFO B, and can be changed by rotating
the <VFO B> knob.

1-Hz tuning ( <FINE>) is strongly recommended when tuning in PSK31 signals.

The following data modes are available:

* DATA A can be used for all Audio-shift transmit modes, including PSK31, MFSK,
AFSK, etc. The VFO displays the suppressed-carrier frequency, just as when
SSB modes are used for data. However, compression is automatically set to 0,
and the K3’s dual-tone RTTY filter (DTF) can be selected (pg 30).
USB is “normal” for DATA A.

* AFSK A also uses Audio-shift transmit, but is optimized for RTTY. The VFO
displays the RTTY mark frequency, and LSB is “normal”. The built-in text
decoder can be used in this mode (pg. 31), as well as the dual-tone RTTY
filter (DTF, pg. 30).

* FSK D is identical to AFSK A, except that Direct modulation is used, via DIG 0,
ASCII, or the keyer paddle (pg. 32). The text decoder can be used in this mode
(pg. 31), as well as the dual-tone RTTY filter (DTF, pg. 30).

* PSK D is a Direct-transmit mode for PSK31. It’s the only mode that decodes and
displays PSK31 signals with the text decoder (pg. 31).
Like FSK D, PSK D lets you transmit via DIG 0, ASCII, or the keyer paddle
(pg. 32). You can also use auto-spot with PSK D if the tuning aid
is displayed (<CWT> , pg. 32).

The DATA MD display shows the data speed in bps on VFO A. This is relevant only
if the text decoder is on. Depending on the mode, other data speeds
may be available; select them by rotating <VFO A>.

Also shown is the current sideband (LSB or USB ). If this sideband is considered
“data reverse” for the present mode, then REV also appears. You can use
<ALT> to switch to the other sideband if required.

Mark/Shift and Pitch Selection (<PITCH>)

Hold <PITCH> to view and change the received mark tone and shift (AFSK/FSK)
or center pitch (PSK).

In AFSK/FSK modes, you have a choice of several mark tone/shift combinations.
These apply to both the text decoder and the RTTY dual-tone filter. Use
<VFO A> to change the selection.

When using a computer, select a tone/shift combination that’s compatible
with your software. If you’re using the K3’s text decoder, you may find
that a lower mark pitch makes signal tuning easier.


RTTY Dual-Tone Filter (DTF)

Hold <DUAL PB> to turn on the RTTY dual-tone filter (DTF). This creates two
filters, one centered on the mark tone, the other on space, which can
often improve RTTY copy. The filter graphic changes to reflect this (see below).

When DTF is on, the range of the WIDTH control is adjusted to better match the
characteristics of the filter. SHIFT, LOCUT and HICUT are disabled.

The dual-tone filter can be used in any mode that works with AFSK or FSK,
including DATA A, AFSK A, and FSK D. The on/off state of DTF is
saved independently for each of these modes.

FSK Transmit Polarity

You can invert the logic level of the FSK IN line (pg. 50) in FSK D mode

Mic Gain, ALC, and Monitor Level

If you’re using an audio-shift transmit mode (LSB , USB , DATA A, or AFSK A),
you’ll need to set the MIC level while watching the ALC meter.
You can use the same procedure outlined for voice modes (pg. 26), except that
speech compression should not be used.

In all cases (SSB modes as well as DATA), you can optionally use <MON>
to monitor your data signals. The procedure given for voice modes can be used
(pg. 26). The MIC setting does not apply to direct-modulation data modes
(FSK D and PSK D), since no audio is used for transmission.


Advanced Operating Features

Text Decode And Display

The K3 can decode transmitted and received CW, as well as received PSK31 and
RTTY. Decoded text is displayed on <VFO B>. In data modes, you can
use the K3’s internal keyer to transmit PSK31 and RTTY signals (pg. 32).

When text decode is enabled, turning the <RIT/XIT> offset control does not
flash the offset value. This would disrupt the text display.

CW Text Decode Setup

To set up CW text decode:

* Set MODE to CW.

* Hold <TEXT DEC> , then select CW 5-40 (lower WPM range) using <VFO B>.
Below the CW icon you should see a T, showing that text decode is enabled.
The TX ONLY setting decodes only CW you send (internal keyer); the T does not
appear in this case.

* Adjust the threshold (THR) using <VFO A>. Start with AUTO. Manual settings
(1-30) improve copy in many cases (see below). Tap <CWT> to exit text-decode

* You’ll probably want to turn on <CWT> as a tuning aid (pg. 28).
This also enables auto-spot.

CW Text Decode Tips:

* SPOT (or auto-spot) a signal first, then tune slowly until recognizable
words appear.

* In difficult conditions, reduce WIDTH to as low as 50 Hz (100-200 Hz for
faster CW).

* To optimize text decode, use manual threshold settings. Start with THR 5.
With <CWT> on, adjust the threshold so that the CWT bar flashes in sync
with the received CW signal.

* To decode very fast CW, use CW 30-90.
The K3 uses slow AGC during CW text decode, overriding the selected AGC setting.

DATA Text Decode Setup

To set up text decode for DATA modes:

* Set <MODE>and select either AFSK A, FSK D, or PSK D mode using <VFO B>.
Tap <AFX> to DATA. Then hold <DATA MD> to exit the data-mode display.

* For AFSK A or FSK D, hold <PITCH> and select the desired mark/shift setting.
The lowest mark tone selection (915 Hz) may be more pleasant to listen to
than higher tones. (The pitch for PSK D mode is fixed at 1000 Hz.)
Tap <SPOT> to exit the pitch display.

* Hold <TEXT DEC> , then select ON using <VFO B>. Below the DATA icon you should
now see a T, showing that text decode is enabled.

* Adjust the threshold (THR ) using <VFO A>. Start with THR 0. Higher settings
prevent text decode on weak signals or noise. Tap <CWT> to exit
text-decode setup.

* You’ll probably want to turn on CWT as a tuning aid (pg. 28).
This also enables auto-spot.

DATA Mode Text Decode Tips:

* Use <FINE> tuning with PSK D. SPOT (or auto-spot) a signal first,
then tune slowly in 1Hz steps until recognizable words appear.

* In difficult conditions, reduce WIDTH to the per-mode minimum.

* In AFSK A and FSK A modes, the RTTY dual-tone filter may help (DTF, pg. 30).

* RTTY text may shift to figures due to noise. If you assign "CONFIG:TTY LTR"
to a programmable function switch, you can tap it to quickly shift back to



You can use data modes completely stand-alone (i.e., without a computer).
Just turn on text decode (pg. 31), and send CW using the internal keyer.

CW message buffers can also be used for CW-to-DATA. This makes it easy to drop
your callsign in after a CQ, send a contest exchange, or play a “brag tape”
during QSO.

To set up for CW-to-DATA operation:

* Referring to page 11, use <MODE> , <DATA MD>, <TEXT DEC>, and <PITCH> to set
up text decode. Select either FSK D or PSK D mode. A small T should appear
below DATA icon.

* If you haven’t used text decode before, try tuning in a few stations
(turn on CWT ; pg. 31).
Tips for improved copy in tough band conditions are provided on page 31.

* Plug a keyer paddle into the PADDLE jack. The first time you try CW-to-DATA,
set PWR to 0 watts or use TX TEST mode (pg. 13).

* All CW you send will be transmitted as data and displayed on VFO B.
You’ll hear a CW sidetone, as well as PSK or FSK tones. Adjust the data monitor
volume using <MON>. To adjust the CW sidetone monitor level, temporarily switch
back to CW mode.

* Whenever you pause, the K3 will remain in a data idle state for about four
seconds before automatically dropping. To extend the timeout, send the
CW double-dash ("-...-", or BT prosign), which is not transmitted as data.

* To cut short the idle transmit period and exit to receive mode, send "..--"
(IMmediately exit). This character is not transmitted as data.

* When recording CW messages for use during CW-to-DATA, you can add "..--"
at the end to cut the idle time when they’re played back.
The CW abbreviation for “and” (ES) is not used in data modes and might lead
to confusion. Other prosigns can be used, including KN, SK, and AR.
If you set VFO B for CW mode rather than DATA mode and use cross-mode SPLIT
(pg. 34), your CW will not be converted to DATA.

Tuning Aids: <CWT> and <SPOT>

Tapping <CWT> turns the upper half of the S-meter into a CW/DATA tuning aid.
If no bar appears in the tuning area, the threshold may be set too high;
hold <TEXT DEC> and select a lower THR value.
When a received CW or PSK31 signal is centered in the passband, the CWT display
will appear as shown below.

In RTTY modes (AFSK A and FSK D), mark and space tones are represented by three
bars each, with mark to the left of the CWT pointer, and space to the right.
When only weak signals are present in the mark/space filters, 1-3 bars will
flicker on either side, leading to a “ghosting” effect, as shown here.

As you tune the VFO close to an RTTY signal, the number of bars will initially
increase on one side or the other. Keep tuning until you see a rough balance
between left and right bars. (Also see DTF, pg. 30, and "CONFIG:TTY LTR".)

Manual SPOT

If <CWT> is off, you can tap <SPOT> , then manually tune the VFO until
the received signal’s pitch matches the sidetone. If you find pitch matching
difficult to do, try auto-SPOT (below).


To use auto-spot, first turn on <CWT> . Use a narrow bandwidth (200 to 500 Hz).
Tapping <SPOT> will then automatically tune in a received signal that
falls within the CWT display range.

Auto-spot may not be usable if more than one signal is in the CWT range,
if the signal is extremely weak, or if the code speed is very slow.

Auto-spot coarse-tunes PSK31 signals, but you’ll need to fine-tune them
in 1-Hz steps (<FINE>).


Audio Effects (<AFX>)

If you have stereo headphones or stereo external speakers, you can take
advantage of the K3’s DSP audio effects. These create an illusion of greater
space, similar to stereo. For many operators, <AFX> provides a less fatiguing
receiver sound, and it can even improve weak-signal copy.

"MAIN:AFX MD" is used to select the desired AFX setting. Available selections
include DELAY 1-5 (quasi-stereo), and BIN, which is similar to Binaural I-Q
(see QST magazine, March, 1999).

Tap <AFX> to turn the selected effect on or off. This can be done even
within the "AFX MD" menu entry.
Stereo audio effects may not be available when the sub receiver is turned on.
Main/sub dual receive is already a stereo mode, with different material
routed to each audio channel.

Dual Passband CW Filtering

Dual-passband filtering allows you remain aware of off-frequency CW signals
while listening to one signal centered in the passband. This can be useful
during contesting or DXing, as well as when searching a band for weak signals.

Hold <DUAL PB> to turn on dual-passband filtering.
This sets up a narrow filter (focus), set within a wider passband (context)
that is attenuated by about 20 dB. The filter graphic reflects this:

The width of the context filter can be varied over a wide range using WIDTH,
while the focus filter bandwidth is fixed. The current preset will keep
track of both the state of <DUAL PB> and the context width.
Hold <DUAL PB> again to return to normal filtering.

Receive Audio Equalization (EQ)

The K3 provides 8 bands of receive audio equalization via the "MAIN:RX EQ" menu
entry. You can use receive equalization to compensate for the physical
acoustics of your station (the room, headphones, speakers, etc.), or just to
tailor the audio to your personal preference.

In the RX EQ menu entry, the VFO A display shows 8 individual vertical
bargraphs. The example below shows various amounts of EQ applied to the 8 bands.

The center frequencies of the 8 audio EQ bands are
50, 100, 200, 400, 800, 1200, 2400, and 3200 Hz.
To select a band to change, tap 1-8 on the keypad.
For example, tapping 1 selects the 50-Hz band.

Next, rotate <VFO A> to specify an amount of boost or cut (+/- 16 dB). The
illustration above shows the 800 Hz EQ band (0.80 kHz) being set to +1 dB of

You can tap <CLR> to reset all of the RX EQ bands to 0 dB (no cut or boost).

Transmit Audio Equalization (EQ)

Transmit audio equalization is provided to compensate for variations in
microphones and your voice. "MAIN:TX" EQ works exactly the same as RX EQ,
and can be used during transmit.

If you’re using ESSB (pg. 34), a separate set of transmit EQ settings is
provided. When ESSB is on, the TX EQ menu entry name changes to TX* EQ as
are reminder of which TX EQ set you’re changing.

While adjusting TX EQ, you can listen to the voice monitor signal using
headphones (use <MON> to set the level), or listen to the K3’s transmitted
signal on another receiver.


SPLIT Operation

Normally, VFO A is used for both receive and transmit. When SPLIT mode is
selected, VFO B becomes the transmit VFO. The SPLT icon turns on,
and the TX arrow points to B (pg. 12).

In addition, the Delta-F LED (.f) turns on (yellow). This will alert you
at a glance that your receive and transmit frequencies and/or modes are
not the same.

Extended Single Sideband (ESSB)

ESSB refers to the use of a wider transmit audio bandwidth than is traditionally
provided by SSB transceivers. An increase in bandwidth may improve fidelity in
voice communications, and may be less fatiguing to listen to.

The K3’s normal SSB receive bandwidth is about 2.7 to 2.8 kHz.
If you have a 6 kHz filter installed, you can listen to ESSB stations up to
approximately this bandwidth by adjusting the WIDTH control.

ESSB transmit is set up as follows:

* Locate the "CONFIG:TX ESSB" menu entry, and change the value from OFF to one
of the provided selections (3.5, 4.0, etc.). See cautions below.

* With ESSB enabled, the transmit EQ menu entry name changes to "MAIN:TX* EQ"
to allow you to independently adjust EQ at the selected wider bandwidth.
The amount of adjustment required at each EQ band may vary significantly
depending on the selected ESSB transmit bandwidth.

* If you assign TX ESSB to a programmable function switch, pressing it will
alternate between ESSB TX OFF and the last bandwidth you selected using the
menu. Carrier suppression, passband shape, delay characteristics, fidelity, and
other aspects of ESSB performance are not specified. Use ESSB only after
carefully monitoring your signal.

Settings above 3.5 kHz may have flatter passband response and better fidelity,
but there may also be an increase in low level transmit spurious responses
(typically < 80 dBc).

General-Coverage Receive

If you wish to tune the full 0.5 to 30 MHz range with low loss, you can install
a KBPF3 module. This module includes eight band-pass filters that cover all
of the areas between the ham bands. The K3 will automatically switch between
the narrow ham-band filters to the KBPF3 filters as you tune the VFOs.

A KBPF3 module can be installed on the RF board (for use with the main receiver)
and/or on the sub receiver module (KRX3).

The "CONFIG:VFO CRS" menu entry can be used to select coarse VFO tuning rates
for AM and SSB modes. AM coarse tuning rates include 5, 9, and 10 kHz,
matching the requirements for various broadcast band segments.
Sensitivity below 1.8 MHz will be reduced due to the high-pass response of the
T-R switch, which protects the PIN diodes.

VFO B Alternate Displays

The VFO B display can show time, date, supply voltage, current drain,
KPA3 heatsink temperature, front panel compartment temperature, and other useful
information. Tapping <DISP> turns the selected alternate display on or off.
Rotate the VFO B knob to select the desired display.

If "CONFIG:TECH MD" is ON, additional VFO B alternate displays will be available
for alignment and troubleshooting. These are described in the K3 Service Manual.

Alarm and Auto Power-On

Once you’ve set the K3’s real-time clock ("CONFIG:TIME"), you can use
"MAIN:ALARM" to set an alarm. This can be used to remind you of a schedule,
net, or start of a contest.

When an alarm is set, an asterisk (* ) appears in the time display.
(Time can be displayed by tapping <DISP> .)

The K3 will turn ON automatically if it was off at alarm time. It will be set
for the same band and mode that was in effect when power was turned off.


Using the Sub Receiver

The KRX3 option adds a fully independent, high-performance second receiver,
or sub receiver to the K3.

With the sub receiver installed, you can monitor two different frequencies or
even two different bands, using different modes, filter bandwidths, or
other settings as required. It's even possible to do diversity receive.
In this case, the VFOs for the two receivers would be linked together, and
you'd use two different antennas.

The sub receiver (or "sub" for short) has the same specifications and
performance as the main receiver. This sets the K3 apart from most other
transceivers in its class; others may provide only a simple "dual watch"
function – with no independent crystal filtering – or an independent
sub receiver with mediocre performance.

The sub receiver also has the same filter options as the main receiver.
Up to five crystal filters can be installed in the sub receiver, as well as a
general-coverage L-C band-pass filter module (KBPF3, pg. 42).
The sub also includes an I.F. noise blanker.

There are three main modules associated with the KRX3 option: the sub receiver
itself; a KSYN3 synthesizer; and a second I.F. DSP. All three must be installed
and enabled before the sub receiver can be used. For information on installing
and configuring the sub receiver, refer to the KRX3 option installation manual.

Sub Receiver Controls

There are several controls directly related to the sub receiver:
the <SUB> switch, <VFO B> (and its associated display), SUB AF GAIN, and
SUB RF GAIN (which can be assigned to either main or sub squelch instead
using "CONFIG:SQ SUB). Other sub receiver settings can be viewed or changed
using BSET, described later.


turns the sub receiver (and SUB icon) on.

If you're using stereo headphones or speakers, you'll hear the sub receiver
on the right side, and main receiver on the left. With a single speaker or mono
phones, the two will be added together, and the MAIN and SUB AF GAIN controls
will adjust the relative amount of signal from each.

BSET: Direct Sub receiver Control

Normally, all receive-mode controls (including PRE , ATT N, <NB> , SHIFT,
WIDTH, etc.) pertain to <VFO A> and the main receiver. To view or change the
settings for the sub receiver (VFO B), hold <BSET>. VFO A will show BSET.
While in BSET mode, the S-meter will reflect the sub receiver's signal level.
You can change the sub receiver control settings, as well as the MODE .
You can also change the sub receiver’s band using <BSET>
if "CONFIG:VFO IND" (VFO A and B independent) is set to YES.

Tap <A/B> or hold <BSET> again to exit BSET.

Split Mode with the Sub receiver

When operating split, <VFO A> is the receive frequency and <VFO B> the transmit
frequency. If the sub receiver is on, you'll be able to listen to both your
receive and transmit frequencies in receive mode. Hold SPLIT to turn split mode
on or off. In many cases you may want to set up the two receivers differently.
For example, if you're working DX split, you can listen to the DX station in a
very narrow bandwidth on the main receiver (<VFO A>), while using a wider
bandwidth for VFO B so you can look for a clear calling frequency.

Sub Receiver RF Input Sources

The sub receiver gets its RF input either from the main receiver (sharing the
main antenna jacks or <RX ANT> IN), or from its auxiliary antenna input.

There are four possible ways to wire the sub receiver’s auxiliary RF input,
as explained in the KRX3 option installation manual. "CONFIG:KRX3" is used to
specify which of these you’ve used (see pg. 50).

For a full description of sub receiver RF input sources, please see Main and
Sub Receiver Antenna Routing (pg. 37).


Receive Antenna In/Out

The <RX ANT> IN/OUT jacks, supplied with the KXV3 option, have various uses:

* Low-noise receiving antenna: Some operators use a Beverage, tuned loop,
or other low-noise receiving antenna. You can connect such an antenna to the
RX ANT IN jack, then tap <RX ANT> to select it. The RX icon will turn on.

* Narrowband filters or preamps: You can "patch in" a specialized filter or
preamp between RX ANT IN / OUT. Tap <RX ANT> to switch the filter in (per-band).
It will be in-line only during receive, so you can use crystal filters or
amplifiers with low power ratings.

* Test signal injection: The RX ANT IN jack is ideal to inject a test signal,
because the generator won't be damaged if you transmit.

* Receiver comparisons: If you connect the RX ANT OUT jack to a second receiver,
and leave the RX ANT IN jack open, you can A/B test the K3 against the other
receiver. When the RX ANT is not selected (RX icon off), the K3 will be
receiving on its main antenna jack, and the other receiver will have no input.
If you then tap <RX ANT> , the K3 will have no receive antenna,
while the other receiver will be operating from the K3's main antenna.

If you’re comparing the K3 to a transceiver and using its transmit/receive
antenna, be sure to set its power to 0 so you won't damage the KXV3 when
you transmit.

Buffered I.F. Output

The KXV3 provides a buffered (isolated) first I.F. signal at the IF OUT jack.
This signal is at approximately 8.215 MHz, compatible with some panadapters
(also known as spectrum scopes).

You must use a short, very high-quality coax cable between the K3 and
the panadapter. Additional isolation may also be required. If signals are
allowed to leak into the buffered I.F. output, they will be audible on quiet
bands and can degrade K3 receiver performance.

Using Transverters

Nine user-definable bands are provided for use with transverters. Once enabled
individually, these bands will appear in the band rotation following 6 meters.
You can use Elecraft XV-Series transverters and most other transverter types
with the K3.

Transverter Band Setup

Transverter bands are set up using the "XV menu" entries. In all cases, tap 1– 9
within the menu entry to select a transverter band to configure.

* "XVn ON" must be set to YES to enable transverter band n.

* XVn RF selects the transverter operating frequency in MHz.

* XVn IF specifies a K3 band to use as the transverter I.F. (7, 14, 21, 28,
or 50 MHz).

* XVn PWR sets the K3 power output range to be used with this transverter band.
L0.01L1.27 specifies a power level in milliwatts, which requires the KXV3 option
(use the XVTR IN and OUT jacks). H00.0-H12.0 specifies power in watts, and
selects the K3’s main antenna jack(s) for output.

* XVn OFS is used to compensate for any frequency offset in the transverter’s
oscillator/multiplier chain. The value shown is in kHz.

* XVn ADR specifies an Elecraft XV-Series transverter selection address (see
transverter manual). Further details on these menu entries can be found in the
"CONFIG" menu listings. For information on transverter control connections and
band data, see pg. 19.

CAUTION: We recommend the use of milliwatt-level drive with transverters (via
the XVTR IN and OUT jacks). If you use the K3’s main antenna jack(s),
you could accidentally transmit into a transverter at high power.



The K3's scanning features let the K3 tune any band segment continuously, with
or without the receiver muted (Some bands may be excluded from scanning for
regulatory reasons.) Scanning can be used to monitor any portion of a band, from
a 1-2 kHz range where a station or net is expected to appear, to an entire band.

Sometimes a band that appears “dead” may actually have several stations present.
You can use scanning to find these stations for you while accomplishing
other tasks.

Scanning while muted allows the K3 to ignore stable carriers (key-down signals
with no modulation), unmuting only when "interesting" signals are found.
Scanning with the receiver "live" (not muted) is especially useful when
listening for weak signals on very quiet bands.

Scanning Setup

To use scanning, you first need to store the desired tuning range in a memory.
After that, you’ll be able to simply recall the memory, then start scanning.
You can set up scanning ranges for various bands, modes, etc.

To set up a scanning memory:

* Set <VFO A> to the starting frequency, and VFO B to the ending frequency.

* Select the operating mode, preamp/attenuator settings, and filter bandwidth.
Also select the tuning rate, which affects speed of scanning.

* Store this setting in any memory (pg. 16).

* To start scanning:

* Recall the memory using MV .

* Hold SCAN to start scanning. To scan with the receiver live (unmuted),
continue to hold SCAN until you see <AF> ON (about 2 seconds). You can stop
scanning by manually rotating VFO A, tapping any switch, hitting the key or
keyer, or pressing PTT. To restart, hold SCAN.

Channel Hopping

Scanning over a numbered memory range, rather than a frequency range, is
referred to as channel hopping. This is included in the K3 primarily for use on
60 meters and on transverter bands. The U.S. 60-meter channel assignments
correspond to VFO settings of 5330.5, 5346.5, 5366.5, 5371.5, and 5403.5 kHz.
USB is the only mode allowed on this band.

Memories to be used for channel hopping must be consecutive, and must be
assigned a text label that starts with an asterisk (* ).

To set up channel hopping:

* Set <VFO A> to the first frequency in the intended channel-hopping range.

* Tap MV, then select a memory (00-99) using <VFO A>.

* Rotate <VFO B> to select each label position in turn as indicated by the
flashing cursor.

* Use <VFO A> to change characters. The first character must be an asterisk (*);
other label characters are optional.

* After editing, tap <MV> again.

* Set up all other memories to be used for channel hopping.
Channel-hop scanning is started, stopped, and restarted in the same way as
normal scanning (details at left).


Main and Sub Receiver Antenna Routing

The simplified block diagrams in this section show how antennas are routed to
the main and sub receivers. The heavy line shows the default RF path. All
antennas are protected from electrostatic discharge by surge arrestors.
Receive-only antenna inputs include carrier-operated relay circuitry (C.O.R.),
indicated by asterisks (* ).

Basic K3 (no KAT3 or KXV3)

As shown in Figure 1, the basic K3 is supplied with one antenna jack (ANT1,
SO239). The signal from ANT 1 is routed through the antenna input module to the
main receiver (as well as to the transmitter). The KRX3 sub receiver, if
installed, can share the ANT 1 signal via a passive splitter and relay K1. When
the sub receiver is off or is switched to its auxiliary RF input, K1 bypasses
the splitter so it will have no effect on either receiver.

An extra RF I/O connector location is provided (AUX RF, BNC). The sub receiver’s
auxiliary input can optionally be routed to this connector. K1 then selects
either the main RX path or AUX RF as the sub receiver’s RF source. The sub
receiver has its own full set of ham-band and optional general-coverage
band-pass filters (KBPF3), but its image rejection will be best when sharing the
main path, which includes the receive/transmit low-pass filters.

Figure 1. Basic Main/Sub Receiver Routing (no KAT3 or KXV3) (not shown)

K3 with KXV3 RF I/O Module

If the KXV3 option is installed (Figure 2), a separate receiving antenna can be
connected to the <RX ANT> IN jack. Relay K2 then selects either ANT1 or <RX ANT>
for the main receiver. (Note: The low-pass filters will not be in the path when
<RX ANT> is selected. This will rarely be an issue, since the main receiver has
a full set of ham-band band-pass filters. You can use external filters with <RX
ANT> IN if required.)

Relay K1 allows the sub receiver to share the main receiver’s RF source, or use
its auxiliary RF input. This means that two receiving antennas could be used.
But it’s also possible to route a single receiving antenna to both the <RX ANT>
IN and AUX RF jacks using a “Y” adapter. This would allow the sub receiver to
use the antenna connected to <RX ANT> IN even if the main receiver were using
ANT 1. No external splitter is required because only one of the receivers will
be connected to the receiving antenna at a time.

Not shown is the <RX ANT> OUT jack. The <RX ANT> IN/OUT jacks can be used
together to “patch in” an external band-pass or low-pass filter or low-noise
preamp for the main (shared) RF path; see pg. 17.


Figure 2. Main/Sub Receiver Routing with KXV3 Installed (not shown)

K3 with KAT3 <ATU>

The KAT3 internal <ATU>, replaces the KANT3 antenna input module, provides a
second SO239 antenna jack (ANT 2). As shown in Figure 3, relay K3 routes either
ANT 1 or ANT 2 to the main RF path. The antenna not routed to the main path (the
non-transmit antenna) is available for the sub receiver. Relay K1 selects either
the main RX path (show here), or the non-transmit antenna.

The sub receiver’s auxiliary input can optionally be routed to the AUX RF
connector rather than to the non-transmit KAT3 antenna. The sub receiver would
be able to use either the main path (transmit antenna) or AUX RF.

Figure 3. Main/Sub Receiver Routing with KAT3 Installed (not shown)


K3 with KAT3 and KXV3

Figure 4 shows the antenna possibilities with both the KAT3 and KXV3 installed.
The main receiver can use ANT 1, 2, or <RX ANT> IN. The sub receiver can either
share the main receiver’s RF source, or use its auxiliary input, meaning either
the non-transmit KAT3 antenna or AUX RF. In the latter case, you could use two
receive- only antennas – one for each receiver – or wire <RX ANT> IN to AUX RF
as described previously.

Figure 4. Main/Sub Receiver Routing with KXV3 and KAT3 (not shown)

Antenna Selection Controls

Main Receiver

Tap <ANT> to select ANT 1 or ANT 2. To select the receive antenna (<RX ANT> IN),
tap <RX ANT>. The RX icon will turn on. In this case, you’ll still be able to
tap <ANT> to select ANT 1 or 2 for use with the transmitter.

Sub Receiver (if Installed and Turned On)

First, hold BSET (<VFO B>/subreceiver direct control). BSET will appear on the
VFO A display. While in BSET mode, tapping <ANT> switches the sub between the
main RF path and its aux input. If the sub is sharing the main RF path, the
antenna icons will be the same for main and sub. If the sub is using its aux
input, the antenna icons will reflect the sub’s aux RF source ("CONFIG:KRX3)":

Antenna Icons Sub Receiver Auxiliary RF Source
ANT 1 or 2 (opposite of main) KAT3 <ATU> non-transmit antenna
ANT RX AUX RF in parallel with <RX ANT> IN on KXV3


Remote Control of the K3

With appropriate software, any computer with an RS232 port (or a USB-to-RS232
adapter) can be used to control the K3. K3 to computer connections needed for
RS232 communications and control functions are covered on page 18.

Third-party logging and contesting software is available for various computers
and operating systems. Most applications written for the K2 should work with the
K3, and some provide K3specific features.

For a list of K3-compatible software applications, including configuration
requirements, please visit www.elecraft.com/K3/software.

Remote-Control Commands

The K3 has a rich set of remote-control commands, including over 150 commands
that directly control the two DSPs. With appropriate software, various
extensions to DSP functionality can be made available to the operator, including
customized filters, fine control over noise reduction, per-mode parametric EQ,
absolute level metering in dB, and unique tuning aids.

K3 remote-control commands use ordinary ASCII text, so they can be easily tested
using a terminal emulator.

For example, the command “FA;” returns the current <VFO A> frequency. Using the
same command, you can set the <VFO A> frequency, e.g. “FA00007040000;” sets the
VFO to 7.040 MHz.

Many new commands are provided in addition to the core set of commands supported
by the K2. A few examples:

“DB;” returns the contents of the <VFO B>
display, while “DBxx;” (xx=00-13) selects a
<VFO B> alternate display mode (time, supply
voltage, etc.).

“TT1;” (text-to-terminal) routes decoded CW/DATA text to the PC terminal
program, in addition to the K3’s <VFO B> display.

“RVM;” and “RVD;” retrieve MCU and DSP firmware revisions.

“SW” and “MN” commands provide access to all switch and menu functions.

This is a small sample of the commands available to both professional software
developers and those who might wish to experiment with simple remote control

Please refer to the K3 Programmer’s Reference for further details.



K3 option modules and crystal filters add significant new capabilities to the
transceiver. They can be installed at any time (see pg. 43). All modules are
plug-in, requiring no soldering or cable assembly.

The presently available options are described briefly below; please refer to our
web site for further details on these as well as our full range of 5- and 8-pole
crystal filters.

KAT3: Wide-range internal 100-W automatic antenna tuner with dual antenna jacks.

KPA3: Internal 100-W upgrade for the K3/10, with two large fans and separate
circuit breaker.

KDVR3: Digital voice recorder, usable both for message record/playback and
general audio recording.

KRX3: High-performance, fully-independent sub receiver with its own set of 5
crystal filter slots, 32bit DSP module, noise blanker, optional general-
coverage band-pass filter array (KBPF3 – see below), and auxiliary antenna

KBPF3: General-coverage band-pass filter array that allows the K3 main or sub
receiver to cover the entire LF and HF range of 0.5 to 30 MHz. (If you want
general coverage in both main and sub receivers, two KPBF3 modules are

KXV3: RF I/O module, including receive antenna in/out jacks (see pg. 36),
transverter interface (pg. 36), and a buffered I.F. output (pg. 36). The RX ANT
in/out jacks can be used to patch-in external per-band filters or low-noise

KTCXO3-1: High-stability TCXO; 1 PPM, firmware correctable to better than 0.5
ppm (see calibration instructions, pg. 47).

Firmware Upgrades

New features and improvements are available to all K3 owners via firmware
upgrades. Upgrades may also be required when you install new option modules.

Please visit the Elecraft K3 software page (www.elecraft.com/K3/software) to
obtain our free firmware download utility.

The K3 firmware download utility may not be available on all common computer

Checking your Firmware Revision

Use the <CONFIG> menu’s FW REVS menu entry to determine your firmware revision.
The serial number of your transceiver, if needed, can be obtained using the SER
NUM menu entry.

K3 Firmware Self-Test

If the K3 detects an error in its firmware (an incorrect checksum), it will
flash the TX LED and show MCU LD on the LCD (with backlight off).

If this occurs, connect the K3 to your computer and reload firmware. While
firmware is loading, the Delta-F LED (.f) will flash. When the download is
complete, the K3 should reset and run normally.

Forcing a Firmware Download

If you accidentally load an old or incompatible firmware version and find the K3
unresponsive, do the following:

(1) unplug the K3 from the power supply and wait 5 seconds;

(2) plug the power supply back in;

(3) hold the K3’s <POWER> switch in; after about 10 seconds, you’ll see the TX
LED flash (you’ll also see MCU LD on the LCD);

(4) load the correct firmware version.

Other Ways to Upgrade Your Firmware

If you don’t have Internet access, you can purchase a firmware upgrade on CD.

If you don't have a computer, you can send your K3 to Elecraft to be upgraded.
See Customer Service and Support, pg. 10.



Configuring your K3 involves installing options and crystal filters, as well as
customizing menu settings based on your personal preferences.

Option modules come with their own installation manuals. Once they’re installed,
they must be enabled using their associated menu entries (see pg. 50).

Crystal Filter Setup

Crystal filter installation is covered in detail in Appendix A (pg. 67). Once
filters have been installed (or moved), all of the steps described below must be

Filter Bandwidth

* Turn the K3 on.

* Hold <CONFIG> (the hold function of the <MENU> switch) to access the <CONFIG>
menu group.

* Locate the FLx BW menu entry, which will be used in the next step to set up
filter bandwidths. “x” will be replaced with 1 through 5, corresponding to
crystal filters FL1-FL5.

* Tap <SUB> to set up sub receiver filters. Otherwise, make sure the <SUB> icon
is OFF.

* Tap 1 or use <XFIL> to select FL1.

* Using <VFO A>, adjust the bandwidth parameter so that it matches the filter
installed at the FL1 position. Use the filter information table you filled out
in Appendix A.

* Select the remaining filters by tapping 2 through 5 or <XFIL> , adjusting
their bandwidth parameters according to the table.

* Stay in the menu as you continue on to the next filter setup step.

Filter Frequency Offset

* Use <VFO B> to find the FLx FRQ menu entry.

* Tap <SUB> to set up sub receiver filters. Otherwise, make sure the <SUB> icon
is OFF.

* Tap 1 or use <XFIL> to select FL1.

* Adjust <VFO A> so that the parameter matches FL1’s marked frequency offset (as
recorded in the filter information table, Appendix A). The default value, 0.00,
corresponds to the nominal filter center frequency of 8215.0 kHz. Most 5pole
filters will have an offset, e.g. “-0.91”. (This has no effect on performance;
firmware compensates for the offset.)

* Select the remaining filters and adjust their frequency offsets as required.

Receive Filter Enables (Per-Mode)

You must specify which of the five crystal filters is enabled for receive in
each mode.

* Use <VFO B> to locate the "FLx ON" menu entry.

* Tap <SUB> to set up sub receiver filters. Otherwise, make sure the <SUB> icon
is OFF.

* Tap <MODE> until the LSB icon appears.

* Tap 1 or use <XFIL> to select FL1.

* Set FL1 ON to YES or NO using <VFO A>. You should enable both narrow and wide
filters for use in SSB modes, since they may be used during copy of data, SSB,
or AM signals.

* Use <XFIL> to go to FL2-FL5 in turn, and enable or disable these filters for
LSB mode.

* Tap <MODE> to select each of the other modes in turn (USB, CW, DATA, AM, and
FM). For each mode, set up the FL1-FL5 enables.

Filter Loss Compensation

Narrow crystal filters tend to have more passband loss than wide filters. You
can compensate for this effect by specifying an amount of added gain to use for
each filter in receive mode.

* Use <VFO B> to find the "FLx GN" menu entry.

* Tap <SUB> to set up sub receiver filters. Otherwise, make sure the <SUB> icon
is OFF.

* Tap 1–5 or <XFIL> to select a filter to modify.

* Use <VFO A> to set the gain in dB. In general, you’ll want to add 1-2 dB for
400-500 Hz filters, and 3-4 dB for 200-250 Hz filters.

* Select the remaining filters and adjust their gain parameter as required.


Transmit Crystal Filter Selection (Per-Mode)

This step applies only to filters on the RF board.

* Select CW mode by tapping <MODE>.

* Use <VFO B> to find the "FLTX CW" menu entry.

* Rotate <VFO A> to select a CW transmit filter (2.7 or 2.8 kHz). Note: Key
clicks may result if a narrower filter is selected for CW transmit.

* Tap <MODE> to select LSB . The menu entry will change from FLTX CW to FLTX SB.

* Select the filter to be used during SSB and DATA transmit (2.7 or 2.8 kHz).
This setting is overridden automatically for ESSB (pg. 44).

* If applicable, select a 6-kHz filter for AM (FLTX AM), and 12.5 kHz for FM
(FLTX FM). If you’re using a 2.7-kHz 5-pole filter for SSB transmit, you can
optionally fine-tune its FLx FRQ parameter to equalize LSB and USB transmit
characteristics. Monitor with a separate receiver and use headphones, or have
another station listen.

Option Module Enables

K3 options can be installed at any time. Once an option has been installed, use
the associated "CONFIG" menu entry to enable it (see list below). Then turn the
K3 off and turn it back on. This allows the K3 to find and test the module.

* KAT3 <ATU> module: set KAT3 to BYP.

* KBPF3 general-coverage band-pass filter module: set KBPF3 to NOR (if you’re
installing a KBPF3 on the sub receiver, tap <SUB> while in the menu entry).

* KXV3 RF I/O module: set KXV3 to NOR .

* KRX3 sub receiver: set KRX3 to NOR -ANTx where x is your selected wiring for
the sub receiver’s auxiliary antenna (1 = unused KAT3 <ATU> antenna, 2 = AUX RF
jack, 3 = AUX RF in parallel with the <RX ANT> IN jack on the KXV3). For details
on sub receiver antenna sources, see pg. 22. You may also need to set up crystal
filters for the sub receiver.

* KDVR3 voice recorder: set KDVR3 to NOR .

* KPA3 amplifier module: set the PA <MODE> menu entry to PA NOR. See menu entry
listings for information on other settings.

Miscellaneous Setup

We suggest setting up at least the menu entries below. You may wish to review
the other menu entries as well, starting on pg. 49.

Mic Gain / Bias

"MAIN:<MIC> SEL" is used to select either the front- or rear-panel mic, or LINE
IN. If a mic is selected, you can also tap 1 to select Lo or Hi mic gain range,
and tap 2 to toggle mic bias on/off. See pg. 13 for Elecraft mic bias

AF Gain Range

"CONFIG:AF GAIN" specifies LO or HI <AF> gain range. The default is HI. The LO
setting should be adequate for many stations, and is less likely to result in
speaker distortion at max volume.

Time and Date

"CONFIG:TIME" sets the 24-hour real-time-clock (RTC). Tap 1 / 2 / 3 to adjust
HH/MM/SS using <VFO A>. This URL shows UTC as well as all U.S. time zones:

"CONFIG:DATE MD" selects US (MM.DD.YY). or EU (DD.MM.YY) date format using <VFO

"CONFIG:DATE" is used to set the date. Tap 1 / 2 / 3 to adjust MM/DD/YY or

VFO Setup

Several <CONFIG> menu entries are provide to control VFO behavior:

* VFO CRS sets up the per-mode COARSE tuning rate

* VFO CTS is used to specify the number of counts per knob turn (<VFO A> and B):
100, 200, or 400

* VFO FST selects the normal VFO fast tuning rate (20 or 50 Hz)

* VFO IND, if set to YES, allows <VFO B> to be set to a different band than <VFO
A> (only applies if the sub receiver is installed)


<VFO A> Knob Friction Adjustment

The <VFO A> knob’s spin rate can be adjusted by moving the knob in or out
slightly. The rubber finger grip on the <VFO A> knob covers the knob’s set
screw, so it must be removed first.

In the following procedure, use only your fingernails; a tool may scratch the
knob. Using your fingernails at the point identified below, pull the finger
grip forward slightly. Rotate the knob and repeat until the grip can be pulled

Use the supplied 5/64" (2 mm) Allen wrench to loosen the set screw.

Between the knob and front panel are two felt washers which, when compressed,
reduce the spin rate. Move the knob in or out in small increments until the
desired rate is obtained. Then re-tighten the set screw and replace the finger

<VFO B> Knob Friction Adjustment

Use the supplied 5/64" (2 mm) Allen wrench to loosen the <VFO B> knob’s set

Between the knob and front panel is a felt washer which, when compressed,
reduces the spin rate. Move the knob in or out in small increments until the
desired rate is obtained. Then re-tighten the set screw.

Real Time Clock Battery Replacement

K3 components or modules can be easily be damaged by ESD (electrostatic
discharge). To avoid this, put on a grounded wrist strap (with 1 megohm series
resistor) or touch a grounded surface before touching anything inside the
enclosure. An anti-static work mat is strongly recommended.

The battery for the real time clock/calendar is located on the left side of the
RF board. To access it, turn power off, then remove the top cover as described
in Appendix A.

Remove the old battery. Replace it with the same type of 3-V lithium coin cell
(CR2032, BR2032, equivalent). The (+) terminal is clearly marked on the battery;
it must be oriented as indicated by the (+) symbol on the RF board. Re-install
the top cover.

To set the time, date, and date format, refer to the following <CONFIG> menu
entries: TIME, DATE, and DATE MD.


Calibration Procedures

All calibration procedures are firmware- based. Please do not adjust any of the
trimmer capacitors or potentiometers inside the K3; they been carefully aligned
at the factory.

Most calibration procedures use Tech-Mode menu entries. To enable these, set
"CONFIG:TECH MD" to ON. Set "TECH MD" to OFF afterward.


This procedure is normally done at assembly time or by the factory.

* Hold <CONFIG> and find the "CONFIG:VCO MD" menu entry. Set the parameter fully
clockwise to CAL. Exit the menu. The synthesizer will be tested and calibrated.

* To calibrate the 2nd synthesizer (for the sub receiver), locate "CONFIG:VCO
MD" and set the parameter to CAL, tap <SUB> to turn on the <SUB> icon, then exit
the menu.


If desired, power readings shown during <TUNE> can be adjusted to match an
external wattmeter. To account for all K3 circuitry involved, this must be done
at 5.0 W, at 50 W (K3/100 only), and at 1.00 mW if the KXV3 option is installed.

Low-Power (5 W) Wattmeter Calibration

* Switch to 20 meters.

* Put the <ATU> into bypass mode (hold <ATU> ).

* Connect a 50-W capable dummy load (5 W for K3/10) and an accurate wattmeter to

* Switch to ANT1 by tapping <ANT>.

* Set power to exactly 5.0 watts.

* Hold <CONFIG> and locate the "CONFIG:WMTR LP" menu entry.

* Hold <TUNE>; adjust menu parameter for a reading of 5.0 W on the external
wattmeter. Then tap <XMIT> to exit TUNE.

* Tap <MENU> to exit the menu.

High Power (50 W) Wattmeter Calibration

This applies to the K3/100 only. Use the same procedure as shown for 5 watts,
but set power to 50 W. The wattmeter calibration menu entry name will change to

1.0 Milliwatt Meter Calibration (KXV3)

This applies only if you have the KXV3 option installed (RF I/O module).

* Set the "CONFIG:KXV3" menu entry to TEST, which forces all bands to use the
KXV3’s transverter output jack, and output to be limited to 0-1.5 mW. The
wattmeter calibration menu entry name will change to "CONFIG:WMTR MW ".

* Connect a dummy load and an accurate RF voltmeter to XVTR OUT.

* Set power to exactly 1.00 milliwatts (0 dBm).

* Hold <TUNE>; adjust the WMTR MW menu parameter for a reading of 0.224 Vrms on
the external voltmeter. Then tap <XMIT> to exit TUNE.

* Set "CONFIG:KXV3" back to NOR .

Transmitter Gain

This procedure is normally done at assembly time or by the factory. It
compensates for per-band transmit gain variation, providing accurate power
control. It must be done on every band.

Low-Power (5 W) TX Gain Calibration

* Switch to 160 meters.

* Put the <ATU> into bypass mode (hold <ATU> ).

* Connect a dummy load to ANT1.

* Switch to ANT1 by tapping <ANT>.

* Set power to exactly 5.0 watts.

* Hold <TUNE> ; the power reading shown on VFO B should be about 5 watts.

• Tap <XMIT> to exit TUNE.

* Repeat this procedure on 80-6 meters.


High Power (50 W) TX Gain Calibration

This applies to the K3/100 only. Use the same procedure as shown for 5 watts,
but set power to 50 W, and use a 50-W dummy load. The <TUNE> power output
indication should be about 50 watts.

Calibrate TX gain at 50 W on ALL bands.

Milliwatt TX Gain Calibration (KXV3)

This applies only if you have the KXV3 option installed (RF I/O module).

* Switch to 160 m.

* Set the "CONFIG:KXV3" menu entry to TEST, which forces all bands to use the
KXV3’s transverter output jack, and output to be limited to 0-1.5 mW.

* Set power to exactly 1.00 milliwatts (0 dBm).

* Hold <TUNE>; the power output indication on the <VFO B> display should be
about 1 mW. Then tap <XMIT> to exit <TUNE>.

* Repeat the above procedure on 80-6 m.

* Set "CONFIG:KXV3" back to NOR .

* Tap <MENU> to exit the menu.

Reference Oscillator

The K3’s reference oscillator is a TCXO, or temperature-compensated crystal
oscillator. It is normally calibrated at assembly time or by the factory. There
are two types: 5 ppm and 1 ppm.

Before attempting reference calibration, allow the transceiver to warm up at
room temperature for about 15 minutes (cover on).

The 5 ppm TCXO (standard) can be calibrated using an accurate frequency counter
(Method 1), or by zero-beating the sidetone against a reference signal or
broadcast station (Method 2).

The 1 ppm TCXO (optional) can also be calibrated using Method 1 or 2. However,
its accuracy can be improved to better than 0.5 ppm by directly entering
supplied calibration data (Method 3). Be sure to keep the data sheet that was
supplied with the oscillator.

Method 1 (Frequency Counter):

* Locate the "CONFIG:REF CAL" menu entry. (If the menu entry name is REF xxC,
tap 1 to change it to REF CAL).

* Connect a frequency counter with +/-1 Hz or better accuracy to J1 on the
reference oscillator module. Measure the exact frequency in Hz.

* Using <VFO A>, set the REF CAL parameter to match this frequency. Then exit
the menu.

Method 2 (Zero-Beating):

* Select CW mode. Set WIDTH to about 2.8 kHz. (A wide filter passband is
necessary since you may need to move the REF CAL parameter a significant

* Tune the K3 to a strong commercial AM broadcast station (e.g. WWV), or another
known-accurate reference signal. Set the VFO to the exact, known frequency of
the signal.

* Using MON , set the sidetone monitor level to roughly match the volume level
of the received broadcast or reference signal.

* Locate "CONFIG:REF CAL". (If the menu entry name is REF xxC, tap 1 to select

* Tap SPOT to enable the sidetone.

* Adjust the REF CAL parameter, using <VFO A>, until the sidetone is zero-beated
with the signal. As you approach the correct frequency, you’ll hear an
undulating “beat note” between the two signals. The slower the beat note, the
closer they are. If it pulses at a rate of once per second or slower, you’re
within 1 Hz of the signal.

* Cancel SPOT and exit the menu.

Method 3 (1 ppm TCXO Option):

* Locate the "CONFIG:REF CAL" menu entry. Tap 1 to change the name to REF xxC.

* Locate the calibration data sheet, which shows frequency vs. temperature over
a wide range.

* For each data point, tap 2 or 3 to select the calibration temperature, then
use <VFO A> to set the specified oscillator frequency in Hz.

* Tap <MENU> to exit the menu.


Front Panel Temperature Sensor

• Turn the K3 OFF. Allow about 15 minutes for the radio to cool to room

* Turn the K3 ON.

* Locate the "CONFIG:FP TEMP" menu entry. Adjust the parameter to match the
reading of a room thermometer. Note: Deg. C = (deg. Fahrenheit - 32) * 0.555.
Front panel compartment temperature can be monitored continuously. Tap "DISP",
then use VFO B to select the FP xxC alternate display.

PA Temperature Sensor

• Turn the K3 OFF. Allow about 15 minutes for the PA heatsink to cool to room
temperature. Do not turn the K3 ON during this period.

* Turn the K3 ON.

* Locate the "CONFIG:PA TEMP menu entry. Adjust the parameter to match the
reading of a room thermometer. Note: Deg. C = (deg. Fahrenheit - 32) * 0.555.
PA heat sink temperature can be monitored continuously. Tap DISP", then use <VFO
B> to select the PA xxC alternate display.


S-meter calibration is normally quite accurate using the default settings.

Calibrating the S-meter requires a 50-ohm, 50microvolt signal (an accurate
signal generator such as an Elecraft XG1 or XG2 is recommended). In most cases
the default parameter values will provide adequate S-meter accuracy.

• If you’re calibrating the sub receiver’s S-meter:

(1) tap <SUB> ;

(2) hold BSET to switch the S-meter and controls over to the sub receiver;

(3) tap <ANT> if necessary to set up the sub to share the main RF path (pg. 40).

• Switch to 40 m (or a band applicable to your signal generator) and select CW

  • Set transmit power to 0.0 W using PWR .
  • Turn preamp on (PRE ), attenuator off (ATT ).
  • Tap <AGC> to select slow AGC (AGC -S).
  • Bypass the <ATU>, if installed, by holding <ATU> .
  • Set RF GAIN to maximum (fully clockwise). (Note: If you’ve assigned the RF

gain control for the present receiver to squelch, its RF gain will default to
maximum unless you’re controlling RF gain from a remote-control computer

  • Normalize the DSP filtering (hold <NORM>; pg. 11).
  • Connect the signal generator to ANT1 and set it for 50 microvolts RF output.
  • Tune to the frequency of the signal generator (tune for peak audio response).

You can also use auto-spot (pg. 28) to accurately match the pitch of the signal,
ensuring that it is centered in the passband.

  • Locate the "CONFIG:SMTR PK" menu entry; set it to OFF.
  • Locate the "SMTR SC" menu entry (S-meter scale). Use the <VFO A> knob to set

it to the default value (14).

  • Adjust "SMTR OF" (S-meter offset) for an S-9 reading.
  • Switch the signal generator to 1-µV output; the S-meter should now indicate

about S-2 to S-3. If not, change" SMTR SC" by 1 unit (try 15 first, then 13,
16, then 12). After each SMTR SC change, re-adjust the "SMTR OF" setting for an
S-9 indication.

• When you have completed this procedure, disconnecting the signal generator
should now show NO bars on the S-meter.


Menu Functions

There are two groups of menu functions: <MAIN> and <CONFIG>. Tap <MENU> to
access the MAIN menu; hold <CONFIG> to access the <CONFIG> menu. You can hold
<MENU> to Menu entries that you’d like quick access to can be assigned to
programmable function switches (pg. 13).


Tapping <DISP> while viewing the menu shows help information about the present
menu entry in the <VFO B> display area. For most entries, the default parameter
value is shown in parentheses at the start of the help text. Long help text
strings can be interrupted by tapping any switch.

Entry: Default: Description <AFX> MD: Delay 5 Audio Effects. Available
selections: DELAY 1-5 (quasi-stereo), and BIN (similar to Binaural I-Q).

ALARM: OFF: Set alarm/Auto-Power-On time. Tap 1 to turn alarm on/off; tap 2 / 3
to set HH / MM.

LCD ADJ: 8: LCD viewing angle and contrast. Use higher settings if the radio is
used at or above eye level. If adjusted incorrectly, bargraphs will be too light
or heavy during keying.

LCD BRT: 6: LCD backlight brightness. Use DAY in bright sunlight, 2 to 8 for
indoor lighting.

LED BRT: 4: LED brightness (relative to LCD backlight brightness). Exception: if
LCD BRT is set to DAY, LEDs are set to their maximum brightness.

<MIC> SEL FP, low Mic/line transmit audio source, mic gain range, and mic bias.
Source selections: range, FP (front panel 8-pin <MIC> jack), RP (rear panel 3.5
mm <MIC> jack), and LIN E IN bias on (rear-panel LINE IN jack). Tap 1 to toggle
between .Low and .High mic gain range for the selected mic. Tap 2 to turn mic
BIA S on/off (turn on for electret mics).

MSG RPT: 6: Message repeat interval in seconds (0 to 255). To repeat a message,
hold <M1> – <M4> rather than tap. A 6 - 10 sec. interval is about right for
casual CQing. Shorter intervals may be needed during contests, and longer for
periodic CW beacons.

RPT OFS: 2400: Sets the transmit offset (in kHz) for repeater operation, from
–2560 kHz to +2540 kHz. Per VHF band or band segment.

RX EQ: +0 dB: Receiver audio graphic equalizer. <VFO A> is used as an 8-band
bargraph, where each each character shows the boost or cut (-16 dB to +16 dB in
1 dB increments) for a given band <AF> band. The 8 bands are 0.05, 0.1, 0.2,
0.4, 0.8, 1.2, 2.4 and 3.2 kHz. Tap 1 -8 to select an <AF> band. <VFO A>
selects boost/cut. Tap <CLR> to reset all bands to +0 dB.

TX EQ: +0 dB: Transmit audio graphic equalizer (voice modes only). Functions the
same as RX EQ, TX* EQ each above, and can be adjusted while in transmit mode.
TX*EQ indicates TX ESSB in band effect, which has its own set of transmit
equalization settings.

VOX GN: 0: Adjusts the sensitivity of the VOX to match your mic and voice.

ANTIVOX: 0: Adjusts immunity of the VOX circuit to false triggering as a result
of audio from the speaker or 'leaked' from headphones.



Tech Mode Entries

Menu entries that include [T] are tech mode entries. These are only visible if
"CONFIG:TECH MD" is set to ON. They are are normally left at their defaults.
Entries further described as “Advanced” or “Troubleshooting” should be changed
with caution. The default values are strongly recommended for “Advanced”
functions; tap <DISP> to see the default value, which appears in parentheses at
the start of the help text.

Sub Receiver Settings

Menu entries that include "SUB" have two different settings: one for the main
receiver, and one for the sub receiver. Tapping <SUB> within a menu entry will
turn the SUB icon on (if the KRX3 option is installed), indicating that the sub
receiver parameter is displayed. When you first enter the menu, SUB will always
be off.

Entry: Default: Description

2 TONE [T]: (Troubleshooting.) Turns on built-in 2-tone generator for SSB
transmit tests. The internal 2-tone generator only works if LSB mode is

AF GAIN OFF: LO: Sets AF GAIN range. Available selections are HI or LO.

AFV TIM [T]: (Advanced.) Integration time for AFV and dBV displays in ms. See
<VFO B> alternate displays and K3 Service Manual.

AGC HLD [T]: 1000: (Advanced.) AGC “hold” time for voice modes. Specifies the
number of milliseconds that the SLOW AGC value is held after the signal drops
below the level that set the AGC. This is often helpful for SSB voice operation.

AGC PLS [T]: 000: NOR:
(Advanced.) NOR enables AGC noise pulse rejection.

AGC SLP [T]: (Advanced.) Higher values result in ‘flatter’ AGC (making signals
at all amplitudes closer in <AF> output level).

AGC THR [T]: 10: 5
(Advanced.) Sets AGC onset point; a higher number moves the onset up.

AGC-F [T]: 120: (Advanced.) Sets fast AGC decay rate; a higher number means
faster decay.

AGC-S [T]: 20: (Advanced.) Sets slow AGC decay rate; a higher number means
faster decay.

BAT MIN: 11.0: Low-battery warning threshold; 11.0 recommended. The parameter
flashes if it is set higher than the present supply voltage.

CW IAMB: A: Iambic keying mode (A or B). Both modes produce self-completing dots
and dashes. Mode B is more efficient for operators who practice “squeeze” keying
(pressing both paddles at once), because an extra dot or dash is inserted on
squeeze release. Mode A lacks this feature, and may be more appropriate for
those who only press one paddle at a time (often called “slap” keying).

CW PADL: Tip=dot: Specifies whether left keyer paddle (“tip” contact on the
plug) is DOT or DASH.

CW WGHT: 1.00: CW keying weight. Adjusts element/space timing ratio for the
internal keyer.

DATE: N/A: Real-time-clock date, shown as in the format selected by "CONFIG:DATE
MD" (MM.DD.YY or DD.MM.YY). Tap 1 / 2 / 3 to select month / day / year.

DATE MD: US: Select US (MM.DD.YY) or EU (DD.MM.YY) date formats.

DDS FRQ [T]: {DDS: (Troubleshooting.) Controls DDS tuning directly to check DDS
<XFIL> range for freq synthesizer troubleshooting purposes. Rotate <VFO A> CCW
and CW to find limits where L (lock) changes to U (unlock). Correct DDS
frequency is restored after exiting the menu and rotating either VFO.


DIGOUT{n}: LO: Directly controls two general-purpose digital output lines on the
AUX I/O connector. {n} = 0 or 1. Tap 1 to alternate between the two. These are
TTL-level signals with a nominal output voltage of 0 V (LO) or 5 V (HI).
Recommended max. load is 15 mA (enough to power one LED, for example).

FLx BW SUB: 2.70 (FL1): Crystal filter FL1-5 bandwidth in kHz, where x=1 to 5
(FL1-FL5). Tap 1 -5 or <XFIL> to select filters.

FLx FRQ SUB: 0.00 (FL1): Crystal filter FLx center freq as offset from nominal
(8215.0 kHz). Use the offset value specified on the crystal filter’s label or
PC board, if any. For example, if an Elecraft 5-pole, 200-Hz filter were labeled
“-0.91”, adjust <VFO A> for –0.91.

FLx GN SUB: 0 dB (FL1): Crystal filter FLx loss compensation in dB. 0 dB
recommended for wide filters; 2 dB for 400 or 500 Hz filters, and 4 dB for 200
or 250 Hz filters.

FLx ON SUB: ON (FL1), per-mode: Used to specify which filters are available
during receive. Each filter must be set to ON or OFF in each mode. You can tap
<MODE> within the menu entry.

FLTX{md}: FL1 (all modes): Used to specify which crystal filter to use during
TX. {md} = CW/SB/AM/FM. Choose filters with bandwidths as follows: SSB, 2.7 or
2.8 kHz (also applies to data); CW, 2.7 or 2.8 kHz; AM, 6 kHz; FM, 12 kHz or

Note: If you’re using a 2.7-kHz 5-pole filter for SSB transmit, you can
optionally fine-tune its FLx FRQ parameter to equalize LSB / USB transmit
characteristics. Monitor your signal on a separate receiver, using headphones.

FP TEMP: N/A: Used to calibrate the front panel temperature sensor. It must be
calibrated if you wish to use the REF xxC menu entry to calibrate the optional 1
PPM TCXO. You must convert °F to °C in order to enter the value. Deg. C = (deg.
F - 32) * 0.555.

FSK POL: 1: 0 = Invert FSK transmit data polarity, 1 = Normal data polarity.

FW REVS: N/A: Rotate <VFO A> to see firmware revisions of the MCU (uC), main DSP
(d1), aux DSP (d2), flash parameters (FL), and KDVR3 controller (dr).

KAT3: Not Inst: KAT3 <ATU> mode; normally set to BYP or AUTO (you can alternate
between these settings using the <ATU> switch). Modes L1-L8, C1-C8, and Ct are
used to test KAT3 relays. Mode LCSET allows manual adjustment of L/C/net
settings. When in this mode, tapping <ATU> <TUNE> shows the L & C value; C is
changed with <VFO A>, L is changed with <VFO B>, and ANT toggles between Ca and

KBPF3: Not Inst: If KBPF3 option is installed: set to ON, exit menu, and turn
power off/on.

KDVR3: Not Inst: If KDVR3 option is installed: set to ON, exit menu, and turn
power off/on.

KIO3: NOR: Determines function of BAND0-3 outputs on AUX I/O connector. See pg.

KNB3: Not Inst If KNB3 option is installed: set to ON, exit menu, and turn power

Note: the K3 can’t be used without a KNB3; Not Inst is for troubleshooting only.

KPA3: Not Inst: Set to PA NOR if KPA3 100-W amp installed. Set to PAIO NOR if
KPA3 is not installed, but the KPAIO3 transition PC board is. Other settings
include PA BYP (disables KPA3 if installed), PA fan test settings (PA FN1-FN4 or
PA IO FN1-FN4), and PAIO BYP (if transition board is installed, but not the KPA3
module, this setting can be used to test the high power bypass relay).

KRC2: - Controls the KRC2 band decoder’s accessory output settings. Shows OFF or
ACC 1-3 if a KRC2 is detected; --if not.


KRX3: Not Inst: If KRX3 option (sub receiver) is installed, set parameter to
NOR-ANTx where x is your selected wiring for the sub receiver’s auxiliary
antenna (1 = unused KAT3 ATU antenna, 2 = AUX RF jack, 3 = AUX RF in parallel
with the <RX ANT> IN jack on the KXV3). For details on sub receiver antenna
sources, see pg. 22.
Note: the sub receiver option includes three modules: receiver, synthesizer, and
DSP. All three must be installed, or the K3 will report an error on power-up.

KXV3: Not Inst: If KXV3 option is installed: set to ON, exit menu, and turn
power off/on. This option is required for use of RXAN T and low-level
transverter I/O.

LCD TST: OFF: Changing the parameter turns on all LCD segments.

LIN OUT: 30: Sets the LINE OUT level. LINE OUT connections go to PC soundcard

NB SAVE: NO: Set to YES to save noise blanker on/off state per-band. Noise
blanker levels, both DSP and I.F., are always saved per-band regardless of this

PA TEMP: N/A: If a KPA3 (100-W PA module) is installed, shows KPA3 heatsink
temperature and allows it to be adjusted. See calibration procedure on page 48.

PTT-KEY: OFF-OFF: Allows selection of RTS or DTR RS232 lines to activate PTT or
key the K3. See pg. 18. Note: If a computer or other device asserts RTS or DTR
while you’re in this menu entry, the K3 will switch to TEST mode (zero power
output) as a precaution. The TX icon will flash as a reminder. To avoid this,
make sure software applications have flow control and/or keying options turned
OFF while you’re changing the PTT-KEY selection.

REF CAL: or 49380000: Used to precisely calibrate the K3’s reference
oscillator,. <VFO A> is used to set the REF xxC Hz reference oscillator
frequency in Hz. Tap 1 to alternate between REF CAL and [T] REF xxC. xx is a
data entry point from –20 to +70. REF CAL can be used with either TCXO (see
Method 1 or 2, pg. 47). REF xxC is used with the 1 ppm TCXO (Method 3). Tap 2
or 3 to move the data entry point up or down. See calibration procedure, pg. 47.

RS232: 4800 b: RS232 communications rate in bits per second (bps). During
firmware download (via the K3FW PC program), the baud rate is set automatically
to 38400 baud, but it is then restored to the value selected in this menu entry.

SER NUM: N/A: K3 serial number, e.g. 02000. Cannot be edited from the menu.

SMTR OF: 024: S-Meter offset; see calibration procedure (pg. 48).

SMTR SC: 014: S-Meter scale; S-9 = 50 uV, S=3 = 1 uV with Preamp = ON, and AGC
ON. See calibration procedure (pg. 48).

SMTR PK: OFF: Set to ON for peak-reading S-meter.

SPLT SV: NO: If set to YES, <SPLIT> state is saved per-band.

SPKRS: 1: Set to 2 if using two external speakers. This enables binaural effects
in conjunction with the <AFX> switch, as well as stereo dual-receive if the sub
receiver is installed. For further details, see pg. 33.

SPKR+PH: NO: YES = Speaker is ON, even when headphones are plugged into PHONES
jack. See detailed discussion on pg. 19.

SQ MAIN: 0: Main receiver squelch value or RF gain potentiometer assignment. If
set to RF INN ER, the inner (smaller) RF/SQL knob controls main squelch rather
than RF gain. If set to RF OUTER, the outer ring (larger) RF/SQL knob controls
main squelch rather than sub receiver RF gain.

SQ SUB: 0: Sub receiver squelch value or RF gain pot assignment. If set to RF
OUTER, the outer ring (larger) RF/SQL knob controls sub squelch rather than sub
RF gain.


SW TEST [T]: OFF: Changing the parameter displays SCN ADC. Hold any switch to
see scan row and switch ADC reading. Used for troubleshooting only.

SW TONE: OFF: Sets up switch tones or audio Morse feedback on any control

TECH MD: OFF: Set to ON to enable Tech Mode menu entries (those marked with [T]
in this list).

TIME: N/A: Real-time-clock view/set. Tap 1 / 2 / 3 to set HH / MM / SS. To see
the time and other displays during normal operation, tap <DISP> (see pg. 34).

TTY LTR: Performs an RTTY FIGS to LTRS shift when the text decoder is enabled in
RTTY modes. Cannot be changed within the menu itself; must be assigned to a
programmable function switch.

TX ALC [T]: (Troubleshooting.) Set to OFF to disable transmit ALC in CW mode.
This is required when adjusting band-pass filters and can also be used for
troubleshooting, but should not be used during normal operation. (Be sure to set
parameter to ON afterward.)

TX ESSB [T]: OFF: Extended SSB transmit bandwidth (3.0, 3.5, 4.0 kHz, etc.) or
OFF. See pg. 44.

TXGN{pwr} (Troubleshooting.): 00: Shows transmit gain constant for the present
band and power mode, where {pwr} = LP (0-12W), HP (15-120W), or MW (0-1.5 mW).
The gain constant is updated whenever the <TUNE> function is activated on a
given band at one of three specific power levels: 5.0 W, 50 W, and 1.00
milliwatt. See transmit gain calibration procedure, pg. 46. If TX ALC (above)
is OFF, the TXGN parameter can be set manually, at very fine resolution. This
should only be done for troubleshooting purposes.

TXG VCE [T]: 0.0 dB: Balances voice transmit peak power in relation to CW peak
power in <TUNE> mode. Typically left at 0.0.

VCO MD [T]: 064: (Troubleshooting.) VCO L-C range view/change/calibrate. Once
the VCO is calibrated (pg. 46), the parameter which appears here will include
NOR at all times. You can change the setting to troubleshoot VCO L-C ranges.
When finished, set the parameter back to NOR 127, then exit the menu and change
bands to restore the original setting.

VFO B->A: Copies <VFO B>’s frequency to <VFO A>. Cannot be used within the menu
itself; must be assigned to a programmable function switch.

VFO CRS: Per-mode coarse tuning rate (hold COARSE and tune <VFO A> or B). Also
applies to the <RIT>/<XIT> tuning knob if "CONFIG:VFO OFS is set to ON, and both
<RIT> and <XIT> are turned OFF.

VFO CTS Per-mode: 200: VFO counts per turn (100, 200, or 400). Smaller values
result in easier fine- tuning of VFO; larger values result in faster QSY.

VFO FST: Specifies the faster of the two VFO tuning rates (<RATE> ). The faster
rate is 50 Hz per step by default, but can be set to 20 Hz if desired. In this
case, VFO CTS = 400 is recommended to ensure adequate fast-QSY speed.

VFO IND: 50 Hz: If set to YES, <VFO B> can be set to a different band than <VFO
A>, which allows listening to two bands at once (main/sub). This menu entry is
not available unless the subreceiver is installed.

VFO OFS: NO: If ON, the <RIT>/<XIT> offset control can be used to tune <VFO A>
in large steps when both <RIT> and <XIT> are turned off. The step sizes vary
with mode (see VFO CRS), and are the same as the COARSE VFO tuning rates.

WMTR {pwr}: 100: OFF: Wattmeter calibration parameter. {pwr} is the power mode:
LP (0-12W), HP (15-120W), or MW (0-1.5 mW). See calibration procedure (pg. 46).

XVx ON: NO: Set to YES to turn on transverter band x (1-9); tap 1 – 9 to select
xvtr band.

XVx RF: 144: Lower edge for xvtr band x (1-9); 0-999 MHz. Tap 1 – 9 to select
xvtr band.


XVx IF: 28: Specify K3 band to use as the I.F. for transverter band x (1-9). Tap
1 – 9 to select xvtr band. I.F. band selections include 7, 14, 21, 28, and 50

XVx PWR: H: 0.1 Allows fixed or variable power level for XVTR band x. Tap 1 – 9
to select xvtr band. H x.x (High power level) specifies a value in watts, and
use of the main antenna jack(s). This should be used with caution, as you could
damage a transverter left connected to these antenna jacks accidentally. L x.x
(Low power level) species a value in milliwatts, which requires the KXV3 option.

XVx OFS: 0.00: Offset (–9.99 to +9.99 kHz) for transverter band x (1-9). Tap 1 –
9 to select xvtr band. Compensates for oscillator/multiplier chain errors.

XVx ADR: TRN1: Physical decode address (1 to 9) assigned to transverter band x
(1-9). Tap 1 – 9 to select xvtr band. Applies to attached Elecraft XV-series
transverters and Elecraft KRC2. Also see "CONFIG:KIO3. Note: Decode address
range may vary depending on the type of attached device.



The K3 is a highly modular transceiver. With the information provided here,
you’ll be troubleshooting to the module level, not to the component level. In
many cases, problems can be resolved by changing a menu setting, loading new
firmware (pg. 42) or initializing parameters to factory defaults (see below).

Hardware troubleshooting procedures, including detailed module substitution,
voltage checks, signal tracing, etc., can be found in the K3 Service Manual. Due
to the use of fine-pitch ICs (integrated circuits) in the K3, most signal
tracing must be done very carefully using fine-tip probes. Please do not attempt
this unless you have experience in troubleshooting surface-mount assemblies;
otherwise, you could damage your K3.

the test gear specified in the Service Manual. These settings have been aligned
at the factory, and if mis-adjusted, could degrade performance. Elecraft support
can suggest alternative procedures in some cases.

Parameter Initialization

Menu parameters are stored in non-volatile memory (EEPROM and/or FLASH). It is
possible, though rare, for parameters to become altered in such a way as to
prevent the firmware from running correctly. If you suspect this, you can
reinitialize parameters to defaults, then restore a previously-saved
configuration (or re-do all configuration steps manually; no test equipment is

* If you have a computer available to do configuration save and restore, run the
K3 Utility program, then use the Configuration function to save your present
firmware configuration.

* If you don’t have access to a computer, you should write down your menu
parameter settings. The most important are "CONFIG:FLx BW and "CONFIG:FLx FRQ
(for each installed filter x; also tap <SUB> to obtain sub receiver crystal
filter settings, if applicable). You should also note the settings of option
module enables (all <CONFIG> menu entries starting with ‘K’, e.g. "CONFIG:KAT3)
. If you don’t record your crystal filter and option settings, you may have to
remove the K3’s top cover (and sub receiver, if installed) to verify which
options as well as crystal filters are installed, as well as the frequency
offsets noted on the crystal filters (depends on filter type).

* Turn the K3 OFF (using the K3’s <POWER> switch, not your power supply).

* While holding in the SHIFT/LO knob (which is also labeled NORM below), turn
power ON by tapping the K3’s <POWER> switch. Let go of the SHIFT/LO knob after
about 2 seconds. You should now see EE INIT on the LCD.

* When EE INIT completes after a few seconds, you may see ERR PL1 or other error
messages due to reinitialization. Tap <DISP> to clear each message.

* If you have a computer, restore all parameters using the Configuration
function of the K3 Utility program.

* If you don’t have a computer, manually re-enter all menu parameters that you
wrote down, above, then redo firmware configuration and calibration (starting on
pg. 43). You can omit any steps pertaining to parameters you’ve already restored

* See if the original problem has been resolved.


General Troubleshooting

The most common symptoms and their causes are listed below. Most are related to
firmware or control settings. If the problem persists, please contact Elecraft
support (see pg. 10). Outside normal business hours, you may be able to get
advice by posting a message to our email reflector.

* TX LED is on all the time: In any mode, this symptom could indicate that PTT
is being held on by external equipment. Disconnect anything connected to the AUX
I/O and RS232 connectors. In voice modes, this could be caused by having the
<VOX> gain set too high. Disconnect the microphone, then set the <VOX> menu
parameter lower.

* “NEW K3UTIL SOFTWARE REQUIRED” message appears on the LCD: This indicates that
you must install a new version of the K3’s firmware upgrade program (K3 Utility)
in order to load the latest K3 firmware. After installing the new version of K3
Utility, reload all new firmware (MCU, DSP, etc.).

* Error message appears on the LCD (ERR PL1, etc.): refer to Module
Troubleshooting (below) for troubleshooting steps. Some error messages result
from turning on option modules that are not actually installed (see
"CONFIG:KAT3, KBPF3, etc.).

* N/A shown on the LCD (Not Applicable): The switch or knob function you’re
trying to use does not apply in the present mode or context.

* HI CUR or HI SWR warning (K3/100): Check load impedance and power supply
voltage. If supply voltage is low and/or load impedance is lower than 50 ohms,
current can go up for a given requested power level. Reduce power if necessary.

* HI TEMP warning (K3/100): PA heatsink temperature has exceeded 84C (PA drops
into bypass mode). Check fans, power supply voltage and current, and load
impedance. Allow heatsink to cool. Reduce power if necessary. Make sure the
"CONFIG:PA TEMP menu entry is calibrated (allow heatsink to cool to room
temperature, then compare menu reading to actual).

* ALC OFF is displayed on <VFO A>: Set "CONFIG:TX ALC to ON. ALC should only be
turned off during band-pass filter alignment (see Service Manual).

* <VFO B> is blank: You may have CW or DATA text decode display turned on (<TEXT
DEC>, pg. 28) with the THR (threshold) control set too high for text decode to

* <VFO A> or B display doesn’t change when the corresponding knob is rotated:
You probably have the affected VFO locked (pg. 11).

* Can’t transmit in CW mode: (1) Make sure the key or keyer paddle is plugged
into the correct jack. (2) You must have <VOX> selected (<VOX> icon on) in
order to use full or semi break-in CW. (3) You may be in <SPLIT> mode, with <VFO
B> set for a voice or data mode rather than CW. Tap A/B or use <BSET> to check
<VFO B>’s mode.

* Key clicks in CW mode: You may have a narrow crystal filter selected for CW
transmit. Use 2.7-2.8 kHz. See the "CONFIG:FLTX CW menu entry.

* Can’t use the mic in voice modes: You may be in SPLIT mode, with <VFO B> set
for CW or data mode rather than a voice mode. Tap A/B or use BSET to check <VFO
B>’s mode.

* No power output: You may have routed RF through the KXV3’s XVTR IN/OUT jacks,
either by switching to a transverter band, or by setting "CONFIG:KXV3 to TEST.
Another possibility is that power has not been calibrated on the present band
(pg. 46).

* No received signal: Possibilities include (1) receiver being squelched (if
RF/SQL controls are assigned to squelch via "CONFIG:SQ MAIN or SQ <SUB>, rotate
squelch controls fully counter-clockwise); (2) RF GAIN too low (set RF gain
controls fully clockwise); (3) filter bandwidth too narrow (set WIDTH or tap


<XFIL> , and also verify filter configuration settings); (4) switching to an
open receive antenna on the KXV3 (<RX ANT> IN); (5) switching the KAT3 to an
open antenna jack; (6) "CONFIG:REF CAL parameter not adjusted properly.

* Received signal too low in amplitude: (1) Try setting "CONFIG:AF GAIN to the
HI range; (2) check headphone and speaker plugs and cables; (3) make sure that
"CONFIG:RX EQ settings are either flat or have not been set for a large amount
of cut; (4) recheck all filter configuration settings, particularly the
"CONFIG:FLx BW, FLx GN, and FLx FRQ menu entries; (5) verify that "CONFIG:REF
CAL is properly adjusted.

* General problem with transmit and/or receive performance: Many problems can be
caused by the power supply voltage being too low or by a noisy or intermittent
supply. Check your power supply’s on/off switch, voltage, fuses (if applicable),
and DC cabling. The K3 provides both voltage and current monitoring (pg. 34).

* General problem with firmware behavior: (1) Check all relevant menu settings
(see MAIN and <CONFIG> menu listings in the previous section). In addition to
the information in the manual, each menu entry provides help text by tapping
<DISP> . (2) Try loading the latest microcontroller and DSP firmware. Review the
release notes for changes that may be related to your symptoms. (3) If the above
suggestions don’t help, you can try reinitializing the firmware (pg. 55). Be
sure to save important parameter settings first.

Module Troubleshooting

Error Messages (ERR xxx)

An error message may be displayed on <VFO B> at power-up or during normal
operation. In most cases error messages are due to a problem with a single
option module, and may be due to incorrect firmware configuration.

If you see an error message on <VFO B> (ERR XXX): Write down the error message,
as well as any associated error data shown on the <VFO A> display (e.g. E
00005). Then tap any switch to clear the error code. Multiple errors may occur;
in this case, write down each of the messages and <VFO A> data, if any, before
you clear them.

See Error Msg table (below) for details on specific ERR messages and their
associated data values.

Module Removal

or installing modules. If you drop a metal tool inside the K3 with power still
applied, you can short a power supply or control line, resulting in damage to
the RF board or other modules.

* Module de-installation procedure: To see if an option module is the cause of
an error message, you must de-install it as described below, or you may not be
able to tell if removing the module had any effect:

* Turn off power

* Remove the module

* Set the associated <CONFIG> menu entry to NOT INST. (See "CONFIG:KAT3, etc.)
Note: If the affected module is on the KRX3 (sub receiver), you must tap <SUB>
to display its configuration setting. Otherwise the setting shown applies to the
main receiver. This applies to the KBPF3 and KNB3 modules, as well as crystal
filters, all of which are duplicated on the RF and sub receiver boards.

* Turn power off and wait at least 5 seconds

* Turn power back on


Error Message List

Error Msg: Problem: Troubleshooting steps

ERR 12V: The circuit breaker on the KPA3 module may be open. PA drops into
bypass mode, fans switch to level 2, and PA temp display mode is not available.:
Check for short from PA module’s 12V line to ground. If there’s no short, try
resetting the circuit breaker. If there is a short, remove the KPA3 module. Set
"CONFIG:KPA3 to PAIO NOR. While waiting for a replacement, you can use the K3 at
reduced power.

ERR AT3: KAT3 not responding: De-install the KAT3 module (see above). If this
eliminates the error message, the KAT3 may be defective. You can substitute a
KANT3 antenna input module temporarily, if available.

ERR BP1: No response from RF board BPF shift registers:
* De-install option
modules one at a time

ERR BP2 No response from KBPF3 option shift registers: De-install KBPF3 on RF

ERR BP3: No response from sub RX BPF shift registers: De-install the KRX3 module

ERR BP4: No response from sub RX KBPF3 option: De-install the KBPF3 module on

ERR DS1: No main DSP SPI echo: Reload DSP1 firmware

ERR DS2: Main DSP SPI echo not inverted: Reload DSP1 firmware

ERR DS3: No AUX DSP SPI echo: Reload DSP2 firmware. Note: "CONFIG:KRX3 must be
OFF unless the KRX3 option is installed, which includes the aux DSP module

ERR DS4: AUX DSP SPI echo not inverted: Reload DSP2 firmware. Note: "CONFIG:KRX3
must be OFF unless the KRX3 option is installed, which includes the aux DSP

ERR DSE: Missing echo from a DSP command: Reload DSP1 firmware (and DSP2
firmware, if applicable).

ERR DSX: Extended DSP command timeout: Reload DSP1 firmware (and DSP2 firmware,
if applicable).

ERR EE1: On-chip EEPROM read/write test failed: MCU may be defective (front
panel). Try re-loading MCU firmware first; then try initializing parameters (pg.

ERR EE2: External EEPROM read/write test failed: EEPROM may be defective (front
panel). Try re-loading MCU firmware first; then try initializing parameters
(pg. 55)

ERR FW2: General firmware problem: Try re-loading MCU firmware first; then try
initializing parameters (pg. 55)

ERR IF1: RF board IF GROUP not responding (A6810 or KNB3-U2): De-install the
KNB3 module on RF board. Note: The K3 cannot be operated without a KNB3, because
this module includes T-R switching circuitry. Do not attempt to bypass it using


ERR IF2: Sub RX IF GROUP not responding (A6810 or KNB3-U2): De-install the KNB3
module on KRX3 first (tap <SUB> when in the KNB3 menu entry). If that doesn’t
eliminate the error message, de-install the KRX3 module. Note: The sub receiver
cannot be operated without a KNB3, because this module includes T-R switching
circuitry. Do not attempt to bypass it using jumpers. The main receiver can
still be used.

ERR IO1: MISO line stuck low (asserted): De-install option modules one at a
time. If no failing option module can be found, there may be a problem on the
RF board.

ERR IO3: KIO3 not responding: The KIO3 may be defective. Note: The K3 can be
operated temporarily without the KIO3 installed. You’ll need to use headphones,
and there will be no computer or <AF> I/O available on the rear panel.

ERR LPF: No response from LPF shift registers: De-install option modules one at
a time. If no failing option module can be found, there may be a problem on the
RF board.

ERR PA1: KPAIO3 module not responding: Remove the KPA3 module and set
"CONFIG:KPA3 to PAIO NOR. If this eliminates the error message, the problem is
likely to be on the KPA3 module. If not, the problem may be on the KPAIO3
module; remove it as well, and set "CONFIG:KPA3 to NOT INST.

ERR PL1/2 V: PLL out of range on band change (to view actual PLL voltage, set
"CONFIG: TECH MD to ON, then tap <DISP> and use <VFO B> to locate the PLL1 and
PLL2 voltage displays). Verify that the oscillator can on the KREF3 is fully
plugged in and is not in backwards. Make sure all internal cables are plugged
in, specifically the cables between the KREF3 and KSYN3 modules (synthesizers).
Try re-calibrating the

ERR SY1/2: General problem with PLL, VCO, or other applicable VCO:

ERR SY3/4: circuitry on a synthesizer module. <SUB> within the menu entry if you
ERR SY5/6 ERR PL2, to make sure you’re calibrating
the sub receiver’s synthesizer). If this
doesn’t work, try removing the 2nd
ERR VCO VCO calibration errors. <VFO A> will show error synthesizer (for the sub
receiver), and set
ERR VC4 data, e.g. E 00039; report this value to
Elecraft customer support.
eliminates the error, the sub synth may be
defective. You can also try swapping it
with the main synth to see if it can be
calibrated in this slot.

ERR REF: Missing KREF3 module Verify that the oscillator can on the KREF3 is
fully plugged in. Make sure all internal cables are plugged in between the KREF3
and other modules. If this doesn’t help, the problem may be on the KREF3 module
or the RF board. Note: The K3 cannot be used without a KREF3 module.


ERR TXG: Transmit gain constant out of range: This usually indicates a problem
with band-pass filter alignment or one of the low-pass filters. In either case
it could affect one or two bands. See service manual.

ERR XV3: KXV3 not responding: De-install KXV3 module


Theory Of Operation

Please refer to the block diagram of the K3 shown at the end of this section.
Schematics and additional details can be found in the K3 Service Manual.


The RF PCB (Printed Circuit Board) is the heart of the K3 transceiver, both
physically and electrically. During assembly, it serves as an attachment point
for other PCBs as well as chassis panels, acting as the glue that holds things
together. During operation, the RF board provides signal routing to and from all

Over two-thirds of the RF board’s components are surface mount devices (SMDs),
located on the bottom side of the board. These are pre-installed and tested at
the factory. The use of SMDs minimizes stray coupling in RF circuits, reduces
system cost, and allows the K3 to fit in a modest-size enclosure, compatible
with home or field operation.

The RF board is divided into several functional areas, which are described

Low-Pass Filters (LPFs)

The relay-switched low-pass filters, used during both transmit and receive, are
located in the back-right corner of the RF board. These filters can easily
handle 100 watts, and are common to both the K3/10 and K3/100. Some LPFs cover
one band, while others cover two bands that are close in frequency. The input to
the LPF section comes from the KPA3 100-W amplifier module, if installed; if
there’s no KPA3, the input comes from the 10-W amplifier (see below). The output
of the low-pass filters is routed through the forward/reflected power bridge,
then on to either the antenna input module (KANT3), or the KAT3 automatic
antenna tuner, which plugs in at far right.

Low-Power Amplifier (LPA) and T/R Switching

The large hole near the back-middle area of the RF PCB is where the 10-W
low-power amplifier module plugs in. The LPA has three connectors that mate with
the RF board, and its power transistors attach to the rear bottom cover, which
serves as a heat sink. This construction method allows the 10-W module to be
tested separately during production. Also in this area is the T/R
(transmit/receive) switch, but you’ll need to turn the RF board upside down to
see most of the components. The K3’s T/R switch uses high-power, high-isolation
PIN diodes rather than relays, resulting in no switching noise during keying.

Low Power Amplifier (LPA)

The low-power amplifier module is capable of up to 12 W power output, and in the
case of the K3/10, is the final amplifier stage. In the K3/100, it provides
drive to the KPA3 module. The LPA has three gain stages, the last two of which
use high-power MOSFET transistors to allow coverage up through 6 meters. At the
input to the first gain stage is a 5-dB attenuator, which is switched in under
firmware control at certain power levels to optimize transmit gain distribution.

Band-Pass Filters (BPFs)

At back-left is the bank of ham-band BPFs. These filters are just wide enough to
cover each ham band, so they provide good rejection of IMD products during both
transmit and receive. Hi-Q components, including large toroids, ensure low loss
and high signal-handling capability. General coverage receive capability can be
added to the K3 with the KBPF3 option, which includes another 8 band-pass
filters that cover all of the areas from 0.5 to 28 MHz that are not covered by
the filters on the RF board. The KPF3 module mounts directly above the


main BPF array, and due to very short connections, has no effect on the
performance of the main BPFs during ham-band operation.

First I.F. Stages

The front-left portion of the RF board is dedicated to the receive/transmit
first I.F. (intermediate frequency) circuitry, most of which is on the bottom of
the board. The first I.F. is 8.215 MHz, which is low enough to permit the
construction of high-quality, narrow-band crystal filters, but high enough to
offer good image rejection. The I.F. stages are reversible; i.e., they’re used
in one direction in receive mode, and the other during transmit. In receive
mode, the filtered signal from the BPFs is first routed through a relay-switched
attenuator, then to a low-noise diode-switched preamp, high-level switching
mixer, and post-mixer amp. The signal next encounters the noise blanker (KNB3),
then the crystal filters (see below).

Crystal Filters and 2nd I.F.

In either receive or transmit mode, the I.F. signal is routed to one of up to
five plug-in, 8.215-MHz crystal filters (FL1-FL5). These can be fixed-bandwidth,
or in the case of FL3-FL5, optionally variable-bandwidth. Following the crystal
filters is the receive I.F. and second mixer, which mixes the 8.215 MHz down to
an I.F. of 15 kHz for use by the digital signal processor module (DSP).
Excellent 2nd-I.F. image rejection is obtained by cascading an additional
crystal filter just ahead of the second mixer. There’s also a 15 kHz transmit
I.F., which is mixed up to 8.215 MHz on the KREF 3 module, which plugs in near
the front-middle of the RF board.

Support Circuitry

Several other modules plug into the RF board. The KPAIO3, located at the back
edge of the RF board, is a vertically mounted board used as an interface between
the RF board and the KPA3 100-W amp module. It provides current sensing, bypass
relay, and other functions for the KPA3, and eliminates the need for any
interconnecting cables. The KIO3 and KXV3, in the back left corner, provide RF,
audio, and digital I/O. The main synthesizer, used for the main receiver as well
as the transmitter, plugs in at front left and is attached to the front shield.
To the right of this is the reference oscillator module (KREF3), as well as the
second synthesizer, used for the sub receiver. These also attach to the front
shield. The Front Panel/DSP module plugs in at the very front of the RF board.
Finally, at the far right you’ll find two low-noise linear voltage regulators,
one for 5 volts and the other 8 volts. Both are heat-sinked to the right side

Noise Blanker

There are two noise blanker subsystems in the K3: the KNB3 module, and a
DSP-based blanker (see DSP on page 64). The KNB3 is a narrow I.F. pulse blanker
that plugs into the RF board. Its broad input bandwidth ensures minimum
stretching of fast noise pulses, so it’s ideal for suppressing noise from power
lines, thunderstorms, and auto ignitions. The DSP blanker can be used on many
other types of noise, including radar and other noise with complex waveforms
that might cause heavy intermodulation if an I.F. blanker were engaged. Using
the two blankers in combination is often extremely effective.

The KNB3 includes a triple-tuned bandpass/time-delay filter, wide-range AGC, and
a noise gate. You can think of the noise gate as a switch that is normally
closed, allowing received signals to pass unimpeded. When a noise pulse appears,
it is amplified to a high level and used to trigger a one-shot circuit. This
opens the noise gate very briefly (from 5 to about 100 microseconds) to blank
the noise pulse. Both the threshold at which blanking action occurs and the
length of time the gate is opened are under control of the operator.

1st Mixer

The 1st mixer combines signals from the input band-pass filters with the output
of the synthesizer to obtain the 1st I.F., at 8.215 MHz. The mixer is based on a
video switching IC with very low ON resistance, resulting in low loss and high
signal-handling capability. Since this type of mixer requires low drive, there’s
very little leak


through of the local oscillator (synthesizer) signal. The mixer also
incorporates a balanced VHF low-pass filter to suppress both internally and
externally generated VHF/UHF spurs. This keeps the K3’s HF spur complement
extremely low, despite the use of a down-conversion system architecture.

KANT3 and KAT3

The basic K3/10 includes a KANT3 antenna input module. If you’ve ordered a KAT3
antenna tuner, the KANT3 is not required and will not be supplied with the kit.
In either case, the module plugs into the RF board at the back-right corner.
Both the KANT3 and KAT3 provide antenna surge protection, as well as resistors
for bleeding off static DC charge. The KAT3 provides a wide-range, switchable
C-in/C-out L-network for matching a variety of antennas with SWR as high as 10:1
(100 W) or 20:1 (10 W). There are 8 inductors and 8 capacitors in the L-network,
each switched with a DPDT relay for high reliability. The KAT3 also includes a
second antenna jack and associated switching relay. There’s an additional jack
on the board for routing the unused (nontransmit) antenna to the KRX3 sub
receiver module.


All audio and digital/computer I/O is routed through the KIO3. The KIO3 is made
up of three PC boards: Main, Audio IO and Digital IO.

The Main KIO3 board plugs directly into the RF board. It includes a relay to
disconnect the right speaker channel in case a mono speaker is plugged into the
external speaker jack, isolation transformers for Line In and Line Out signals,
a connection point for the internal speaker, a low-noise oscillator to provide
voltages for the RS232 serial interface, and various control line inputs and
outputs for external transverters, band decoders, and the like. This board also
contains a differential output microphone amplifier to equalize the gain between
the front and rear microphone jacks, as well as to provide noise immunity for
the microphone signal from the rear panel area.

Circuitry to allow use of the serial port RTS or DTR signal lines as PTT and/or
KEY inputs is also located on this board. This feature is to support logging and
control programs which may use these lines for controlling transmit/receive
switching or CW keying.

The Digital IO board plugs into the KIO3 Main board. It includes a DE-9 serial
port connector for use with an external PC, and a DE-15 accessory connector for
external band decoders (such as the KRC-2), transverters (such as the Elecraft
XV-series), and similar devices. It is also the connector to which direct FSK or
PSK signaling is applied.

The Audio IO board includes three stereo outputs: headphone jack, speaker jack,
and a transformer-isolated Line Out jack. It also provides two monophonic
inputs: microphone and an isolated Line In. The Microphone jack can provide bias
for an electret microphone when enabled via the MAIN:MIC SEL menu entry.

Both Digital and Audio IO boards include extensive bypassing and decoupling to
help prevent RF signals getting into the radio through cables attached to their
respective connectors.

Front Panel and DSP

The Front Panel is a large plug-in module that includes both the Front Panel and
DSP boards, as well as the Aux DSP (if a sub receiver is installed) and digital
voice recorder module (if the KDVR3 option is installed).

Front Panel Board

This board provides the K3’s user interface: 35 custom-labeled switches; two
dual-concentric potentiometers for gain and squelch control; seven shaft
encoders; custom, 240-segment, high-contrast LCD; and 13 discrete LED


indicators. Mic and headphones can be plugged into the front panel, or
optionally at the rear panel (see KIO3 description, pg. 63).

The Front Panel PCB also includes the microcontroller unit (MCU), which manages
the operation of the K3. All inputs, whether from a switch, knob or external PC,
are recognized and acted on by the MCU. All control outputs – such as switching
from transmit to receive, sending a CW code element, adjusting the transmitter
power, controlling LED brightness, etc. – are produced by the MCU.

The Front Panel also contains a large amount of EEPROM memory for parameter
storage, and FLASH memory for program storage. This allows the K3 to be
re-programmed with the newest firmware by a simple download from the Internet.
It also enables the K3 to remember your favorite settings, particular
configuration preferences, and the last setting of controls when power is
removed from the radio.

DSP Board

The K3’s Digital Signal Processing (DSP) capabilities provide a rich set of
features to help combat QRM and QRN while generating some of the cleanest
signals to be found in Amateur radio today. A 32-bit floating point DSP is used
for highest performance.

In receive, a 15 kHz IF signal from the RF board is buffered and then digitized
by a 24-bit Analog to Digital Converter (ADC). This provides over 100 dB of
dynamic range within the passband of the selected crystal (roofing) filter.
After the ADC, the DSP converts the signal into a floating point value so
dynamic range is not compromised during further processing. Noise blanking and
limiting, AGC, amplification, IF and <AF> filtering are all done within the DSP.
Several noise blanking algorithms (methods) are available in the DSP, and a
sophisticated AGC system is employed. AM, FM, SSB and CW detectors are also
implemented by the DSP. Various audio effects, such as Quasi-Stereo and
Binaural, are provided here as well as combining the audio signals from the KRX3
(if installed).

After processing, the resulting audio signals are generated in a stereo 24-bit
Digital to Analog Converter (DAC) and applied to separate amplifiers for
headphones (front and rear) and speaker. A separate 24-bit DAC and amplifier
provide Line Out signals that are not affected by the <AF> Gain control. This
output is typically used by sound card digital mode software.

In transmit, Line In, rear or front Microphone signals are sent to a 24-bit ADC
and then processed by the DSP. In speech modes (SSB, AM and FM) and
soundcard-based data modes, <VOX> is derived from these signals as well as
receive audio. Microphone equalization, bandpass limiting, conversion to 15 kHz
IF, envelope clipping and filtering (if applicable) are all done in DSP, then
the signal is passed to another 24-bit DAC and presented to the RF board as a 15
kHz IF signal. Direct FSK, direct PSK and CW signals are generated within the
DSP for those modes.

Thus, the DSP is responsible for all signal processing between audio and the 15
kHz IF for both receive and transmit. Like all other modules in the K3, the DSP
is managed by the MCU.

The DSP board is piggybacked onto the Front Panel board as part of the Front
Panel assembly. The Auxiliary DSP (used if the KRX3 Second Receiver Option is
installed) and the KDVR3 option plug into the DSP board.


The KREF3 module’s 49.380-MHz temperature-compensated crystal oscillator (TCXO)
is the common signal source for the K3’s synthesizers. This signal is also
divided by 6 to provide the 8.230-MHz signal used by the second receive and
transmit mixers. Firmware is used to compensate for any small drift in the TCXO
and its derived signals, resulting in excellent stability (with the
high-stability option, better than +/- 0.5 PPM over the 0 to 50 C temperature
range). In addition to the TCXO and dividers, the KREF3 provides the 2nd
transmit I.F. mixer, which converts the DSP's 15-kHz transmit I.F. output to
8.215 MHz. This signal passes through a wide crystal filter to ensure good
rejection of the carrier and other mixer products before being routed to the RF


board. The KREF3 obtains its DC and low-frequency I/O signals via an 8-pin
connector on the RF board, but its RF outputs are fed to the RF board (and sub
receiver, if applicable) via coax cable assemblies.


Low phase noise is key to both receiver and transmitter performance. In the K3’s
synthesizer module (KSYN3), we start with a clean, wide-range voltage-controlled
oscillator (VCO). The VCO frequency is placed near the desired band of operation
using 128 carefully-selected L-C combinations, which keep the ratio of fixed
capacitance to tunable capacitance (varactor diodes) as high as possible.

The VCO is held exactly on frequency by a phase-locked-loop IC (PLL), which
samples the VCO output continuously and compares it to its high-stability
reference input. The PLL’s reference input is obtained from a
direct-digital-synthesis (DDS) IC, which is tunable in about 0.2-Hz steps. The
reference for the DDS itself is the 49.380-MHz signal from the KREF3 module.

To keep the synthesizer’s output signal virtually spur-free, the DDS is followed
by a 4-pole crystal filter. This eliminates both directly-occurring spurs and
the Nyquist sampling spurs that normally accompany a DDS-driven PLL system.

The combination of all of these noise-minimization techniques results in very
low phase noise and negligible discrete spur content.


K3 Block Diagram (not shown)


Appendix A: Crystal Filter Installation

Damage to your K3 due to electrostatic discharge (ESD) can occur if you don’t
take proper precautions. Such damage is not covered by the Elecraft warranty,
and could result in costly repairs. We recommend that you use an anti-static
mat and wear a conductive wrist strap with a series 1-megohm resistor. An
alternative is to touch an unpainted, grounded metal surface frequently while
you are working. Do this only when you are not touching any live circuits with
your other hand or any part of your body.

To avoid marring the finish, place a soft cloth under cabinet panels; do not lay
them directly on your work surface. Also, do not use a power screwdriver of any
kind, as it can slip and gouge the paint.

Installation Procedure

Disconnect the power cable and all other external cables from the K3.

Remove only the top-cover screws identified in the drawing below.

Press gently at the indicated point near the back edge (X), then lift off the
top cover at the front. Unplug the speaker, then set the top cover aside in a
safe place.

The screws that hold the top cover in place are an important part of the K3’s
structural design. Please be sure to re-install all of them afterward. Put on
your wrist strap or touch a grounded surface before touching any K3 components
or modules in the following steps. If you have the KRX3 option installed, refer
to its manual for instructions on removing the sub receiver module.


Locate the crystal filters you presently have installed in slots FL1 - FL5 on
the RF board (or sub receiver).

There may be a mix of 5-pole filters (below left) and 8-pole filters (right).

Review the information below to ensure that your crystal filter setup conforms
to K3 requirements.

You can install up to five crystal filters (FL1-FL5) on the RF board, and five
on the sub receiver (KRX3). FM operation requires a 12.5 kHz or wider filter. AM
transmit requires a 6 kHz filter, and SSB/DATA/CW transmit requires a 2.7 or 2.8
kHz filter; other bandwidths can be used for receive in these modes. Filters as
narrow as 200 Hz can be used for CW and narrow-band data receive. A mix of
5-pole and 8-pole filters can be used.

There are two rules regarding where these filters can be installed in the K3 and
how they’re used:

Rule #1: If you plan to use a particular filter for both transmitting and
receiving (main receiver), you’ll need to install it on the RF board. You can
optionally install a filter of the same or similar bandwidth on the sub receiver
for receive-only use. (This is recommended since it will keep the receivers

Rule #2: You can install any filter in any slot, and can leave any slot empty in
anticipation of installing a crystal filter there later. However, you should
install the widest filter closest to FL1, the next widest to its left, etc.

Here are two examples that could each apply to either receiver, assuming you
follow the rules above:

FL1 6 kHz (AM) FL1 {saved for FM filter}
FL2 2.7 kHz (SSB/CW/DATA) FL2 6 kHz (AM)
FL3 1.8 kHz (SSB/CW/DATA) FL3 2.8 kHz (SSB/CW/DATA)
FL4 500 Hz (CW/DATA) FL4 {saved for variable-bandwidth filter}
FL5 200 Hz (CW/DATA) FL5 400 Hz (CW/DATA)


Fill in the table below (include sub receiver info, if applicable). Use pencil,
since you may change the configuration later. BANDWIDTH can be obtained from the
model number of each filter. 5-pole filters have a FREQ OFFSET marked on the
side of one of the crystals, e.g. “-0.85”. The offset for all 8-pole filters is


If you’ll be changing RF board filters: Turn the K3 upside down, placing a soft
cloth beneath it.

Remove the seven black pan head screws retaining the front bottom cover, then
lift the cover off.

Remove the screws holding any existing filters that you’ll need to move to
obtain the order listed above (on both the RF board and sub receiver).


Turn the K3 right side up. Unplug all filters to be repositioned (those whose
mounting screws have been removed). Lift the filters at each end carefully,
first one end then the other, until the connectors separate.

Reposition the filters as required. They will only fit one way. If you put one
in backwards, it will not fit within its outline, and the standoff will not line
up with the screw hole in the RF board (or subreceiver board).

Turn the K3 (or sub receiver module) upside down again. Install the mounting
hardware shown below.

Filters may be supplied with either a black 3/16” or bright-plated 1/4” pan-head
screw. A screw longer than 1/4” may extend into the 8-pole filter unit and
damage it.

Do not over-tighten the screws. Excess torque may pull out the threaded

Re-install the bottom cover (if applicable) using seven 4-40 x 3/16” black pan
head screws. Replace the screws securely, but do not over tighten them. All
screws must be used to maintain shielding performance. The top cover and sub
receiver (if applicable) will be re-installed in at later step. Turn to Crystal
Filter Setup (pg. 43). Follow all instructions for the main receiver and
transmitter. If you have the KRX3 option, re-install the sub receiver module as
described in the KRX3 manual. Then turn to Crystal Filter Setup and follow all
instructions for the sub receiver.

Position the top cover on the K3, with its rear tab inserted under the top edge
of the rear panel. Then plug the speaker wire into P25 on the KIO3 board at the
left rear of the K3. Secure the top cover with 4-40 x 3/16” flat head screws at
all locations. This completes crystal filter installation.


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