TW-1 Talking Wattmeter
1445 Parran Road, PO Box 48 St. Leonard MD 20685-2903 USA
LDG TW-1 Talking Wattmeter
Table of Contents
Jumpstart, or “Real hams don't read manuals!”
Getting to know your TW-1
Care and Maintenance
Warranty and Service
Congratulations on selecting the LDG TW-1 talking wattmeter. The
TW-1 is a breakthrough product, providing accurate and precise RF
power and SWR readings aurally, by synthesized voice over a
self-contained speaker. It is ideal for situations when you need to
watch something else while making an adjustment, or for visually
LDG pioneered the automatic, wide-range switched-L tuner in 1995.
>From its laboratories in St. Leonard, Maryland LDG continues to
define the state of the art in this field with innovative automatic
tuners and related products for every amateur need.
Jumpstart, or “Real hams don't read manuals!”
Ok, but at least read this one section before you transmit:
1. Attach the RF input jack (right connector when viewed from back)
to your transmitter or transceiver with a 50 ohm coaxial jumper cable.
2. Attach your antenna to the RF output (left connector when
viewed from back).
3. Connect a 12 volt power supply capable of delivering 200 ma to
the 2.5 x 5.5 mm coaxial power jack (center positive).
4. While transmitting RF, press and release the left-hand button.
The unit will speak the forward power level.
Adjust the volume to the desired level.
5. While transmitting RF, press and release the center button. The
unit will speak the reverse power level.
6. While transmitting RF, press and release the right-hand button.
The unit will speak the SWR.
7. The unit will turn itself off after use.
0 - 2,000 watts, auto-ranging +/- 5% accuracy (10% on 6 meters)
1 watt or 1% power resolution
Verbose or terse speech
Tone mode for continuous feedback
Speaks in English, Spanish or German
Size: 5 x 4.5 x 3 inches Requires 12 volts at 200 ma, 2.5
x 5.5 mm jack, center positive
Getting to know your TW-1
Your TW-1 is a quality, precision instrument that will give you many
years of outstanding service; take a few minutes to get to know it.
On the front panel, there is a volume knob and three push-buttons:
Volume: adjusts the volume of the synthesized voice
Forward: measures forward power in watts (FWD Button)
Reverse: measures reverse power in watts (REV Button)
SWR: measures the standing wave ratio (SWR Button)
Readout resolution is 1 watt or 1% of the reading, whichever is
larger. For example, if the reading is 75 watts, 1% would be 0.75
watts, so the achieved resolution would be 1 watt. The readout
would go from “Seventy Five Watts” to “Seventy Six Watts” as you
increase power. At a reading of 245 watts, 1% would be 2 watts
(rounded off), so the resolution would be 2 watts; the reading
would go from “Two Hundred Forty Five Watts” to “Two Hundred Forty Seven Watts”.
There is no range switch; the TW-1 auto-ranges from 0 to 2,000
watts. There is no On/Off switch; the TW- 1 automatically turns
itself on during use and off after use.
On the rear panel, there are two SO-239 RF connectors. The
right-hand connector is the RF input (labeled Radio) for connection
to your radio, and the left-hand connector is the output to your
tuner or antenna (labeled Antenna).
The 2.5 x 5.5 mm jack coaxial DC power connector is on the right.
The TW-1 is intended for indoor use only; it is not water
resistant. If you use it outdoors (Field Day, for example) you must
protect it from rain.
Position your TW-1 in a convenient spot on your operating desk, as
close to your transceiver or transmitter as practical. Connect the
input jack to your transceiver with a 50 ohm coaxial jumper (not
provided) of suitable power handling capacity. Connect the output
to your tuner or antenna.
Your TW-1 requires 12 volts DC at 200 ma. Connect a suitable power
supply to the 2.5 x 5.5 mm coaxial DC input jack using the provided
2.5 x 5.5 mm jack coaxial power connector (center positive).
Caution: High RF voltages may be present on internal components
when transmitting. Never operate your TW-1 with the cover removed.
Setup options are selected by pressing and holdingbuttons or
combinations of buttons while you apply DC power. The simplest way
to apply power for setup is to unplug the DC power plug, wait
10 seconds, then re-insert the DC power plug from the back of the
TW-1, but you could also turn the DC power supply off then on again.
Setup options are retained indefinitely, even if DC power is removed.
Your TW-1 will speak in English, Spanish or German; the default is
English. To set the language, press and hold a button while
connecting DC power:
FWD Button: English REV Button: Spanish SWR Button: German
To reset to a different language, simply remove DC power, press and
hold the appropriate button and reconnect DC power.
Your TW-1 will speak in one of two different modes: Verbose and
Terse. In Verbose mode, the TW-1 speaks in full sentences, as in
“The forward power is ninety seven watts”. In Terse mode, only the
numerical value is spoken, as in “ninety seven”. The default is
After you become accustomed to your TW-1, you will likely want the
shorter readouts, without all the extra chit-chat. To select
“Terse” mode, press the REV and SWR buttons together while you
apply DC power. Thereafter, on pressing a button when RF is
present, only the numerical value will be spoken.
To return to “Verbose” mode, press the FWD and REV buttons together
while you apply DC power.
Simply adjust the volume control to the desired audio level as you
use your TW- 1.
Spoken readouts are available on demand; the readout is spoken on
button release. There is no need to set the power range; your TW-1
auto-ranges from 0 - 2,000watts. With RF present, press and release
a button to produce the following spoken readouts:
FWD Button: forward RF. power (Verbose mode example: “The forward
power is ninety seven watts”) (Terse mode example: “ninety seven”)
REV Button: reverse RF power (Verbose mode example: “The reverse
power is three watts”) (Terse mode example: “three”)
SWR Button: SWR (Verbose mode example: “The - SWR is two point
one”) (Terse mode example: “two point one”)
Your TW-1 works best with a constant RF carrier. Using a voice mode
(SSB for instance) would require you to talk and listen at the same time.
When adjusting a manual tuner or vacuum tube transmitter or
amplifier, it is often desirable to have a continuous readout of
power or SWR. Your TW- 1 provides this by playing a tone whose
pitch goes up and down with the power or SWR.
To place your TW-1 in Tone mode, simply press and hold, any of the
three buttons for more than three seconds before applying RF. The
TW-1 will beep to indicate it has changed to Tone mode; release the
button when you hear the beep. When you apply RF, the TW-1 will
emit a continuous tone who's pitch is proportional to the power;
the higher the power, the higher the pitch. You can select either
Forward (FWD Button) or Reverse (REV Button) power. for tone readout.
You can also select SWR for tone readout, as above,(SWR Button).
The pitch of the tone is proportional to the SWR; the higher the
SWR, the higher the tone. If the SWR is above about 3: 1, the tone
will pulse to indicate that the SWR is excessive.
After 30 seconds with no RF present, the TW-1 automatically reverts to
Speech mode (verbose or terse, whichever you have set). You can also
manually reset it to Speech mode by pressing and releasing any of the buttons.
The TW-1 will beepto indicate that it has returned to Speech mode.
The TW-1 is primarily intended for visually impaired hams, and
those of us more “experienced hams who must resort to bifocals,
making small meters hard to see at any distance.
The TW-1 is also very useful, for special situations when you need
to “watch” more than one meter, as when you are tuning, the output
stage of a vacuum tube transmitter or amplifier. With your TW-1 in
Tone mode, you can easily watch the plate current meter on the
transmitter or amplifier while listening to the power output on
your TW-1 in Tone mode.
The TW-1 is perfectly suited to mobile use. Simply install it in a
convenient location near your operating position, and provide 12
volts DC through a fused line (fuse not included; LDG recommends a
2 amp fast-blow fuse). SWR Tone mode is especially useful when
tuning a “screwdriver” antenna while watching the road. LDG
strongly recommends pulling over to a stop before adjusting your
antenna, but we realize that not everyone does this; you know who you are.
Care and Maintenance
Your TW-1 meter is essentially maintenance-free; just be sure to
observe the power and voltage limits discussed in this manual. The
outer case may be cleaned as needed with a soft cloth slightly
dampened in a mild household cleaning solution. As with any modern
electronic device, your TW-1 can be damaged by temperature
extremes, water, impact or static discharge. LDG strongly
recommends that you use a good quality, properly installed
lightning arrestor in the antenna lead.
You should never have to remove the cover, but if you do, be sure
that no wires are within 2 inches of the SWR sensor or the SO-239
connectors when you reassemble the unit.
We are happy to help you with your TW- 1. Telephone technical support
is available at 410-5 86-2177 weekdays from 9 am to 5pm Eastern Time.
Inquiries by Fax at 410-586-8475 are welcome, and prompt e-mail support
is available at firstname.lastname@example.org.
Warranty and Service
Your TW-1 is warranted against defects in parts or workmanship for
two years from purchase. The warranty does not cover damage due to
abuse or exceeding specifications. This warranty applies to the
original purchaser only; it is not transferable. A copy of the
receipt showing the purchaser's name and the date of purchase must
accompany units returned for warranty service. All returns must be
shipped to us, pre-paid; we will not accept units with postage due.
A return form is provided on our web site for your convenience.
If you need to return your TW-1 to us for service, package it carefully,
keeping in mind that we will re-use your packaging to return the unit
to you. A self-addressed return-shipping label, while not required,
will help insure speedy and accurate delivery of your repaired unit.
Include a full description of the problem, along with your name, address
and a phone number or e-mail address where we can reach you with any
questions. Repairs average about 3 to 6 weeks.
We will be glad to service your TW-1 after the warranty period has ended.
We will notify you of all charges by phone or e-mail, and bill you after
repairs are completed.
If you have an idea to improve our software or hardware, please send us
a description. If we incorporate your idea in the TW- 1, we'll send you
a free upgrade as a “thank you”.
We encourage everyone who uses the TW-1 to contact us (card, letter
or e-mail preferred) telling us how well it works for you. We are
also always looking for photographs of our products in use; we
frequently place such pictures on our Web site (www.ldgelectronics.com).
Disclaimer: The information on this site is provided as
a public service to the blind and visually handicapped community. While we have
done our best to ensure the information provided is accurate, please realize
the use of any information on this site is solely at your discretion and we
take no responsibility for use or attempted use of this information.