AT-11 Datasheet, PDF (8/15 Pages) List of Unclassifed Manufacturers – AT-11 Automatic Antenna Tuner

socket for U1 was installed correctly. Make sure U2 is installed correctly. Check D20 for polarity. Check the
SIP resistor for proper orientation.
One or more relays energizes on power up: Check for correct positioning of all transistors. If a
transistor is found to be bad, just about any 2N3904 type or equivalent will work. Check solder joints.
Can't get 4.5 volts on FWD: Make sure T1 was wound correctly. Make sure the wire from the SO-239
passes through the center of T1. Check polarity of D18 and D19. If you can't get 100 watts out of your radio,
use 10 watts and set FWD and REV to 1.5 volts.
LEDs don't work: Check for polarity on LED1-4. The flattened side of the LEDs should go to ground.
LEDs work, but won't tune: Check Q1-17 and D1-17 for polarity.
LEDs flash randomly at high power or relays chatter or unit locks up: Excessive stray RF on board or
poor grounding. Try reducing power to 5 to 10 watts during tune to find match. AT-11 may also be outside of
tuning range.
Tech Support: Telephone technical support at 410-586-2177 is available most days from 6 to 9 pm
Eastern Standard Time. Replies by FAX [phone]) are welcome, e-mail ([e-mail]) is also
answered on a daily basis.
Last Resort: As a last resort only, LDG Electronics will attempt to repair any problems. As much as we would
like to do it for free, we just can't. We have a flat fee of $50 plus parts to repair an AT-11 (most resistors
and capacitors are included in that fee). The 68HC11 chip is the most expensive at $20. The 34064 is $5.
Relays are $4 each. The 78L05 is $1.
We will not attempt to repair any unit that has been soldered with acid core. We reserve the right to
refuse repair due to excessive problems or damage due to construction.
Before any unit is sent to us, you must first call to get return authorization. All units sent back must be
prepaid, either by check, money order or Credit Card unless other arrangements are made. Package the unit
carefully and keep in mind that we will use your packaging to return the unit back to you. Include a description
of what problem you are having along with your name, address and a phone number that you can be reached at
in case we have questions. Repairs average about 4 to 6 weeks, depending on the particular problem.
Upgrades: We are continually trying to put more features in the software of the AT-11. The software was
locked in with version 1.7 at the time of the QST article. There were only seven bytes (out of 512) of code
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