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Old July 5th 05, 04:41 PM
Roy Page
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I had a similar with some of same symptoms, eventually eliminated the
problems by changing of audio panel.
Various radio shops never found a specific fault.
What audio panel do you have ?

Roy


"three-eight-hotel" wrote in message
oups.com...
I have been struggling with a radio problem for some time now and am
having a tough time finding the real "root cause"! (I have a Narco -
Mark 12D)

It started several months back, when I would occaisionally get a "stuck
mike". After several phases of trouble-shooting, it appeared to be a
problem with the audio panel, which was replaced and seemed to solve
the problem.

A month or so ago, I lost contact with ATC while shooting some practice
approaches... Apparently, they could hear me, but I couldn't hear them
(confirmed by using my hand-held). Ever since then, I have been having
strange issues with the radio, but it will occaisionally work fine for
20 minutes or so???

Symptoms:
1. No side-tone when transmitting???
2. Occaisional loss of reception on known frequencies
3. No response (on known frequencies) to transmissions

I took the radio into a Narco dealer and they confirmed a problem with
the transmission switch (replaced a diode) and yellow-tagged the radio.
I put the radio in the plane and it worked like a champ for about 30
minutes and started to exhibit the symptoms again??? I took it back to
the dealer and the bench tested it for a couple of hours and said that
it worked fine and everything was within specs! :-(

I'm worried about throwing good money after bad and don't even know
where to begin in resolving this issue. (I can't afford to throw a lot
of money at new avionics and would like to get what I have working, if
at all possible)

Does anybody have any recommendations at troubleshooting this problem?
My mechanic is at a loss as well. The loss of side-tone, while
transmitting, seems to be an interesting issue...

Any suggestions would be greatly appreciated!