Garmin 430 Comm Woes...help needed

[Bonanzabob]

I have been fighting a problem with the comm section of my Garmin 430 for over a year now. It's intermittent. Sometimes it works, sometimes it doesn't. Now it seems to be completely out. I can hear the carrier when the transmit key is depressed, but there's no audio. The mikes work fine on my Comm 2...a very dependable KX-165. I have had an avionics shop work on it twice. It was sent to Garmin for overhaul twice. Both times they said they found nothing wrong but replaced the communications board anyway. The radio shop replaced and rewired both comm antennas and rewired the audio panel (a KMA-24). I just inspected the "rewiring job" and I think they just re-wired the connections to the comm-1 terminals. Garmin charged $800 for the overhaul plus shipping, the avionics shop charged nearly $2,000 (and that's a whole other story) and STILL I can't depend on the Garmin 430. I have tried different mikes and keyed the setup from both the pilot and co-pilot side. I've used the PTT on the yoke, and substituted the handheld mike. Same results. Well...the "good news" is that the comm now seems to be completely crapped out, so maybe another radio shop can find the problem. I am wondering if there is an external pre-amp which may be to blame. I am located in Southern California and I fly a J-35 Bonanza. This has been very frustrating, especially because I fly frequently in the L.A. basin and communications loss with ATC is a hazard. Has anyone had a similar problem and if so, how did you fix it?

Bob

[Bob Meder]

I've flown in lots of different planes with 430's, and I've never seen that type of problem. My experience has always been the opposite; the 430 has been the good radio and the other one (if it isn't a dual 430 or a 530/430 installation) is the flakey radio (if it's flakey at all).

Since Garmin's looked at it and it, presumably, passed their inspection, I might suggest that you find another shop or tech, and have radio bench-checked with you present. If the comm features check out properly outside of the airplane, then I'm afraid they'll have to work backward from the radio tray in the plane to see where the fault may be.

[Mike Switzer]

Given that you have sent it back to Garmin & they found no problem, and both PTTs & the handheld mike do the same I would suspect either the audio panel or the wiring between it & the 430