Ive been chasing a problem with my GNC355 for quite some time. I had it installed last year but unfortunately the installer passed away shortly after the install so I cant really go back to him for a fix. Anyway, when I key the mic to talk for any longer than 2 seconds, the GPS signal drops out and I get a GPS signal lost. It will then reacquire the signal and come back online after a few more seconds. Obviously this is not going to work for any type of IFR flying and it has delayed me from working on any IFR approaches. I thought that maybe it was the fact that I had an old Narco CP136 audio panel but since I had plans ot replace it in the near future, I didnt put too much thought in to it. I recently had the Narco swapped for a PS Engineeering 450b but the issue has now followed to the new audio panel. Any ideas?