Sounds like a RESISTOR is changing value causing the bias to change on the
input preamp.

"Pete KE9OA" wrote in message
. ..
Another eBay special that "worked perfectly". It doesn't matter if I put
in an external audio source from an audio oscillator or a microphone. I've
tried three good microphones, and have the same problem. When I first key
the mic, Tx audio is fine, but it quickly, almost abruptly fades after
about 2 seconds. Has anybody seen this problem?

Pete