Hi Stan,
It would be helpful if you were to also give us a little more info about your RV-12 so references to the proper wiring drawings can be made. Is it an older RV-12 that has the audio panel or a newer version using the GTR 200 radio? If the GTR 200, perhaps try something easy ... unplug it and firmly re-seat the radio in the enclosure.
In addition to what Julian asked .... curious, is the audio from the SkyView also noisy in your headset until things warm up ... or is the noise only an issue when you press the push to talk button?
It almost sounds like you may have a flaky grounding or perhaps a pin in one of the connectors that is not fully seated … when the connector gets warmer the pin expands and makes better contact?
For troubleshooting connector wiring, I have made up some test wires with various combinations of the male pins and female receptacles crimped onto the wires. These really come in handy trouble shooting wiring issues with DB style connectors.
My suggestion would be to first remove the Options connector from the AV-50000A module and ohm out the wires on pins 24, 25, 26, 27, 28, 29 to their respective left and right headset/mic jacks. The readings between the left and right side should be nearly identical … try to wiggle the wires a little while looking at the meter to verify the connections are electrically solid. Also verify that the headset jack mounting nuts are tight and that the jack body is not grounded at the seat pan … the insulating washers should be in place and verified to be isolating the body of the headset jack from the seat pan. While at it I would also make sure the push to talk button pins 1 & 3 on the Fuselage connector are providing a solid ground to the radio.
If all seems well between the Options connector and the headset/mic jacks and the isolation washers are doing their job, I would work on verifying all connector pins associated with the audio circuits are fully seated in the connector body. This can be accomplished by using male and female connector pins inserted into the appropriate connector positions to see if the male pins or female receptacles inside the connector body move during the insertion … a sign the pin or receptacle is not fully seated in the connector body. Use your appropriate wiring diagram and follow the audio/mic circuits from connector to connector testing the audio circuit with your test wires. Also, make sure to test the appropriate pins on the AV-50000A module’s connectors and taking ohmmeter readings.
Keep working your way back to the radio if you have the GTR 200 (which I'll assume you do). Pop the radio out and inspect it's connector as well.
Hope this helps somewhat ... and that you discover your issue.