On Tuesday, November 10, 2020 at 1:14:13 PM UTC-5, John DeRosa OHM Ω http://aviation.derosaweb.net wrote:
On Tuesday, November 10, 2020 at 1:31:05 AM UTC-6, Eric Schwartzy wrote:
I tried with 3 different headsets that all work on Mic2 plugs (listening and speaking). I am going to check the wiring with another radio today. Is it possible to have 1 mike "dead" and the other working fine, they have different amplifier or so in the radio ?
Regards
Eric

Eric,

I assume a traditional headset plugged into jacks and not a boom microphone.

- Different internal amplifiers for the two mics is probably but without a schematic hard to tell. Even so at some point mic 1 and mic 2 audio is combined internally.
- Swapping in a KNOWN GOOD KRT2 transceiver is a very simple way to see if you radio is at fault.
- A loose, corroded, broken, connector on the rear can mimic your issue.
- The microphone 1 gain setting could have be changed but unlikely.
- The headset jack #1 on the panel may be broken. If #1 jack is for the front seat of a tandem aircraft, or the left seat of side-by-side aircraft, then this is the most used jack which could point to this being the culprit.