Good morning Mike.
Thank you for the quick response !!!
I haven't yet tested the levels on the data line between microphone and IC2820 radio but i will do this for you in the next days.
The IC2820, IC2725 and IC208 uses the same microphone but only the IC2725 has a direct connection at the control head.
If there is a simple possibility to convert the levels for 2820, i will figure out this and send you the results.
For the moment i can use my 706 microphone :-)
best regards from Switzerland: Christoph