Icom HT Headset with IC-2820H

[K5JY]

I’ve gotten used to using the Icom HS-85 headset with my Icom IC-92AD HT in the car, and would like to be able to use it with the Icom IC-2820H mobile rig I’m contemplating.

The speaker-to-earphone connection looks fairly straightforward – the 2820 specs show a 3-conductor 3.5mm phone jack, driven at 8 ohms, and the HS-85 has a 3-conductor 3.5mm phone plug, with an 8ohm earbud, so a simple extension cord ought to work.

It looks like Heil makes an adapter cord, AD-1iCM, that has the right connectors for the mike (modular plug on one end, and a 2-conductor 2mm phone jack on the other,) and the HS-85 mike connector is a 2-conductor 2mm phone plug. But the 2820 specs say the mike impedance ought to be 600ohms, and the HS-85 mike is 2Kohms. Should I look for a small transformer with 3.33:1 winding ratio, or something close? Also, I’m not sure what the capacitor is/does on the AD-1iCM (the “C” in the product ID.)

Suggestions?

[K5JY]

Found a TON of info on mike connectors and wiring diagrams at http://homepage.ntlworld.com/rg4wpw/date.html The site also explains the capacitor in the Heil adapter (it blocks the DC Icom uses to power electret elements.)

I'm still looking for the mike element type for the one in the HS-85 headset, and a solution for the impedance mismatch.