Thanks, KG4RUL, for posting that schematic. I'm planning to build an adapter as well.
I'm pretty much a rookie at this, so please pardon some questions.
1. My headset is a David Clark H10-13.4S, which has a mono/stereo switch on its cable (which I believe affects only the earphones). As well, it has what appear to be four conductors on the microphone plug (the plug is a PJ-068 [.206-inch phone plug] type). This confuses me, because your schematic shows only three connections, and also because the only .206-inch plugs I can find show three connections as well. This drawing refers:http://www.switchcraft.com/Drawings/S13B_CD.pdf
This is a photo of my headsets plugs. The microphone one is in the foreground:http://i292.photobucket.com/albums/mm1/hazydavy99/DSC_0657.jpg
Can anyone explain how a four-conductor microphone plug corresponds to KG4RUL's schematic?
2. I tested the pins on the 8-pin microphone connector on my IC-7200 and found that pin 2 delivers 9 VDC, rather than the 8 VDC specified in its schematic.
This is okay, right? KG4RUL stated that the David Clarks want 5-15 VDC. Is that on the David Clark site somewhere?