I was inspired to try to adapt the headset I use for VOIP to the K2, since I
wanted to play with SSB a little. I got the idea from something that W2ENY is
selling on ebay :-) I'm writing this up so it's in the archives in case someone
else has the idea (and remembers to look).
How hard could this be, I figured? Well ... read on.
Finding the 8 pin part was easy at Radio Shack. I looked up the pinouts, hooked
up PTT to a mono 1/8" jack and AF to another 1/8" jack. I plugged everything in,
but got no audio response. That was just weird.
I fiddled around with plumbing for a while - I plugged the mic into my laptop
and the laptop audio out to the adapter, and that worked. After an hour of
pulling out my hair, I realize that the microphone is a noise-cancelling mic,
and thus it must get power from somewhere.
A bunch of web searching led me to
http://www.epanorama.net/documents/pc/multimedia_microphones.html
which tells me that the PC standard is to supply +5 on the ring of the
connector.
I also found
http://marc.info/?l=elecraft&m=109408122407776&w=2
in the Elecraft archives! I should have looked there first. It reminded me that
there was +5V on pin 6. So I set about to put a 2.2K resistor in the 8-pin shell
and use a stereo jack for the mic.
That didn't work, either. Huh? Oh. There's no voltage on pin 6. It turns out
that when I installed the KSB2, I didn't strap all the pins in the mic
configuration header, just 1/2/7/8. Easy to fix.
Hey! That was ... better. But intermittent. I couldn't figure out why. It took
another hour or so to discover that I had slightly melted the insulation on the
PTT lead in the 1/8" jack and it could short to ground! Also a straightforward
fix, once I found it.
I'm trying to use this with VOX. I'm not sure I'm going to be happy with the
results, though ... we'll see.
Mostly, though, I think I prefer CW!
73 de chris K6DBG
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