[Elecraft] computer headset for K2/K3 SSB

[Christopher A. Kantarjiev]

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