[Kenwood] microphone for TS940

[Rob Neece]

I was given a headset and boom mic from a fellow who supplies them to race 
car teams.  It is comfortable and definitely kills the ambient 
noise.  Connecting it to my TS940 has turned out to be a challenge, partly 
because I didn't want to completely replace the cable.  I had to open up 
the headset and rewire it a bit to keep the PTT circuit separate from the 
mic circuit, but that worked out well.  Now everything works, but the audio 
is poor.

Specifically, the VOX on the 940 keys very reluctantly, and my voice sounds 
like all high frequency.  To key the VOX you have to increase mic gain too 
much or shout, which has the same effect.  My guess is that the VOX circuit 
doesn't respond to the high audio frequencies well.  In any case, the mic 
element should be good quality for communications and I expect good 
audio.  Hopefully somebody has seen and heard these symptoms before.  Is 
this an indication that the mic impedance is not matched to the rigs 
input?  Should I use a step-up (step-down) transformer?

There is another possibility.  The mic might require some voltage to 
work.  I think 8V is available at the mic jack on the 940, but it seemed 
like a bad gamble to try to connect it to that.

Rob
KK4R