[aprssig] Wilson radio mic pinout?

[David Rush]

Anybody have a clue what the microphone pin-out for a Wilson 1550 VHF rig 
might be?
I picked up this crystal-controlled boat anchor at a ham fest with hopes of 
using it for APRS (and curious how short of a TXDELAY I can get away with, 
since it's a crystal rig - no PLL to wait for!).
The mic it came with appears to be kaput - I couldn't get it to key up at 
all.  By poking around on the four-pin microphone connector I was able to 
get it to transmit, but I still don't know where the audio goes.

David, KY7DR