Paul Keys at Columbia Electronics may have one:
http://www.columbiaelectronics.com/ and sometimes lists on Epay, also Mike Murphy (Murphyjunk.net) had some parts as well, though not sure if he has that specific module. Could also try
www.americanmilspec.com as he had some 524 and 246 parts as well.
I *think* when I fixed my last one with the cut leads on the A9000, I keyed up transmit on high and measured the voltage present on the top of the final (secured by that collar) and found nothing measurable. That led me to the circuit diagram which I think showed a direct connection to the socket on A9000 which, of course, was clipped.
I would say it's really unusual to have a problem with A6200 itself unless it's either of the tubes, and even at that - the radio will handle a regular VSWR of 4:1 so it's pretty hard to blow the final unless you're transmitting into an open circuit, and I've *never* seen the other tube blow, though I've changed out a couple of finals - mostly because the antenna relay on the front was bad and the transmit energy was going nowhere - and a couple through bad AMU matches (MX-6707s full of water or with pinched coax in the lead from AMU to whip.)
One other thing that happened with the demils is that they'd take the A6400 back half off the radio, pull the shielding and sometimes either or both of the tubes, and then haphazardly reinstall it - sometimes not even on the same radio - paying no attention to the gear alignment or gear position. Normally that shows up as low output or really noisy output or a dial that won't select all the frequencies available though.
Check your Transmit/ Receive antenna relay on the front, too by doing a continuity check between the BNC main 'ANT' front panel connector center pin and the the input pin from the transmitter coax when you hit the transmit switch on an audio accessory (just disable the transmitter itself, first obviously - pull the final, ideally.) I have had MANY of these fail through age and use, and pulling them apart to clean/ adjust contacts etc. does not work.
A9400s also go. If you're on HIGH and hit transmit, does the fan spool up? Basically that module contains some high-power transistors that provide your fan voltages and voltages to feed the A9000 module which in turn gives you your HV for the final etc. They come in two flavours: Silicon, and Germanium. The original Germanium transistors are pretty much all doomed thanks to a known issue that apparently will eventually affect all of them - but the Silicon ones are pretty hardy. The module will be labelled A9400 if Germanium, and A9400A if Silicon. I've never had a Silicon one go, but have replaced a bunch of the Germanium variety.
