These were used in the (very) older generation GRC series radio sets to help bridge the gap between the armor guys who ran down in 20-28 Mhz and the infantry guys who were all running up in 40 something to 50 range. Basically, you would add an RT-70 to your already staggering supply of radios in your vehicle and it provided a low power FM set that would let you directly speak to your accompanying infantry guys who were using the PRC-10 or PRC-6 radios. Additionally, the AM-65 also provided an interphone amplifier (intercom system) for your vehicle if you needed it.
I have had a few of these in the past, we used them to sort of bridge the gap between our transition from modern radios to period correct radios for Operation East Wind. When they run, they are pretty decent little sets but with the 100 KHz steps, we had a bit of a hard time talking to sets that were much more modern than they were. We could talk ok to RT-67s, but attempts to talk to the P-126 radios (we were attempting to use these to substitute for Soviet vehicle radios) were largely fruitless.
Additionally, they are all getting pretty old and we were seeing a fairly high failure rate with them so it soon became obvious that we were just as well off sticking pack sets in the vehicles till we could finally source the correct P-123 radios for them.
I have never seen one that was demilled. I don’t think the army much cared about that sort of thing at the time. They pop apart pretty easily, just separate the two halves and unlock the Dsus fasteners on the front then the shell comes right off of them. They are just about completely stuffed with tubes and gadgetry, you ought to rapidly notice if something was yoinked out.
As far as use goes, just check the power supply module on the back end of the AM-65 and see what voltage it says it is. (tag on the front is supposed to say this too but always double check) then apply the requisite voltage to the supply plug pins (you’ll have to look the configuration up, I do not remember it), next see if there is already a jumper wire on the multi pin plug in the middle of the AM-65 (again, don’t remember which wires but most of the ones I got were already jumped), then with the doggy bone cable plugged between the two sets. Plug in a handset or speaker. Flip the power switch to intercom and listen for the vibrator power supply to start buzzing. Once it’s up power wise you should be able to hear yourself speaking across the side tone when you hit the PTT and talk on the handset. If so, your AM-65 is looking good.
Next, flip the power switch over to the RT-70 position and adjust your volume and squelch till you can hear something. If you get a rushing noise in the handset that changes when you turn the dial you’re likely to at least be at a starting point. Now just go learn about radio and get your HAM license…
