[ARC5] R-25/ARC-5 Stabilized Receiver

[Mike Morrow]

> The receivers were tuned on the ground using A.R.C's OA-4 
> Crystal Frequency Generator.

I suspect that the O-4/ARC-5 was a relatively rare piece of equipment, even in the heyday of AN/ARC-5 usage.  I've heard of very very few in the 40 years that I've followed the military surplus scene.  Even the T-15, T-16, and T-17/ARC-5 MF transmitters are more common!

Some version of the LM would be the most obvious external pre-flight calibration signal source.  Perhaps that's why there are a lot of used AN/ARC-5 receivers that have the MX-20/ARC-5 power adapter installed, when only the BCB R-24/ARC-5 was supplied from the factory with the MX-20 for use with the AN/ARR-1.

The LM can be easily adjusted for any frequency in the range of the AN/ARC-5.  The O-4 requires a special odd-ball crystal for each desired frequency.  The O-4 was the answer to a question that wasn't being asked!

Mike / KK5F