[Milsurplus] Re: Navy ABA-1

[Mike Morrow]

> But Mk-III iff, aka BC-966 180-210mhz iff
> transponder, sed "radio receiver" on dog-tag.

That was the Mark III/G SCR-695-A (USN ABF-*) transponder.  The Mark III-only ABK-* (USAAF SCR-595-A) was also marked as a radio receiver, but the game wasn't played too well.  The pre-JAN USN component class system was still used accurately on the ABK-* main unit name plate, which has "Cxx-43AAY" on it.  Class "43" means "receiver-transmitter."  That would be similar to having a JAN component bearing a "Radio Receiver" noun name on the tag, but "RT-xyz" as the component ID on the same tag.

The circuit design of these Mark III IFF sets is unusual, and if one were captured intact and analyzed, it would probably at first appear to be just a receiver.  The trick was that the receipt of an interrogating pulse would cause the receiving circuit to oscillate and become a transmitter.  Cute.

The more one analyzes the clever vacuum tube circuit designs that appeared during and before WWII, the more one has to respect greatly the elegance and ingenuity of the designers, engineers, and technicians that were responsible for them.

Mike / KK5F