[Milsurplus] More questions on AN/XXX.. more

[J. Forster]

In the AN/XXX nomenclature, there are prenumbers for the individual components:

AT-1/APN-2
ID-14/APN-1
MD-7/ARC-5
R-20/ARC-5
RT-1A/APN-2
SA-1/APN-1
T-20/ARC-5

The meanings of these examples are pretty obvious, but does anyone have a
complete list?

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ALSO, does anyone know if the same designations were used under both the SCR and
AN/ systems? I'm inclined to think so, but would like confirmation. (i.e. did a
battery stay a BA-, a dyno DY-, ...)

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Thanks,
-John