[Milsurplus] SCS-51

[Jack Antonio]

On the AN/ARN-5, there was another receiver in
the ARN-5 series, the R-47/ARN-5. It was a super-regen, and
my manual says only a limited number "are in the
field for training purposes". It goes on to say in fine
print not to use the receiver in areas with multiple
transmitters due to the lack of adjacent channel selectivity.

The R-57 is a single channel unit, which the manual says is
for use on 3 channels by changing the crystal, "The two crystals
not in use are stored in the receiver".

The R-89 is a 3 channel unit, but there are 6 channel select
relays(2 relays for each crystal), and holes punched in the metal work 
for 3 additional crystal sockets.  So it appears they were thinking 6 
channels right from the start. The crystals are CR-1/AR units.
There was also an R-89A and R-89B, which a quick read of the
manual indicates differences in strong signal characteristics.

I have an R-268B/ARN-5B which is a 10 channel unit, with
HC-6/U crystals. It looks like it was modified from an R-89.

But I have no idea of the time frame when the later receivers
came out.

Jack Antonio WA7DIA
scr287 at sbcglobal.net