[Milsurplus] ARC-5 Receiver and other tube questions

[C.Whitaker]

de WB2CPN
Air Traffic Control in Europe right after WWII used
these frequencies:
Control Towers  6.440 KHz and "A" and "B"  116.1 and 121.5
Airways Stations:  4.220 KHz and "C" and "D"  137.88 and 140.58
In Berlin, at Templehof, we radio checked with everyone from
Champino to Preswick every shift change.  We checked with
Gatow on "B" and "C"  every day. (They had female voices
at Gatow.)   We had a lot of 32RA's and BC-779's HF in towers,
and T-4's for airways.  VHF used BC-640's and 639's.  Towers
did have Air Associates equipment, BC-797 (?) and BC-201.
BC-201 had a variable squelch, which nothing else had.
Trivia:  Except in movies and on training bases, airplanes did
not talk to other airplanes all that much.   Airplanes talked to
control towers and airways stations.  (And DF stations and
Ground Controlled Approach.)  There was tactical air
communications, a lot of it.  Also very important, the 522's
required crystals. A command would have a "crystal bank"
set up.  At one point during the air battle for Europe the lack
of crystals became such a problem that it was addressed at
the highest level.   It's in the book.
73  Clete