Folks,
The recent Armstrong-Superhet discussion on the ARC-5 list got me
looking around for the earliest military superheterodynes.
That might be the BC-113 Tuner with the BC-116 amplifier in
SCR-133/134/135. There's reasonable documentation on these, but
it didn't work all that well. Design started about 1924 by Fort
Monmouth, about the same time Armstrong and Harry Houck were doing
the superhet design for RCA. . This was a separate converter and
IF/AF amp in the fashion of Armstrong's original design, and tuned
250-1500 KHz.
These use VT-5 tubes (W.E. 215A's)
Then from "Aviation_in_the_U.S._Army,_1919-1939" P. 232:
"In 1928, a board of Air Corps and Signal Corps officers, headed
by Mai.
Horace M. Hickam, concluded that two types of radio communication
were
required: "command" communication within a pursuit, bombardment,
or
attack unit in the air, or between units in combined operations:
and "liaison"
between aircraft in the air and Air Corps or other units on the
ground. The
equipment on hand did not meet requirements. As an interim
measure, the
board suggested modifying present transmitters and adoption of a
new
receiver (BC-152). being developed by the Signal Corps. Compact,
light, easy
to install, and simple to operate. the BC-152 was compatible with
any of the
three ground sets then standard for aircraft communication, as
well as with
the Air Corps' interphone. Three plug-in coils for 250-400,
400-850, and
850-!500 kilocyclcs afforded a broad frequency range. With one
coil the
receiver weighed only 10 pounds: with all three, 11.5 pounds. Much
smaller
and thinner (12 x 8 x 2.75 inches) than previous sets, it became
known as the
"pancake receiver.""
Any info on BC-152 would be appreciated.
Al