[ARC5] Receiver BC-224-A vs. Transmitter BC-AA-191

[Mike Morrow]

Hue wrote:

> Popular Science for Jan. 1942 has some B-17 photos. One shot shows the
> second op handing the first op a BC-375 tuning unit. A task critical
> to the mission.  Also seen, the distinctive BC-224-A.

I wrote:

> Then obviously there was no 28vdc BC-375-*.  More likely it was a
> BC-AA-191...or early BC-191-*...for 14vdc.

I was incorrect to suggest that the BC-AA-191 transmitter and the BC-224-A receiver were used together.

The 1934 GE BC-AA-191 is the immediate predecessor to the later common BC-191-* and BC-375-* transmitters.  It lacked the antenna tuning circuits and antenna switching relay of those later units, among other smaller differences.

The 1936 RCA BC-224-A was the first in the long-lived BC-224-*/BC-348-* aircraft liaison receivers.  It has significant and visually obvious mechanical and some electrical differences from the models that followed.  It looks more like an aluminum BC-312-*.

The BC-224-A was used in only two aircraft radio sets:

SCR-187-A (1936), with transmitter BC-191-A
SCR-238-A (1936), with transmitter BC-307-A.

The BC-AA-191 was used with five aircraft and four vehicular radio sets:

-AIRCRAFT
SCR-AA-185 (1934), with receiver BC-AD-219 (also part of SCR-AB-183)
SCR-AB-185 (1935), with receiver BC-AF-229 (also part of SCR-AF-183)
SCR-AA-187 (1934), with receiver BC-AD-219 (also part of SCR-AB-183)
SCR-AB-187 (1935), with receiver BC-AE-229 (also part of SCR-AE-183)
SCR-AC-187 (1936), with receiver BC-AG-229 (also part of SCR-AG-183)

-VEHICULAR (Ground)
SCR-177 (1935), with receiver BC-189-A
SCR-180 (1934), with receiver BC-189
SCR-188 (1935), with receiver BC-189-A
SCR-193 (1934), with receiver BC-189.

There was no system in which the BC-224-A and the BC-AA-191 were used together.

Mike / KK5F