[Milsurplus] BC-457

[David Stinson]

Dan Cox wrote:
> Hello, it is my understanding that according to a radio familiarization 
> manual I found online for the b17 that it had a 453,4 and 5 receiver as 
> well as TWO 457 transmitters.  Now one receiver is for navigation but 
> why have two transmitters that only cover one band?...

As Mike was saying: this is only one possible configuration.
The "navigation" receiver (BC-453, 200-550 KC) was used
for some navigation, but was primarily used to talk to
traffic control towers, which transmitted on longwave (typically 278 KC)
and received the aircraft on HF (typically 3105 KC).
Army Airways stations were usually around 4.4 MC both ways.
A B-17 flying from base to base within the U.S. would typically
be equipped with a BC-457 and BC-458 to give a 4 MC and a 6 MC
Army Airways channel transmit, a BC-454 and BC-455 for
Army Airways receive and a BC-453 for "beam" navigation
and range weather.
If they were flying to civilian airports (yes, they did and quite
often), they'd need BC-696, BC-458, BC-453, BC-454 and BC-455
to use these frequencies:

Air to Control Tower 3105 or 6210 TX, 278 RX
Air to Air: 3105 or 6210 both ways.
Navigation and Range Weather RX: BC-453 LF

It's important to note that the BC-453 was quite secondary
for actual long-range navigation, since that's what
the Navigator and his radio compass did.
A pilot might "fly the beam" with the BC-453 when close,
but otherwise it was for taking to the Control Tower.

Back to the road with me,
73 Dave S.