[Milsurplus] BC-457

[Mike Morrow]

Dan wrote:

> 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.

Take it with a grain of salt.

The two-transmitter rack that was in the typical SCR-274-N installation could have any combination of BC-696, 457, 458, or 459 transmitters installed.  If two identical transmitters were installed, it would mean that two frequencies were desired that were within the range of one transmitter.

I don't suppose this was normal, though.  I don't think multiple identical transmitters would be in storage for all the aircraft in a squadron.  Besides that, except for the BC-458 which covers frequencies at the high end of the BC-454 and the low end of the BC-455 receivers, two identical transmitters would require manual tuning of the appropriate receiver.  Since there is NO provision for spotting the receiver frequency to a transmitter, the receiver adjustment would be problematic unless two identical receivers were installed (and BC-450 control box dials changed).

While you can bank on the typical SCR-274-N installation as having the BC-453, 454, and 455, about all you can say is that any two (mostly likely different) of the four transmitters were installed in the rack.

73,
Mike / KK5F  Now one receiver is for navigation but 
why have two transmitters that only cover one band?  Why not have a 
transmitter that covers each of the other two receivers coverage?  I 
wonder if maybe the manual is wrong.

Thanks
Dan
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