[Milsurplus] Pre-WWII Aircraft Radio

[Mike Morrow]

Michael wrote:

> Taking things out of order, the Navy didn't replace the RAX with the
> BC-348 but rather got them as part of AN/ARC-8 installations aboard
> aircraft acquired from the AAF. 

That agrees 100 percent with what I've learned.  I'd be very interested
in any information indicating the use by the USN of the BC-348 in any other
context.  Which is probably too bad, since other than not having remote
tuning capability it's a good candidate as the best airborne communications
receiver in one box in the world until just after WWII!  If multiple units
are allowed, then the RAX-1 is a better contender.  I leave out countermeasure
receivers like the AN/ARR-7.

> At the same time, the GO-7, -8 and -9 also stopped at 18 MC which indicates
> to me that the Navy found the higher frequencies inadequate to their needs
> or stopping at 18 MC adequate to their needs...

That seems supported by the excellent 1940 Collins ATC, whose coverage ended
at 18100 kHz, identical to the 1940 GO-7/8/9.  I suspect the USN just didn't
find it worth the effort to go any higher.  In fact, it seems that frequencies
below 9050 kHz were not of great interest for aircraft communications, command
or liaison [GF-*, GP-*, ARA/ATA, ARB/ATB, ATD (ignoring the almost non-existent
high range tuning unit), even the ATC when used with ARB].

> On the other claw, they must have had some reason to at least attempt using
> the 18-26.5 MC range or they likely wouldn't have tried.

That's part of the interesting mystery of the development of such sets.  What
motivated GE to produce the 1938 GO-4 with capability to 27000 kHz, when all
earlier GO-* transmitters were half that, 13575 kHz?  That's a notable advance
in technology to produce such a set.  I'd *love* to come across the manual for
a GE GO-4/5/6, though it still would not answer most questions.

Even after WWII, commercial and miliary aircraft HF sets seldom extended
coverage above 25 MHz until the end of the 1950s with sets like the AN/ARC-58
and AN/ARC-94.  A 28 MHz aircraft transmitter in 1938 was an achievement.

Mike / KK5F