[Milsurplus] Pre-WWII Aircraft Radio

[Kludge]

-----Original Message-----
From: milsurplus-bounces at mailman.qth.net
[mailto:milsurplus-bounces at mailman.qth.net] On Behalf Of Mike Morrow
> I'd be very interested
> in any information indicating the use by the USN of the BC-348 in any
other
> context.  

My Navy-converted BC-348-Q suggests they did do something with them beyond
the original intent but I haven't a clue what.  When I can get it out of
storage to take some pics, I'll put them up somewhere to show the front
panel.  (Maybe by then some kind soul will take pity on a poor disabled vet
and send me a dynamotor for it.  :-D )

> 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!  

Even without remote control, it was.  

> If multiple units are allowed, then the RAX-1 is a better contender.  

Discounting wider frequency range, electrically I'd put them on about a par.
Unfortunately, I've never had one to use so I don't know first hand.  If
anyone has a set laying around they really don't want ... :-D

> I leave out countermeasure receivers like the AN/ARR-7.  

If anyone happens to have one (or an AN/ARR-5) laying around they really
don't want ... :-D

>> 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.  

Also included are the various shipboard transmitters and, if you want to
expand to include Army ground equipment, the BC-610.  18.1 MC seems to be
the magic cutoff.

> 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].

I'm assuming you mean "above."  :-)

For the shipboard aircraft, this is very true.  For the long range patrol
aircraft (VPB or VP squadrons) and some long range transports, the upper
half of the range apparently was necessary since the GO & ATC (and later
derivatives) were used in them with a variety of receivers.  

>> 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.

What would answer some would be the bid paperwork and the workups to it
including NRL documentation.  Unfortunately, it's been converted to
something else long since so we'll never know.  

> Even after WWII, commercial and military 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.  

I suspect that spectrum sharing with the civilian HF high altitude en route
airways frequencies might have had something to do with that.  Commercial
air travel was rapidly replacing the railroads as the preferred method of
getting from point A to point B which required more and more spectrum space.
Also, I believe commercial company radios were in this range as well which
added to the crowding.  Civilians also expanded with equipment like the 618S
and 618T radios which begot the AN/ARC-38(A), which was channelized rather
than crystal controlled like the civilian version, and various military rigs
starting with the AN/ARC-94 respectively.  

> A 28 MHz aircraft transmitter in 1938 was an achievement.

That's a resounding understatement.  :-)

Best regards,
 
Michael, WH7HG ex-K3MXO, ex-KN3MXO, WPE3ARS, BL01xh ex-Mensa A&P PP BGI 
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