[ARC5] Re: [Milsurplus] LF in a B-17?

[David Stinson]

Hue Miller wrote:
> Interesting. The Army came kinda late to LF in aircraft, didn't it? That would
> seem to shoot down the JAN coordination theory.  Also, if LF was necessary
> to coordinate with Mexico, etc., how did the US Army handle this before LF
> onboard was mandated? ....
Cooperation between forces in the Americas was
late in some cases.  I don't think Mexico actually
got into service until right at the beginning of 1945.
Some South American countries- Brazil comes to mind-
waited until the Germans were whipped to "declare war"
on them.  The American theater commanders would need
to coordinate with these people, especially on
anti-submarine patrols.

This "banana republic" LF-MF connection is, as I've stated before,
still a theory, based on the fact that these folks were using
old ships that would have met the specifications of
the 1920s-early 1930s naval treaties, which specified freqs
less than 2 MC for almost everything, including aircraft.
As to where they would have gotten it-
someone must have built it, because the U.S. Navy
used it up to the early 1930s. I don't have my book on
that handy- Westinghouse and GE come to mind among the
builders of Navy transmitters in the 1920s.
Can one of you Navy ship-board experts chime in?

The GF/RU apparently had this "tactical" LF/MF
capacity added early; Mike Hanz found a GF coil
dated 7-1-1940 that tunes 1250-1500 K.C.,
serial number 42 built by A.R.C.
This would certainly have made a very lame DFing signal.
I can think of no reason to equip a short-range,
tactical command transmitter with this frequency range
other than to communicate with old ships still using
the Naval treaty frequencies.  Not a decisive
piece of evidence, but an interesting one.
There isn't quite enough evidence to settle the
matter, especially concerning the LF-MF ARC-5s.
We'll find it eventually.

> Here's something i think is interesting, altho i don't know what it means - if
> anything. In the Navy's aircraft transmitter ATD, just about every one you see
> has a combination of 550 - 1500, 1500 - 3000, and 3000 - 9000 kcs. tuning units.
> You only rarely see the LF band tuning unit. 

I have one. Brag brag ;-).
That might be explained by both the limited deployment of
the ATDs and their use in scouting-type aircraft (according to
the documentation we have).  Scouting craft would not be classed
as "ocean transiting," so wouldn't need to meet the requirement
of the 500 KC distress monitor periods.
I have a partial TBM torpedo bomber manual here
(the part concerning the radios, of course).
This aircraft is not "ocean transiting."
There is no mention of the installed ART-13
having an LF oscillator or LF loading coil.

73 DE Dave AB5S