[Milsurplus] Those ATD Long/Medium Wave T.U.s

[David Stinson]

----- Original Message ----- 
From: "Mike Morrow" <kk5f at earthlink.net>

>The USN was attached to the 500 to 1500 kHz operating region, 
>for >reasons not well documented.

I wish some retired person would spend a little
time in the A.R.C. archives in Washingtoon and
see if we can settle the question of the 500-2000 KC
range rigs.  The only "retirement" I'm ever going
to see is the kind that comes with 6 feet of dirt. ;-)

There isn't any documentation available and may
never be, but I've heard two ideas (other than the
obvious 500 KC Watch/Distress capability required
for over-water missions)
that are at least credible and one that's "out there"
but came from a Navy vet.

The U.S. Navy during WWII needed to
communicate with the naval assets of "tertiary"
powers.  Those forces were typically equipped
with older gear that complied with the late
1920s international Naval agreements,
which assigned Longwave and Mediumwave
frequencies to both ships and aircraft.

If  a patrol flight of TBMs off  Costa Rica
were to see an unidentified group of  small
armed ships, those craft were probably equipped
with 500KC and a couple of more Mediumwave
frequencies.  They would not have access to
"Restricted" U.S. Navy sectionals from which
to determine an HF channel, nor were they likely
to invest in an HF transmitter which would add
expense without adding a needed capability.
Mediumwave would be the only way
to talk to them.

There are also cases of  Navy patrol aircraft
using Medium Wave as a "homing beacon"
while orbiting a target or group of survivors.
That explains one reason for the capability
in something like an ATD or ART-13, but
does not account for the AN/ARC-5 Command
Sets for Medium Wave.  No sane engineer
is going use the fractional E.R.P available from
a little Command transmitter through a lossy
loading coil to be a homing beacon.  The only
reasonable design mission of these sets is to do
Command communications on Medium Wave.

For instance- If your TBMs are going to
meet-up with a group of  Columbian patrol
bi-planes, they might want to talk with
you on 1505 KC and their tower, where
you need to refuel, might be listening on 1505KC.
Does anyone have a sectional from 1942 or 43
that covers South or Central American
airfields?  1944 or 45 sectionals probably wouldn't
address this issue since Uncle would have
provided updated equipment to the airfields
he wanted to use by then.

The "Out There," "maybe" story came from
a WWII vet many years ago who said his unit
would fly small, fast aircraft equipped with
Broadcast Band transmitters and wire recorders
to broadcast "surrender" messages to
Japanese garrisons on bypassed islands.
I think that unlikely as a "designed mission,"
but as a "field innovation," I don't see any
reason to call the man a liar.  People did
some pretty wild things to get jobs done.

73 DE Dave AB5S