[ARC5] Gibson Girl and Other Emergency Radios on 500 kHz

[Mike Morrow]

Wayne wrote:

> I recall reading that the Gibson Girl was a copy of a WWII Luftwaffe
> emergency transmitter.  Anyone ever hear of that?

A good description with pictures and technical details of the history of the
"Gibson Girl" may be found at http://wftw.nl/gibsongirl/gibsongirl.html .

There you will see the German Not (emergency) Sender (transmitter) 2. 

> And I think the US models included not only 500 KHZ but an 3MHZ range
> HF frequency as well.

No.

All of the US WWII GG models were the SCR-578-*, consisting of the BC-778-*.
The BC-778-* operates on 500 kHz A2 (MCW) mode only.  The automatic SOS keying
disk sends SOS correctly as one character ( ...---... and not ... --- ... ).

For aircraft overflying Arctic regions, the USAAF also proposed adding a MF
receiver to the SCR-578-* Gibson Girl transmitter.  The receiver was the
dry-battery powered Setchel-Carlson Model 591 beacon band (190 to 420 kHz)
receiver, with JAN nomenclature of AN/CRR-1.

During WWII, larger suitcase-sized 500 kHz emergency transmitters were carried
on merchant vessels worldwide.  These often had a small lead-acid battery and
a hand crank for power.  US versions of these such as those made by Federal
Telegraph could be set to send not only SOS ...---... automatically, but also
S S S (... ... ...).  That was the signal that a submarine attack was the cause
of the emergency...information that would be valuable to any rescue effort.

After WWII the T-74/CRT-3 Gibson Girl was introduced which operated on 500 kHz
A2 or 8280 kHz A1.  The HF channel was changed by the very early 1950s to 8364
kHz A1.

Also post-WWII, the USAF attached an emergency keying unit AN/ARA-26 to sets
like the AN/ARC-21, 58, 65, and 618S-1 to auto-key an SOS plus aircraft ID while
the aircraft was still operating.  The KY-65/ARA-26 sent SOS *incorrectly*
as ... --- ... instead of the correct ...---... and it would be interesting
to know if that was intentional, or a design screw-up on the KY-65.  I believe
the latter.

The US Navy purchased in the Korean War era the AN/SRC-6 (RMCA ET-8053) and
AN/SRC-6A (Mackay Type 401-A) lifeboat radio sets.  These units provided both
transmission AND reception of the emergency frequencies of 500 kHz A2 and 8364
kHz A1.  The TRF 500 kHz receiver was broad enough to hear anything about +/- 12
kHz, and the 8364 kHz receiver was tunable from 8250 to 8750 kHz.  These were
complex sets with a superheterodyne HF receiver and seven or more vacuum tubes.
Working the integral hand crank generator must have been very trying!  See the
size and internals of the AN/SRC-6 at http://www.oh6vm.fi/ET-8053/ .  The
AN/SRC-6A is similar but about 25 percent smaller and lighter.  My AN/SRC-6A
still has the ship's USN call sign of NRKO on the panel, which means it was
used aboard the USNS Asterion (T-AF-63).  The Asterion was laid down in 1944,
saw service in the Vietnam War, and was removed from service and sold for scrap
in 1973.

Throughout the remainder of the Maritime Morse era (to 1999), smaller and more
efficient sets performing the functions of the AN/SRC-6* were developed and
marketed to the world's merchant fleet.  By the 1970s most were completely
solid state.

I have all of these military units in my collection, and several of the
late-model merchant marine service lifeboat models as well.  They are
radios from a romantic never-to-return, never-to-be-forgotten era!

Mike / KK5F