military: Life-raft emergency set 'Gibson Girl' BC-778; SCR-578

The life-raft emergency set SCR-578 contains a radio transmitter BC-778, called "Gibson Girl" for its shape. It was used in the WW2 by US-Amercan forces in case of an emergency. A guest, Jim Mandaville, has explained the following:

The "round thing" is a door which opens to expose a cylindrical chamber.  Mounted on the back of the door is a reel with the antenna on it.  The antenna is about 92 m long (only about one sixth wavelength at the operating wavelength of 600 m.)  Some models also had a second frequency in the short wave range, either 8280 or 8364 kHz.  This used the same antenna, which was then more efficient.

The antenna lead-in wire (about 1.5 m long) comes out from the back of the chamber.  It has a spring clip on the end so you can attach it to the antenna.  The antenna itself is raised at its far end by a kite or a hydrogen balloon (both of which are supplied in the original radio package).

The radio is operated in a sitting position, with the radio held vertically between one's upper legs, with the crank at the top.  The straps go around the thighs to hold it firmly in place while the operator cranks.  That is why the case has that "Gibson Girl" shape -- so it can be held more easily. It is quite a bit of work to operate the crank and maintain the minimum voltage (which is indicated by a light on the top of the case)!

It is rather amazing how the insides of the radio are kept waterproof through the use of gaskets at all case openings.  When new, it could be thrown into the sea and would float and not leak, and still operate when taken out of the water.

This transmitter was a close copy of the German NS2 (Notsender Gerät 2). The British captured  one of these from a crashed German plane and made a copy themselves. Another captured unit was sent to the U.S., where it was promptly copied in a somewhat different version.  The whole idea was German and copied by G.B. and the U.S.

Thank you, Jim.

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