[Boatanchors] Fox Hole Radios , variable capacitors and more parts sets

[William L Howard]

Subject: Re: [Boatanchors] Re Fox Hole Radio
 Since variable capacitors were not common in the field, the circuit
basically used stray capacitance and inductance between two coils to
tune.

If you  can get several single edge razor blades and a lot of screws and
nuts, you can build a variable capacitor. Held together by long screws
with nuts between each razor blade, you have the stator. The rotor was
made the same way but instead of two screws down the sides, the rotor
had it in the center.

I managed to make up a one tube set this way. Used a wooden block with a
grove filled with lead pencil marks for the grid leak resistor, took the
tin foil from several packs of cigarettes and made a capacitor, used a
liberated set of German 3000 ohm headset and a US type, four pin. Tube
socket was a wooden block with four holes in it. Same for the headphone
socket. Used 100 turns of #22 wire for the grid coil and about 20 turns
for the antenna coil.  50 foot copper wire antenna and pole stuck in the
ground for ground lead. It actually worked.

For a real wartime boat anchor radio set, see the story of "Winnie the
War Winner" pictures of the set are on the Australian War Memorial site.
It was also a transmitter and a receiver made from junked radios. It was
credited with saving an Australian unit for certain death as they were
able to get through to Brisbane and get a relief convoy sent to evacuate
them.

There was also an article about someone who made a reproduction of the
one tube radio in a canteen while in a Japanese POW camp.  Yet another
"Foxhole" type radio was also made in a POW camp, using bamboo etc. as a
rectifier for the camps AC power to get DC for the tube plate.

Bill Howard

William L. Howard Ordnance Technical Intelligence Museum
wlhoward@gte.net  Web Site www.wlhoward.com Phone: 727-585-7756