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free103point9 Newsroom has moved to of March 18, 2010 A blog for radio artists with transmission art news, open calls, microradio news, and discussion of issues about radio art, creative use of radio, and radio technologies. free103point9 announcements are also included here.

Saturday, July 04, 2009

How to build a radio in a POW camp

By Cory Doctorow in Boing Boing:
This first-hand account of the construction of a clandestine shortwave radio by British POWs in a Japanese camp in Singapore really reminds me of James Clavell's magnificent novel King Rat, my all-time favorite war-novel, which revolves grippingly around the construction, discovery and consequences of a hidden shortwave in the Changi camp (both Clavell and Ronald "St Trinian's" Searle were interned in this camp).

BJ: Can I just ask you - the components for the low voltage battery cells that you produced, where did you get all the components from?

RGW: Well, zinc wasn't hard, there was some sheet zinc lying on the aerodrome and we pinched quite a bit of that because that would be eaten away during the use of the cells for the low voltage. I don't know what would have happened if that ran out. I think someone produced two lantern cells which did for a while, but it was mainly on this home-made cell system, which wasn't efficient but nowhere near as inefficient as the rectifier was. We must have been consuming... Ah Ping said he had to turn up a lot of power to keep the lights what they wanted. We were dispersing such an amount of power in this four test tube rectifier for the high tension.

A variable capacitor was another component we had to bring in. We couldn't make a variable capacitor, it was impossible. We had to take two plates off the one we had to get a high enough frequency. Yes, I can't remember why we didn't go up a bit in inductance; it was largely a trial and error business really. Except that in a regenerative receiver you had some idea when you were near a station because the receiver was so sensitive as all regenerative receivers are.

It had a piece of meat skewer type wood which I had a hole drilled in by a pen-knife, and we glued this in with some of our glue or something, into the capacitor shaft so that we could tune it by holding a little stick across it, fixing it at about six inches because one couldn't get one's hands any closer to the set because it was in a state of very near oscillation where the maximum sensitivity is, just before it bursts into oscillation. With a fairly clear HF band, it wasn't long before we knew roughly, by putting a couple of marks on the stick, where it was. We knew that the Voice of America was due for a transmission and I don't think we ever knew the frequencies because the BBC didn't announce frequencies, they just came on the air and broadcast.

Construction of Radio Equipment in a Japanese POW Camp (via Make).

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