Hacking When It Counts: POW Canteen Radios

Of all the horrors visited upon a warrior, being captured by the enemy might count as the worst. With death in combat, the suffering is over, but with internment in a POW camp, untold agonies may await. Tales of torture, starvation, enslavement and indoctrination attend the history of every nation’s prison camps to some degree, even in the recent past with the supposedly civilizing influence of the Hague and Geneva Conventions.

But even the most humanely treated POWs universally suffer from one thing: lack of information. To not know how the war is progressing in your absence is a form of torture in itself, and POWs do whatever they can to get information. Starting in World War II, imprisoned soldiers and sailors familiar with the new field of electronics began using whatever materials they could scrounge and the abundance of time available to them to hack together solutions to the fundamental question, “How goes the war?” This is the story of the life-saving radios some POWs managed to hack together under seemingly impossible conditions.

No Atheists in a Foxhole

Many POW radios are extensions of foxhole radios, a common pastime of soldiers in WWII. A resourceful soldier living in the field could likely have scrounged or looted a complete radio, or at least could have rounded up the parts to make a decent regenerative receiver for news and entertainment in the field. But the local oscillator of even such a modest receiver could be detected by the enemy, so crystal radios were preferred. With nothing but a tuned circuit and rectifier cobbled from a safety-pin and a razor blade, crystal foxhole radios were undetectable and could be used to tune in commercial broadcasts and military transmissions.

A replica foxhole crystal set. Photo: Bill Jackson
A replica foxhole crystal set. Photo credit: J.G. Jackson

Foxhole radios would be easy to replicate in the POW camps, and to some degree might operate better than they would in the field. POWs often used the long runs of barbed wire in the camp fences as antennas, and the waste produced by the camp led to ample opportunity to scrounge parts.

With that in mind, many of the POW hackers looked for ways to improve their foxhole radios. The most obvious improvement was adding a capacitor to the coil to create a proper LC circuit, rather than depending on the stray capacitance of the antenna. Scoring a variable capacitor to tune the radio was an even bigger coup.

Life or Death Hacking

A step up from the foxhole-style crystal set was a simple regenerative receiver. The richer scrounging and greater likelihood of finding mains or battery power in the POW camp led to these receivers, grouped under the general heading of canteen radios from one common way of concealing them.

One especially well-documented build was that of an American amateur radio operator named Captain Russell Hutchison. He built a fairly complex single tube regenerative receiver into a standard GI canteen while interned by the Japanese in the Cabanutuan concentration camp in the Philippines.

Hutchison had the relative good fortune to be tapped as the fix-it guy for the camp; even the Japanese relied on him to repair their gear. Radios looted by Japanese soldiers made it to Hutchison for repair, and pilfered parts began to accumulate. Eventually Capt. Hutchison had enough parts to build his radio, which was sensitive enough to copy shortwave transmissions from as far away as San Francisco using a covert antenna of fine wire woven into a clothesline.

Hutchison’s radio was a matter of life and death in more than one way. The most pressing concern was being discovered with the set, which would result in summary execution. To avoid that fate, Hutchison took elaborate measures beyond the canteen subterfuge to ensure that as few men in the camp as possible knew about his hack.

Despite several near-misses, the radio was never discovered and Hutchison eventually made it out of the camp alive. But the radio served another life and death role. Far from being just an amusement to pass idle hours, the radio was used to monitor the progress of the expected invasion of Japan. The POWs realistically feared their captors would execute them and destroy the evidence of their atrocities as soon as Allied boots hit the Japanese Home Islands; the radio kept the POWs one step ahead so that they could try to escape before the bullets started flying.

Something from Nothing

As impressive as Hutchison’s hack was, at least he had manufactured components to work with. There were other POW hackers that weren’t so fortunate, but still needed the connection to the outside world that radio provided. With the same mortal stakes at play, these hackers built radios from almost nothing. Take the case of one Lt. Colonel R.G. Wells, a British officer interned in a Japanese concentration camp in Borneo. In 1942, he created almost every component of a superheterodyne receiver from found objects. Capacitors were made from the foil lining of a tea chest and the few precious scraps of newspaper that weren’t horded for alternate duty in the latrines. Resistors were pieces of string impregnated with burnt cinnamon bark. Bare wire was insulated by rubbing flour nicked from the mess into palm oil and caking it onto the wire. A chromic acid wet cell was concocted of potassium dichromate “donated” by the camp pharmacy and zinc trouser fly buttons. When that proved insufficient to power the radio, Wells built a chemical cell that both rectified the camp’s AC supply and dropped the voltage to a usable level.

The only components Wells couldn’t conjure out of thin air were the vacuum tube and the headset. Wells’ detailed oral history of the radio doesn’t say much about where the tube came from, but it does record that the headset was smuggled into the camp. Given enough time, the resourceful Col. Wells no doubt could have manufactured a headset; indeed, a Vietnam POW named Richard Lucas built the headset for his foxhole radio using a core of nails wrapped with wax-insulated wire in a bamboo resonator with a tin can lid for a diaphragm. He reported that it worked well enough to hear several stations, but that the headset would have worked better with a magnet to bias the coil.

As impressive as these hacks are, more amazing still is the fact that all of it was done from memory. These POWs came into camp with nothing but their dog tags and the clothes on their backs, and sometimes not even the latter. There were no reference books or cheat sheets. The circuits these men built under impossible conditions, often with only the rawest materials, were committed to memory, probably from days and nights of experiments in the pre-war years. Their hobby paid off in a big way and allowed them to hack their way through a more difficult time than any of us can likely imagine.

55 thoughts on “Hacking When It Counts: POW Canteen Radios

  1. In the sixties there was an article about this in “CQ”. One camp in Europe had a multi-tube radio, but thy hid it in some liquid like oil, which meant it had to be dried out every time they wanted to use it. The bigger the radio, the harder it was to hide.

    One POW camp in Europe apparently had a transmitter, but it was never used. They didn’t want to be caught but they wanted it in case at the end there’d be trouble and they then could call for help.

    There was a book out of the library about WWII POWs, and apparently officers had some level of preparation for evasion and escape. Perhaps that included something out crystal radios. But also, luxury goods were included in the Red Cross packages deliberately. Not just for the prisoners, but for the purpose of bribing guards. That probably got needed tube or part. And just as in the fiction of “The Great Escape” (yes, I know the movie is based on real events, but it’s different from the book), once a guard was bribed, it was that much easier to get stuff from them, the fear of being revealed the continuing leverage.


  2. I watched a documentary about POWs in germany where they had a transmitter and hid their antenna in the nazi flag pole! somehow the guards never saw nothing…..notthhhhing!

  3. Dan, take note that your flippant heading about foxholes is pretty offensive to some atheists. Substitute your own deeply-held convictions for the word “atheists” and see if it rubs you the wrong way.

    Otherwise, very cool article!

        1. Your reply makes no sense. So atheists refuse to serve in foxholes? Atheists think the military is useless so they avoid it to do “what needs to be done”? Atheists are people like any other. Some serve in the military. Some are brilliant. Others are idiots. Nothing special about them.

    1. Speak for yourself. I’m secure enough about my beliefs (or lack thereof, to be specific) to not be offended by something so petty, especially in the context of an article about events in the 1940s.

          1. Wikipedia – atheism is specifically the position that there are no deities. One inclusive, contemporary definition holds that atheism is the rejection of belief that any deities exist.

            But nobody is without “faith”. Even atheists have to believe that things are going along ok, the sun will come up, they probably won’t get mugged, their doctors know what they are doing, etc etc.

            Biggest problem with atheism – who do you yell to during great sex?

            As a kid I did make a foxhole radio using a razor blade and a pencil lead as the detector. Pretty cool.

          2. Axioms and postulates are beliefs without evidence or proof: if A, B and C allow you to conclude D, E, F and G, and if the latter 4 are observed, that is not a proof of A,B and C. Everyone has faith in things! Some people however try to find the most minimal set of faith (dogmatic axioms/postulates) that still explains what they or others observe.

          3. Ludwig, one does not accept axioms on faith, or even believe them, that’s not what it is about. They are only a point of departure for making logical constructions, and as such can be quite arbitrary. Furthermore one can create whole consistent logical systems out of one set of axioms, and another, just as valid, using a contrary set. Faith, in the way the term is used discussing religion, has nothing at all to do with these.

        1. Aleks, you seem to think that is witty or something, but you could hardly be more wrong. Atheism doesn’t mean one refuses to believe in a higher power. It means one doesn’t believe. In fact, the only people who say they would be unswayed by evidence are on the other end of the spectrum.

          You, and most people it appears, view things as a single dimension: atheist < agnostic < theist. But most atheists consider (a)gnosticism orthogonal to (a)theism. That isn't just some trickery; the meaning is apparent right in the word root. (A)gnosticism is a question of knowledge; (a)theism is a question of belief.

    2. Offensive to atheists? Are they THAT worried about their belief system? Only those ignorant of history would find the well-known saying to be offensive or flippant.

      1. It’s not a matter of being offended or fear of being converted, it’s a matter of oppression and subjugation. Many (religious people) truly believe this phrase and people, pastors, senators, even the military itself has used that line of thinking to force religion on people or at the very least punish them for not believing, as well as alter how the military spends money.

        When I was in basic training Atheists were given cleaning duties while others went to church, and it didn’t stop there. It wasn’t that long ago that you still HAD to choose a religion for your dog tags as well, non-denominational was as close as you could get. Pastors would also harass you as well because they were given freedom to preach to whomever they wanted, while most were nice, there was one I avoided any time he came around. And many of them are fighting for more freedom to preach and recruit within the ranks, there was a lawsuit over this just a few years ago.

        1. You must of been in a different branch of service that i was. I was in the USAF from 1980 to 1990, and never saw religion pushed anywhere. I wasn’t much of a churchgoer myself. However, I did go to Chapel at Lackland (boot camp) every week because 1) it was one of the few refuges from the TI’s, 2) it was also one of few places to mix with women, and 3) you could hit up the roach coach for snacks.

    3. [Nate B] is henceforth diagnosed with Terminal Coddling-Induced Cultural Hypersensitivity. Care-givers are warned that even the simplest of statements or actions may trigger him. The condition is incurable and highly contagious, especially amongst college students.

  4. I urge everyone interested in POW/MIA issues to read this information. It’s well researched and a factual account by the Pulitzer Prize winning author of “The Killing Fields”. No one in the “mainstream” media, and even Fox News, covered it. It’s a vast conspiracy to conceal the truth from the American public. It would literally be a scandal of epic proportions in which many political careers would end ignominously.


    “A case can be made that no living American journalist can write with greater credibility on Vietnam War matters. And he had labored for years researching and exhaustively documenting the story of American POWs abandoned in Indochina—a story that if true might easily represent the single greatest act of national dishonor ever committed by our political leaders.”

    1. My father, an American and Air Force vet of the Vietnam War, was a crusader in the 70s and 80s for the POW/MIA cause. Though the war was a IMHO gigantic superpower imperial money and power game played grinding the lives of Asians and Anglosphere draft soldiers, the way even these supposedly upper class officers were abandoned was surprising. Very Wag the Dog and makes me glad I was never a pawn or even a disposable knight or rook in that chess game. If anything he said that the POW rescue movement was mostly self interested mercenaries and prestige event fund raisers out to bilk the families, some my father was close to. I remember how surprised he was when Boris Yeltsen informed the world of several US POWs ready to come home within days of the dissolution of the Supreme Soviet and USSR, and then the disappointment of Yeltsen withdrawing this statement within 48 hours after speaking to then US President George H. W. Bush.
      These radios are great, though even then it required the critical mass of POWs only seen in a total war. The SE Asian bamboo pit or Hanoi Hilton was either so austere for both prisoner and guard or with strict and professional Soviet and Vietnamese oversight in Hanoi, as well as such low average per capita personal wealth that it seems that a hack like this or anything beyond a snatched bundle of herbs to supplement a diet was all the hack a person could make. With even speaking often prohibited though tap code was an easier than Morse code to learn comm hack. https://en.wikipedia.org/wiki/Tap_code

    2. Couldn’t read anything that is theamericanconserative. You are either American or unamerican. Your knowledge may vary. Get more it won’t hurt. Knowledge doesn’t have sides or labels. We are on a sphere. If dirt has sides, nothing will grow in it.
      As an American it felt good September 12,13,14… but it didn’t last a fortnight. Dam elephants, the parties have to leave!
      Animal Farm!
      Platinum, and a war. Thank God we are on to the next phase, not materiel but what really counts.

      1. Just FYI this is the journalist and author of The Killing Fields.
        It is telling that he couldn’t get published by a source on the left when it seems that most of the US MIA abandonment movement are Nixon era and forward neocons. I get that the US was tired of the war, but at least France manned up and paid to get it’s POW soldiers and airmen back. Just strange considering what a big deal the POW/MIA thing seems to be to Americans of that 70s and 80s time period.

    3. That’s a good way to keep people from reading your link: “It’s a vast conspiracy to conceal the truth from the American public.”

      Trot out the conspiracy talk, and people will think you’re just one more conspiracy theorist nutbag.

      1. No intent to denigrate the radios sets. I was a ham long before I got mixed up with metalworking. Did you read the article? The lathe was an extraordinary piece of work done in the same conditions as the radios. A lot more POW radio sets got made than did lathes. The lathe was a LOT harder to hide than a radio set.

        BTW this puts the recent concrete lathe to shame.

        The article link is a scan from one of Guy Lautard’s “Machinist’s Bedside Reader” volumes.

        1. They were all pretty inventive, all the gadgets they built with whatever little was at hand, or scrounged. The things that made their lives more pleasant, like radios, but the things for tunnelling and their methods to create counterfeit identification. Even cooking, making desserts (or maybe alcohol) with what was at hand.

          It meant that somewhere among them was the needed knowledge, unless they could scrounge that from books (I suspect there’d be limits on what technical books they could get their hands on). But probably they needed deeper knowledge, many can build a radio from off the shelf components, fewer know how to build those components (though I guess circa WWII more people knew how to build electronic components from scratch than later, it wasn’t that long from the early days of radio). But they also had to know enough to see value in the every day things they had access to. I suppose some of it was trial and error, but some things must have been done through knowledge. I thought I’d read that they did develop film, and if so, they had to know what chemicals were used, and what items they could extract them from.

          Of course, once invented, it became part of the culture. Someone figures out how to make a spoon, and then others follow, making their own. I haven’t read of entrepreneurship at the POW camps, though it did happen in the Soviet gulag.


  5. Was this story by any chance inspired by Hack a Day’s visit to the InfoAge Science Center last weekend? They had an exhibit on exactly this, just around the corner from VCF11.

    1. Nope, just something I found by accident many moons ago while researching another article. I’d have loved to stop by VCF and environs, but alas, personal business kept me away.

      1. Sorry you missed it, I went for VCF, but I found so many other gems in that complex! Thanks for a great post, I really appreciate the widening variety of content like this that we’re seeing here as of late.

  6. From what I’ve read about foxhole radios, the guys who built them were radio hobbyists as kids. Radio was the new, bleeding edge high tech that kids could readily get into.
    It’s almost like modern hackers using arduinos for everything.

    1. Most likely some could, if doing so served an important purpose. I always wonder how man has made it this far seeing how many seem to believe the present can’t match the past. What they would do and how they would go about it it will be different due to the match of technology.

  7. Dan, I think it was within “Beacons in the Night: With the OSS and Tito’s Partisans in Wartime Yugoslavia” by Franklin Lindsay, that I read about the OSS putting things like radio tubes and i.f. coils in the middle of various innocuous goods sent to prisoners of war in Red Cross packages. There was a charming story about some elderly gentleman who made contact about a quarter century ago, that still had a chest signed out to him, that he had taken home. It was full of “secret” things that he was unsure who to remit to, and he was anxious about it decades after the war. The museum of such things has a baseball “loaded”–wound around a radio coil. Tubes, no doubt, could be done in a similar fashion (in the days before ubiquitous x ray machines).

    1. Yes, the book I read (about POWs in WWII) said the Red Cross packages were used in this way. They’d put things that were useful in the packages, be it chocolate to bribe the guards or something that could be used in some other fashion, but also things hidden in the packaging.

      But I can’t remember details, there was a risk and I can’t remember how much the Red Cross was involved. The POWs would often “give their parole” in relation to some things, for the sake of distraction or whatever. So if they needed tools to build sets for a play, they’d promise not to use the tools for other things. So those tools weren’t available for general use. Smuggling in the packages would seem to be a reason for the Germans to stop those packages, but I can’t remember what the book said about this.


      1. I believe you’re thinking of Lloyd Shoemaker book, “The Escape Factory.” It’s his story of his time with the MIS-X, a WWII War Department agency devoted to helping POW’s to escape and evade their captors, and support prisoners in the camps. Some of the items shipped to prisoners included cameras, maps and compasses, a pistol(!)… and a radio hidden in a softball. The book has an x-ray of this ball.

  8. Take a serious look at this one: http://www.radio-caterina.org/ . Needs to be mentioned as an hackaday story itself.
    The site is only partly translated but Google Translate should fit for each page that is still in Italian.
    Site contains full hacks, photos, a documentary, an original diary and the book written many years after these events.
    This is the story of the radios (8) developed inside the lager camps between 1943 and 1945. Caterina was the name of the most famous one, Mimma was probably the best one even if it was a little bit huge. Antenna’s hacks are the best one but hopefully there’re more to read on.
    Some times ago I have spent a full day with REAL GEEKS (aged from 70 onwards…) in a local country fair, they were part of a local HAM radio club, definitely one of my best days. One of these guys was a friend of Mr.Olivero who built it and was “a part” (outstanding) of the antenna when the device was working. Another one was a friend of Elettra (Marconi) and told me about the family, what the father did and early hacks to get something working (microphones, amps, …). I enjoied the part of their museum they carried with them and I remained there for the full day to listen to their tales like a little kid in front of their grand parents. They teased/pranked me for a while (as a joke) because I’m an IT guy and for them information technology is cool but it’s nothing compared with ham,electronics,physics.
    I sat down on a small chair between them and enjoied their time just like a small kid with his grandpa.

  9. The headset bias magnet could have been made by nicking a lug nut, orienting it on magnetic north, and whacking it a bunch of times with a heavy object. It doesn’t make a particularly strong magnet, but if you can do it without attracting too much attention, you might be able to make one strong enough to bias a coil.

  10. Great article.
    Takes me back to the time of the radio shack kits with the spring binding posts. Even came with a crystal earphone and allowed broadcast reception in the AM band no batteries!
    These simple kits are still available at well stocked electronics stores. Great for the science class project at this time of year.
    Almost sounds like a Hackaday dare….. scrounge one…… no purchased parts.

  11. Well, the article already covered WWII/Nazis and the comments have devolved to religious banter sooo…Godwin’s Law confirmed.

    Really interesting article though, spy/POW/heist hacks are always really interesting for me.

    My favorite would have to be Tony Stark’s POW hack of the Iron Man prototype in the first movie. ;)

  12. Great thread guys! If you are interested in the world of MIS-X escape gadgetry, you may want to take a look at my new 350 page book on “Evasion and Escape devices produced by MI9, MIS-X and SOE in WWII”. It covers the history of the organisations, need and development of the gadgets and includes over 700 images – including an entire chapter on codes and radios. I was lucky enough to find quite a few surviving clandestine radios to be able to photograph, including a British one concealed within a gramophone and left in full view every day…



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