Construction of Radio Equipment
In a Japanese PoW Camp
This is a transcript of a 1995 recording made by Lieutenant Colonel R G Wells, on the construction of radio equipment in a Japanese Prisoner of War camp.
Outside News Wanted
It was about the beginning of 1942 when I was a prisoner of war of the Japanese, when I was ordered to go on a working party which eventually finished up in Sandakan in British North Borneo. 2,000 odd of us were on this work party and it wasn't long before we noticed the absence of information as to the international situation, what was happening in the outside world, and the whole camp had a real craving to get news by whatever means. Escape parties were being organised, but none of these was very successful. The next thing people turned to was a means of getting some radio news, and this is where the building of a radio set became an urgent requirement.
The main thing, of course, was that we didn't have any components and although we had some contacts outside which later on were helpful in the building of this receiver, it limited our requirement to a regenerative receiver as distinct from a superheterodyne receiver and the decision to do that was borne out by the results. The high frequency spectrum during that time of the war was fairly quiet in that part of the world and the BBC, we hoped, would be able to be received. This was aided by the fact that the Japanese in their wisdom called a friend of mine out one evening to repair their radio set and he took the opportunity, of course, to switch over to the short wave bands, with headphones while doing that, and picked up the BBC successfully. That day was memorable because it was the day that the BBC broadcast the death of the Duke of Kent in an aircraft crash. That was the only news we had of the outside world for something like six months.
Creating the Capacitor
The problem building the set, of course, was the need to build components, so until we could build some components there was nothing much we could do. A look at the circuit diagram of a regenerative receiver indicates a number of capacitors - about two or three are required - low capacitors to make the oscillating part of the system work, and in fact from memory we needed in the grid circuit at least one .01 microfarad capacitor and there was no chance we could get this anywhere, or any other components. So we hit upon the idea of taking some tin foil or aluminium foil from the tea chest which the Japanese supplied with the rice rations, then by the well known equations for calculating capacity and the relationship of the distance between the plates and the area of the plates we built a capacitor or, at least, I built a capacitor which according to calculations should have been about .01 microfarad. If I could put an aside here, I built a replica of this capacitor some years ago, and it went out to Simpson barracks where we had some friends in the testing laboratory, and with great excitement the Warrant Officer concerned said "We will see how good your calculations were"; so he put it on his equipment which was accurate to many decimal points and read on his display unit .009 microfarad, so we thought we were pretty good. I said "Touché" to him because he didn't think we could do it. I made two or three of these, and I still have one of them that would work if I built the receiver again, which I have been thinking about doing but there's always something else, like a lot of other projects which one has as one gets older.
We had to insulate the layers of [the capacitators] which we did by putting a layer of newspaper (a few people had newspaper and various things, for other reasons than newspaper of course, but then we had no other toilet requisites in the party) and by soaking this in some coconut oil we could insulate each layer after we wound it, and with a piece of this bee wire - we had something like fifty feet of it - wound round this part of the fish plate, we made a fairly good choke coil. And then a bigger capacitor, which was no trouble, having had success with the small one, to just wrap as much tin foil as we could round another sheet of newspaper which finished up about 18 inches long by about three quarters of an inch in diameter. We didn't even try to measure the capacitance of it, because we couldn't do anything about it anyway, except put more wire on. And that in effect was a fairly good rectifier, a very dangerous one because we had the 110 all right but we had a bit over that by the time we had rectified it, and we don't know because we had no means of measuring it.
What did you have in the way of tools, if any, and how did you connect the components of the wireless without, presumably, a soldering iron?
No soldering iron, no solder of course, and no other system really available but to twist and wrap with some coconut oil paper, or cardboard or something, and very gently lift it. It was on a platen of wood we obtained somewhere; it was about a foot by a foot or something, so we just mounted the components on that. A meat skewer on the capacitor - oh, we had a capacitor too, a capacitor, a valve and a headphone, which were external to camp components we had. We didn't have any tools at all, except someone obtained the use of a sledge hammer - for what purpose I don't know because one of those would not be needed to escape; other than cutting up the soft iron of the fish plate which was about the only reason we needed anything, the rest were just twisted wires. We just wanted to get one usable because we didn't know whether it might be blown up or captured; we weren't worried, the main thing was initially a short term aim (as well as a long term aim) that it might last. Fortunately, it lasted for over a year - sixteen months until the arrests took place, but that's another story.
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 penknife, and we glued this in with some flour 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 about a quarter of an inch away from the BBC - I don't think we ever knew the frequencies because the BBC didn't announce frequencies, they just came on the air and broadcast.
A Cinnamon Resistor
The resistors were another problem. We found out that we could use the impurities in some of the tree wood and the bark, particularly cinnamon bark which was available by getting through the wire only about 2 feet, and we could normally pinch that while the Japanese sentry was moving around. We used a piece of string with the material rubbed on it from the burning of the cinnamon bark which had some impurities in it (we didn't have a chemical analysis); we weren't very fussed because most grid-leak resistors were about a megohm or thereabouts and we had no means or any way we could measure a megohm, so it was largely a trial and error thing to see if it would work. We made a number of these bits of string and tied them round different things to dry them out to get the thing going. Eventually about an inch, three quarters of an inch to an inch, was about the right order of things to get about a megohm resistance. They were the two main things.
Headsets and Valves.
Now the things we couldn't provide, couldn't do. We had to make coils; they were largely trial and error, one could calculate the inductance of these if one had access to some means of measuring the wire gauge and the space between them. So that was largely a trial and error business.
The two biggest components, or two biggest requirements, were we needed some headphones and we needed a valve, and I thought that the rest could be made locally with a bit of luck. On the question of the headpiece an outside contact smuggled in one headphone, which was better than no headphone, and a valve - no valve holder but one can't have everything in this life.
Again, the valves you used in the receiver were...?
Only one, that's all we had, which was brought in by Mr Mabey*. He smuggled in a pipe to me, a smoking pipe, with some tobacco. Lovely gentleman. Unfortunately, I never had long with him, he died soon after being arrested. His widow lived at Hove with her sister; the two are deceased now.
Power to Run the Radio
The other trouble was the power supply. The Japanese main around the camp which provided the power was 110 volts roughly according to the power station meter which we couldn't help but see, because we delivered the wood there while the power station was running; I switched over when no one was looking and the frequency was about 60 Hz, not 50 Hz as we thought, not that this worried us anyway but to know that it was manageable.
So two problems remained for the power supply. The first one was the A-battery or low voltage supply necessary for the filament of the valve. We started with a couple of dry cells, but these didn't last very long and we had to make something then. Through being friendly with the pharmacist with the party, we got some potassium bichromate and made up a bichromate cell, which is probably well known in the text books but not of very practical use. It's fairly hungry for zinc and it needs some sulphuric acid which one can't throw around or hide easily, but it served for some time and was quite successful but, in the end, had the operation lasted very long, we would have been in trouble for that. Two of these cells provided about 3 volts to 4 volts, and 6 volts was a bit too much because each cell was running at a bit over 2 volts, about 2.2 volts.
The components for the low voltage battery cells that you produced, where did you get all the components from?
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.
Building a Power Supply
The biggest problem was a rectifier to rectify the AC into DC without dropping it to a low voltage, because remember in those days we needed high voltages for the B supply, or anode supply, but in these days we bring everything down to small DC voltages; we needed to get them up as high as we could. That was a partial failure in that using aluminium foil again and oxidising one piece of it, or length of it folded over, with some weak acid and then using the two electrodes, one of clear aluminium and one of a zinc salt and aluminium, we could make a rectifier. We wouldn't be so audacious as to call it a rectifier now, because it had a reverse voltage of something like 30 or 40 volts, which wasn't exactly ideal, but for DC we had no option. The result was that I made a bridge rectifier but the only problem was that after 15 minutes the electrolyte began to boil, so it was really passing current in both directions but a little bit more one way than the other. So a single cell, an extra rectifier cell, was the only way I could close this down a bit, and some smoothing. This we achieved with part of a fish plate from the railway line which was being used at the aerodrome to move the dirt from one place to another by manpower, about six men on these, and the odd fish plate used to disappear anyway for various reasons. I dropped one off at the power station and asked the Chinese under my breath if he could cut it into three little sections which he did, he didn't want to know why.
Then again using some palm oil and some bee wire which was in fairly plentiful supply, which we stole - it was a bit risky because the Japanese were cultivating a couple of beehives outside the wire and of course this wire used to disappear for various things unrelated to radio - and we put the palm oil along the wire stretched out and rubbed this palm oil on it, thickening it with a little bit of flour and then heating it; the flour bound the palm oil together and formed a fairly good insulation over the wire. Good, but lucky, and with a lot of travelling.
Receiving the Signal
Finally, the valve; we joined the valve by winding the clean little bee wire around it and then plugging it with any insulating material we could get to make it stick, - no valve holder, of course. So eventually we produced a receiver of sorts, except it wouldn't oscillate. We tried building more, another choke coil, and this went on for ages; there was no possibility we could get this valve to oscillate. I think it's recommended according to a friend of mine who had an amateur licence, he thought that about 120 volts was the best we could get and there was no way we could get that by trying to smooth this any more. So the only avenue open was to bribe one Chinese working at the power station who was very much our way, and of course in those days was a nationalist Chinese. The capital of China in those days was Chungking, and I told him we could get him some overseas news from Chungking if he would slowly wind his field coil power up on the generator every night starting at about 9 o'clock bit by bit, and get it up to about 130 on his meter. He understood, and after that I said half an hour to drop it again, very quietly and slowly because it may affect the lights "....and you no speak about that because you get chopped, you know, and we will give you Chungking news...." This was duly done and for about six months we had reliable communication. The first trial on air had too much hum, and we had to modify a few things two or three times in attempts to get it right, and in the end we had a workable situation which was worth exploring.
Capacitors right, choke coils right, one head phone, we had some old rag so we tied it round the head and tied it on, or string, or whatever we could get. With the hope of recording something we took some paper, which wasn't in plentiful supply, but the odd piece of paper we could get. Running notches down the left hand side, about a quarter to a half inch apart down the paper, and bending it over so that these little pieces stuck up in the air, and in the pitch darkness one could then put the headphones over one's head with eyes looking out for possible interruption by the Japanese - we had some lookouts, or cockatoos as the Australians called them, around the place to warn us at the oncoming of the Japanese - and with great trepidation we heard Big Ben chiming one night. Of course only one of us heard it but we were so full of enthusiasm. It was the BBC all right; it was quite a clear signal but it was somebody talking about growing hops in Kent. This broadcast went on for something like three quarters of an hour without any interruption, but ultimately the signal faded out and I was very annoyed. I was asked the next morning by my senior officer what was the news, and I said "we've got good news; I can't talk here, come this way." So he came along and said "what's this news you're talking about." I said I didn't actually hear any news, and he became very annoyed with me and said what the hell did I mean, and I said "if the British primary producing experts are capable and able to spare the time to talk about growing hops in Kent, Britain must still be alive and floating with their thumbs up, and as far as I'm concerned that's the best news I could hear!"
What did you use for an aerial?
A clothes line. All the huts had a clothes line of some sort so we just took a thin wire from that and wrapped it round the edge, knowing that a normal sentry wouldn't take any notice of it, and we just dragged that across the side of the hut and brought it in, and odd people with our permission would put their loin cloths out and hang them over this when they washed them so it looked as if it was being used. The toilet in the sleeping block was a hole in the ground and it was verboten to be used by anybody except to put our radio set in when it wasn't in use; everybody respected our wishes in that regard!
I think the best thrill was, well two or three thrills, which were momentous I suppose and of great excitement, almost excitement of crying with excitement, and the first was I think when we heard a full news bulletin of something like 400 aircraft over Dresden or somewhere, pounding the place to pieces; we were very pleased about all this. But from the land point of view, from the beginning of '42 I think, I can't remember, but sometime just before the Battle of Alamein, and we heard some of the troop movements in preparation for that. The bulletins in those days were fairly long and gave a lot of detail.
Unfortunately the first lot of rectifiers blew up about 2 days after this so we were out of business for something like 5 or 6 weeks. Of course, the rumours started to flood in as to what was happening, what wasn't happening, the war would be over in 5 minutes and all these mainly optimistic things; but there were a few super-pessimists who said we would never get off the island, and would die there, and that sort of thing. But the thrill, I think, was when reception was restored again and we had to do another little bit of fine tuning because everything you changed seemed to affect something else; the whole thing was very sensitive and wouldn't have stood up to present day quality assurance bump tests!
So back there on the first night we missed the BBC for some reason, and the next thing was the Voice of America which had a headline which ran something like this: "The war is over in North Africa, Rommel is knocked to pieces, he's out of the Middle East and the Middle East is finished, the future for this and that ............" That was the end of the American news in about three sentences! No other detail, so I said we would go back at about 12.30, and hope that Ah Ping hadn't pulled the voltage down too far, to see what we could hear. Again, the BBC was a little low but it suddenly came quite bright and lifted in volume, and Big Ben chimed again and there was a voice in the wilderness calling. It was a lovely sensation to hear Big Ben playing in those days, and every time I hear it now I become excited. The announcement, initially in a most depressing vein, described all about the 8th Army's movements, and it was here that it did this, and this regiment drew up and did that, on and on this went for something like 15 to 20 minutes, and we tried not to follow it because we had our eyes on too many other things, lookouts and so on. But a lovely flow of English and if you had a tracing board you could have traced out exactly where everything was in situ, but of course that wasn't the aim of our exercise which was to get news. At the finish of the news the polite sentence said "It must be considered now that as all resistance in North Africa has been overcome the Allies victory must be assured" or something like that. And that was all he said, but he took a few minutes to describe everything that happened, so you had a clear picture. But the Americans seemed to be creating for a public that just wanted the headlines, three headlines and that was all; no other interest in anything else. That was one of the happy moments of the system.
We had the problem, of course, of writing the news because naturally a lot of people wanted to know it and a lot of people could be told it without its origin. This is why we used the piece of paper we took with us (Gordon Waite and the other officer who used to share some of the work), and as soon as we heard about 30 bombers over Dresden or something, you just put 30 BD, or B for Berlin, and feel the paper down when you felt it coming to the end, and pick up the next little bit of bend and write along that in the pitch dark, hoping that you've got something in the morning. Surprising how legible it was, just triggered a couple of words like that. Unfortunately, I was in deep custodianship with the Kempitai when the Atom Bombs were dropped and I didn't hear that news on the BBC; it was relayed to me. We didn't keep these things, of course.
Getting off the technical side now, the radio set didn't betray itself. Some criticism could be levelled at us I suppose. We trusted too many people; we had no intelligence training then, of course, or anything like that and we were inclined to trust every Asian we met who smiled at us and who said he was one of us. Anyway, while this was going on at the aerodrome and once the troops heard, we had to tell the troops the good news of course. We said we had heard from an unknown source that the war is getting better, or something like that - we had to give them a sanitised version. It was probably all they wanted but, naturally, two or three senior officers wanted to know as much as they could because they may be the ones who would have to take some decisions one day about it.
You talked a lot about the construction of the receiver and I would be very interested to know where the transmitter fitted in to this; were you developing that alongside?"
"No, the receiver first; we had that, and then we started the transmitter as a rather low priority of course, but one it would be nice to have. I had finished the two 6L6G's to make a push-pull amplifier that was the RF output to be, and the oscillator, and we had the capacitor but were missing a few more components and that was about where we were. In other words, in the course of events, had he been an expert with some sort of knowledge of electrical engineering, we would never have got away with two 6L6's sitting up on a block of wood with a few capacitors and things hanging on them, but obviously the Court Martial officers were normal, without disrespect to Infantry Officers, and they had no knowledge of telecommunications.
The Kempitai and the Raid
Unknown to us an Indian - I don't like saying this and I'm not being racist, it could have been any nationality - blackmailed a Chinese who was helping us on the aerodrome picking up bits of iron for us and various other things. He blackmailed him but the Chinese wouldn't talk, so the Kempitai arrested the Chinese and put him on a rack; he mentioned in the course of his cries for help - which was not a nice thing to think about but I don't blame him - he mentioned Captain Matthews** and a couple of other people; I think I would have done the same thing at that stage.
The Japanese then decided to make a raid on the camp, which they did, and I was then charged and taken away by the Captain; he wanted the receiver and I gave it to him in the end after a lot of leading him round the camp with his soldiers. I could almost laugh at some of the things that happened. He must have told them he was looking for a radio set; a Jap soldier came running up to him with a piece of metal which looked like a piece of horse harness or something; the Captain almost kicked him and told him what to do. So in the end I decided that I couldn't talk to anybody before the rest of the troops on this parade ground, and I felt so conspicuous. He walked back and said "Are you going to tell me because we want the wireless set?", so I said "Yes, I've just thought where it might be". So I went across and told him where the hole was, and they dug the hole up and, of course, there was the transmitter. He said "Ah, you've been sensible at last", so he took the transmitter and they took it away.
From that day on, I was worried about this because I knew the receiver was OK and the troops would be happy about that; they would still be able to get news. And then he took me up to the platform where he stood and addressed everyone. All he said in English was "You all look at this man, you will never see him again" and led me off. I had a sort of a dying wish, going in on the vehicle to Sandakan to be interrogated, that somehow or other this set could be preserved and, of course unknown to me, it was. They continued using it but not until after about a week or so - their nerves were a bit shaken. But they used it for some months afterwards until the big moves came and it was a successful source of morale lifter.
During the trial, that was when the shock came to me when this transmitter was brought out by the prosecution as evidence that we had been using a receiver, but the Court accepted it. It was never mentioned after that because had it been, I don't think either of us would have been alive, because we had planned to get some crystals from the Philippines and try and fit them in this set then we could call them on CW and give them some news about ourselves. But we did get some news by other means, via an agent taking a sandalwood vessel across, that the British and Australian authorities knew where we were, and it was proved at the end of the war that they knew exactly where to come for us. They had guerilla parties in behind the lines, but they couldn't contact us and they had to watch some of our people just die virtually, because they were there and there would have been trouble otherwise.
* Believed to be Mr Mavor Mr Mavor worked for the Sandakan Power and Light Company and was arrested along with Captain Lionel Matthews GC MC, Dr James Patrick Taylor and others; Mr Mavor's wife was later interned in Batu Lintang.
** Captain Matthews was executed by the Japanese for his involvement in the radio 'plot'; Dr Taylor and Mr Mavor were sentenced to 15 years' imprisonment for their part. Sadly Mr Mavor died of beri-beri on 5 May 1945 at Outram Road jail in Singapore.
*** Ah Ping, was in charge of the powerhouse engine-room at Sandakan.