From: military-radio-guy Full-Name: Dennis R Starks To: military radio collectors#2 Fcc: Sent Date: Fri, 5 Dec 1997 06:32:07 Subject: Military Collector Group Post, Dec.5/97 Message-ID: <19971205.063050.2831.5.military-radio-guy@juno.com> X-Status: Forwarded X-Mailer: Juno 1.38 Military Collector Group Post, Dec.5/97 Index: OLGA; NORWEGIAN RESISTANCE RADIO SET By: LTC William L. Howard MAGIC EYE TUBES; by John Mackesy HUMOR; **************************************************** OLGA; NORWEGIAN RESISTANCE RADIO SET By: LTC William L. Howard In September 1939, the Germans invaded Poland and WW II began. Within days, Britain and France declared war on Germany. British troops moved onto the continent of Europe and took up positions with the French. Along with all the other preparations for war, Prime Minister Winston Churchill created the Special Operations Executive, The SOE, charged with the mission of ?Setting Europe Ablaze? The Secret Intelligence Service or SIS still had the mission to gather intelligence. Agents operating behind the lines would provide the necessary information and co - ordinate activities of resistance movements. The war began as a face off between armies, the French in the Maginot Line, the British on the northern flank facing the Germans in their positions. Referred to as the ?Phoney War? or ?Sitzkreig?, very little happened. In preparation for a May 1940 invasion of the territory of France and the low countries of Belgium, Luxembourg and Holland, the Germans moved to secure Norway and Denmark. On 9 April 1940, the Germans moved into Norway and occupied the country. Thus the Norwegian Resistance was born. In May 1940, the Germans invaded France and in a matter of weeks, over ran the British and French Forces. The British evacuated their forces from Dunkirk and began planning for the eventual return to the continent. Most of the overrun countries established governments in exile in London. At the beginning of 1941 various resistance groups in Norway were brought into an organization named MILORG, Military Organization. This was created to support a possible allied invasion from the west to liberate Norway and to establish law and order in the event of a German collapse, They also conducted sabatouge operations, most notably against the Heavy Water Plant at Rujukan which delayed the development of the NAZI atomic bomb. MILORG was under the command of the Norwegian Military in London and was joined to the SOE. It is reported that MILORG had approximatly 40,000 men under arms. However, before the British could begin supplying arms and equipment, it was necessary to establish radio communication between England and MILOG. The major burden of communication was placed on the British Type 3 Mark II, also referred to as the ?B 2? set. (See ELECTRIC RADIO 1995) These sets provided the main comminication link to the base station in England. Usually these B 2 sets were found in each district. Most war movies of the Norwegian resistance show this set in operation. Each district, however had to maintain communication with the out lying areas. Procurement of radios for this purpose was a top priority for MILORG. The man who supplied MILORG with these radios was Salve Staubo, founder of Hovding Radiofabrikk in Oslo. The production of these sets has been covered in the article ?The Story of ?OLGA? Illegal Norwegian Transmitter-Receiver? in Radio Bygones, Oct/Nov 1991. Less well known and discussed are the ?Home brewed? sets made by the Norwegians from components air dropped from England. These sets were designed so the resistance could monitor BBC and listen for coded messages. They were a very crude but effective means of listening to radio broadcasts. They were also, I suppose, considered more expendable than the OLGA or the B 2 sets. If one of these were captured by the Germans, another could quickly be made. I was fortunate to be loaned one of these sets by LTC Kevin Cunningham, currently stationed in the Penatagon. He had been given the set by the son of his former landlord in Norway. It was a rememberance of him as he was killed in an unfortunate accident. His name was Per Anton Thorvik and while he was not a member of the Norwegian Underground during the war, he had many friends who were and had used this type set. Col Cunningham packed up the set and sent it to me. On first look, it looks like any other home brewed radio of the 1920?s. The most distinguishing feature was the excellent cabinet it came in. Although ?Home Made? the wooden cabinet was an excellent piece of workmanship, a tribute to the Norwegian furniture makers, no doubt, who made it. The radio is made from components that were supplied by the British. While most of the components were taken from 1920s and 1930?s stocks, the tube panel was apparently custom made. Interestingly enough, all the components were made so that they could be assembled with out resorting to a soldering iron! It took me a while to figure out what the circuit was but it turned out to be a three stage regenerative receiver. The first stage was an RF amplifier of sorts, the second stage was a regenerative grid leak detector and the last stage was an audio amplifier. The tube line up was a Phillips B 443 as an audio amplifier, a Phillips B 409 as the detector and an unknown tube as the RF amplifier. Unknown as the glass broke on the trip to Florida. My guess was that is was a transmitting tube since the plate was connected to the cap on top, which is normally the grid in a receiving tube.. All tubes were the four pin continental base which made replacement very difficult. The tubes did not have sockets as we think of sockets. A bakelite board had been drilled at the factory and the pin sockets and terminal screws were installed. The connections underneath were then wired to the screw binding posts. All the user then had to do was screw the panel to a wood base and start wiring. Weather this was standard practice in Britain during the 1930s is not known. I have never seen anything like it in the U.S. This led me to the conclusion that it was made for resistance groups. The other components in the set were two variable capacitors, two rotary switches, two fixed capacitors, a resistor in a glass fuze type holder, a jack, which I initially thought was for the headphones and two more sockets for something called a Hoitaler, (which I later found out meant Loudspeaker), two antenna coils which were identified as Rheinartz type coils, and a smaller coil that had a hinge so it could be moved back and forth in relation to the one antenna coil. The final manufactured item was a wire wound rheostat for controlling the filament. The first thought I had was it would have been simpler to use two tubes, why use three? You really didn?t need an RF amplifier. Then I realized that they were concerned about German radio direction finders picking up the signal generated by the tickler coil and re radiated out the antenna. This was solved by adding an RF amplification stage. Adding an RF amplication stage also solved some other problems. As was pointed out in the 1933 Radio Amateurs Handbook, a regenerative detector followed by one or two stages of amplification and used for CW and telephonie work would bring in amateur signals from all over the world.. At times a radio frequency amplifier ahead of the detector is very desirable. The increase in sensitivity (and perhaps selectivity) can be put to use in receiving signals from great distances. A further advantage of such an amplifier is that it isolates the detector from the antenna, reducing the radiation for the oscillating condition and making it impossible for the antenna, swaying in the wind, to cause the received signal to waver. Considering the weather conditions in the mountains of Norway, this must have been a necessary consideration. The components all had either screw terminals or came with the leads attached at the factory. It probably came in ?kit? form with all the components needed except the cabinet. This would allow the builder to use any form of concealment that was handy and would keep the radio out of sight of the Germans. This particular set was in a cabinet and looked like a radio. I had the basic circuit figured out very quickly but in tracing it, there were several items which were very strange to me. One set of sockets was marked Hoitaler and there was a small jack socket, which I assumed was for the headphones as it seemed to be in the B + circiuit. What I assumed was the socket for a headphone plug, however , turned out to be something else. It was a jack socket but was too small for any plug I had ever seen. I then took the tube mounting board off the base and examined the wires underneath. I quickly discovered this was in the filament circuit! All filaments under the board were wired in parallel except the RF stage which was partly in parallel and partly wired to another power supply. I located a pair of German headphones and they fit in the socket marked Hoitaler. I then figured out that this jack socket was the filament on/off switch. It must have been a metal pin, which when inserted into the socket effectivly shorted the socket and thus completed the circuit. I suppose that a simple pull ring was attached to it which would allow a quick disconnect in case a German Radio Direction finder was spotted and it also served as a key which would keep un authorized users, to include small children, from turning the set on, which would have been possible with a simple on/off switch. I had been so used to looking at WW II Japanese sets and other sets of the period that I was used to seeing red wires for the high voltage circuits. In this case, however, the red wires were for the filament batteries and the green wires were for the plate or anode voltages. Once I realized what these wires were, following the circuit became much easier. The set was designed to make use of two filament batteries. One battery was used to power the RF amplifier and voltage was controlled by a wire wound rheostat. The tube was wired on one side of the filament to the other tubes but was isolated from them by the rheostat and a connection to a separate filament supply. The other two tubes were wired in parallel and the connection to the other filament battery was controlled by the on/off switch. As the RF amplifier tube was broken, I had no way to tell what tube was used and the thought occured that it may have been a transmitting tube which had a different filament voltage. Having asked one expert about this possibility the comment was made, ?amplification is amplification? so the consensus was it could have been a transmitting tube. Since the entire set was assembled from 1920 vintage parts, it is possible that the British designers simply cleared out a ware house and designed a set using what was on hand which included the transmitting tubes of the 1920s. The second stage was the detector stage. This was a regenerative detector. There was, however, no regeneration control. The regeneration was controlled by swinging the tickler coil in an arc to and from the antenna coil. The final stage was an audio amplification which was connected to the detector stage through an interstage transformer. It looked exaclty like the circuit in the 1940 ?Shortwave Beginners Handbook.? That circuit used a C-battery but in this set one of the filament batteries was used to provide the negative connection for the transformer secondary. In an effort to get the set operational, I had to make a power plug. Using a block of wood, cut to shape and with holes drilled in it so the power plug would fit, I used ball point pen springs to form the contacts and then soldered wires to the springs. And it worked!! The power plug had connections for the two filament supplies, the ground and antenna connections. The next project was to make two power supplies that would look some what authentic. Two small wooden crates were found and 9 volt transistor batteries were wired in series to produce 27 and 90 volts to start. The second crate was filled with Radio Shack single D cell holders and connections were made at each end, one for the filament and one for the detector/amplifier tubes. This would provide 1 1/2 volts for US tubes and could be re-wired to provide 3 1/2 volts for the European 4 volt tubes at a later stage. The next part was to make up a tube socket panel for US four pin tubes such as the Type 30 or VT 97?s that were still in use in the 1930?s and are easier to find than the British tubes.. I was also considering the possible construction of a reproduction of the set, until I found out the approximate cost a similar cabinet made in a wood shop at todays prices!! The current cost was $180.00 I opted out for a front panel and base!! Once the tube panel was constructed, I proceeded to wire it into the original set using clip leads. I made up an indoor antenna using a 50 foot copper wire and plastic insulators. With an ungodly number of jumper wires I finally managed to get the detector stage working. Sound, sort of in the headphones! I tried to see what sort of a station could be picked up before attempting to get the audio amplifier stage working. There was nothing! I was not that surprised as there are only two local stations powerful enough to be picked up in this area. And they shut down at sunset! I was going to try again in the morning when I received a phone call from a former resident of the area who was an expert on 1920 vintage sets. I had sent him some photographs and a pictorial and schematic that I had drawn. His first comment was that the coils looked like long wave coils, common in Europe but almost useless in the U.S. There was supposed to be one station in this area, the Egmont Key station which is an avaition beacon, on I believe 377KC. It was part of the instrument landing system for Tampa Innternational Airport and another one out in the middle of Tampa Bay coded Picnic which is used as the outer marker on the ILS system for runway 36L. He also said that with a really good out side antenna, I might be able to pick up modern submarine teletype signals. I had a local HAM operator who had a long wave capable receiver monitor the airwaves during a 24 hour period and he said the band was dead. I gave up further efforts to get the set operational. To get the set to a condition where it would work and pick up broadcast signals would require a set of new coils or rewinding the old coils.. This would would then take the set from it?s original condition as a set built by the Norwegian resistance and convert it to just another 3 stage radio of the 1920?s, which can still be found in some quantity. I decided against any further restoration since it was not my set to begin with and that would lower the value of the set. In discussing the set with Craig Smith he commented that ?One way comm. (out to the resistance) would likely have been on broadcast freq.(whatever that was). Long wave 200-500KC used huge high powered trans and was prone to static in the summer, but had great range and relative resistance to fading.--MW our broadcast band 550-1600KC was a compromise between power and range requirements and was as high a freq. as could easily be reached w/ trans of the early 20's.--SW anything from 1.6mc-30mc or so , and anything above that was VHF. ? Since there is a great distance between London/Great Britain and the far reaches of Norway, it made sense that this would have been the ideal system for one way communication with the resistance.For two way communication, the short wave sets would have been used. Craig also pointed out that ?I really don't know for a fact what Freq the Brits used to communicate with the resistance movements. I would guess shortwave because of the greater range for low powered sets.? The OLGA sets covered 3.5 Mc/s to 16 Mc/s and the British B 2 suitcase covered 3 to 16 Mc/s This set, while not as esoteric as the British B 2 set and the Norwegian OLGA sets, still deserves a place in the history of the Norwegian resistance during WW II. It is hoped that anyone reading this article with more knowledge of the subject will contact the author by phone or by e-mail at: wlhoward@gte.net. THE WILLIAM L. HOWARD ORDNANCE TECHNICAL INTELLIGENCE MUSEUM e-mail wlhoward@gte.net Telephone AC 813 585-7756 **************************************************** MAGIC EYE TUBES; THE EM84/6FG6 INDICATOR TUBE by JOHN MACKESY VK3XAO Most of us will have at least a nodding acquaintance with the `Magic Eye' tube - a device properly termed an `electron ray tube'. `Magic Eyes', most commonly the sharp-cutoff 2E5, 6E5 and their remote-cutoff counterpart, the 6U5/6G5, were widely used from the mid-'30s to the '50s. Apart from their tuning indicator applications, they were also used in test and measurement equipment, e.g. L-C-R bridges, and as level indicators in tape recorders. Indicator tubes were rarely used in military equipment, two notable exceptions being the SCR274N/ARC-5 Command transmitters and the RAF R1155. The 6-pin base 2E5, 6E5, 6U5/6G5 and their octal-based relatives the 1629 (12V fil.), Y63 and EM34 (just to confuse things, 6U5/6G5s also exist in octal base!) all shared the same architecture. This consisted of a triode amplifier section and an internal fluorescent `target' viewed through the end of the tube. The target phosphor glows green when excited, the fan-shaped display occupying a 100 degree sector of the circular target. The control electrode (which is mounted between the cathode and target) is connected to the triode section, from which it receives its potential. When the control electrode is less positive than the target, it repels electrons from that sector to produce a shadow on the target behind it. The size of the shadow increases as the potential difference between the target and the control electrode increases. At zero grid voltage, the `fan' is open; as the grid becomes more negative (AVC voltage increasing) it closes. On a 6E5 this occurs at about -8V, on a 6U5 at about -22V. Although useful and deservedly popular for tuning indication, this type of display has somewhat limited resolution. Then again, from a purely stylistic point of view, the large permanently glowing area of the tube adds a certain aura to an otherwise undistinguished radio dial. Enter the EM84/6FG6. Although conceptually similar to the *E5, 6U5 etc, structurally it's radically different. 1. The luminous target phosphor is deposited on the inside of the envelope (like a CRT). 2. The display is viewed through the side of the tube, not the end. 3. A standard Noval envelope is used. The EM84/6FG6 display pattern is very different to the more traditional types, and is probably best described as looking like a pair of greenish curtains which open and close in response to the grid voltage. The target phosphor is deposited on the side of the envelope, and is 39 mm long by 10 mm wide. At zero grid volts the shadow is approx. 21 mm long, the `curtains' closing completely at about -22V. Weak signal sensitivity of the indicator is enhanced by a variable-mu characteristic; the shadow length will change about 6 mm between 0 to -2 grid volts. Although we tend to think of indicator tubes in the radio context (some of us, anyway) the EM84/6FG6 saw wide use in the burgeoning home tape-recorder market of the '50s. In this application, the high resolution display made it a useful level indicator. Whither the EM84/6FG6 today? Although a useful and attractive device, its late-'50s origins put it at the end of the vacuum-tube radio era. Consequently, it was not as widely used as the *E5/U5 tubes, and can be rather hard to find. A good source is derelict '50s tape recorders - these are often available very cheaply at swap-meets and garage sales. Using the EM84/6FG6 The EM84/6FG6 may be operated in any position. To me, the display seems more "logical" when viewed horizontally, but this is a very personal choice, and is based on application as a tuning indicator. When used in pairs as stereo power indicators, vertical mounting seems to have a certain following. Power consumption is very low, typical of this class of tubes, which means it can usually be added on to existing equipment without any problems. Base connections: Pin #1 triode grid Pin #2 internal connection Pin #3 cathode Pin #4 filament Pin #5 filament Pin #6 fluorescent target Pin #7 ray-control electrode Pin #8 internal connection Pin #9 triode plate According to the "Brimar Radio Valve and Teletube Manual (No. 7) "In normal use, the Ray-control Electrode (pin 7) is connected to the triode plate (pin 9)" The following data was taken from RCA Receiving Tube Manual, Technical Series RC-22, published 7-63 by Radio Corporation of America, Electronics Components And Devices, Harrison, N.J.) EM84/6FG6 DATA Ray-Control Electrode Voltage: Without current flowing through series triode-plate resistor: 550V max With current flowing through series triode-plate resistor: 300V max Fluorescent-Target Voltage: Without current flowing through series triode-plate resistor: 550V max With current flowing through series triode-plate resistor: 300V max/150V min Cathode current:: 3 mA max Triode-Plate Dissipation: 0.5 W max Filament: 6.3V at .27A Typical Operating Conditions Triode Plate Supply Volts: 250 Triode Plate Resistance: 1 Meg Series Triode Plate Resistor: 470K Triode Grid Supply volts: -22 Triode Grid Resistor: 3 Meg Triode Plate mA at 0 Grid Volts: .45 mA Triode Plate mA at -22 Grid Volts: .06 mA Fluorescent Target volts : 250 Fluorescent Target Current at 0 Grid Volts: 1.1 mA Fluorescent Target Current at -22 Grid Volts: 1.6 mA Other indicator tubes (by special request): One type of indicator tube made the transition into the digital age - the "Nixie Tube". (Nixie is a trademark of the Burroughs Corp.) These enjoyed a brief vogue in the late '60s/early '70s, being widely used on test equipment, up-market receivers and (wait for it!) - cash registers. The Nixie tube is a device which gives an image of the numbers 0-9 (usually). It's basically a common anode tube, with 9 cathodes, each in the shape of the numbers 0-9. A voltage of about +160 is applied to the anode. The tube contains a small amount of neon; when a cathode is connected (via suitable switching circuitry) to ground, an orange glow forms around it. The display may be viewed through the end or the side of the tube, depending on the type. A filter is often fitted to adjust the display colour. On a personal note, I'd always wanted to own a piece of gear using Nixies. When I was offered an HP 312A Wave Analyzer (really a very good 0-18 Mhz receiver, AM, CW, USB & LSB modes) which has 7 Nixies to give a frequency resolution down to 10 Hz, I jumped at it. It works beautifully, and the display is a great conversation starter. Although Nixies have a long life, it's becoming very difficult to find replacements. If anyone out there knows of a source of Burroughs B5991 tubes, I'd really like to hear from you. The (later) 312B uses a standard 7-segment LED display. Note: "Suitable switching circuitry" can be discrete devices or the TTL 7441 References: RCA Receiving Tube Manual RC-22 (1963). Mullard Valve Tube and Semiconductor Guide (undated). BRIMAR Radio Valve & Teletube Manual No.7 (undated). `70 Years of Radio Tubes and Valves', John W. Stokes, 1982. (This is an exceptionally good read, and deserves an honored place on every tube enthusiasts bookshelf). ------------------------------------------------------------------------------------------- Ed) John, when you told me of your "Magic Eye" tube article, I had thought you might forget those sideways mounted rectangular ones. But I see you've not left anything out, I'm impressed. My youth was spent as a radio & TV tech(early 70's, 14 years old), & I just loved these things. Even though I'm profusely color blind & can only see them in a dimly lit room. Their demise did not really come until the late 60's/early 70's for TV's, & higher power quality stereos this because those units still had horizontal output tubes(for the TV's), or high/mid power audio output tubes(for stereos), and some public address, & gitear type amps utilized them even longer. I think it safe to say that the only real thing that killed them was the lack of an existing power source in the equipment in question, I/E like you say, no more tubes/no more Magic Eye's. I still have some excellent test equipment using them, & they are never shut off. One last comment, in over 25 years of service work, I don't think I've ever seen a bad one. Dennis ************************************************************ HUMOR; Quasimodo After Quasimodo's death, the bishop of the cathedral of Notre Dame sent word through the streets of Paris that a new bell ringer was needed. The bishop decided that he would conduct the interviews personally and went up into the belfry to begin the screening process. After observing several applicants demonstrate their skills, he decided to call it a day when a lone, armless man approached him and announced that he was there to apply for the bell ringers job. The bishop was incredulous. "You have no arms!" "No matter," said the man, "observe!" He then began striking the bells with his face, producing a beautiful melody on the carillon. The bishop listened in astonishment, convinced that he had finally found a suitable replacement for Quasimodo. Suddenly, rushing forward to strike a bell, the armless man tripped, and plunged headlong out of the belfry window to his death in the street below. The stunned bishop rushed to his side. When he reached the street, a crowd had gathered around the fallen figure, drawn by the beautiful music they had heard only moments before. As they silently parted to let the bishop through, one of them asked, "Bishop, who was this man?" "I don't know his name," the bishop sadly replied, "but his face rings a bell." {You want more, you say?} The following day, despite the sadness that weighed heavily on his heart due to the unfortunate death of the armless campanologist (now there's a trivia question for you), the bishop continued his interviews for the bell ringer of Notre Dame. The first man to approach him said, "Your excellency, I am the brother of the poor, armless wretch that fell to his death from this very belfry yesterday. I pray that you honor his life by allowing me to replace him in this duty." The bishop agreed to give the man an audition, and as the armless man's brother stooped to pick up a mallet to strike the first bell, he groaned, clutched at his chest and died on the spot. Two monks, hearing the bishop's cries of grief at this second tragedy, rushed up the stairs to his side. "What has happened?" the first breathlessly asked, "Who is this man?" "I don't know his name," sighed the distraught bishop,"but he's a dead ringer for his brother." ------------------------------------------------------------------------------------------ When finished reading use browser back button or go to http://www.prc68.com/MCGP/MCGP.html