Some Rare German Radios

Agent Radio

Agent Radio The Germans had a xmtr/rcvr , "Der Sender-empfanger",designated as the SE100/11. It was smaller and lighter in weight than the SSTR-1 or the British Mark II, but less sophisticated in its design. It measured only 16 x 5.25 x 2.5 inches and could easily be carried in the agent's luggage or hidden away in a very small space. Interesting that the identification controls were stamped in English, possibly other languages as well. While the controls were marked in English, it appears that all the components were obviously German. It might fool a civilian but not a radio technician.

Fortress Emergency Transmitter

Fortress Emergency Transmitter I recently had the opportunity to examine a very rare WW II radio, the Fortress Emergency Transmitter or FESTUNGNOTSENDER b. John Orahood managed to obtain the set and was kind enought to send me some photos. After some time, he sent the set to me for further examination. There is very little information available on the set but it was shown in the 1945 Handbook on the German Army. The set that John sent me had the E.E.I.S. ( Enemy Equipment Identification Service ) markings on the side and had several captured document tags indicating that it was captured and processed by 1st U.S. Army. In all probability, this set is the one shown in the TM. In 1933 the German military adopted a new field telephone, the Model 33. This set was housed in a Bakelite case and was built on a removable metal frame. On the right side was a small magneto for ringing voltage, in the centre was the bell and network and on the left side was a housing for the 4.5 volt DC battery for talking. The handset rests in a cradle on top. This telephone became the basis for the Fortress Emergency Transmitter. Only the case and the magneto were used.

Fortress Emergency Transmitter

The transmitter is constructed on a Bakelite board which has the magneto mounted on the right side, the tube, variable capacitor, coils, internal key and resistors were in the centre. On the left were the major components of the power supply consisting of two 2.5 MFD electrolytic capacitors in a can, a 16 MFD Electrolytic capacitor, a selenium rectifier and a filament transformer. A neon bulb in the antenna circuit was mounted under a window which allowed the operator to view the neon bulb as he keyed the transmitter.

A small bulb in a housing on top provided an indication that the magneto was working. There was also a socket for connecting an external keyer. Two large screw terminals were on the far left for connecting the antenna and counterpoise. The brown Bakelite board on which the components are mounted was then covered with a thin white plastic top panel which had all the markings on it as well as the Wehrmach acceptance stamp. This strip of plastic did not hold up well and parts have cracked off. The magneto crank was stored in the top cover along with a clock which had been removed from this set. On the back side was a canvas pouch which held the antenna and counterpoise wires and the supplemental instruction manual. Brief instructions were also on a data plate on the top cover.

The magneto puts out 84 volts AC when cranked rapidly. This AC voltage is applied to the two 2.5 MFD capacitors in a can which in turn were connected to a selenium rectifier and to a 16 MFD capacitor. As the magneto was cranked, the capacitors were alternately charged and discharged through the rectifier circuit and to the storage capacitor. This was a voltage doubling circuit which resulted in the 84 VAC being converted to 164 VDC. The 84 VAC was also fed to a small filament transformer which stepped it down to 2.5 volts AC for the tube filament and for the indicator light.

The transmitter is a Hartley Oscillator based on an RE 134 tube. The Hartley Oscillator takes some of the energy in the plate coil and feeds it back through the grid coil, almost like a regenerative receiver. An interesting feature of the tank circuit is the variable capacitor. It is mounted on a Bakelite board just to the left of magneto. There is an extra set of gears on the magneto and the variable capacitor's bow tie shaped rotor, which causes the rotor to spin through the stator as the magneto is cranked. The rotor spins at a very high rate of speed. This causes the frequency to sweep through the entire range. The internal key is connected between B + and the tube plate. The external keyer is connected across the internal key. It is labelled "Zeichengeber" which translate literally as signal giver. There may have been an automated signal device used with this set but that is not certain.

To place the set in operation, according to the data plate, First one opens the cover an screws in the magneto crank, then connects the antenna and counterpoise to the terminals on the set. Then one man holds the case steady with his left hand and cranks with his right hand. The second man then operates the key or keyer. The data plate also gives instructions for winding the clock once a week and checking the time and resetting the clock on a daily basis.

This set had serial number 5039 and a date of 39, usually indicating that it was made in 1939, however the magneto had a manufacture date of 1940 so I concluded that the b version was adopted in 1939. There must be an even earlier set but one has not been found. It may be that it was a limited production model and refinements were made and the b version was ready by 1939. With a serial number of 5039, there must be at least 5038 other sets somewhere. Since they look like a telephone, I assume that most GI souvenir hunters passed them by, thinking they were a telephone.

What I found most interesting was that after 50 + years, the tube filament was still good as was the Mazda light bulb that indicates the Magneto was working. Testing the various points in the power circuits, the capacitors were still good and so was the filament transformer. The only damage to the set, other than the missing clock, was a broken resistor lead which was easily fixed. Some time after this article was published, I was informed that the owner had replaced the capacitors. Some few months later, another of these sets showed up in Europe and I was able to get it. The cover for the filament lamp was missing, the Mazda lamp was missing and the capacitors were all bad.

Considering that there were literally thousands of bunkers in Europe, it is surprising that more of these sets have not turned up. Unlike most of the radios of WW II this set has little application in HAM radio, which is why HAMs probably did not send them home in large numbers. In fact since it takes two people to operate the set, it is little more than a curiosity to be put on the shelf. The set is however a very unique application of a telephone magneto to power a radio set. As such it deserves a place in any display of German radio Equipment.

For single seat fighters a very small " Seenot Sender " was developed which could be carried in the pilots flight suit. This was the NSG 4 "Jager" and was made by the firm of Lowe-Opta and operated on 58.4 to 58.8 MHz. It had a long steel tape antenna and transmitted with 0.3 watts. It was powered by a small Nicad battery and a mechanical vibrating choper. The range for search aircraft flying at 300 feet was approximately 40 miles. These sets are all very rare items and few examples survived the war. They are, however, the first of a long series of what are now called survival radios.

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