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SE 109/3
Abwehr spy radio set

The SE 109/3 was an espionage transmitter/receiver developed during WWII, in 1942, by OKW-Aussenstelle Wurzen 1 for use by the German Security Service, the Abwehr. The radio went into production in 1943 and was used by the Abwehr but also by its successors Rechs­sicher­heits­hauptamt (RSHA) Gruppe VI F, RSHA/Amt Mil and OKH/Fremde Heere Ost (FHO). After WWII, the radio was used by Organisation Gehlen (OG) and even by the Bundesnachnrichtendienst (BND).

The complete radio set (transmitter and receiver) is housed inside a medium-sized tin case, much like a biscuit tin of the era, which is why the set is often referred to as Keksdose (biscuit tin), just like its 3-piece predecessor, the SE 108/10. 2

The set is powered by an external battery pack that provides 1.2V (LT), 90V and 270V (HT), but can also be used with an (optional) power supply unit (PSU) that is coupled directly to the power socket at the rear. The 3 Watt crystal-operated transmitter can have up to two fixed channels in addition to a flexible one with a plug-in crystal.
Abwehr SE-109/3 spe radio set

The receiver is freely adjustable over the entire frequency range, but has a somewhat limited span (3.2 to 6.5 MHz) compared the transmitter (3.3 - 7.5 MHz). 3 The transmitter is suitable for CW only and was used for sending messages in morse code, using the built-in removable morse key. Note that all text on the top panel and the knobs is in English. This was done to hide the actual (German) identity of the equipment, and to assist any non-German-speaking Abwehr operators.

Each radio came with a 2-page instruction sheet that was available in multiple languages. The sheet carried the serial number of the radio and was accompanied by a calibration sheet that converts the linear scale of the receiver into frequencies. The sheet also contains the (hand-written) frequency ranges of transmitter and receiver, the frequencies of the (optional) internal crystals and the required length of the antenna wires. See for example the sheet for #580 [A].

Approximately 500 units were built during WWII [5], most of which fell into the hands of radio amateurs once the war was over. Shortly afterwards however, in 1946, the Americans established a new German intelligence agency that became known as Organisation Gehlen (OG). The new OG subsequently recruited old Abwehr personnel, most of which were radio amateurs, and tried to re-activate the wartime agents in the Eastern Block. As the OG urgently needed radio equipment, they tried to buy back as many SE 109/3 (and other) sets as possible, which is one of the reasons why Abwehr spy radio sets are so rare [5]. The SE-109/3 was succeeded in 1953 by the 12WG.

  1. OKW = Oberkommando der Wehrmacht (Supreme Command of the Armed Forces) in Nazi Germany during the Second World War. Aussenstelle = Outpost.
  2. In Louis Meulstee's book Wireless for the Warrior Volume 4, the SE-108/10 is referred to as SE-100/11 [1]. Both names are believed to be correct.
  3. Note that different frequency ranges were used for specific missions [1].

Complete setup SE 109/3 with crystal and Wehrmacht headphones SE 109/3 with crystal Abwehr SE-109/3 spe radio set Front left view Rear view Morse key removed Examples of suitable crystals
The SE 109/3 measures 20 x 14 x 6 cm and weights just 1.7 kg. It has controls and connections at all sides, except for the bottom. The case consists of a rectangular tin frame with rounded corners and easily removable top and bottom panels. The left 2/3 is occupied by the receiver, whilst the remaining 1/3 houses the transmitter. The top panel has three large holes through which the black metal DF11 valves of the receiver are visible. The holes provide their cooling.

Antenna and counterpoise for the receiver should be connected to the banana sockets at the top panel. A dynamic 4000Ω earpiece, or a pair of 2 x 2000Ω headphones should be connected to the banana sockets at the left of the front panel. A suitable Rosinski Kleinhörer was supplied.

All controls of the receiver are located at the left side panel. The ON/OFF switch is used to enable the LT voltage for the filaments. The knob closest to the rear, is used for adjusting the receive frequency between 3.2 and 6.5 MHz. 1 When tuning, the current setting can be read from the linear index scale at the top panel. Reaction is controlled with the knob closest to the front.

All controls of the transmitter are located at the right side panel, where also a suitable transmit antenna should be connected. The transmitter can have up to two built-in crystals with a fixed frequency, selectable with a rotary selector at the right. In addition, an external crystal may be inserted in the crystal socket at the center of the top panel (set the Xtal selector to position 3).

The ON/OFF switch is used to enable the LT voltage to the filaments of the DLL22T valve. The transmitter is only suitable for CW transmissions (morse), using the internal morse key at the front. When in transit, the morse key can be removed and stored inside the device. There is no connection for an external morse key. When transmitting, the antenna-coupling knob and the oscillator tuning should be adjust for maximum output, using the indicator at the top right.

The SE-109/3 is powered by external batteries, or an external Power Supply Unit (PSU), that should be connected to the 4-pin socket at the rear. The image above shows the position of the power socket, which is a so-called break-connector (German: Brechkupplung) that was commonly used by the German Luftwaffe (Air Force). The radio needs three voltages: 1.2V, 90V and 270V.

  1. Note that different frequency ranges were used for specific missions [1].

Abwehr SE-109/3 spe radio set Front left view Rear right view Front view Rear view Top view Front side Rear side
Left side Right side Receiver ON/OFF switch Crystal selector Frequency tuning scale Crystal socket with frequency table Indicator (meter) Meter and meter-selector
Serial numbers
Most SE-109/3 radios have a serial number that consists of 3 or 6 digits. This serial number is somehow 'encrypted', so that it is not possible to determine from the surviving samples how many devices were manufactured. However, from talks with the person who was responsible for the tin enclosures, Rudolf Staritz determined that approx. 500 units were made [5][10].

If the serial number is present, it is usually written on the receiver's tuning scale with a pencil, as shown in the example on the right. The serial number of this device is 398.

Furthermore, the serial number may also be written on the front panel of the device (or in fact anywhere else on the radio's body) either with a black or a blue pencil. In our case, the serial number is also present on the front panel.
Receiver tuning scale

Parts and accessories
Storage cases Operating instructions Morse key Earphone (Kleinhörer) Standard high-impedant headphones Plug-in and internal quarz crystals
Storage case   wanted item
When in transit, the SE-109/3 was usually stored in a small plywood case that was covered with black faux leather. It had two leather straps to keep it closed. A similar box was available for the battery pack that housed the 1.2V battery for the filaments and three 90V anode batteries.

The image on the right shows an SE 109/3 outside its storage case. The battery case has extra space for the cables, ear piece and crystals [11]. In this case, the battery box has been converted into a mains power supply unit (PSU).
SE-109/3 with serial number 683, with storage case and PSU [10]

The image on the right shows a near-mint SE 109/3 radio inside an original storage case. Note the small cut-out in the top lid that accomodates the lens of the receiver's tuning scale. Als note that the case has no room for the cables, ear­phone, crystals or any other accessories.

Photograph kindly supplied by anonymous collector. Click the image for a closer view.

Operating instructions
The SE 109/3 was usually supplied with a four page instruction guide. On the first two pages, it is explained how the radio and its batteries are to be connected and operated. The frequency range of the radio and the frequencies of the enclosed crystals are hand-written on the second page.

The third page shows the position of the various controls and connections on the radio's body, whilst the last page shows a personalised curve that translates the receiver's linear tuning scale (0-180) to actual frequencies (2900-5600 kHz).

A copy of an original SE 109/3 instruction sheet is available for download below [A]. As these sheets were probably individually hand-typed at the time, or perhaps three simultaneously by means of carbon paper, the text contains many typographical and lingual mistakes. It is very likely that most, if not all, sheets are unique.
Operating instructions

As the original (scanned) instruction guide is barely readable, we have made a reproduction of it, in which we have also corrected some obvious errors and spelling mistakes. The editable fields and the frequency chart have been left blank, so that it can be tailored for a specific radio.

 Reproduction of the original instructions

Morse key
The SE-109/3 has a built-in key that is located at the front side of the radio at a convenient hight. The arm with the black bakelite knob is removable and can be stored inside the device, in a small brass bracket that is attached to the panel between the transmitter and the receiver.

The radio was originally supplied with two arms for the morse key: one inserted at the front, and a spare one inside the radio [A]. In most cases however, one of them has been lost over time. Note that, unlike on earlier devices, there is no connection or socket for an external morse key.
Operating the removable morse key

In case the morse key of your SE-109 radio is missing, the drawing below should provide enough information to create a suitable replacement. The arm consists of a square shaft with a circular Ø 3 mm stub at the end that is inserted into the radio. A hardened Ø 1 mm pin keeps it straight up. The arm is made of steel, whilst the knob is made of black bakelite.  Download as PDF file

Earphone   wanted item
Although the receiver is suitable for connection of virtually any type of high-impedant head­phones, it was originally supplied with a small 2000 Ω dynamic earphone, known as Ohrhörer or Kleinhörer, supplied by K. Rosinski in Berlin.

This earphone had a diameter of 34 mm and weighted just 35 grams. To accomodate the user, it was supplied with three different olive-shaped in-ear pieces. The Rosinski Kleinhörer was available well before the war. The image on the right was taken from the August 1937 issue of the DASD amateur magazine CQ-MB. [3][4]

K.Rosinski Kleinhörer in 1937

The Rosinski Kleinhörer was also supplied with the earlier SE-98/3 spy radio set, often in combination with a Maus morse key, as shown in this photograph that was taken by Rudolf Staritz in the early 1980s. Over the years it has appeared in many of his publications [11].

Alternatively, the SE 109/3 could also be used with a common pair of high-impedance head­phones, that were also used with Wehrmacht equipment of the era. The headphones shown here are the Dfh.f. 40.

The headset consists of two speakers with an impedance of 2000 Ω each. Note that the headphones are connected in series with the anode of the DL11 AF amplifier valve, and carry a +90V DC voltage. This means that the wires should be properly isolated.

The transmitter is crystal operated in the range 3.3 - 7.5 MHz. 1 A suitable crystal with a pin distance of 19 mm 2 should be installed in the crystal socket at the center of the top surface. Note that for this, the crystal selector at the right side (marked Xtal), should be set to position 3.

Although virtually any type of quartz crystal with the appropriate base can be used, the radio set was commonly supplied with cylindrical plug-in crystals, such as the ones shown in the image on the right. The left one is for 4,3443 MHz and is made by Steeg und Reuter 3 in Bad Homburg.
Examples of suitable crystals

  1. Alternative frequency ranges are known to have existed.
  2. The socket's pin distance is 19 mm, but crystals with a pin distance of 20 mm will often fit.
  3. Dr. Steeg & Reuter is now part of Jenoptik AG.

Internal crystals
In additon to the external crystal that is installed on top of the device, as described above, it was also possible to (optionally) install two internal crystals for fixed channels. These crystals were permanently installed and wired, and could not be swapped easily. They were mounted to the panel between the transmitter and the receiver.

The image on the right shows the two internal crystals. When present, they are available at settings 1 and 2 of the crystal selector 1 (Xtal). Furthermore, their frequencies were engraved in the black plate below the external crystal socket.
Internal crystals wired to the rotary selector

  1. Note that the Xtal selector has four usable settings, but that only positions 1, 2 and 3 are used. Position 4 is unwired. Also note that positions 5-8 are mapped to positions 1-4.  More...

Operating the removable morse key Removable morse key Morse key removed Removable arm Placing the removable arm in the bracket The arm of the morse key stored inside the device Internal crystals wired to the rotary selector View at the internal crystals after removing the meter
Crystal socket with frequency table Quarz Crystal Examples of suitable crystals SE 109/3 with crystal
The radio was usually powered by an external battery pack that was stored in a ply wood case, similar to the case in which the radio itself was stored. The battery pack was either connected via a 4-pin male/female extension cable, that was inserted to the right side of the box, or via a cable that was directly wired to the battery or batteries. The image below shows both cable types.

The cable with the loose ends should normally have four 3.5 mm screw-in plugs that fitted the batteries of the era. We have temporarily fitted 4 mm banana plugs in order to test the device.

The other one is an extension cable that has a male plug at one end and a female plug at the other end. This cable was used for connection between the radio set and the battery case or for connection of an external power supply unit. The plugs that are used here, are so-called break-connectors (German: Brechkupplung) that were commonly used by the Luftwaffe (Air Force).
Battery cable and power extension cable

There are two known battery arrangements that were used with the SE 109/3. The first one (A) is shown below. It is similar to the battery arrangement of the SE 98/3, with the exception that the LT voltage is 1.2V rather than 3V. The HT voltages are made with three 90V anode batteries that are connected in series, with a tap after the first battery. This produces +90V and +120V HT.

Arrangment of the batteries

There was also an arrangment (B) that consisted of two external battery cases, one for the LT voltage and one for the HT voltages. The LT battery case housed five large heavy-duty 1.2V dry batteries that were connected in parallel. The HT battery case accomodated five LS-Zwerg batteries of 60V each, that were connected in series, with a tap after the second battery. Each of the battery cases had a male and a female socket that was fully wired, so that they could be connected to the radio in any order using two of the male/female extension cables shown above.

Alternative battery arrangment

Note that in this arrangement the HT voltages are somewhat higher than with arrangement (A): +120V for the receiver and +300V for the transmitter. The higher voltage for the receiver should not cause any trouble. For the transmitter it means that the DLL22T valve was operated outside its specifications. It would produce more power, but would also be more vulnerable to antenna mismatches. This is probably one of the reasons that very few DLL22T valves have survived.

The diagram above shows how in the case of arrangement (B) the battery cases were cascaded. The LT and HT cases could be swapped as they were both fully wired. Furthermore, the battery cases could be connected directly to the socket of the radio without any cables being used, as the connectors are at the same height. Move the mouse over the image to see the alternative setup.

Power supply unit   wanted item
The radio can also be powered by an optional external power supply unit (PSU) that is housed in a small tin box, similar to the SE-108/10 PSU.

The PSU can be placed behind the radio set and is plugged straight into the break-connector at the rear. Alternatively, it can be connected via an optional extension cable.

Note that the PSU of the earlier SE-108/10 radio can not be used, as it has a different pinout.
Photograph not yet available

Battery cable and power extension cable Power extension cable Battery cable Power cable for testing
The interior of the SE-109/3 is easily accessible for repair, inspection of the valves, swapping the fuses and for storing the arm of the morse key when transporting the radio set. Both the top and bottom panels can be removed easily like the lid of a biscuit tin, giving access to the interior. The image below shows the interior of the SE-109/3 as seen from the top. About 2/3 of the space is taken by the receiver (left). The three large black DF11 valves of the receiver are clearly visible.

Top view of the interior of the SE-109/3

The remaining 1/3 (right) is taken by the transmitter. This compartment also contains the indicator that is used to check the voltages and the transmitter's output power. Receiver and transmitter are separated by a tin panel that also accomodates the two internal crystals (when present). The transmitter's tuned circuit consists of a large variable capacitor at the center, and a coil with multiple taps in the top right corner. The antenna socket is also at the top right.

Bottom view of the interior of the SE-109/3

The transmitter is built around one DLL22T double-penthode valve, that is clearly visible from bottom side of the unit. This side also houses the passive components that are soldered directly to the valve sockets. At the top left is the circular current transformer that is used to measure the transmitter's output power. The fuses for the 1.2V and 270V lines are located at the top centre.

SE-109/3 with top panel removed Bottom side with bottom lid Interior - top view Interior - bottom view Interior - top view Interior - botyom view Receiver Transmitter
TX valve Receiver tuning scale Meter function selector Fuses Corrected wiring at the base of the first valve Meter function selector Internal crystals wired to the rotary selector Adjusting the transmitter's tuned circuit
Circuit diagram
The circuit diagram of the SE-109/3 has been published in Louis Meulstee's excellent book Wireless for the Warriour Volume 4 [1], and also in a number of publications in Radio Amateur magazines. This circuit diagram was taken down by Gerhard Salzmann (DL2IE) from a genuine sample in 1984 [5]. Unfortunately, the transmitter had been removed from the sample from which he took down the circuit diagram, as transmitters were illegal in post-war Germany. He therefore made a few educated guesses, based on the design of the transmitter of the SE-98/3.

Because the circuit of the surviving SE-109/3 radio sets, and the transmitter in particular, is significantly different from the published circuit diagrams, we will be discussing both variants below. We have created new circuit diagrams that reflect the actual situation. Many thanks to Günter König (DJ8CY), who took down the actual circuit diagrams for a presentation in 2006 [5].

Below is the circuit diagram of the E-109 receiver. The design is based on that of its predecessor, the E-108, but rather than using three different valves, the receiver of the E-109 is built with three identical DF11 valves. As the 4-pin power socket is inside the receiver's compartment, it is shown here as well. The power lines to the transmitter section are at the bottom right.

Original receiver circuit diagram [1]
Please note that the actual circuit and the value of some components, differs from the original circuit diagram shown above. In 2006, German collector Günter König recreated the actual circuit diagram from the device in his collection [5]. His corrected circuit diagram is shown here:

Corrected receiver circuit diagram [5]
The receiver is powered by two voltages: +1.2V for the filaments (LT), and +90V for the anode voltage of the DF11 valves (HT). Both power lines are interrupted by the main switch (S1), but note that the +90V line is not protected by a fuse. The +270 line is used only by the transmitter.

The circuit consists of three stages, each of which is built around a DF11 valve. The first stage is a so-called reflex receiver [7], which acts as the RF-stage, but also as the first AF-stage. The second valve is the Audion stage [8], which acts as a detector. The third valve amplifies the audio signal to headphones level and has a 4000 Ω ear piece connected in series with the anode of V3.

Audio response of the E-109 receiver [5]

Note the presence of an audio filter to improve the sound quality of the CW tone. It consists of a 40H coil (L3) in the anode line of V1 in combination with a 400 pF capacitor to ground, and an LC circuit around L4 in the output stage of V3. This combination results in the audio response that is shown in the diagram above. The curve has its optimum around 800 Hz [5].

Below is the original circuit diagram of the transmitter as it has been published over the years in a number of magazines. This is also the circuit diagram that is shown in Louis Meulstee's book Wireless for the Warrior Volume 4 [1]. It is uncertain whether any of surviving the SE-109/3 unit are built according to this circuit diagram, as the ones that have been found, all have a crystal selector. It is our impression that this circuit diagram was only used during the development.
WARNING - this circuit diagram contains many errors and should not be trusted. Use the circuit diagram below instead.
Original transmitter circuit diagram as published
The actual circuit of the S-109/3 transmitter featured on this page, differs significantly from the circuit diagram above. First of all, the transmitter has two (optional) internal crystals in addition to the external one, plus a rotary switch to select between them (S5). The circular internal crystals are mounted to the panel between transmitter and receiver and are connected with one side to ground. As a result, the oscillator feedback loop is different. Furthermore, the tuned circuit does not contain a transformer but consists of a single coil with 8 output taps to match the impedance.

Actual transmitter circuit diagram

The power switch is not in the 270V rail as shown in the original diagram, but in the 1.2V rail. It switches the filaments of the DLL22T valve and allows the transmitter to be turned OFF to save power. The 270V is always present and is protected by a 50mA fuse in the receiver section. The morse key does not switch the anode current of the DLL22T, but controls the g2 voltage.

Another difference with the original diagram is the position of the antenna current transformer and the addition of a second circuit to measure the antenna output level. The first circuit (built around D1) measures the antenna current when using a low-impedant antenna, whereas the second circuit (D2) measures the antenna voltage in case a high-impedant antenna is used. Both diodes, D1 and D2, are Siemens Sirutors, which are basically stacks of copper-oxide tablets [9].

The circuit diagram above is thought to be the correct one. It has been verified against the circuit diagram that was taken down in 2006 by Günter König, who went through the same exercise and used his diagram in a presentation [5]. Both diagrams are identical (but have a different layout).

About the rotary selectors
The SE-109/3 has three rotary selectors that each have eight positions. The eight positions cover the entire circle, so that each position represents a step of 45°. The selectors have no end stop. Due to the symmetrical layout of two of the these switches, only four positions can be used.

The leftmost drawing above shows the internal construction of these selectors, as seen from inside the device. A contact strip that is attached to the shaft, connects two opposite contacts. In the example, points 1 and 5 are connected. The next position connects 2 and 6, etc. In order to use the switch as a 4-position selector, contacts 5, 6, 7 and 8 are usually wired together.

The transmitter's antenna selector is the only one that actually uses all eight positions of the rotary selector. It is constructed differently and does not interconnect the opposite contacts. The rightmost drawing shows the construction of the antenna selector. All eight positions are used.

Just like any other Abwehr spy radio set, the SE-109/3 is an extremely rare find. Most radios were destroyed by RSHA personnel at the end of WWII, and the ones that have survived may have been used by radio amateurs (HAMs) and have probably been modified. But even if you find one that is in near original condition, it is wise to check the circuits and the wiring before powering it up.

The SE-109/3 in our collection was found in near-original condition. No modifications were made, but a previous owner had attempted to restore the unit and replace some of the internal power lines that had become brittle over time.

Although proper vintage wires had been used to replace the old brittle ones, a mistake was made when reconnecting them, probably as a result of the differences between the circuit diagram and the actual circuit. As a result, the +270V line was connected to the filaments of the DLL22T transmitter valve, causing its premature death.
Replacement wire for the 1.2V connection

Sadly, the DLL22T is an extremely rare valve, so finding a replacement will be very difficult if not impossible. Furthermore, there are no plug-in compatible alternatives that have the same form factor. Luckily, Günter König (DJ8CY) has developed a very good temporary solution by using a Russian subminiature valve with the same specifications. This solution is further described below.

Before applying the necessary voltages to the device, check the power lines carefully to see if they are connected to the appropriate parts. It is quite possible that a mistake has been made in an earlier restoration attempt. Also check the 1.2V lines for short circuits and for open lines.

At this stage it might be a good idea to test only the receiver or the transmitter, but not both. In case of the transmitter, supply the HT voltage to the device, but leave the 1.2V line switched OFF. No current should be drawn via the HT line. Now lower the HT voltage from 270V to just 150V.
Close-up of installed reproduction valve

This will help to avoid any damage when things go wrong later. It also reduces the output power of the transmitter valve. Next, apply 1.2V to the LT line and switch ON the transmitter. The 1.2V LT line may draw up to 200 mA. At this point, the (150V) HT line should still draw no current.

Ensure a proper crystal is installed in the crystal socket on top of the device, and set the crystal selector to position 3. Connect a wire antenna to the transmitter's antenna socket, and connect a proper counterpoise to the G-socket at the top.

Set the meter-selector to PLATE TR. so that the transmitter's output power can be measured. Once the valve has heated up, press the morse key and check the currents. The HT line should now draw a modest current in the 40 mA range. If this is the case, carefully tune the oscillator tuning knob so that the system starts oscillating.
Transmitter section with correct DLL22T valve

If this is the case, you should see a reading on the meter. Note that you may have to select a different tap on the tuning coil in order to properly match the impedance of the connected antenna. In any case, find the combination of the antenna matching selector and the oscillator tuning that gives a maximum reading on the meter. You should now be able to transmit.

If all goes well, you may now raise the HT voltage to +270V. The transmitter should then produce an output power of 2 - 3 Watts. When using a replacement valve (see below), it might be wise to use a maximum voltage of, say, 200V.

With the receiver, we follow the same procedure. First apply the 90V HT voltage and verify that some of that voltage arrives at the anode of each DF11 valve. In our case we had to restore the wiring around the socket of the first valve, i.e. the reflex stage, as someone had mirrored the connections in a previous restoration attempt.
Corrected wiring at the base of the 1st valve

At this stage the HT line should not draw any current. If this is the case, connect a pair of 4000Ω headphones and apply 1.2V to the LT line by switching ON the receiver. The LT line should now draw 60-75 mA. At the same time, you should hear some noise in the headphones. Note that you may have to turn the REACTION knob for the optimum noise level. Now connect an appropriate antenna and counterpoise and try to tune-in to a signal, whilst readjusting the REACTION knob.

Making a replacement for the DLL22T
The DLL22T is extremely rare and there are no plug-in compatibles with the same form factor. In 2006 however, collector Günter König [5] developed a gap-fill solution by using a Russian 1P24B (1П24Б) miniature pencil valve and solder it onto the base of a broken or dismantled valve.

The 1P24B is used in Cold War Russian spy sets like the R-353. It has the same specifications as the DLL22T, but is much smaller, allowing it to be mounted in the existing space without any modifications to the wiring of the SE-109/3. And more importantly: the 1P24B is widely available.

If you have a similar radio set with a broken DLL22T, you might want to build a functional replacement for it. Here is how to do it. First find a Russian 1P24B pencil valve, plus an old valve with a loctal base, such as the Russian 2Ж27Л, that will be disassembled as we need its base.
Materials needed for creating a replacement valve

The image above shows the original DLL22T valve (centre), the miniature 1П24Б (right) and the 2Ж27Л in its aluminium enclosure (left). Inside this enclosure is a common glass valve. Use a small saw to cut off the base of the aluminium cylinder, approximately 5 mm from the bottom.

Now comes the tricky part: cut off the base of the glass valve, approx. 5 mm from the bottom. This can best be done with a rotating saw blade such as a Dremel. Once this is done, remove the interior from the demolished valve, but leave the contact pins at the base intact, as we will need them later for mounting the replacement valve.

The contact pins on which the old valve interor was mounted, should now be made solderable. This means that a thin layer has to be milled-off from each pin. This can be done with a dental drill. Try whether the pins can be soldered.
Prepared base and Russian 1P24B valve

This leaves us with a glass base with contact pins on both sides, and a aluminium holder in which the glass base can be fitted. Affix the glass base inside the aluminium holder using a strong two-component adhesive and wait until it is hardened. This may take up to 12 hours or even longer.

Once the adhesive has hardened, we can build up the replacement valve. Place the newly made base in a small vice and prepare the base for soldering. At this point it might be a good idea to solder a bridge between the pins a(1) and a(2) and between pins g1(1) and g1(2) of the base.

When Günter König built his replacement valve in 2006, he mounted the 1P24B pencil tube as deep inside the new base as possible. However, as the 1P24B is a rather long valve, we decided to mount it under a 45° angle, giving it a bit more space and protecting the anode at the top.
Mounting detail

Now solder the relevant wires of the russian pencil tube onto the pins of the base. In our case, we have used small silver-plated rivets in which the wires of the valve are joined with a contact pin of the base. This makes soldering much easier and adds to the overall strength of the construction.

The image above shows how this can be done. The wires of the 1P24B are very thin and are very close together, so be careful not to cause any short circuits. Use insulation where necessary.

The last wire to be connected is the anode of the 1P24B, which at the valve's top. To make the construction stronger, a thicker wire is used.

When you are finished, check and re-check all wires to ensure that the correct lines of the 1P24B valve are connected to the appropriate pins of the base. After that, check it again.
Close-up of installed reproduction valve

If the base is correctly wired and no shorts are found, your replacement valve is ready for use. Install it in the socket and turn on the power. Ensure that you use a proper laboratory power supply unit with a current limiter, to avoid damage in case you made a mistake. Furthermore, it might be wise to reduce the HT voltage to around +150V, which is the nominal voltage of the 1P24B. This will protect the valve against excessive dissipation caused by antenna mismatches. If all goes well, you should now be able to demonstrate the transmitter of the SE-109/3 again.

In case you want to give this method a try, the above diagram shows how the replacement valve should be wired to the existing socket. Note that both sockets are seen from the bottom of the valves. Do not use the original DLL22T valve as the base for the construction, as it is too rare. Instead, use a cheap Russian surplus valve with a loctal base, like the 2Ж27Л that we used here.

 Pinout of the 1P24B valve    Pinout of the DLL22T valve

Materials needed for creating a replacement valve Russian 1P24B valve Old Russian valve taken apart Prepared base and Russian 1P24B valve Mounting detail Original DLL22T valve (right) and reproduction (left) Reproduction valve installed instead of DLL22T Close-up of installed reproduction valve
Comparison of the two valves 1
  DLL22T 1P24B Remark
Uf 1.2 ··· 1.4 V 1.08 ··· 1.34 V Both filaments connected in parallel
If 0.2 A 0.255 A Both filaments connected in parallel
Ua 120 / 150 V 150 / 300 V Nominal / Max
Ug2 120 V 125 / 200V Nominal / Max
Ia 15 mA 17 mA DLL22T: 2 x 7.5 mA
Ig2 4 mA 3 mA DLL22T: 2 x 2 mA
S 1.5 mA/V 2.8 mA/V Slope
Pa 1.5 W 2.5 W Nominal values. DLL22T: 2 x 0.75W
J ? < 3 µS Impulse @ Ua = 400 V, Ug2 = 300 V, Ik = 800 mA

From the above table it is obvious that the DLL22T is driven well beyond its maximum ratings. Although this is common practice with transmitter valves, it significantly reduces the valve's life. Furthermore, this can only be done when the circuit is actually oscillating (i.e. when a crystal is present and the tuned circuit is in resonance), as otherwise there will be no current limiting.

The same is true for the russian 1P24B valve that was used in Cold War Soviet spy radios sets like the R-353 and the R-354. In the R-353 it is used in one of the transmitter's driving stages, and in the R-354, three of them are used in parallel in the PA stage to produce 10 Watts of RF.

  1. Table kindly supplied by Günter König (DJ8CY) [5].

Power socket
The SE-109/3 is powered via the 4-pin circular male socket at the rear. This is a so-called break connection (German: Brechkupplung), that was also used by the German Luftwaffe (Air Force) during WWII. Below is the pinout when looking into the male socket, from the rear of the device.

  1. HT +270V TX (via 50 mA fuse)
  2. 0V (Ground)
  3. LT +1.2V filaments (via 400 mA fuse) 1
  4. HT +90V RX (unprotected)
  1. In some publications this line is erroneously designated as +12V.

DLL22T transmitter valve
The DLL22T valve that is used in the S-109/3 transmitter, was manufactured during World War II by Tungsram in Budapest (Hungary). The suffix 'T' denotes that it was made by Tungsram. It was also made by Philips/Valvo as the DLL22, but without the 'T' suffix. 1 Below is the pinout of the Tungsram DL22T. At the left is the circuit symbol. At the right is the bottom view of the valve [6].

Bottom view of the DLL22T (left)

  1. The pinout of the Philips/Valvo DLL22 should be identical to that of the the Tungsram DLL22T, but the information in the surviving valve databooks is conflicting [6]. Furthermore,the Philips/Valvo variant might be higher, and may not fit inside the SE 109/3.

DF11 receiver valves
The DF11 is a black metal German valve, made by Telefunken, of which three are used in the receiver. It is a directly heated Penthode that is suitable for RF, IF and AF applications. It has an LT voltage of 1.2V and a typical Anode voltage of 90V. Below is the pinout of the DL11. Note that the terminals of the unused pins (marked n.c.), are used as a mounting hub for other components.

 DF11 datasheet

Pinout of the German DF11 valve

1P24B valve   1П24Б
The Russian valve 1P24B (1П24Б) is not used in the SE-109/3 radio set, but is shown here as a possible replacement for the extremely rare DLL22T. The 1P24B is very similar to the DLL22T, but has a different anode voltage and different maximum ratings. The pinout is given below.

 1P24B datasheet

Pinout of the Russian 1P24B replacement valve

Technical specifications
  • Model
  • Dimensions
    6 × 14 × 20 cm
  • Weight
    1.7 kg
  • Model
  • Frequency
    3.2 - 6.5 MHz 1
  • Modulation
    AM, R/T (A1, CW)
  • Valves (tubes)
    DF11 (3x)
  • Sensitivity
    < 2µV
  • Model
  • Frequency
    3.3 - 7.5 MHz 1
  • Modulation
  • Valve (tube)
  • Output
  1. This is the standard frequency range. Other ranges were used for specific missions [1].

  1. Bedienungsanweisung für SE 109/3
    Operating Instructions for SE 109/3 (German).
    Serial number 580. 3 pages. Copy obtained from [10].
     Corrected instructions with chart (reproduction)

  2. SE 109/3 Circuit diagram (corrected)
    Günter König (DJ8CY), April 2006 [5].

  3. DF11 valve datasheet
    Telefunken. December 1941, March 1942.

  4. Russian valve 1P24B (1П24Б) Datasheet
    Replacement valve specifications. 1960.
  1. Louis Meulstee, SE 109/3
    Wireless for the Warrior - Volume 4. Retrieved August 2016.

  2. Arthur Bauer, Some Aspects of the German military Abwehr wireless service...
    ...during the course of World War Two
    15 September 2003. p 10. 1

  3. CQ-MB, Description of the K. Rosinski Kleinhörer
    DASD club magazine (German). August 1937. Page 125.

  4. CQ-MB, Advert of the K. Rosinski Kleinhörer
    DASD club magazine (German). Date unknown. 2

  5. Günter König (DJ8CY), Das Agentenfunkgerät SE 109/3
    Power Point Presentation. Langebrück/Dresden, 28 April 2006.
    Personal correspondence September 2016. 3
     SE 109/3 Circuit diagram

  6. Radiomuseum and contributors, DLL22T
    Website. Retrieved September 2016. → See also DLL22

  7. Wikipedia, Reflex receiver
    Retrieved September 2016.

  8. Wikipedia, Audion receiver
    Retrieved September 2016.

  9. Radio Museum and contributors, Siemens Sirutor
    Retrieved September 2016.

  10. Archiv Rudolf Staritz, various photographs, circuit diagrams and descriptions
    Obtained from the Heinz Lissok Archive, June 2012. #CM301583.

  11. Rudolf F. Staritz, Image of Maus morse key and Rosinski Kleinhörer
    Reproduced here by kind permission of the author.
    Retrieved October 2016 via Arthur Bauer [2].

  12. Various collectors, personal correspondence
    The following collectors have contributed to this page: Manfred Bauriedel, Helmut Fünfgelder, Thomas Höppe, Günter Hütter, Günter König, Rudolf Staritz.
  1. Note that in this document the SE-109/3 is erroneously called SE-108/3.
  2. Document kindly supplied by Thomas Höppe.
  3. Reproduced here by kind permission from the author.

Further information
SE 109/3 with crystal and Wehrmacht headphones
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