Abwehr spy radio set
The SE 98/3 was an
developed during WWII by OKW-Aussenstelle Berlin-Stahnsdorf 1
for use by the German Security Service,
the Abwehr, mainly in the Eastern war
The device was introduced in 1941 and was manufactured by OKW Stahnsdorf. From 1942 onwards it was made by OKW-Aussenstelle
Wurzen. It was one of the most widely used Abwehr radio sets during WWII
and is in fact a miniaturized version of the
SE-97/3 suitcase radio.
The radio set consists of a small 3 Watt S-98/3 crystal-operated
transmitter and an adjustable E-98 receiver that are mounted on
together with a small power connection block.
The subframe slides into a larger frame that also holds the batteries.
The batteries are held in place by an elastic band at either side of
the frame. The complete SE-98/3 assembly slides into a metal container with
a watertight top lid.
The image on the right shows a typical SE-98/3 radio set inside its metal
container without top lid, complete with morse key and headphones.
The radio is powered by four internal batteries that last one full year
when using it 15 minutes each day .
Despite the fact that the SE 98/3 was one of the most widely used
Abwehr radio sets,
only very few have actually survived. Most sets were lost during
the war, or were destroyed by its users at the end of WWII.
As a result it is arguably the most rare Abwehr set as well.
OKW = Oberkommando der Wehrmacht (Supreme Command of the Armed
Forces) in Nazi Germany during the Second World War.
Aussenstelle = Outpost.
The diagram below shows the SE-98/3 after it has been removed from its
storage container. Although it can be used whilst seated inside the container,
we have removed it here to show the various features of the set as it is
mounted inside a U-shaped frame. The lower half of the frame is occupied
by the batteries that provide the LT voltage (3V)
and the HT voltages (90 and 270V).
The upper half of the frame holds a subframe with the receiver (right)
and a small transmitter, both of which are connected to the small
terminal block in front of the transmitter.
The S-98/3 transmitter is the smallest of the two units and is built
around a KL2 valve that delivers an RF output power of 3 Watts in CW (A1).
It is shown below with a suitable crystal installed at the left.
The E-98 receiver is the largest unit of the set and is mounted at the right
half of the subframe. The one shown here is a reproduction that is partly
rebuilt from original parts (recovered from the water) and new-old-stock (NOS)
parts. The receiver contains three valves (DF11, DAF11 and DL11) and has a
frequency coverage of 2.1 to 8.2 MHz, whilst the transmitter covers 3 to 8 MHz.
The SE-98/3 was distributed in the grey metal container with watertight top lid,
as shown above. The metal container was usually packed inside a leather
briefcase of the era, complete with the necessary accessories, such as
headphones, morse key, antenna wires, crystals and tools. There was no
power supply unit (PSU), as the SE-98/3 is powered by batteries that lasted
one full year.
The exact types of batteries that were used with the SE 89/3 are currently
unknown. There are indications that a large 3V battery may have been used
in combination with a large 90/270V LT battery, or 3 smaller 90V LT batteries.
There are also indications however, that four equally sized batteries were used
as shown in the image on the right. The batteries shown here are reproductions
to visualize what they may have looked like. The can be filled with ordinary batteries so that the radio can be demonstrated.
Virtually any type of morse key can be connected to the two banana sockets
at the bottom left of the transmitter. The SE-98/3 was normally supplied
with a small Bakelite® morse key that was nicknamed Maus (mouse).
The image shows a typical Maus with a 2-pin plug at the end of
its wire. Note the half-moon button at the front of the key, which
was often used for 'spy' equipment. Another type of Maus has a
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's ear, it was supplied with three different olive-shaped
in-ear pieces. Two earphones were often connected in series to obtain
4000 Ω. The image on the right shows a Rosinski Kleinhorer aside a
Maus morse key . Click for a
The image above was taken by Rudolf Staritz in the early 1980s. Over the
years it has appeared in many of his publications .
The Rosinski Kleinhörer was available well before the war.
It was advertised, for example, in the
August 1937 issue
of the DASD amateur magazine CQ-MB. 
Alternatively, the SE-98/3 could also be used with a
common pair of high-impedance headphones,
that are also found 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 SE-98/3 was typically used with quartz crystal in a cylindrical
enclosure, such as the one shown in the image on the right.
The crystal should be inserted into the two banana sockets at the
bottom of the left side of the transmitter.
The SE-98/3 needs four batteries that are installed in the lower section
of the U-shaped metal frame, below transmitter and receiver. The batteries
are connected to the terminal block in front of the transmitter. One of the
batteries (the leftmost one) provides the 3V LT voltage for the filaments
of both devices. The 3V rail is protected by a 400mA fuse as shown in this
The other three batteries each provide 90V and are connected in series
to obtain the +270V LT voltage for the transmitter. The +270V
rail is protected by a 50mA fuse. A tap after the first 90V battery
provides the +90V HT voltage for the receiver. The +90V rail is not
protected by a fuse.
Although both power sockets are wired identically, the +270V rail is not
used by the receiver.
The transmitter consists of a metal frame that holds all components,
and a U-shaped metal case shell that is held in place by four recessed screws.
It has controls and connections on two of its sides. Sockets are present for
connection of the morse key, the crystal and the antenna.
The image on the right shows the interior of the transmitter after the
metal case shell has been removed. The big KL2 valve is at the far corner.
The meter at the front panel is used for checking the RF output, as well as
the battery voltages. It is operated with a small lever below the meter.
The circuit diagram of the S-98/3 transmitter is given below. It shows how
the transmitter is built around a single KL2 valve that acts as the oscillator
as well as the Power Amplifier (PA), delivering approx. 3 Watts RF output.
The crystal is inserted into a socket at the left. The transmitter is turned
ON by connecting 3V to the filament of the valve via the ON/OFF switch.
The actual CW transmission is controlled by the morse key that directly
switches the 270V anode voltage.
At the bottom right is the meter. By default it is used for checking the
RF output of the device. This is done by picking up a small amount of RF
energy with the transformer (K) and rectifying it by means of a Siemens
Sirutor, which is in fact an array of diodes connected in series .
The voltages of the radio set can be checked by moving the metal lever
(hidden behind the PA Tuning knob) away from its default position.
From left to right it checks RF Power, +3V, +90V and +270V.
Note that +90V is not used by the transmitter. It is only required by the
The interior of the receiver can be accessed by removing four screws from
the sides and taking off the case shell. This reveals a frame with all
components that is mounted to the front panel.
The image on the right shows the interior of the receiver after the case
shell has been removed, seen from the top rear side. Note that the valves
are mounted upside down. The circuit is built around three Telefunken
metal valves: a DF11 that is used as RF pre-amplifier, a DAF11 as the
oscillator/detector and finally a DL11 as the AF amplifier that delivers
audio to the headphones.
The circuit diagram of the E-98 receiver is given below, which is actually
a miniaturised version of the E-97 receiver. Power is applied to the circuit
via the 4-pin connector at the bottom right, of which the +270V terminal is
not used. Both the +3V and the +90V rail are passed via the ON/OFF switch.
The +3V LT voltage is supplied to the filament of the DF11 via a 10 Ohms
resistor. Note that the filaments of the other two valves (the DAF11 and the
DL11) are connected in series.
The receive antenna is not shared with the transmitter. Instead a separate
wire antenna and a suitable counterpoise should be connected to the ANT and
GND terminals at the left. A high-impedant pair of headphones should be
connected to the headphones terminals at the top right. Note that the headphones
are connected in series with the anode line of the DL11 valve, which means
that the wires carry a voltage of +90V. Ensure that these wires are properly
The transmitter and receiver are eached powered via the terminal block
at the front edge of the radio, just in front of the transmitter. There
are two 4-pin male sockets that are wired identically. The sockets provide
the +3V LT voltage for the filaments, and the +90V and +270V HT voltages
for the anodes of the valves. Note that the receiver does not require
+270V. The power sockets are wired as follows, when looking into the male
sockets from the front of the device:
CaseSuitcase or metal container
Frequency2.1 - 8.2 MHz
ModeAM R/T and CW (morse)
ValvesDF11, DAF11, DL11
Frequency3 - 8 MHz
ModeCW (A1, morse)
OscillatorQuartz crystal operated
Any links shown in red are currently unavailable.
If you like the information on this website, why not make a donation?|
© Crypto Museum. Created: Monday 05 September 2016. Last changed: Tuesday, 11 October 2016 - 19:07 CET.