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Spy radio set
The SP-15 is a complete spy radio station
that was developed in Germany
in the early 1960s by Wandel & Goltermann and H. Pfitzner
for the German Intelligence Agency Bundes Nachrichtendienst (BND).
It was intended for special forces (SF) and stay-behind organisations
(Gladio).
Certain parts of the SP-15 radio station were also used by the
organizations of other countries.
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A complete SP-15 radio station consisted of a receiver (FE-8),
a transmitter (FS-7),
a burst encoder,
such as the RT-3 or
the GRA-71, an AC mains power supply unit
a 12V battery power supply unit, various battery chargers and a box
with various accessories, spare parts and tools.
The image on the right shows the transmitter (left), the burst encoder
(front), the 12V battery PSU (right, bottom) and the receiver (right, top).
Different configurations of the SP-15, and various types of burst
encoders, were used in different countries (see below).
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For use by agents, the radio set was usually packed in a leather
suitcase. For the Special Forces a special webbing unit
was available, allowing the units to be carried on the chest.
When used by stay-behind organizations (Gladio)
the various units were often stored in a water tight container.
The SP-15 was succeeded by the SP-20 in the
1970s, but remained in use in some countries well into the 1980s.
In The Netherlands, for example, the SP-15 was used until it was
replaced by the fully digital RACAL PRM-4150 in the mid-1980s.
Finally, all SP-15 units, and indeed all other spy sets in Europe,
were replaced by the pan-European FS-5000 (Harpoon)
built by AEG Telefunken.
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The receiver was developed by the German manufacturer Wandel &
Golterman (W&G) in 1958 and was given the designator BN-58.
The company is widely known for the production of high-end electronic test
equipment such as audio and HF spectrum analyzers and calibration equipment.
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The BN-58 is one of the first small receivers that was completely
transistor-based. It featured very low power consumption.
The double conversion superheterodyne receiver has an IF of 1.635 MHz
and covers 2.5-24MHz divided over two ranges.
This receiver was used again in the late-1970s, with the newer
SP-20 spy set, as it was considered better then the
newly designed digital receiver. For this reason, BN-58 receivers are
in short supply and are difficult to find.
 More information
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The SP-15 was sometimes equipped with an extra receiver
for the broadcast frequencies. It was suitable for the
reception of AM and CW signals. Like the FE-8 receiver (above)
it was fully transistorized and was built by the same
manufacturer.
More information
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Transmitter FS-7 (FSS-7, BN-22)
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The transmitter of the SP-15 was developed by Pfitzner
in Germany and was called FS-7.
It has two valves (EL95 for the oscillator and EL81 for the HF power amplifier)
and one transistor (OC450) and is suitable for CW (A1, morse) only.
The transmitter is also known as BN-22.
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Maximum power output was 10W or 20W, switchable from the PSU (see below).
The transmitter is crystal operated and the frequency is determined by a quartz
crystal which is inserted in a socket on the front left of the unit.
Some units were later modified for use with an external synthesizer
(see below).
More information
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Two different versions of the DC power supply unit were available
(12V and 24V) but only one of these was supplied with the SP-15
radio station.
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The version shown here is for use with 12V batteries, e.g. as used
in a car. It contains a power inverter with a fairly small transformer
and two PNP Germanium power transistors (AUY22, AD105 or TF90).
The power supply was used to set the maximum output power of the
transmitter. A switch at the front panel allowed selection between
20W and 10W (i.e. full and half power).
The pictures below give a good view of the interior of the PSU.
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A relay was used to prevent the unit from being connected the wrong way
around. The circuit diagram is glued inside the lid. At full power,
the PSU would draw approx. 8A from the battery.
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The SP-15 came with a large number of accessories, some of which are
shown here.
The most remarkable one is the surprisingly cheap looking morse key,
made of a rather poor quality plastic.
In use, the key is not as bad as it looks as it's rather heavy.
Furthermore, the plastic is shielded on the inside.
Other accessories include antennas and cables.
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In order to minimise the risk of detection during a transmission,
a burst encoder was often used in combination with the SP-15.
The burst encoder allowed a pre-recorded message to be played back
at very hight speed, so that the transmission was kept as short as
possible.
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The first burst encoder to be issued with the SP-15 was this
electro-mechanical RT-3 unit.
A small military-grade metal box that allowed a message of
25 characters to be stored mechanically. Once on-air, the message
was played back by operating a hand crank.
Later, more advanced burst encoders were issued, such as the
GRA-71,
MMP
and Speicher.
More information
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For a long time, the SP-15 was used in combination with the
American military GRA-71 burst encoder that allowed the dots and
dashes of the morse characters to be recorded on a piece
of ferro-magnetic (audio) tape.
Especially for use with the SP-15, they were supplied
in grey hammerite, rather than the usual black as
used by the US Army.
More information
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The Speicher (Eng: memory) was a fully electronic burst encoder
for sending numbers at high speed in morse code. It was powered
directly from the mains and was housed in a similar case as the
SP-20 spy radio set.
The Speicher was probably issued in the 1970s to replace the
rather limited RT-3.
Eventually it was replaced itself by the
more advanced MMP.
More information
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The MMP was a fully electronic high-speed (1200 baud) burst
encoder that was used with both the SP-15 and the
SP-20 spy sets.
The MMP replaced older devices, such as the mechanical
RT-3,
the American AN/GRA-71
and the early electronic Speicher.
It could hold more than 1000 letters and numbers in its battery-bakced
CMOS memory and send them at various speeds between 15 and 1200 baud.
More information
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For burst transmissions at very high speed, such as the 1200 baud
mode of the MMP burst encoder shown above, the existing keying methods
were not adequate and this primitive FSK Modulator was developed as
an alternative.
It was inserted between the crystal and the crystal socket of the
FS-7 transmitter.
More information
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For use by special forces and reconnaissance units, a special webbing
pack was developed that allowed the various units to be worn on the
chest. The webbing pack had a pocket for the transmitter and power
convertor and another one for the receiver and the accessories.
Power for the set was delivered by a separate (heavy) battery belt
that would be worn around the waist.
The belt contained 10 rechargeable NiCd batteries of 1.2V/10Ah each.
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Synthesizer
Dutch stay-behind
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In the Netherlands, the SP-15 was used for the national
stay-behind
organisation
O&I (Dutch: Operatiën en Inlichtingen)
during the 1960s and 1970s.
O&I agents were given two green water-tight containers that could be
burried underground, e.g. in the garden of their house. One of these contained
a hand gun, ammunition, cash money and gold (the latter for bribing people).
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The other one contained the SP-15 radio set,
together with a wide range of accessories
such as antennas, crystals spare parts and a burst encoder.
The image on the right shows a typical Dutch SP-15 container with some
of its content. Note the additional synthesizer on the right.
Nearly all Dutch SP-15 sets were destroyed in the early 1990s, when
most of the stay-behind organisations were dismantled.
As far as we know, only two complete sets have survived.
One is on public display
at the Royal Dutch Signals Museum
[4] as part of their spy-set collection.
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The other one is in the collection of Museum Jan Corver [2], the Dutch
HAM Radio museum in Budel (Netherlands),
where it was on public display in 2008 during the special
exhibition Secret Messages. This occasion
gave us the unique opportunity to examine this set more closely.
It is likely that the transmitter was initially crystal-driven, just
like the German version of the SP-15, but that it was later converted
for use with an external synthesizer. Evidence has been found in the
Dutch National Archives, that the synthesizer was added in the mid-1970s [5].
It was built for the Dutch organization by RACAL in the UK.
A complete set consisted of the following items:
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In total, the Dutch bought 160 synthesizers from RACAL around 1974
for the total amount of NLG 2 million (approx. 900,000 EURO). That
means that the price for a single synthesizer was EUR 5625 in 1974!
Part of this money was probably spend for the IFS-7 interface box
(see below).
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The standard FS-7 transmitter was modified for use
with the external synthesizer. The
crystal socket
at the front left of the unit was removed and replaced by
a small aluminium panel.
The modified transmitter was
designated FSS-7 (German: Frequenz Synthesizer Sender).
The wide black connector at the left side
was rewired in order to support the external RACAL synthesizer
and a small black interface box (IFS-7) was inserted
between transmitter and PSU,
with the new synthesizer connected to its front.
The image on the right shows the complete kit.
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A morse key, or an external burst encoder, was no longer directly
connected to the transmitter, but to a DIN socket on top of the IFS-7
interface at the center.
The IFS-7 also had a built-in calibrator (operated with the red
push-button) and a crystal socket
at the front, allowing the old crystals to be used again.
This was useful in case of a faillure of the synthesizer.
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The Dutch (Gladio) version of the SP-15 is known to have been
used in combination with various burst encoders. Some of these
were on display at the Dutch Signals Museum [4].
The only known surviving SP-15 container, that is now in the
collection Museum Jan Corver, was found with the Speicher
burst encoder shown in the image on the right.
More information
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Inside the container were two grey boxes with tools and accessories.
Each box was closed with a canvas strap to avoid the contents falling out.
Inside the boxes were the standard tools, such as srewdriver and pliers.
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Various adapters were supplied to allow connection to a variety of mains
(lamp) sockets. Two wire antennas were supplied, one for the receiver and
one for the transmitter, the latter being of the roll-up type (visible in
the image on the right).
Other accessories were earphones, fuses, insulators, test cables, audio
cables, insulation tape, earth (ground) connectors and a rechargeable
pocket light.
Detailed images below.
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- Helmuth (Jimboy) Meyer (DJ2EI), Agentenfunk!
Backgrounds on many different spy radio sets. 1
- Museum Jan Corver, Exhibition Secret Messages
The Dutch version of the SP-15 was on display during this exhibition.
- Louis Meulstee, Wireless for the Warrior, volume 4
ISBN: 0952063-36-0, September 2004.
- Museum Verbindingsdienst, Burst Encoders for Stay-Behind use
Dutch Signals Museum.
Photographed by Crypto Museum. 25 February 2009.
- Geschiedenis van de Sectie Algemene Zaken, Hoofdstuk VI, Consolidatie
History of the Section General Affairs, Chapter 6, Consolidation.
pp. 79 - 80 (Dutch)
Describing the period May 1970 - December 1981.
Dutch National Archives. Top Secret.
Partly declassified and released in 2007 under the FOI Act.
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© Copyright 2009-2013, Paul Reuvers & Marc Simons. Last changed: Saturday, 21 June 2014 - 08:20 CET
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