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USA WWII OSS CIA SBO
The set consists of a transmitter, receiver,
power supply unit (PSU) and a collection of spare parts,
each housed in a metal enclosure and covered by a removable lid. It was
usually supplied in a fibre board transit case, but was often
used outside the case and in varying configurations.
Some users operated it from within a travel suitcase.
The image on the right shows the dark green fibre board transit case with the various modules
in upright position, ready for use. Although the set is often shown
like this in museums, the lid cannot be closed as the receiver is too high. 3
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Prior to the US entering WWII, the OSS had a very basic radio set for
clandestine operations. It had the advantage that it could be powered from
both AC and DC mains networks, but had otherwise a number of design
deficiencies. This prompted the OSS to come up with an improved design [2].
The task was given to Major Henry Shore, who was a former employee of the
Radio Corporation of America (RCA). Shore wanted
RCA to be involved with the project, but the company was too busy with other
wartime projects for the US Government. It was then agreed that RCA
employee Earl Anderson would work on it in his own time, using the existing
AC/DC radio as a starting point.
The first version of the SSTR-1 was released in 1942, its name being a
combination of the model number of the transmitter (SST-1) and the receiver
(SSR-1).
The prefix 'SS' is the abbreviation of 'Strategic Services'
(OSS).
Throughout the war, the design was updated several times, resulting
in the addition of a letter-suffix to the model. 4
After the war, the SSTR-1 remained in use by the newly established CIA
until at least 1953, despite the fact that new
clandestine radio sets like the
RS-1 and RS-6 had meanwhile
become available [2].
The SSTR-1 was also used as a temporary solution by several European
Stay-Behind Organisations (SBOs)
in the early days of the Cold War —
for example in The Netherlands
and in Belgium — until it was replaced by newer radio sets.
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SSTR-1 is the abbreviation of Strategic Services Transmitter Receiver No. 1
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The SSTR-1 was known also as TR1, for example by the Dutch post-war
Stay-Behind Organisation O&I.
In that case, 'TR' is the abbreviation of Transmitter Receiver.
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The receiver has to be placed on its side
before the lid of the transit case can be closed.
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Receiver model numbers from SSR-1-A to SSR-1-G have been observed,
whilst transmitter model numbers range from SST-1-A to SST-1-E.
➤ More
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The image below gives an overview of the contents of the SSTR-1 transit case.
At the far left is the SSR-1 receiver, which is higher than the other modules.
It is powered by the SST-1 transmitter to its right. The transmitter is in
turn powered by the largest module: the SSP-1 power supply unit (PSU).
The PSU is powered by a 6V DC source,
or directly from the AC mains. The remaining space – at the far right –
is taken by the accessories and a range of spare parts.
The headphones should be connected at the top left of the receiver.
When transmitting, the operator can use the internal morse key – located
at the front edge – or the supplied external key, which can be connected
to the jack socket to the left of the internal key.
The transmitter produces ~ 15 Watts.
Note that in the setup shown above, it is difficult to operate the internal
morse key, as it is just below the edge of the fibre board transit case.
This indicates that the set was not intended for operation from within
the transit case, but had to be removed from it for proper use.
The PSU has three functions. It can act as a:
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Mains PSU For powering the device from the mains (90-230V AC) Inverter For powering the device from a 6V DC car battery Charger To charge a 6V battery from the AC mains
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From the start of WWII until his arrest by the Germans in February 1943,
van Schendel was the chief marconist
of the OD. He trained many clandestine radio operators 2 and
occasionally operated a clandestine station himself,
in particular for communication with England.
The OD mainly used radio sets provided by the British SIS
and SOE, such as the Mark V and Mark VII
(Parasets), the Type 3 Mark II (B2)
and the Type A Mark III (A3).
When these were in short supply however, radios from American origin were
supplied instead, such as this SSTR-1.
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The image above shows the SSTR-1 transmitter (SST-1) and receiver (SSR-1)
that were in possession of
Ton van Schendel
some time after WWII. It was used by the OD during the war
and/or by the Dutch Stay-Behind Organisation O&I
in the early days of the Cold War.
As far as we know,
these are the only surviving parts of van Schendel's radio set.
It is unknown whether the original PSU was lost, or whether it
was never provided. It is possible that the set had been supplied
without the original PSU and that an alternative PSU – made
locally by the OD – was used instead.
➤ More about Ton van Schendel
➤ More about the Ordedienst (OD)
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Stay-Behind organisations
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After WWII – at the beginning of the Cold War –
the SSTR-1 remained in use until at least 1953, despite the fact that
newer CIA spy radio sets, like the RS-1
and RS-6, had meanwhile become available.
In the early days of their existence, some European
Stay-Behind Organisations (SBOs)
used leftovers from WWII
as a gap-fill solution until newer sets became available to them.
The stay-behind use of the SSTR-1 is confirmed for the following countries:
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in most cases, the SSTR-1 was supplied in a dark green fibre board
transit case, such as the one shown in the image on the right. It contains
the receiver, transmitter, PSU and all accessories and spare parts.
The lid is held in place by 8 spring loaded clips, and has a rubber gasket
to make it water resistant. Note that this is not a suitcase.
The radio set has to be removed from the case before operation. In some cases,
the complete set was placed inside a regular travel suitcase.
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The receiver is the leftmost module in the transit case. It is
higher than the other module and has to be placed on its side before
closing the lid of the transit case. When in transit, the controls of the
receiver can be covered by a metal lid.
There were at least four versions of the receiver,
each with a different frequency range and specifications.
The one shown here is an SSR-1-G, which covers 2.4 to 16.3 MHz,
divided over two ranges which can be tuned freely.
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The transmitter is placed to the right of the receiver.
It is crystal-controlled and is suitable for the transmission of
CW signals (morse) only. When in transit, it can be
covered by a metal lid.
There are at least two versions of the transmitter, with
slightly different specification. The one shown here is an
SST-1-E. It covers 3 to 15 MHz and has an output power between
8 and 15 W.
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The PSU is the heaviest module and is placed to the right of the
transmitter. When in transit, it can be covered by a metal lid
that also holds 2 spare fuses.
The PSU allows the radio set to be powered from virtually any AC mains
network in the world between 90 and 230 V.
The PSU can also be used as a power inverter, in which case a 6V DC
source can be used to power the radio set. In addition, the PSU can be
used as a battery charger, allowing a 6V battery to be charged from the AC
mains.
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The SSTR-1 was supplied with the headphones shown in the image on the right.
It is connected to the SSR-1 receiver by means of a 6 mm jack.
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The transmitter is suitable for CW (morse)
transmissions only, and can be oprated with the
internal morse key located at the font edge.
The tranmitter can also be used with an external morse key, which
must be connected to the 6 mm jack sockeet to the left of the internal
morse key. The morse key shown in the image on the right was supplied with the
set featured here.
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The transmitter is crystal operated. The crystal socket, at the centre
of the transmitter, accepts a wide range of crystal shapes, such as the small
FT-243 shape and the larger US and UK crystals with a pin distance of
19 mm.
➤ Crystal shapes
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In most cases, the SSTR-1 was supplied with a wire antenna, consisting of
two long pieces of electric wire. An additional (short) piece of wire was
used to connect the radio set to ground.
In some cases, alternative antennas were used, such as the roll-up mesh antenna
shown in the image on the right. Ideally, each wire should be a ¼λ
long, but longer wires can easily be tuned for maximum RF output.
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To allow the SSTR-1 to be repaired in the field, it was supplied with a range
of spare parts, such as spare valves, fuses, vibrator, egg isolators, light
bulbs, tools, etc.,
some of which are shown in the image on the right.
➤ List of spare parts
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Operating instruction and technical descriptions were provided in the form
of the small A5-size booklet shown in the image on the right. It contains
many photographs of the exterior and interior of the modules, along with
clear descriptions on their use.
➤ Read the manual
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- 6J5
- 6K8
- 6SC7
- 6SG7
- 6SA7
- 6SQ7
- 6SN7
- 6L6
- 7V7
- 7J7
- 7F7
- 7Z4
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Device Clandestine suitcase radio set Purpose Agent communication Model SSTR-1 Year 1942 Country USA Organisation Office of Strategic Services (OSS) Development OSS employees,
Radio Development & Research Corporation,
Pioneer Electric and Research (Forest Park, IL, USA) Manufacturer Radio Development & Research Corporation (transmitter),
P.R. Mallory Co. (PSU),
Finch Telecommunications (Passaic, NJ, USA) Users OSS, agents, resistance, CIA, stay-behind Receiver SSR-1-A, D, E or G (see below) Transmitter SST-1-A or E (see below) PSU SSP-1-C, SSP-1-D, SSP-2, SSP-3 or SSP-4 (see below) Generator Hand-crank power generator GN-35 or GN-44
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Model SSR-1-A Frequency 2.8 - 16.6 MHZ Bands 3 (2.8-5.1 MHz, 4.5-9.1 MHz, 8.3-16.6 MHz) Circuits RF stage, Oscillator/Mixer, Detector/AF, AF amplifier Modulation AM R/T, CW Valves 6J5, 6K8, 6SC7 (2x) Dimensions 241 x 102 x 76 mm Weight 2300 grams
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Model SSR-1-D Frequency 2.9 - 16 MHZ Bands 2 (2.9-6.6 MHz, 6.6-16 MHz) Circuits RF stage, Oscillator/Mixer, IF stage, Detector/AF, BFO IF 2 MHz Modulation AM R/T, CW Valves 7V7 (3x), 7J7, 7F7 Dimensions 241 x 102 x 76 mm Weight 2300 grams
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Model SSR-1-E Frequency 2.7 - 17 MHZ Bands 2 (2.7-6.6 MHz, 6.5-17 MHz) Circuits RF stage, Oscillator/Mixer, IF stage, Detector, BFO/AF IF 455 kHz Modulation AM R/T, CW Valves 6SG7 (2x), 6SA7, 6SQ7, 6SN7 Dimensions 241 x 102 x 76 mm Weight 2300 grams
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Model SSR-1-G Frequency 2.4 - 16.3 MHZ Bands 2 (2.4-6.3 MHz, 6.2-16.3 MHz) Circuits RF stage, Oscillator/Mixer, IF stage, Detector/AF, BFO IF 2 MHz Modulation AM R/T, CW Valves 7V7 (3x), 7J7, 7F7 Dimensions 241 x 102 x 76 mm Weight 2300 grams
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Model SST-1A Frequency 3-14 MHz Bands 3 (3-5 MHz, 5-8 MHz, 8-14 MHz) Output 8 - 15 W Circuits Crystal oscillator/PA Valve 6L6
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Model SST-1A Frequency 3-15 MHz Bands 3 (3-7 MHz, 6-12 MHz, 8-15 MHz) Output 8 - 15 W Circuits Crystal oscillator/PA Valve 6L6 Dimensions 240 x 102 7.6 mm Weight 1800 grams
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Power supply unit
SSP-1-D
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Mains 90, 110, 125, 150, 200, 230 V AC (40-60 Hz) Battery 6V DC Valve 7Z4 Dimensions 241 x 152 x 89 mm Weight 4500 grams
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- 2 × Antenna wire
- 4 × Antenna insulators
- Coupling plug (for German wall outlet)
- Coupling plug (for French Domestic wall outlet)
- Solder
- Bypass condensers
- Filter condensers
- Vacuum tube 6L6
- Pilot light
- Ground clamp
- Alligator clip
- Spare fuses
- Screw driver
- Knife
- Vibrator unit
- Neon bulb
- Crystal socket adapter
- Vacuum tubes 3 × 7V7, 1 × 7Q7, 1 × 7F7
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- Louis Meulstee, Wireless for the Warrior, volume 4
ISBN 0952063-36-0, September 2004.
- Peter McColum, The SSTR-1 "Suitcase Radio"
Retrieved May 2021.
- Cor Moerman, SSTR-1 radio set of Ton van Schendel - THANKS !
Donated November 2020.
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© Crypto Museum. Created: Friday 21 May 2021. Last changed: Tuesday, 16 July 2024 - 13:46 CET.
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