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SSTR-1
WWII clandestine spy radio set - this page is a stub

The SSTR-1, also known as TR-1, 1 was a modular valve-based clandestine transmitter/receiver set, also known as a spy radio set, developed in 1942 for the US Office of Stratic Services (OSS) — the forerunner of the CIA. During World War II (WWII), the set was used extensively by OSS agents operating on occupied (European) territory, by resistance organisations throughout Europe and in the China-Burma-India theatre [1]. It is the American equivalent of the British Type 3 Mark II (B2).

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 suitcase-style storage case, but was often used outside the case and in varying configurations.   

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). Throughout the war, the design was updated several times, resulting the addition of a letter-suffix to the model. 2 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]. It 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 – until it was replaced by newer sets.

  1. The SSTR-1 was known also as TR-1, for example by the Dutch post-war Stay-Behind Organisation O&I. It is believed that 'TR' is the abbreviation of Transmitter Receiver.
  2. Receiver model numbers from SSR-1-A to SSR-1-G have been oserved, whilst transmitter model numbers range from SST-1-A to SST-1-E.

Features
...

Known usage
Ton van Schendel
A special example of the SSTR-1 is shown in the image below [3]. It is of WWII vintage and was owned by Dutch resistance fighter Ton van Schendel. During the war, he worked for the Dutch radio monitoring service, the RCD, and simultaneously — covertly — for the Ordedienst (OD). 1

From the start of WWII until his arrest in February 1943, van Schendel was the chief marconist of the OD. He trained a large number of clandestine radio operators (marconists) and occasionally operated a clandestine radio set 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 the SSTR-1.
  
SSTR-1 transmitter and receiver

The image above shows the SSTR-1 transmitter (SST-1) and receiver (SSR-1) that were in posession 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 knonw, these are the only surviving parts of his SSTR-1 radio set. It is unknown whether the original power supply unit (PSU) was lost, or was never supplied. It is possible that the set was supplied without the original PSU and that an exsiting PSU of the OD was used instead.

  1. During WWII, the Ordedienst (Order Service) was one of three major resistance organisations in The Netherlands. It provided intelligence to the British MI6 and to the Dutch Government in exile in London. Its task was to act as a law enforcement agency immediately after the liberation of The Netherlands.  More

SSTR-1 transmitter and receiver
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SSTR-1 transmitter and receiver

Stay-Behind organisations
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 (SBO) – such as the Dutch Operatiën & Inlichtingen (O&I) – used WWII leftovers including the SSTR-1.

Parts
Fibre suitcase-style storage case
Transmitter SST-1
TX
Receiver `SSR-1
RX
Power supply unit `SSP-1
PSU
Container with spare parts and accessories
Wire antenna
Transit case
...   

Transmitter   SST-1
...   

Receiver   SSR-1
...   

Power supply unit   SSP-1
...   

Spare parts
...   

Wire antenna
...   

Interior
...

Connections
Valves
  • 6J5
  • 6K8
  • 6SC7
  • 6SG7
  • 6SA7
  • 6SQ7
  • 6SN7
  • 6L6
  • 7V7
  • 7J7
  • 7F7
  • 7Z4
Specifications
  • Type
    Clandestine suitcase radio set
  • Year
    1942
  • Purpose
    Agent communication
  • 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)
  • 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
Receiver   SSR-1-A
  • 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
Receiver   SSR-1-D
  • 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
Receiver   SSR-1-E
  • 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
Receiver   SSR-1-G
  • 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
Transmitter   SST-1-A
  • 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
Transmitter   SST-1-E
  • 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
Power supply unit   SSP-1-D
  • 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
Power supply unit   SSP-1-D
  • Same as SPP-1D, but can also charge 6V battery from mains
References
  1. Louis Meulstee, Wireless for the Warrior, volume 4
    ISBN 0952063-36-0, September 2004.

  2. Peter McColum, The SSTR-1 "Suitcase Radio"
    Retrieved May 2021.

  3. Cor Moerman, SSTR-1 radio set of Ton van Schendel - THANKS !
    Received November 2020.
Further information
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Crypto Museum. Created: Friday 21 May 2021. Last changed: Friday, 21 January 2022 - 09:39 CET.
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