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RR-49 →
CIA spy radio transmitter · 1966

RT-49 was a short-wave spy radio transmitter for the 3 to 24 MHz frequency range, developed around 1966 for the US Central Intelligence Agency (CIA) as part of the RS-49 spy radio set. It was commonly used in combination with the RP-49 power supply unit and the RR-49 receiver.

The device is similar in controls and operation to the RT-3 transmitter of the RS-1 spy radio set and the RT-6 of the RS-6 radio set, but is much smaller and weigths less, due to the fact that it is fully transistorised. The device measures just 137 x 102 x 40 mm and weights just 700 grams.

In most cases the transmitter was operated by means of HC-6/U shaped crystals, as shown in the image on the right. It was also possible to use an external Variable Frequency Oscillator (VFO) or even a digital synthesizer, by using the 3-pin socket to the left of the crystal socket.
RT-49 with crystal installed

The device is suitable for transmission of CW signals only (morse code). Although it is possible to connect a regular morse key, the unit was usually connected to a KE-8 keyer that allowed pre-recorded messages to be transmitted at very high speed. This significantly reduced the on-air time and, hence, the chance of being discovered by means of Radio DIrection Finding (RDF).

HELP REQUIRED — At present, no further information about the RT-49 transmitter is available. We are looking for the full operating instructions and for the circuit diagram. We are also looking for the original RP-49 power supply unit. If you can provide any of these, or if you have additional information, please contact us.
RT-49 transmitter
RT-49 with crystal installed
RT-49 transmitter
RT-49 in upright position
Front panel
Secret CIA polaroid photograph of RS-49 agent radio [3]
Secret CIA polaroid photograph of RS-49 agent radio [3]
1 / 7
RT-49 transmitter
2 / 7
RT-49 with crystal installed
3 / 7
RT-49 transmitter
4 / 7
RT-49 in upright position
5 / 7
Front panel
6 / 7
Secret CIA polaroid photograph of RS-49 agent radio [3]
7 / 7
Secret CIA polaroid photograph of RS-49 agent radio [3]

The image below provides on overview of the controls and connections of the RT-49 transmitter. Power should be provided by the accompanying RP-49 power supply unit (PSU) that must be attached and latched to the left side of the transmitter. The DB9 connector at the left side mates with a connector on the side of the PSU. At the rear right – integrated with the black heat sink – are spring-loaded terminals for connection of the antenna and ground wires, and the receiver.

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When operating the device, a suitable crystal should be installed in the crystal socket at the bottom left and the band selector should be set to the corresponding frequency band. After connecting a suitable antenna, the red button marked KEY should be pressed, whilst the three tuning dials are adjusted for maximum signal, using the indicator lights to find the maximum.

The unit is now ready for use. Although it is possible to connect a regular morse key to the KEYER socket (pins D and F), the transmitter was normally used with a KE-8 keyer, to allow high-speed transmission of a pre-recorded message. This was done to reduce the risk of being discovered.

9-pin male socket at the left side
Antenna terminals
Band selector
RT-49 with crystal installed
1 / 4
9-pin male socket at the left side
2 / 4
Antenna terminals
3 / 4
Band selector
4 / 4
RT-49 with crystal installed

Power   J-100
At the centre of the left side of the transmitter is a 9-pin male DE-9 connector that mates with the female DE-9 connector on the RP-49 PSU. Below is the pinout when looking into the male connector on the transmitter [1].

  1. -
  2. Red
    +42V DC (from PSU)
  3. -
    not connected
  4. Yellow
    0V DC to keyer (isolated)
  5. Green
    –12V DC to keyer (isolated)
  6. -
    not connected
  7. -
    Receiver antenna
  8. -
    not connected
  9. White/orange
    Unknown 1
  1. Connector to centre pin of VFO connector.

Below is the pinout of the KEYER socket of the transmitter, when looking into the socket. The layout of this connector is identical to that of the socket on the KE-8 keyer, but note that there are additional lines that are not used by the KE-8. Also note that the 12V DC power supply for the keyer is isolated (pins C and H). This is necessary as the keyer uses negative logic.

  1. Black
    RF Ground
  2. White/red
    T/R relay control 1,2
  3. Green
    -12V DC power supply (to keyer)
  4. Blue
    Keyed signal (from keyer)
  5. Red
    +42V DC 2
  6. -
    Signal Ground
  7. Yellow
    0V power supply (to keyer)
  1. Active low.
  2. Not used by KE-8 keyer.

  • Year
  • User
  • Purpose
    Agent communication
  • Frequency
    3 - 24 MHz
  • Band
  • Modulation
  • Circuits
    Oscillator/doubler, PA
  • Power
    42V DC, 1.4A
  • Output
  • Dimensions
    137 x 102 x 40 mm
  • Weight
    700 grams
  • White
    3 - 6 MHz
  • Red
    6 - 12 MHz
  • Green
    12 - 24 MHz
  • RP-49 power supply unit
  • Power cable
  • Antenna wire
  • Ground wire
  • Morse key
  • CK-8 burst encoder
  • RP-49 power supply unit
  • Morse key
  1. RT-49 Transmitter, Operating Instructions 1
    CIA, date unknown.

  2. RP-49 Power Supply, Operating Instructions 1
    CIA, date unknown.
  1. Approved for release by CIA on 23 April 2014.

  1. Trip Report - Development f the RT-49 and RP/A-49
    CIA Memorandum, 28 February 1963

  2. Chief, OC-OS to Chairman, Equipment Board, Equipment Procurement
    CIA Memorandum, 2 January 1964

  3. Equipment Board staff meeting, Agenda
    CIA, 9 January 1964

  4. CIA Equipment Board staff meeting, minutes
    9 January 1964

  5. Trip Report - RT-49/RP-49
    24 November 1964

  6. Trip Report - RT-49/RP-49
    22 December 1964

  7. Trip Report - RR-49
    22 December 1964

  8. Inspection Report No. 1 - AN/B-62
    CIA Memorandum, 11 May 1966

  9. Inspection Report No. 5 - RT-49/RP-49
    17 June 1966

  10. Inspection Report No. 6 - RT-49
    CIA Memorandum, 21 June 1966

  11. Inspection Report No. 2 - AN/B-62
    CIA Memorandum, 24 June 1966

  12. Equipment Board Meeting, Agenda
    CIA, 8 November 1967

  13. Long-Range HF Communications Equipment
    7 April 1969
  1. Pete McCollum, The RS-49 HF Radio Set
    Retrieved November 2020.

  2. Louis Meulstee, RT-49
    Wireless for the Warrior, Volume 4, Supplement chapter 146. April 2017.

  3. Unknown source (probably CIA). Secret images of RS-49 set in suitcase
    Crypto Museum archive CM303622. Date unknown, but probably ~ 1965.
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Crypto Museum. Created: Thursday 05 November 2020. Last changed: Thursday, 20 April 2023 - 13:55 CET.
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