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Cold War
TI-462 B   PLUTO
Spy radio transmitter - wanted item

The TI-462 B was a small valve-based crystal-operated agent's transmitter, developed in 1956 in Czechoslovakia by Správa 6 1 for used by the secret state police (StB) and Správa 1. It was supplied as part of the PLUTO spy radio set and covered a frequency range of 3-12 MHz (or 2-8 MHz on some versions), with an output power between 10 and 12 W. The built-in mains power supply unit (PSU) was also used for powering the complementary PLUTO TI-462 A receiver.

The transmitter measured 19 x 10 x 4.5 cm, roughly the same as the receiver, and weighted 1.52 kg. Apart from the PLUTO receiver, the transmitter was supplied with an accessory box of the same size, in which the crystals, morse key, earphones, wire antennas, etc. were stored.

The TI-462 B was suitable for transmissions in morse code (CW) and was usually operated in combination with the built-in automatic morse keyer of the receiver. As an alternative, it could be also used with the small manual key that was mounted towards the front of the accessory box.
Pluto accessory box. Photograph copyright Detlev Vreisleben [3].

The appropriate mains voltage is selected with the fuse. A suitable crystal should be inserted at the front of the radio and three knobs on the top panel (coupling and tuning) should be adjusted for maximum antenna current, using the small neon indicator at the front edge as a guide.

  1. Správa 6 refers to Government Department 6: Communication Technology.

At least two different versions of this transmitter are known to have existed, but it is currently unclear which one came first. The following variants are currently known:

  • Mark I
    This version has a frequency range of 2-8 MHz (same as the initial receiver) and accepts HC-4U and FT-243 crystals that were inserted into a socket at the front.

  • Mark II
    This version has a frequency range of 3-16 MHz (roughly the same as the modified receiver) and requires circular pill-shaped crystals, just like the later NEPTUNE transmitter, that are inserted into a slot at the front.
Help required
We have the full original documentation of the PLUTO spy radio station, which is available for download below. Please note however that the pages are barely readable as they have faded over time. The text is in Czech/Slovak. If you can translate this to English, please contact us.

Technical specifications
  • Frequency range
    3-12 MHz (or 2-8 MHz)
  • Modulation
  • Output power
    10-12 W
  • Antenna imp.
    60-5000 ohm (assymmetric)
  • Weight
    1.52 kg
  • Dimensions
    190 x 100 x 43 mm
  • Mains voltage
    120 / 220 V AC
  • Consumption
    ± 50W
  • Valve
  1. PLUTO Technical Manual (without circuit diagrams)
    1956 (page 1 missing, scanned from original faded document).

  2. PLUTO circuit diagrams
    1956 (scanned from original faded document).
  1. Anonymous, Documentation of PLUTO spy radio set - THANKS!
    Documentation kindly donated by anonymous former user. July 2015.

  2. Louis Meulstee, Wireless for the Warrior, Part 4 Supplement
    Forthcoming. Accessed August 2015.

  3. Detlev Vreisleben, Photographs of missing PLUTO items
    Germany, 10 February 2005. Received August 2015.
Further information
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Crypto Museum. Created: Friday 31 July 2015. Last changed: Wednesday, 28 February 2018 - 23:47 CET.
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