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Cold War
PLUTO   TI-462
Clandestine spy radio station

PLUTO was a modular spy radio station, developed in 1956 in Czechoslovakia by Správa 6 1 for the secret state police (StB) and Správa 1 (espionage), mainly in Western Europe. The radio station consisted of three modules: a receiver, a transmitter and an accessory box, and was intended for clandestine operations on behalf of the Ministry of Interior during the Cold War.

The transmitter was crystal-based and covered a frequency range from 3 to 12 MHz. It had an output power of approx. 12 W, suitable for an operational range of about 1000 km, making PLUTO the ideal radio station for clandestine transmissions from West European countries.

The transmitter was used for sending messages in morse code by means of a small external morse key, supplied in the accessory box, or an automatic keyer that was part of the receiver. In the latter case, a plastic paddle was inserted and attached to the front right of the receiver.

Of the initial version of PLUTO, only 11 complete radio stations were ever built [1]. The receiver was produced in larger quantities, for stand-alone use as well as part of the later SIRIUS spy radio set. Very few PLUTO receivers have survived and most transmitters have been destroyed after they were taken out of service. A complete PLUTO radio set is on public display at the Police Museum in Prague [3]. PLUTO was succeeded in the early 1960s by the more powerful SIRIUS.

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

PLUTO receiver
PLUTO transmitter
Accessory box
Receiver   TI-462 A
The free-running receiver can be adjusted from 2-8 MHz divided over 2 ranges (or 4-16 MHz on the later version). Audio is provided at a level suitable for the supplied crystal earphones.

The receiver is powered by the transmitter, to which it is connected via a metal 6-pin 270° DIN connector that is stored in a compartment at the rear right corner. The early version of the receiver had a built-in automatic morse keyer.

 More information
PLUTO receiver (TI-462A)

Transmitter   TI-462 B - wanted
The transmitter has the same form factor as the receiver and is crystal-operated. It covers a single frequency of 3-12 MHz (2-8 MHz on some versions) and delivers an output power of 12 W, suitable for a distance of ± 1000 km.

Most transmitters were destroyed once they were decommissioned. A good example is on public display at the Czech Police Museum [3].

 More information
Pluto accessory box. Photograph copyright Detlev Vreisleben [4].

Accessory box   TI-462 P - wanted
The radio station was supplied with a small metal accessory box that had the same form factor as the transmitter and the receiver. It contained crystals, wire antenna, power cables, morse key and other accessories.

Most accessory boxes were destroyed once the radio sets were decommissioned. A good example is on public display at the Czech Police Museum [3].
Pluto accessory box. Photograph copyright Detlev Vreisleben [4].

Manual morse key
Mains voltage checker
Mains power cable
Morse key
A simple manual morse key was supplied as part of the accessory kit. It was intended as a backup in case the automatic keyer could not be used, and could be mounted inside the accessory box in such a way that the knob would stick out at the front, allowing the operator to use it directly.

The key has a short cable with two banana-type plugs at the end. It should be connected to the banana sockets at the right side of the receiver.
Morse key

Mains checker
The order to check whether the mains voltage is present and to determine its average voltage, a small mains checker in the shape of a universal mains plug was supplied. One of its sides is transparent allowing the operator to watch the internal neon lamp (closest to the contact pins).   
Mains voltage tester

PLUTO was supplied with a small crystal earpiece that was connected to the right side of the receiver, just above the banana sockets.

Earphones of this type were rather common in those days, as they were also used with the hearing aids of the era.

Mains power cable
This power cable was used to connect the TI-462 B transmitter to the mains AC network. By using a slimline plug with just two pins, it will fit most of the common wall sockets in Europe.

The power supply unit (PSU) of the TI-462 B could be adjusted for a variety of mains voltages, making it possible to operate the radio virtually anywhere in the world.
Mains cable

Other accessories (not shown here)
  • Mains power cable
  • Wind-up antenna
  • Crystals
  • Spare valve

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.

  • Transmitter
    2-8 MHz, or 3-12 MHz (crystal operated)
  • Output power
    15 W
  • Range
    1000-1500 km
  • Area
    Western Europe
  • Receiver
    2-8 MHz and 4-16 MHz (VFO)
  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, PLUTO receiver - THANKS!
    Receiver and documents kindly donated by anonymous former user. July 2015.

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

  3. Czech Police Museum (Muzeum Policie ČR)
    Retrieved August 2015.

  4. 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 - 23:42 CET.
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