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RFT UFT-421
Body wearable Stasi surveillance radio

The UFT-421 is a body wearable covert transceiver built by VEB RFT Funkwerk Dresden in the former DDR (East Germany) in the late 1960s. The radio is rather large, but has a somewhat curved shape which allows it to be carried on the body. It was intended for surveillance tasks and was often used by the Stasi (DDR Secret Police) for observation of suspicious persons. The UFT-421 was considered a special radio and as such it was listed in the Handbuch Sondertechnik [2].

For concealed use, the radio was supplied with a bracket with elastic straps, so that it could easily be hidden under the operator's clothing. A cable, that was usually running through the operator's sleeve, connected the radio to a remote control unit that was carried in the hand of the operator.

The image on the right shows the curve-shaped transceiver of the UFT-421 (center) together with the remote control unit which is visible at the left. The remote control unit holds the volume control, plus two control switches: one for the receiver and one for the transmitter.
  
Complete UFT-421 surveillance radio

The UTF-421 was available in two frequency ranges: 33-88 MHz and 146-174 MHz. The first radios entered service in the late 1960s and the radios were produced well into the 1970s, until they were succeeded by the much smaller Czechoslovakian Tesla PR-35 FAUN in 1977.

The box in which the UFT-421 was shipped Contents of the box Complete UFT-421 surveillance radio Overview of all UFT-421 parts Remote control unit Microphone/speaker combination, disguised as Mikki Radio Vibrator connected to the main unit Battery compartment
Main UFT-421 body Using the control unit Vibrator Operating the transmitter Top panel of the main unit, with channel selector, microphone/speaker connection and antenna socket. UFT-421 in holster Holster Ironically, the text on the main body is in English
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The box in which the UFT-421 was shipped
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Contents of the box
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Complete UFT-421 surveillance radio
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Overview of all UFT-421 parts
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Remote control unit
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Microphone/speaker combination, disguised as Mikki Radio
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Vibrator connected to the main unit
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Battery compartment
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Main UFT-421 body
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Using the control unit
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Vibrator
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Operating the transmitter
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Top panel of the main unit, with channel selector, microphone/speaker connection and antenna socket.
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UFT-421 in holster
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Holster
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Ironically, the text on the main body is in English

Controls
The UTF-421 was a two-way (simplex) radio, with a maximum of four channels that were selectable with a rotary switch on the main unit. The unit was supplied with two antenna's: a rod antenna and a wire antenna. The latter was an open dipole that could easily be hidden under the operator's clothing. The radio is powered by 2 stacked 7.2V NiCd batteries (14.4V total).

The transceiver was supplied with two further accessories: a vibrator unit that could be carried in the pocket, and a speaker/microphone combination that was disguised as an ordinary Mikki transistor radio. Such radios were commonly used in the DDR at the time and would not attract any attention of the public.

It allowed the operator to sit, say, on a bench in a park, pretenting to be listening to a normal broadcast, whilst in reality he was receiving his instructions. The vibrator was used to call an agent who had his volume turned down.
  
Operating the transmitter

The transmitter is controlled with a three-position momentary switch (see above) on the remote control unit. In the center position, the transmitter is off. The other two positions are: SmT (Senden mit Tonruf), for transmission with selective call (tone), and SoT (Senden ohne Tonruf), for transmission without selective call. As the transmitter has a rather low RF output power (0.4 W), the operational range was limited. Under ideal conditions a maximum of 5 km was possible, but when the antenna was carried on the body, the range was sometimes limited to less than 100 m.

The receiver is controlled by another three-position switch. In the center position, the receiver is off. The other two settings are: EmR (Empfang mit Rauschsperre), for reception with squelch, and EoR (Empfang ohne Rauschsperre), for reception without squelch (i.e. open squelch).

Help needed
We are still looking for the operator's manual for this radio. If you have this manual or if you have any other useful informtion that can help us to expand this page, please contact us.

Technical specifications
  • Power: 14.4V DC ± 10%
  • Current: 20-35 mA (RX), 145 mA (TX)
  • Frequency range: 33-88 MHz and 146-174 MHz
  • RF output: 400 mW
  • Tone-call: 1750 Hz ± 50 Hz
  • Dimensions (main unit): 210 x 120 x 35 mm
  • Weight: 500 g
  • Operational range: 50 m to 5 km (depending on antenna and circumstances)
Checklist
  • UTF-421 transceiver (main unit)
  • Remote control unit with cable
  • Vibrator
  • Dipole wire antenna
Other Stasi radios
References
  1. RFT, Begleitheft für Nachrichtengeräte
    Maintenance booklet for radio equipment, 60 pages, November 1973 (German)

  2. Handbuch Sondertechnik, Band 1
    Ministerium des Innern - Publikationsabteilung. 1981. p. 174-178. (German)
    Courtesy Detlev Vreisleben.
Further information
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Crypto Museum. Created: Friday 30 March 2012. Last changed: Tuesday, 13 June 2017 - 17:51 CET.
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