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A-610   SEZHA
Spy radio receiver · 1976

A-610, codenamed SEZHA 1 (Russian: СЕЖА), is a miniature transistorised short-wave (SW) spy radio receiver, developed and manufactured around 1976 by Alfa 2 in Riga (Latvia). 3 It was used during the Cold War for agent communication by the Soviet KGB and other intelligence services of the former USSR and Warsaw Pact states. It is believed to be modelled after the American RR-49.

The receiver is housed in a die-cast aluminium enclosure that measures 110 x 75 x 42 mm and weights 470 grams. The control panel labels are in English. This was done to confuse foreign law enforcement agencies when the device was accidentally discovered, but also to aid foreign agents who generally did not speak Russian.

The A-610 was supplied with accessories in a watertight metal container. It is freely adjustable (VFO), but was also supplied with 25 miniature quartz crystals in a plastic container, for the reception of predetermined SW radio channels.
  
A-610 (SEZHA) receiver

The A-610 is very similar to the American RR-49, which is more than 10 years older (1964), and serves the same purpose. It therefore seems likely that it was modelled after the RR-49 after the latter had been found on captured American spies. As far as we know, the A-610 was used as a stand-alone receiver. It does not seem to be part of a complete radio station.

  1. SEZHA (СЕЖА) is a Russian word which means face. Also transliterated as SEJA.
  2. Until 1971 known as Radiotehnika - Rigas Radio Rupnica (RRR). Alpha was liquidated in 2006.  Wikipedia
  3. At the time, Latvia was part of the Soviet Union (USSR).

PLEASE HELP — We are still looking for additional information about this miniature receiver from the Soviet era, such as operating instructions, a service manual and the circuit diagram. If you can provide any of these, please contact us. We would also like to hear from former users of this device.
RR-49 and accessories stowed inside the container
A-610 with storage container
A-610 (SEZHA) receiver
A-610 (SEZHA) receiver
A-610 (SEZHA) receiver
Front panel
A-610 with earpiece connected
Russian A-610 SEZHA (left) aside the American RR-49
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RR-49 and accessories stowed inside the container
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A-610 with storage container
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A-610 (SEZHA) receiver
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A-610 (SEZHA) receiver
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A-610 (SEZHA) receiver
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Front panel
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A-610 with earpiece connected
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Russian A-610 SEZHA (left) aside the American RR-49

Features
The diagram below provides a quick overview of the controls and connections of the A-610. The device measures 110 x 75 x 42 mm and weights 470 grams. It is housed in a grey extruded metal enclosure and has a die-cast aluminium front panel, that is painted in a slightly brighter grey tone. The internal parts, controls and antenna terminals are all mounted to the front panel.

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At the upper edge is a film-based frequency tuning scale. It has two controls just above the scale: one for coarse and one for fine tuning. If neccessary, the scale can be calibrated by turning on the built-in calibrator (at the bottom right), tuning the frequency until a tone is heard, and lining up the vertical index line with the nearest 1 MHz mark on the scale, using the scale calibration knob.

Antenna and ground wires should be connected to the spring-loaded terminals at the right. The supplied earpiece should be connected to one of the headphones sockets at the left side. The unit is powered by an internal 9V battery and is switched on by turning the volume knob at the bottom left away from the OFF position. For the reception of CW signals (morse code) the BFO should be enabled and adjusted. When crystals are used to determine the reception frequency – instead of the VFO – the switch below the frequency scale should be set to the XTAL position.

American twin
The A-610 is very similar to the RR-49 receiver that was used by the US Central Intelligence Agency (CIA) for the same purpose. The two receivers are shown side-by-side in the image below. Not only are the dimensions very similar, the functions and features are nearly identical. It seems therefore likely that the Soviet A-610 (SEZHA) was modelled after the American RR-49.

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Apart from the similarities, there are also differences. The front panel of te A-610 is made of die-cast aluminium, whilst the RR-49 is housed in a molded enclosure. The crystal socket of the A-610 is suitable for different types of crystals, whilst the RR-49 is only suitable for HC-6U crystals.

 More about the RR-49


Parts
Watertight storage case
A-610 (Sezha) receiver
Quartz crystals
Miniature earpiece
Wire antenna
Ground clip
Storage case
The complete kit is stowed in a watertight grey metal container. The container consists of two metal shells held together by two spring-clips and a rubber gasket at the centre.

The bottom half of the container holds the A-610 receiver, a plastic container with crystals, an earpiece and a ground clip. The upper half – i.e. the lid – holds the spool with the antenna wire, and a piece of felt that protects the front panel of the receiver when in transit.

  
Metal watertight storage container with RR-49 receiver

Receiver
The image on the right shows the bare receiver. After installing a 9V battery, the only additional part needed to operate it, is an earpiece and, of course, a suitable antenna. Using the built-in Variable Frequency Oscillator (VFO), it can be tuned to any frequency in the 3 - 24 MHz range.

In addition, a crystal can be used to use the receiver on a single predetermined channel. A plastic container with 25 such crystals, was supplied with the kit.
  
A-610 (SEZHA) receiver

Quartz crystals
Each receiver was supplied with a small white plastic container with 25 crystals, that could be used for the reception of predetermined radio channels. The frequencies ( in kHz) are printed inside the lid of the container.  List

When unused, the crystal container was normally stowed inside the storage case, aside the A-610 receiver.
  
Inside the crystal container

Earphone
The A-610 has two sockets for the connection of an earpiece, such as the one shown in the image on the right. It allows up to two persons to listen simultaneously. One earpiece was supplied with the receiver.

Note that a typical 2.7 mm USSR mono jack plug is used, which is not compatible with the more common Western 2.5 or 3.5 mm jack.
  
Russian earpiece

Wire antenna
Like most other short-wave spy radio sets, the receiver is supplied with a suitable wire that can be used as antenna. The wire has a plug at one end that can be fitted in the antenna terminal of the receiver.

When unused, the antenna wire is wound onto a metal spool and stowed in the lid of the storage container, where it is held in place by two clips.

  
Antenna wire

Ground clip
The metal crocodile clip shown in the image on the right was supplied with the kit, to allow the ground terminal of the receiver to be connected to a suitable ground (earth), such as the water supply, a heating pipe or the mains ground.

When unused, the clip is stowed in the storage container.
  
Ground clip

Metal watertight storage container with RR-49 receiver
Inside the container
RR-49 and accessories stowed inside the container
Accessories
Earpiece, ear clip, ground clip and crystals
A-610 and crystal box inside storage container
A-610 with storage container
Battery compartment
Crystal container
Crystal container
Inside the crystal container
Inside the crystal container
Russian earpiece
A-610 with earpiece connected
Antenna wire
Ground clip
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Metal watertight storage container with RR-49 receiver
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Inside the container
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RR-49 and accessories stowed inside the container
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Accessories
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Earpiece, ear clip, ground clip and crystals
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A-610 and crystal box inside storage container
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A-610 with storage container
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Battery compartment
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Crystal container
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Crystal container
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Inside the crystal container
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Inside the crystal container
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Russian earpiece
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A-610 with earpiece connected
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Antenna wire
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Ground clip



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Interior
The interior of the receiver can be accessed by removing three recessed miniature screws from the bottom panel, after which the die-cast aluminium front panel can be extracted from the case shell at the bottom. All internal parts are mounted to the front panel, with only the 9V battery compartment and the two jack sockets for the earphones fitted inside the bottom case shell.

Although the exterior of the A-610 receiver is very similar to the American RR-49, the interior is completely different. The design has a typical 1970s Soviet signature, but is extremely well built, as is clearly visible in the images below.

The image on the right shows the densely constructed interior as seen from the top left, with the frequency film scale at the front edge. There are several printed circuit boards (PCBs) that are mounted with the solder side up. At the centre are the 3-gang tuning capacitor and the RF filters for each of the three frequency bands.
  
Interior

A-610 (SEZHA) removed from its enclosure
Interior
Interior
Interior
Internal close-up of the frequency scale
Internal close-up of the frequency scale
Interior detail
Spring-loaded wire terminals for antenna and ground, with black plastic push-button
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A-610 (SEZHA) removed from its enclosure
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Interior
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Interior
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Internal close-up of the frequency scale
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Internal close-up of the frequency scale
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Interior detail
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Spring-loaded wire terminals for antenna and ground, with black plastic push-button

Restoration
The A-610 is built from first class components, so it is unlikely that you will have to restore or repair it, should you ever find one. There are a few things to watch out for though. Due to the use of low-quality plastics and plasticisers — the stuff that gives cables their flexibility — any plastic parts may get damaged when the plasticisers start to evaporate. It is important to realise that in a closed environment like the watertight storage container, these gasses have nowhere to go, and will eventually deteriorate any plastic parts and potentially also the front panel of the receiver.

With the device featured here, traces of plastic deterioration caused by evaporating plasticisers are visible as a series of stains on the plastic crystal container. It was caused by a short piece of cable that was packed inside the container. Similar traces were found on the white styrofoam (polystyrene) interior of the storage container where it has been in direct contact with a cable.

Another example of bad plasticisers are the two push-buttons for the antenna and ground wires, at the right edge of the front panel of the A-610. Over time, these buttons have become brittle.
  
Spring-loaded wire terminals for antenna and ground, with black plastic push-button

When we obtained our A-610, one of the two black plastic knobs already had a crack that a previous owner had attempted to repair with glue. As the glue was blocking the spring-loaded terminal, we tried to remove the knob, but in doing so, it complately disintegrated. The other knob followed suit and also had to be considered lost. Both knobs were eventually replaced.

WARNING — Due to the application of bad plastics and plasticisers, the gasses from evaporating plasticisers may cause damage to other plastic parts and to painted surfaces. When storing the device, leave the storage container open to allow the gasses to escape.

Video footage
The following short video clip was made by Harry Sever and is available on YouTube [2]. It shows how well this miniature solid-state receiver from the 1970s still works after so many years. Harry uses it for the reception of radio amateurs on the short-wave (SW) amateur radio bands.




Specifications
  • Model
    A-610
  • Name
    Sezha (СЕЖА)
  • Product
    XM2.003.000
  • Year
    1976 (est.)
  • Organisation
    KGB and Warsaw pact intelligence agencies
  • Purpose
    Agent communication
  • Manufacturer
    Alfa, Riga (Latvia)
  • Principle
    Superheterodyne, VFO and crystal operated
  • Frequency
    3 - 24 MHz
  • Bands
    3 (see below)
  • Modulation
    AM, CW, SSB
  • Antenna
    Wire
  • Power
    Internal dry battery
Frequency bands
  • White
    3 - 6 MHz
  • Yellow
    6 - 12 MHz
  • Red
    12 - 24 MHz
Accessories
  • Metal container
  • A-610 (Sezha) receiver
  • Plastic box with crystals
  • Wire antenna
  • Earphone
  • Battery
Crystals
Supplied crystals in plastic container (in MHz):

  • 6.307
  • 7.401
  • 7.836
  • 8.286
  • 8.756
  • 9.417
  • 10.388
  • 10.824
  • 11.477
  • 12.382
  • 12.892
  • 13.528
  • 13.956
  • 14.776
  • 15.799
  • 16.227
  • 16.657
  • 17.173
  • 17.617
  • 18.447
  • 18.890
  • 19.328
  • 19.740
  • 20.203
  • 20.599
References
  1. Louis Meulstee, Seja
    Wireless for the Warriour - Volume 4, Supplement chapter 270.

  2. Harry Sever, SPY receiver A610 SEZHA
    YouTube. 19 November 2016

  3. History of the Latvian Soviet Radios
    Retrieved March 2021.
Further information
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Crypto Museum. Created: Sunday 14 February 2021. Last changed: Wednesday, 31 March 2021 - 20:26 CET.
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