Spy radio
Burst encoders
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Severok-K   Северок-к
Russian spy radio set

Severok-K is a true spy radio developed in the USSR around 1993, approx. four years after the fall of the Berlin Wall (1989) and two years after the collapse of the Soviet Union (1991). The silver version of the radio was used internationally for espionage operations and comes with a large number of accessories, including a small light-weight digital burst encoder, various antennas, a battery belt, micropone, headphones, speaker, frequency plug-in units and carrying pouches.
The transceiver can be operated on a limited number of frequencies, that can be set by a combination of a frequency plug-in module and two thumbwheels along the top-edge of the front panel of the main unit.

The image on the right shows the control panel of this rather small radio. All text is in English and the case is finished in silver hammerite, indicating that it was used for international (espionage) purposes. The receiver was also available in the typical Russian 'sand' colour, mainly intended for use by Special Forces (SF).
Severok-K radio

The use of plug-in modules for the various frequency bands was common on early Cold War spy radio sets, such as the R-350 and the R-350M, but was later dropped as they became integrated with the radio. A recent example is the digital R-394KM. It is therefore rather strange that this feature was re-introduced on the Severok-K, despite the fact that it is digital. It is a small radio that can be carried on the human body, but it is a multi-box solution that appears rather clumsy next to the fully self-contained R-394KM, that was introduced several years earlier, in 1988.
Severok-K in carrying pouch Severok-K radio Severok-K with ancillaries in special carrying pouch Severok-K in operation Accessories of the Severok-K Serverok-K Burst Encoder Battery belt Severok-K documentation

The Severok-K is supplied in a large wooden box that contains the radio, a large metal box with the smaller accessories, the antennas, the batteries, a battery charger, documentation, etc.

The image on the right shows the water-tight metal container that holds the smaller items. It is similar to the case of the R-394KM radio. The images below give a good impression of the number of acessories that was supplied. Each item is described in more detail below.
Accessories of the Severok-K

Water-tight metal container Inside the metal container Accessories of the Severok-K Water-tight metal container open Severok-K radio Serverok-K Burst Encoder Wire antenna
 Power filter Cabel for connection to an external battery Vertical antenna holder Double-size screwdriver DKM-S cable Unpacking the frequency plug-ins Battery liquid Plastic box with spares
Kulikov antenna (folded) Block-S Amplifier with built-in speaker battery charger Battery belt Microphone and headset Severok-K in carrying pouch Antenna mast

The main unit is the Severok-K radio itself. Although it is rather small, and therefore very portable, it is not fully self-contained and needs a number of additional devices for its operation. When in operation, the radio station consists of the Severok-K radio, an external battery (belt), a microphone-speaker combination, an antenna, a speech encryption unit and a burst encoder.
All parts are connected via wires, making the total setup rather cumbersome and clumsy. Special carrying pouches can be used to allow the radio and its many accessories to carried on the body. This was probably standard issue with the Russian Special Forces (SF).

The image on the right shows the control panel of the radio. It has three sockets (for power, antenna and microphone) and a range of thumb-wheel selectors. Frequency setting is at the top right (x10 and x1). At the center is the CODE switch that enables encrypted speech mode.
Severok-K radio

Severok-K radio Severok-K with frequency plug-in and Block-S Fitting a frequency module Switching on BLOK-S (Code) Tuning the antenna Tuning the antenna Fitting the vertical antenna Severok-K with vertical antenna

Frequency plug-ins
The Severok-K is supplied with 11 frequency plug-in units, allowing the radio to be operated on 11 non-contiguous frequency segments. One plug-in is normally installed at the side of the radio, whilst the remaining 10 units are stored inside the metal storage container, or are carried around the waist, each in its own cloth pouch.

At the bottom of each plug-in unit is a row of 24 contacts (2 x 12) through which it is connected with the radio. The plug-in can be swapped whilst the radio remains inside its pouch.
Frequency plug-in unit 6.7 MHz

Unpacking the frequency plug-ins The frequency plug-ins stored inside the metal container Close-up of the frequency plug-ins inside the container Frequency plug-in unit 6.7 MHz Frequency plug-in unit 6.7 MHz Bottom view of a frequency plug-in unit Single frequency plug-in in its own customised pouch Frequency plug-in outside its pouch
Severok-K with frequency plug-in and Block-S Fitting a frequency module Accessing the frequency plug-in

Burst encoder DKM-S
Like with most other Russian spy radios, text messages are usually pre-coded using some kind of manual encryption or One-Time Pad (OTP) and then sent at hight speed (burst) in order to avoid detection and Direction Finding.

Severok-K came with the very small leight-weight fully digital burst encoder shown in the image on the right. It consists of a small aluminium box with a keypad and a 5-digit display and should be connected between the microphone and the transmitter.

 More about the DKM-S
Serverok-K Burst Encoder

Serverok-K Burst Encoder Close-up of the sockets on the DKM-S burst encoder View of the battery compartment at the rear DKM-S burst encoder held in a hand Burst encoder in operation DKM-S cable DKM-S burst encoder in carrying pouch DKM-S burst encoder in carrying pouch

Severok-K was supplied with a rather strange combination of microphone and headset (speaker), similar to the outfit used in a (Russian) tank. It came as a complete assembly that was connected to the radio with a single connector.

The headset is of the usual Russian (tank) type and is connected directly to the top of the microphone, with an in-line potentiometer for volume adjustment.
Operating the microphone

Operating the microphone Microphone and headset Microphone and headset Microphone/headset combination Operating the microphone Rear of the microphone Volume adjustment Microphone closed

When operating the Severok-K in, say, a room with multiple people, the receiver's output could be amplified to a more appropriate level. A separate amplifier with built-in speaker was available for this purpose.

The image on the right shows the speaker-amplifier unit. It should be connected between the microphone and the Severok-K and obtains its power from the radio. As the microphone-headset can still be connected, the amplifier can be switched off without loosing audio.
Amplifier with built-in speaker

Speaker/amplifier with its cable stowed away Speaker/amplifier with its cable stowed away Amplifier with built-in speaker Amplifier font view Amplifier plug Adjusting the volume Connector for microphone On/off switch

Severok-K comes with a rather strange black block, called Block-S, that can be attached to the bottom of the radio. Apparently, this is some kind of voice scrambler or speech encryption unit. The block is completely sealed and has only one 8-pin connector and a serial number.

In the accompanying documentation, it is called Block-S Terminator. The 'S' probably stands for Секретно (secret).
Severok-K with frequency plug-in and Block-S

Block-S Bottom of the Severok-K where Blok-S should be attached Block-S and bottom of Severok-K Severok-K with frequency plug-in and Block-S Severok-K with frequency plug-in and Block-S

Severok-K could be used with two types of antenna: a vertical Kulikov antenna, that was mounted directly to the radio, and a wire-antenna for out-door long-distance use. Both antenna types were supplied with the set.

The image on the right shows the wire-antenna as it was stored in the accessories case. It could be carried in a special pocket of the carrying pouch of the Severok-K.
Wire antenna

Wire antenna Using the wire-antenna Severok-K with ancillaries in special carrying pouch Kulikov antenna (folded) Vertical antenna base Antenna connector Fitting the vertical antenna Antenna mast
Severok-K with vertical antenna Assembling the Kulikov antenna Top of the Kulikov antenna Connecting the vertical antenna Antenna-base mounted to the side of the Severok-K Kulikov antenna fitted on its base

A tiny black plastic box was supplied with five spare fuses and five spare light bulbs. The latter are purpose-built and are extremely rare.

The image on the right shows a close-up of such a light bulb and a typical Russian fuse, which is smaller than western fuses. More detailed images below.

Spares box (closed) Spares box (closed) Spares box (opened) Open spares box in a hand Close-up of a lamp Plastic box with spares Spares

In the field, the Severok-K was usually powered by an external battery belt that could be worn around the waist of the operator. The battery belt is of a typical Russian military type and contains a number of wet batteries that are filled with (separately supplied) liquid.
The image on the right shows a typical battery belt as it was supplied with the Severok-K. It is similar to the battery belts that were supplied with earlier Russian spy radio sets, such as the R-394K and the R-394KM.

At one end of the belt is a standard 4-pin military connector that should be connected to the equipment. As the connector is too large to fit the Severok-K, and because the Severok-K does not have a power switch (i.e. it can not be turned off) a separate filter block was used to connect the radio to the battery belt.
Battery belt

The belt consists of two halfs, each of which contains 5 wet battery cells. As each cell produces 1.2V, the total voltage delivered by the belt is 12V. The batteries can be charged by any 13.5V source, such as the battery charger below.
Battery belt Battery belt Opening the battery belt 12V connector Battery liquid Battery liquid container  Power filter Connecting the radio to the battery belt

Battery charger
The above battery belt can be charged directly from the mains by using the supplied battery charger shown in the image on the right. It is suitable for connection to either 220V or 110V mains networks. The cable with the mains plug is stored inside the top lid.   
battery charger

Battery charger Opening the case Battery charger with open lid Control panel battery charger

Carrying pouches
In order to carry the Severok-K and its many accessories around, a series of cheap-looking (probably home-made) carrying pouches was supplied. One pouch was used for carrying the Severok-K radio itself, in such a way that it could be connected and operated whilst in the pouch.
The pouches were made of several different fabrics and the interior was finished with some kind of flower-pattern design, probably left-overs from some sewing production facility.

The image on the right shows the Severok-K receiver packed in its own pouch, together with the folded wire-antenna. A flap on the side of the pouch gives access to the frequency plug-in, allowing it to be swapped without removing the radio. The DKM-S Burst Encoder was stored in its own pouch that could be attached to the waist belt of the radio operator.
Severok-K with ancillaries in special carrying pouch

For each frequency plug-in unit, an individual pouch was available. It has a smally leather strap at the rear, allowing it to be carried on the waist belt of the operator. The frequency of each plug-in is printed on the flap of the pouch, so that it is immediately clear which plug-in is stored where. The flap of the pouches of our Severok-K plug-ins could not be closed as the pouches has been stiched incorrectly. A small modification was necessary before they would fit, indicating that our set was probably never used in action.
Waist belt for carrying the pouches with ancillaries Severok-K in carrying pouch Opening the pouch of the radio Severok-K with ancillaries in special carrying pouch Accessing the frequency plug-in DKM-S burst encoder in carrying pouch Single frequency plug-in in its own customised pouch Frequency plug-in outside its pouch

A brand new Severok-K radio was usually supplied from the depot with a full set of documentation, consisting of the following:
  • Severok-K Technical Description and User Manual
  • Blok-S maintenance booklet
  • Battery maintenance booklet
  • DKM-S maintenance booklet (passport)
  • Speaker/Amplifier maintenance booklet
Full set of documentation for the Severok-K

Full set of documentation for the Severok-K Severok-K documentation Severok-K technical description Severok-K documentation Severok-K documentation Severok-K block diagram

  1. Crypto Museum, Severok-K radio station
    Investigation at Crypto Museum, January 2011.

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Crypto Museum. Created: Saturday 12 February 2011. Last changed: Sunday, 02 October 2016 - 09:16 CET.
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