Spy radio
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USSR spy radio set

P-57, codenamed RION, was an agent communication device, or spy radio set, developed in 1957 in the former Soviet Union (USSR). The device was intended for clandestine operations in foreign countries and was generally operated from within its unobtrusive brown fibreboard suitcase.
The image on the right was probably taken from the original instruction manual, and shows the complete RION P-57 (П-57) radio station tightly mounted inside a standard travel suitcase of the era, much like the British B2 spy set of WWII [3].

The device consists of a PR-56A receiver at the top left, a RION transmitter at the top right, and a mains power supply unit (PSU) at the bottom left. The rest of the space is filled with a spares box and a cable storage box. In the image on the right, a small morse key, connected to the RION transmitter, is fitted on top of the spares box.
RION spy radio set

The transmitter is suitable for the 2.5 to 10 MHz frequency range and delivers an output power of approx. 10 Watts in CW (morse). It can be crystal operated, but is also freely adjustable by means of a built-in VFO. The receiver is suitable for the reception of CW signals between 2 and 12 MHz. The set can be used in simplex or in half-duplex mode. In the latter case, separate RX and TX antennas have to be used, with sufficient distance between them. In the former case, a single wire antenna is connected to the transmitter, which is then shared with the receiver via a loop wire.
Fibreboard travel suitcase RION spy radio set RION spy radio set Front view of the controls Mains power cable connected to the radio set Lifting the hinged frame Hinged frame inside suitcase Headphones and morse key connected to RION radio set

The diagram below gives an overview of the many controls and connections of the radio set. At the bottom left is the power unit to which the mains power cord (or an alternative power source) should be connected. It has a meter for checking the internal 1.5V LT and 240V HT power rails.

The receiver and transmitter are two separate units that are installed in two dedicated bays of a hinged frame. They are held in place by the lid of the narrow storage compartment at the top centre, and are each powered by a small rectangular plug at the bottom left. Note that the pin-out of these plugs are not identical and that the voltages are different as well. For this reason the transmitter bay has a coding pin that mates with a hole in the bottom of the transmitter. For a detailed description of the control, refer to the separate pages about receiver and transmitter.
Two empty bays for receiver and transmitter Lifting the hinged frame Hinged frame inside suitcase Locking pin ensures that only the transmitter can be installed in the rightmost bay Center compartment open when installing receiver and transmitter Connecting the receiver Connecting the transmitter Headphones and morse key connected to RION radio set
Checking the 80V rail Smaller accessory compartment, here shown with work lamp and crystals Crystal installed Headphones and morse key stored in the accessory compartment Connect PSU/inverter externally Mains plug and socket Mains plug installed Mains power cable connected to the radio set

Complete set
A complete RION spy radio station consisted of two leather suitcases. One with the radio station as shown above, and a smaller one with a power supply unit and a power inverter (vibrator). The extra suitcase was intended for use in urban areas where access to a mains AC network was available. It will be obvious from the picture below that RION was not a lightweight radio station.

The weight of the two cases together was approx. 40 kg, which must have required a quite strong operative. The set was built to sustain extreme conditions, such as an operational temperature range from -40°C to +50°C and a relative humidity of 85%.
Receiver   PR-56A
The receiver of the RION radio station was designated PR-56 or PR-56A. It was developed a year earlier than RION (1956) and was also supplied separately, possibly for use with other spy radio sets, which is why it has its own model number. The initial PR-56 has a 3-digit serial number, whereas on units supplied as part of a RION station, the serial number the format 'P570xxx'.
The image on the right shows the bare PR-56A receiver, which is currently the only part of the RION P-57 set that we have in our collection.

The receiver covers a frequency range from 2 to 12 MHz, divided over four bands, each of which is identified with a colour. Audio is delivered to standard USSR headphones. The antenna signal is usually supplied via the transmitter.

 More about the PR-56 receiver
PR-56A receiver
Transmitter   RION - P-57
The transmitter has the same form factor as the receiver and does not have a model number. Its serial number is in the format P570xxx, which indicates that it was developed especially for the RION radio set and that, unlike the receiver, it was not not used as part of another radio set. The transmitter is often identified as P-57 (П-57), but according to the manual it is called RION [A].
The transmitter has a frequency range from 2.5 to 10 MHz, which is slightly smaller than that of the receiver. The frequency can be determined either by a crystal, operating in the 2nd or 3rd overtone, or by the built-in Variable Frequency Oscillator (VFO), selectable by a slide-switch. The crystal socket is located at the front right.

The frequency range is divided over four bands, that cover 2.5-3.5 MHz, 3.5-5 MHz, 5-7 MHz and 7-10 MHz respectively. A suitably long wire antenna should be connected to the banana-type socket at the upper edge, with a counterpoise connected to the banana socket at the left edge.

 More about the P-57 transmitter
P-57 transmitter

Power sources
RION can be powerd in quite a few different ways, but you should note that only one of these methods can be used. No matter which option is chosen, it should always be installed in the empty space at the bottom of the suitcase, and must be connected to the 14-pin power plug that is available in the small compartment at the front right of the control panel.
  • Internal batteries
    A large unit with dry battery cells can be mounted to the bottom of the radio's frame, in the empty space at the bottom of the suitcase. When present, the batteries directly provide the necessary LT and HT voltages to the transmitter and to the receiver.

  • AC Mains
    The radio can also be powered directly from the AC mains, when the optional Power Supply Unit (PSU) is installed. The PSU can be fitted in the bottom section of the suitcase, instead of the batteries. Alternatively, the PSU can be placed aside the radio. In that case, the 14-pin plug should be disconnected from the batteries and connected to the PSU.

  • External battery
    RION can also be powered by a 12V DC source, such as the battery of a car. In that case, the optional vibrator-based power inverter should be used. It can be installed in the bottom compartment of the suitcase, or placed aside the radio, connected to the 14-pin power plug. The 12V DC source should be connected to the radio's 6-pin power socket.

Fibreboard suitcase Morse key Headphones Internal battery pack Internal power supply unit (PSU)
Power inverter Mains power cable Small work lamp
Transmitter crystals (XTALs) Technical Manual

The RION set was supplied in an unobtrusive brown fibreboard (cardboard) suitcase. Inside the case is a hinged metal frame with bays for the receiver and the transmitter. The remaining space is taken by a power connection unit and several storage compartments for cables, morse key, headphones, lamp, antenna wires, etc.

A smaller suitcase contained the mains power supply unit and the power inverter, each of which could be installed in the empty space at the bottom of the larger case, instead of the standard battery pack.
Fibreboard travel suitcase

Morse key
The transmitter is only suitable for transmissions in morse code (CW) and has a small 2-pin socket at its front edge for connection of a morse key.

RION was usually supplied with a black miniature morse key that fitted a slide-mount at the center of the lid of the large accessory compartment. In practice, most operators used an alternative key, as the size and position of the standard one was not very convenient. Both the original key and the slide-mount are missing from our RION set.
Modern USSR morde key that can be used as an alternative

The receiver has a 2-pin socket for connection of a common pair of headphones, such as the one shown in the image on the right. It was supplied as a standard accessory of the RION radio set.

Alternatively, the set could also be used with a common military pair of headphones, such as this one, that had a canvas head band and could be stored more easily.

Battery pack
In situations where no mains network was available (e.g. in a forest), power was provided by a large battery pack that was installed in the empty space at the bottom of the suitcase. It was attached to the bottom side of the hinged frame that holds the receiver and transmitter.

The battery pack consists of three 80V dry cells (BAS-G-80) connected in series, three 1.5V cells (Z-SL-30) also connected in series, and two 1.5V cells (Z-SL-30) connected in parallel.  More
Dry cell battery pack

Power supply unit   PSU
When a mains AC network was available, it was recommended to install the (optional) power supply unit (PSU) in the bottom compartment of the suitcase, in place of the battery pack. The PSU was normally supplied in a separate smaller suitcase, along with the optional power inverter.

The PSU is attached to the bottom of the hinged frame, as shown in the image on the right, and is connected to the frame's 14-pin power plug.
Mains PSU mounted to the bottom of the radio set

In addition to internal batteries and the mains network, the RION set can also be powered from an external 12V DC source, such as the battery of a car. In that case, the optional power inverter should be installed in the bottom section of the suitcase, replacing the battery pack. The inverter is supplied with the PSU in a separate suitcase.

The image on the right shows the power inverter, which uses a vibrator unit and a multi-tap transformer to convert 12V DC into the various voltages needed for the radio set.
Power inverter

Mains power cable
When the mains power supply unit (PSU) is installed in the lower part of the suitcase, the radio set can be powered from the Mains AC network. In that case, the mains power cord shown in the image on the right, should be connected to the square 6-pin power socket at the front right of the set.

The power plug is a common WWII German Luftwaffe connector, made by List and several other manufacturers, and copied in the USSR. The pinout is available below.
Main power cord

Work lamp
The radio set was commonly supplied with a small work lamp that could be connected to the 2-pin socket between receiver and transmitter. This socket provides a voltage of 4.5V and is intended to power a small 6V lamp, with just enough light to read the frequency scales.

The lamp shown in the image on the right is not the original one that was supplied with the radio set, but a suitable replacement. The black clip at the bottom allows the lamp to be affixed to the top lid of the suitcase.
Small clip-on work lamp

Although the transmitter can operate on any frequency within its range, it was usually operated with crystals as they are far more accurate and stable as the internal VFO.

Crystals can be used in the 2nd or 3rd overtone, and the socket at the transmitter's front right is suitable for nearly any type of quarz crystal that has thick pins. The image on the right shows a few examples of crystals that have been found to work well with RION.
Set of crystals

Each RION set was supplied with an operator's manual that also contained a full technical description and circuit diagrams. The image on the right shows an original RION manual that is stamped with the serial number of the radio set.

The circuit diagrams are provided at the back of the manual as fold-outs.

 Download manual
Original technical manual. Photograph kindly supplied by (C) Atomic KGB Bunker [4].

Modern USSR morde key that can be used as an alternative Alternative headphones Mains PSU mounted to the bottom of the radio set Dry cell battery pack Mains PSU Power inverter Mains PSU - interior Power inverter - interior
Original technical manual. Photograph kindly supplied by (C) Atomic KGB Bunker [4]. Original morse key stowed in storage compartment RION spy radio set with original morse key fitted Front panels of PSU and inverter

Bringing an old radio like RION back to life is always difficult. The radio was manufactured in or around 1957 and is now nearly 70 years old. When we acquired the radio in 2017, all of the power supplies (battery, mains PSU and inverter) were missing and the state of the electronics inside the receiver and the transmitter were unknown, although it appeared to be in good shape.
Nevertheless, it is always a good idea with any device of this age, to check the wiring and the connections thoroughly before supplying power to it. A first inspection learned us that the mains power switch was broken and that some of the wiring had been modified over time. Luckily, our friends at the Atomic KGB Bunker 1 in Lithuania were able to provide the original wiring diagram.

A replacement switch was found on eBay and the original wiring was restored. Also on eBay, we found suitable plugs an sockets for the mains connection and for the internal power supply.
Power control unit with ON/OFF switch

It was decided to build a new mains power supply unit (PSU) that could be installed in the empty space below the radio frame. This space is normally taken by either the battery pack, the original PSU or the inverter. This space is approx. 5.5 cm high, which should be enough for a proper PSU.
The image on the right shows the alternative PSU, which is smaller than the original one. It is built with modern components and no attempt has been made to make a replica of the original.

The alternative PSU is housed in a black die-cast aluminium enclosure that can be fitted to the bottom of the hinged frame of the radio set, in such a position that the 14-pin socket mates with the 14-pin plug of the existing wiring.

Inside the PSU is a modern toroidal transformer that has been modified for the required voltages.
Replacement PSU

The next thing to check was the state of transmitter and receiver. As they can both be removed from the frame easily, it was decided to test and repair them outside the frame. We first prepaired a universal test cable from the short lead that came with our PR-56 receiver several years ago.
A quick inspection of the transmitter's interior learned us that it was in good condition, but that the antenna relay was broken and that one of the metal shields was missing. Again, our friends from the Atomic KGB Bunker came to the rescue, and provided us with original replacement parts.

After replacing the broken relay and correcting the wiring of the transmitter's power socket, the transmitter now works again. After connecting a wire antenna and a suitable counterpoise, the antenna matching unit could be tuned nicely and the unit produced the expected output power.
Broken antenna relay

The receiver appeared to be more problematic. The first test revealed that all seven valves were broken, probably as a result of connecting the 80V HT voltage to the filaments. Replacement valves were ordered from several sources on the internet and awaiting their arrival, we swapped the broken receiver for the one we already had in our collection, which was known to be good.
Now it was time to install the transmitter and the receiver in the suitcase's frame and see how they behave when connected to the replacement PSU via the internal wiring. After several additional checks, main power was switched ON and both receiver and transmitter worked immediately.

One last hickup was caused by the indicator (the 3V/300V meter) just above the mains socket on the power module. Although power was supplied to the panel meter, the needle refused to move. A closer inspection revealed that the delicate instrument inside the meter was badly corroded.
Checking the 80V rail

Luckily, we managed to take it apart, clean it up, and re-assemble it, after which it could be used again. Our RION spy radio set is now fully operational and can be demonstrated to the public. Many thanks to everyone who has helped us to make this restoration project a successful one.
  1. Atomic KGB Bunker Museum is a Cold War museum in Lithuania, housed in a cold war era atomic shelder, 6 metres below the surface. It has several thousand items related to espionage, war and radio, and is open to the public on special days [4].  Visit the website

Power control unit with ON/OFF switch Broken antenna relay Antenna relay Test cable for transmitter and receiver Replacement PSU Inside the replacement PSU 14-pin power socket on the PSU Replacement PSU fitted at the bottom of the frame

Missing items
The following items are currently missing from our RION radio set:
  • Original headphones
  • Original miniature morse key
  • Slide-mount for morse key
  • Original work lamp
According to the original parts list, the following items should be present:
  1. Receiver type 'PR-56'
  2. Transmitter type 'RION'
  3. Cassette with set of dry cell batteries
  4. Vibrator (power inverter)
  5. Rectifier (mains PSU)
  6. Fibreboard suitcase No 5 for fitting equipment
  7. Fibreboard suitcase No 3 for vibrator and PSU
Mains power   P1
A 6-pin male socket is available for connection of the mains power cord, at the bottom left of the control panel. This is a so-called LIST plug, or STAF series, (now: Harting) that was used by the German Air Force (Luftwaffe) during WWII. The plug was copied in the USSR and used for many years. Below is the pinout of the male socket when looking into it from the control panel. Note that, when using this connection, the internal Power Supplu Unit (PSU) should be installed.
  1. AC Mains (~95-240V)
  2. AC mains (connected to 1)
  3. not connected
  4. AC Mains (~0V)
  5. Ground
  6. not connected
External battery
The same socket can also be used for connecting an external 12V DC power source, such as the battery of a car. In this case, the internal Power Inverter should be installed in the suitcase.
  1. +12V
  2. +12V (connected to 1)
  3. +4V
  4. not connected
  5. 0V (Ground)
  6. +2V
Receiver power
The diagrams below show the pinout of the power sockets on the PR-56A receiver and the RION transmitter, when looking into the socket from the front of the device. Note that the metal shell is connected to the chassis (i.e. ground or GND). It is used as the ground for the HT voltage (0V).
  1. LT in (+1.2V)
  2. LT out (switched)
  3. G (-4.5V)
  4. HT (+75V)
Note that some receivers have a different wiring of this connector. This is the case, for example, with the PR-56A. Furthermore, in some devices the wiring of pins 1 and 2 have erroneously been swapped. Although this does not affect the operation of the device, it means that the filaments are powered permanently. Also remember that some devices may have been amateurised.

Always check the wiring before connecting the PR-56 to a power source. If the receiver is to be used as part of the RION suitcase (i.e. installed in the metal frame), you may have to correct some of the wiring. In this case, use the internal wiring diagram and the battery wiring scheme below.
Transmitter power
  1. LT (-4.5V)
  2. not connected
  3. LT (0V)
  4. HT (270V)
Internal power   P2
RION is powered by a dry-cell battery pack, a power inverter or a mains PSU, one of which can be fitted inside the bottom compartment of the suitcase. A 14-pin female LIST plug in the cable compartment at the front right is present for connection to the batteries or the power inverter. The diagram below shows the pinout when looking into the female socket on the cable end.
  1. AC Mains 0V (from P1-4)
  2. Ground
  3. Ground
  4. not connected
  5. LT 3V max
  6. Fuse
  7. RX LT 0V
  8. AC mains
  9. not connected
  10. Looped to 8 (AC mains)
  11. TX LT in
  12. TX LT 0V (from P1-3)
  13. not connected
  14. HT
Internal wiring
Below is the wiring diagram of the hinged metal frame that holds the individual components. The wiring diagram is based on the drawings in the technical manual [A] and has been verified against an actual RION radio set. Please note that in practice, variations or modifications are possible. Do not rely on this diagram, but verify it before applying power to the set. Most of the components in the diagram below, are mounted to the rear of the power unit at the front left of the radio set.

The 6-pin socket at the left is the mains power input that is located on the front left of the radio set. It is connected to the large 14-pin plug to which the abtteries, the PSU or the power inverter should be connected. In turn, the 14-pin plug provides power to the receiver and the transmitter.
Battery wiring
The battery pack should be connected to the large 14-pin plug that resides in the empty space below the hinged frame, at the bottom of the suitcase. The diagram below shows how it is wired. Three 80V dry batteries (BAS-G-80) are connected in series, to provide +240V for the transmitter. It has a tap after the first battery, that provides +80V for the receiver. At the top are three 1.5V batteries (Z-SL-30) connected in series to provide the +4.5V LT voltage for the filaments of the transmitter. These batteries are also used to provide the -4.5V grid voltage for the receiver. Two further 1.5V batteries are connected in parallel to provide the 1.2V for the receiver's filaments.

The above diagram can also be used as a guide for the wiring of the PSU, or when creating a replacement PSU, in which case the mains AC voltage will be available at pins 1 and 8 of the 14-pin plug. The correct AC mains voltage should be selected on the voltage caroussel of the PSU.
  1. RION Maintenance Manual
    A.08 TO. 12 July 1957. Serial number 120. 66 pages.

  2. PR-56, Receiver Circuit Diagram
    A138. Date unknown. Retrieved October 2009 from [1].

  3. PR-56, Receiver Components List
    Date unknown. Retrieved October 2009 from [1].

  4. PR-56, Receiver, table of valves (tubes)
    1957. Retrieved October 2009 from [1].

  5. P-57, Transmitter Circuit Diagram
    A145. 1956. Retrieved October 2009 from [1].

  6. P-57, Transmitter Component List
    A145. 1956. Retrieved October 2009 from [1].

  7. P-57, Transmitter, table of valves (tubes)
    1957. Retrieved October 2009 from [1].

  1. scAvenger, Technical description of the RION spy set
    Website with many photographs. Riga, Latvia. 21 January 2005. Retrieved October 2009. 1

  2. Louis Meulstee, Wireless for the Warrior, volume 4
    ISBN 0952063-36-0, September 2004. 2

  3. Radio Scanner, Radio Station 'RION'
    Website (Russian). Retrieved May 2016.

  4. KGB Bunker Museum, Lithuania
    Personal correspondence, February 2017.

  1. Website no longer available in 2016.
  2. In this book the receiver is erroneously called GR-56A.

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Crypto Museum. Created: Thursday 01 October 2009. Last changed: Sunday, 12 March 2017 - 16:20 CET.
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