Spy sets
Burst encoders
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MA-4230 and MA-4231
Electronic morse encoder and decoder

Around 1977, Racal developed a portable morse burst encoder for Special Forces (SF) and other special purposes. The set consists of a morse encoder, the MA-4230, a complementary morse decoder, the MA-4231, and sometimes an MA-4233 thermal printer. The housing of the encoder and decoder units are identical, but the controls on the front panel are different.
The image on the right shows a typical pair. The unit in front is the MA-4230 morse encoder. The one at the back is the MA-4231 decoder.

Each unit measures only 175 x 120 x 50 mm and is made of die-cast aluminium. It weights about 1.1 kg and a rubber gasket makes the unit reasonably waterproof.

A special version of the encoder with an Arabic keyboard layout, the MA-4230A, was developed especially for the Iraqi Army in the period prior to the First Gulf War.
Coder (front) and decoder (back)

Each unit has two - rather special - 5-pin FISHER sockets at the right side. These sockets are used for the connection between encoder and decoder, but also for the connection of a transceiver, a printer and a battery charger. A complete set of units can be connected to any standard Racal radio, by using an appropriate audio cable.

System using a Racal transceiver

When used in combination with a Racal transceiver, power is taken directly from the radio via the audio connector. In that case, no external PSU is needed. Connecting the set to other transceivers (i.e. non-Racal) is also possible. In that case a cable without an audio connector would be supplied by Racal, so that a suitable connector could be mounted later.

System using a non-Racal transceiver

In this situation, power can not be taken from the radio, and an external battery charger has to be used. This charger is generally connected to the MA-4233 printer at the end of the chain. It can however, also be connected to each individual unit in turn, under the batteries are fully charged. The following products are known in this series:
Designator Description NSN  
MA-4230 Encoder -  
MA-4231 Decoder -  
MA-4232 Battery charger -  
MA-4233 Printer 5865-99-539-6085  
MA-4230A Arabic version of the MA-4230 -  
MA-4231A Arabic version of the MA-4231 -  
MA-4233A Arabic version of the MA-4233 -  
MA-4235 Complete system (MA-4230, 4231, 4233, etc.) -  
ST450032 Line interface -  
ST450076 Battery charger -  

MA-4230 Morse Encoder
The MA-4230 is a small self-contained morse encoder. It consists of a die-cast aluminium case with 40 keys and 3 LEDs on it surface. It allows messages to be stored in its 1024 character memory, and sent in morse code at high speed (burst), in order to minimize the chance of interception and detection.

 More information
MA-4230 morse encoder
MA-4231 Morse Decoder
The MA-4231 is an automatic morse receiver, designed to be used either stand-alone or in combination with an MA-4230 at the other end. In the latter case it can be used for the reception of high speed morse transmissions (bursts).

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Arabic version
This special version of the MA-4230 was made by Racal especially for the Iraqi Army just before the first Gulf War (1991). The MA-4230A has Arabic keys on the keypad and forms a pair with the MA-4231A burst decoder.

The MA-4230A unit is based on the same design as the MA-4230, except for a different keypad and different software.

 More information
MA-4230A (Arabic version)

MA-4233 Printer
The MA-4231 morse decoder could be expanded by an (optional) external printer. Especially for this purpose, Racal developed a small ruggedised thermal printer. It connects to the decoder by means of 5-pin Fisher connectors.

 More information
Another close-up of the printer
ST450076 Battery charger
When used in combination with non-Racal radio equipment, the ST450076 battery charger shown on the rights was used. It consists of a small metal frame with a transformer, fuse and power selector. The charger can be configured for both 115 and 230 V mains.

A short piece of wire with a 5-pin Fisher connector, allows the charger to be connected to the MA-4033 printer. Power is then looped through all units by means of the 5-pin interconnection cables.
ST450076 Battery charger

ST450076 Battery charger Typical Fisher connector

Complete set?
The following is pure speculation. When examining the dimensions of the various module, one might jump to the conclusion that the complete set (i.e. encoder, decoder, printer and PSU) might have been intended to be built inside a large briefcase or backpack.
We already noticed that the size of the printer is the same as the size of both units together. Furthermore, each unit has four 3 mm threaded holes at the bottom, allowing it to be mounted on, say, a metal base plate.

If the units are arranged as in the image on the right, a very ergonomic system is obtained: the keyboard is at the front and the printer is at the left, in such a position that is easily operated. All connectors are unobstructed, allowing the cables to run freely between the units.
Complete set
Complete set Complete set Complete set with printer open Operating the complete set Operating the complete set

  1. Racal-Datacom Limited, Technical Manual MA.4230 MA.4230S Morse Encoder
    (with Battery Charger MA.4232)

  2. Racal-Datacom Limited, Technical Manual MA.4231 Automatic Morse Receiver

  3. Army Radio Sales Co, Racal MA-4230A and MA-4231A

  4. Jane's Military Communication 1986, MA 4233 Minature Printer
    p. 453/454. ISBN: 0-7106-0824-1

Further information

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