Spy sets
Burst encoders
Logo (click for homepage)
R-350 Burst Encoder
The burst encoder described on this page is one of the simplest methods of sending information in morse code at high speed. It's a manually operated device that was used with the earliest Russian spy radio sets during the early 1950s, such as the Electron and the R-350 (Orel). It uses standard 35 mm photo film for the storage of encoded messages.
The device shown here is the actual burst transmitter, which should normally be attached to the side of the radio set. A small two-pin plug is used to connect it to the morse key input of the transmitter. It combines three functions.

At the front of the device is a small (black) morse key, which can be used to send messages directly in morse code. For this, the operator must - of course - be trained in morse code first. Sending messages directly in morse code was not general practice and was only used as a safety backup measure.

If the operator was not capable of sending messages in morse code, he could use an 'electric pen', stored inside the device, to send numbers in morse by sliding the pen through one of 10 'slots' on top of the device. Inside the slots, the morse pattern for each number (0-9) was layed out in copper. All the operator had to do, was to slide the pen through the appropriate slot with a constant speed. Again, this method would only be used in case of emergency.
In normal use, the numerical message would be stored onto photo film first, using a separate punching device. The Russians used standard 35 mm film rolls, as this was commonly available around the world and would not attract attention when bought abroad by an agent.

The film would be entered into a slot of the puncher and the operator only had to press the appropriate buttons on top of the device. Each number was represented by a single hole in the film and the film was automatically advanced by one step on each key press.

Once the message was complete, the film was entered into a similar slot at the front of the morse key. Once the connection with headquarters was established, the operator would use a small hand crank to advance the film at a regular speed through the encoder (see the images below).

One has to bear in mind that all messages were converted into a series of numbers first, using some kind of cipher method. This is called a pre-coded message. Various manually operated cipher systems (hand methods) were deployed to encipher a message, ranging from simple matrix operations to truely unbreakable One Time Pads (OTP). The latter was the preferred method for spies and agents operating abroad, often used in combination with the so-called Number Stations, endless sequences of random numbers spoken by an 'automated' woman.
The high speed morse transmitter Attached to the side of the R-350 radio Using the small key to send morse manually Using the pen to send morse numbers Using the crank to feed the film through the transmitter The puncher loaded with film Another view of the puncher Close-up of the film output

Further information

Any links shown in red are currently unavailable. If you like this website, why not make a donation?
Copyright 2009-2013, Paul Reuvers & Marc Simons. Last changed: Monday, 05 March 2012 - 12:30 CET
Click for homepage