Building A Replica Of The MKVII Paraset

Spy Radio Transceiver

©February 2024 - Bill Harris

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February 2024

Paraset" is a combination of the words radioset and parachute.  The unit is a small, low-power, thermionic valve (vacuum tube) CW (Morse code) radio-transmitter-receiver, developed in Great Britain in the early stages of World War II. The set is known as the Whaddon Mark VII, or as simply the MK7 by MI6 (the British Secret Intelligence Service - Section 6), the SOE (Special Operations Executive), and was used for clandestine radio communication primarily in France (Free France Intelligence Service), Belgium and the Netherlands. It was the main set used by the agents in 1941-1942.

The unit was developed at the Royal Signals Special Communications Unit workshops at Little Horwood and the workshops of Waddon Hall, Buckinghamshire, England. The equipment is known as the Paraset because of it's small size and light weight (for 1940's standards), it could be air-dropped by parachute or carried by agents being air-dropped. Resistance agents used the sets to communicate back to England on Nazi troop and ship movements as well as real-time weather conditions.

Large antennas and powerful transmitters were used at Bletchley Park England which assured that agents could communicate with the little Parasets. The set here is a replica built to the same specifications as the original paraset. The circuit consists of a two tube regenerative receiver capable of tuning from approximately 3.0 MHz to 7.6 MHz, one band, and a one tube crystal controlled transmitter, coverage slightly more then the receiver, in two selectable bands. Output power of the transmitter is 3 - 5 watts. Two 6SK7 tube types are used in the receiver circuit, and a single 6V6 used as the crystal controlled transmitter. There is a jack for head phone use and a built in Morse code key.

The first sets were built into wooden cases and later into metal “cash box” type cases. Power for the unit was provide by either battery powered portable vibrator type power supply or power supply using an AC mains source. Very few of the original units survive today. After the war radio equipment was ordered to be destroyed for fear it might fall into the hands of the Soviets. Fortunately, a few survived, there is one original in the British Museum in London, and a few originals in the hands of collectors. Many paraset fans, mostly Amateur (ham) Radio operators, have constructed reproduction sets and use them to make contacts on the ham radio bands.

 

 

 

 

 

 

 

For more detailed information on clandestine radio operations during World War Two

I highly recommend the book "THE SECRET WIRELESS WAR

The story of MI6 Communications - 1939-1954"

by Geoffrey Pidgeon.

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