Wireless Telegraph Set Forward Spark 20 watt B

From RCSigs.ca
Jump to: navigation, search
Wireless Telegraph Set Forward Spark 20 watt B
Wireless Telegraph Set Forward Spark 20 watt B Mk II Rear Station.jpg
Rear Station Transmitter and Receiver
Production history
Introduced 1917
Weight complete Rear Station: 82 lb
complete Front Station: 74 lb

two versions: 65 or 80 metres fixed wavelength
Range 2000 yards

The Wireless Telegraph Set Forward Spark 20 watt B, also known as the Loop Set, was a spark telegraphy set used for forward area communications. The complete set was comprised of a Front and a Rear Station, the equipment not being interchangable. There were three versions produced, a Mk I, I* and II with only minor details different between them. [1]

Rear Station

The Rear Station consisted of a transmitter and a receiver, either a 50 ft (65 metre version) or 60 ft (80 metre version) horizontal wire on two 4 ft folding tripod supports and a 14 ft earth net.

Front Station

The Front Station consisted of a transmitter with a collapsible loop aerial 1 metre square and a receiver with a ground aerial consisting of two 35 ft insulated wires to be thrown out on the ground in opposite directions. The 1 metre square transmitter aerial was made of 3/8 inch brass tubing and was mounted on a small ebonite box (5 1/2 x 2 1/2 x 1 1/2 inches) that contained the transmitter spark gap. Fitted on a service bayonet, the unit was driven into the ground. The operator could be 20 feet away connected by a flexible cable to the second transmitter unit compromising an induction coil and Morse key.

Related Pages

Related Items


  1. Wireless for the Warrior Compendium 1. Louis Melustee. Emaus, 2009. ISBN 978-90-808277-2-1