Many of you will know the Marconi R1155 communications receiver. These were used in the Lancaster bomber aircraft. I’ve had several over the years but, to be honest, I didn’t get on with them.
The Marconi R1155 is one of Britain’s best-known Second World War valve communications receivers. Developed by the Marconi Wireless Telegraph Company, it was designed primarily for use in RAF aircraft, particularly heavy bombers such as the famous Avro Lancaster.
Introduced into operational service in 1940, the R1155 was a sophisticated receiver for its time. It provided both long-distance radio communications and radio direction-finding facilities, allowing aircraft crews to receive messages, identify navigation beacons and determine their position.
More than 80,000 were manufactured during the war, with production shared among Marconi, Ekco, Plessey, EMI and other manufacturers.
The R1155 was normally paired with the equally famous T1154 transmitter, forming one of the RAF’s standard airborne wireless installations. In the Lancaster bomber, this equipment was operated by the wireless operator, who maintained communication with ground stations and other aircraft.
It was also installed in other aircraft, including the de Havilland Mosquito, and adapted for some ground and marine applications.
The standard R1155 covers five bands, from long-wave navigation frequencies through medium wave to short-wave communications.
Band
Frequency range
There are gaps in coverage, notably between 1.5 and 3 MHz on the standard version. The later R1155L and R1155N replaced the lowest-frequency band with 1.5–3 MHz coverage.
The receiver could pick up international short-wave broadcasts, aircraft communications, Morse code transmissions and radio navigation signals appropriate to its operating period.
The R1155 uses ten valves, although only six form the main receiver circuit. One operates as the tuning indicator, while three are associated with direction finding.
The main receiver consists of an RF amplifier, frequency changer, two intermediate-frequency amplifiers, detector and audio stages, together with automatic volume control and a beat frequency oscillator for Morse code reception.
Its 560 kHz intermediate frequency gives reasonably good selectivity for a wartime design, while the RF amplifier provides useful sensitivity on the higher frequencies.
One particularly interesting feature is the combined AVC and BFO circuitry, which differs from the arrangements found in many domestic receivers.