R1155A receiver

R1155 Communications Receiver

Click to visit a web site with T1154 and R1155 detailed information including photos, circuits and layouts in a new window.

General Description

The R1155 is perhaps the best known receiver to be built in the United Kingdom during WW2. Vast numbers of these receivers were built by the Marconi Company, mainly for fitment in aircraft of the R.A.F. These sets were fitted to Lancaster Bombers, such as "G for George", now in the Australian War Memorial in Canberra.

They were one of the few receivers for their time to have a colour coded dial. The colours matched the ranges of the associated transmitter, the T1154, which had appropriately coloured knobs.

There were many models of the R1155, covering differing frequency ranges and incorporating various wavetraps and filters to remove interference within the aircraft caused by the ever increasing complexity of electronic devices added as the war progressed. A major problem with the receiver stemmed from the choice of intermediate frequency, (560kc) which happened to be on the same frequency as a very powerful radio transmitter in the Republic of Ireland!! One version of the receiver, believed to be the R1155M, was mistakenly soldered with acid cored solder on the assembly line. This version was marked "Not to be used in Aircraft".

R1155 internal view

Technical Data

The receiver is a single conversion superhet, with circuitry provided for Direction Finding. A feature of the set is the use of back biasing, which involves the power supply H.T. negative feed not being earthed at the set, but rather being connected to the bias network. Those working on R1155's should note that pin1 of most valve sockets is used as a H.T. feed point, not earth, as is usually the case. Please remember this if you change to metal valves - you will find that you have full H.T. on the metal envelopes!!

The valves used in the receiver are fairly standard CV types, with Australian equivalents able to be used for replacement purposes.

The tuning ranges of all R1155s apart from types L and N were 75kc/s-500kc/s, 600kc/s-1500kc/s and 3-18.5Mc/s. Types L and N (often referred to as the "Trawler Sets"), covered 200-500kc/s and 600kc/s-18.5mc/s, hence covering the 1.5-3.0Mc/s shipping band.

Typical sensitivity is around 10 micro-volts, with an output impedance of 5000 ohms.

The total power consumption is 50 watts (200 mw for headphones).

The web site linked above has circuits, component layouts, photgraphs and much other information on these sets.

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© Ian O'Toole, 2009. Page created: 28/04/03 Last updated: 4/12/2009