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Duxford Radio Society

Imperial War Museum, Duxford, England 

Restored Equipment Details


Gee System Navigation Trainer Type 48 (1945)

Gee System Navigation Trainer Type 48
Gee System Navigation Trainer Type 48
DRS Gee System Test Bench
DRS Gee System Test Bench

Gee System Navigation Trainer Type 48 (UK)

Gee Trainer Type 48 was a low-power ground-based Gee navigation transmitter designed for practice training of war-time RAF Navigators in the use of the Gee navigation system.

The use of this equipment enabled Navigators to practice receiving the Gee signals and plotting their position without the need to spend time aloft in valuable aircraft, consuming scarce fuel.

Gee was a hyperbolic VHF radio navigation system for aircraft that was evolved by British scientists to meet the needs of the RAF during World War II, at a time when both Bomber Command and Coastal Command faced serious navigation difficulties.

Gee allowed an aircraft or ship to determine its position by measuring the time delay between two received radio signals.  The Gee system used three transmitters (one master and two slaves) that were sited about 50 to 100 miles (60 to 160 kilometres) from each other, and transmitted on frequencies in the band 25-85 MHz. The transmitters sent out pulsed radio signals in a four part cycle, with each sequence spaced one millisecond apart.

The signals were typically received by an R1355 receiver,  displayed on the screen of a cathode ray tube indicator 62A and then the location determined by reference to special charts.

The Gee navigation system remained operational until 1970.

The equipment is shown here with the Duxford Radio Society Gee system test bench under going soak testing.

More details to follow. 

This Trainer Type 48 transmitter has components dated October 1945 and carries Serial No. 389, Air Ministry Ref No. 10D/1164.

When received, the equipment was missing its outer case but did include its original whip antenna for broadcasting the Gee signal to receivers within the navigation school classroom.

More details to follow.
The equipment is in the process of receiving extensive electrical and mechanical  restoration and is undergoing soak testing with a R1355 Gee receiver and Indicator Unit No. 62A.

More details of the restoration process to follow.




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