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GBR Transmitter with George Mortimer (1976) Source: MJH



By the early 1960s, the Admiralty had sole use (with the exception of the Time Signal service) of the GBR 16 kHz long wave (now called ‘very low frequency’ VLF) transmitter. Apart from its long range, one of the other advantages of VLF transmissions was that they could penetrate deep oceanic waters.

In the middle of the 1960s, at the height of the Cold War, the Admiralty, with its fleet of new Polaris submarines, was preparing to take on the role of ‘nuclear deterrent’. To be of maximum effectiveness they sought improvements to VLF communications and asked the Post Office to provide an enhanced service from Rugby Radio Station. The design of the transmitter had remained virtually the same since it was originally constructed in 1925, so the Post Office decided it was time to totally rebuild the GBR transmitter incorporating a new design that used just three valves. Three very large valves!

The new transmitter was opened for service by Captain CBH Wake-Walker, Director of Naval Signals, on Wednesday 30th November 1966. The output power had increased from 350 to 500 kW and, as well as sending out messages in Morse code, the new set-up could transmit teleprinter messages using Frequency Shift Keying (FSK).

GBR Main Aerial Tuning Inductor (2002) Source: MJH


Cpt Wake-Walker RN Starts GBR (30/11/66) Source: BT

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