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MSF Phonic Motor Clocks Source: BT



Since 1927, time signals had been transmitted across the world by the GBR 16 kHz transmitter. However, in the late 1940s the National Physical Laboratory (NPL) at Teddington pressed for time signals to be more readily available to people and establishments within this country. It was at this point that the GPO was approached to set up the MSF Time Signal service.

So it was that, after a period of development, the new MSF Time Signal service started on Wednesday 1st February 1950, initially operating (for short periods only) on 5 MHz, 10 MHz and 60 kHz.

Unlike the GBR time signals, which were sent by landline from the Royal Greenwich Observatory, the MSF time signals were generated at Rugby. Crystal oscillators were used as the timing source and 1 kHz Phonic Motor Clocks produced the second/minute pulses. These clocks were designed by the Royal Greenwich Observatory and made by the Muirhead Company in London.

The Long Wave Transatlantic Telephone Transmitter was used for the 60 kHz signal – and this is the reason why the signals are still on this frequency today.

In April 2007, the transmission moved from Rugby to Anthorn Radio Station, near Carlisle, where it’s still in operation.

MSF HF Transmitter ESa Source: BT

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