Long Range
in th UK

Early History

Portishead Radio
1927 to war
in the 70's
in the 80's
GKA today
Transmitter Sites



Last page update
09 August 1998

Content researched by
Terry Slack
Bob Dixon

HISTORY of Portishead Radio
Transmitter Sites

Broadcasting to ships had been taking place since the early days of radio. The Marconi Company had sites at Poldhu (opened 1901 callsign ZZ) and Caernarvon (opened 1914 - callsign MUU) which broadcast to ships on long wave, giving extended range.

No long-range system existed until 1919 when the GPO and the Marconi Wireless Telegraph Company agreed to convert a redundant Imperial Wireless chain receiving station at Devizes in Wiltshire for long-range maritime use. Comprising a 6-Kilowatt valve transmitter, station ''GKT' opened for service early in 1920 with a guaranteed range of 1,500 miles, the receiver and operational staff being on the same site. By 1924 it became necessary to expand the station at Devizes to cope with the increased demand. The GPO constructed a second long-wave transmitter with the additional callsign of GKU and moved the receiver and operational site to Highbridge. By 1926, experiments on short wavelengths had established that world-wide communication could take place and, in the same year, the GPO installed the first maritime short-wave transmitter at Devizes. (rapid expansion of the service and limited space at Devizes led to the requirement for a new transmitter site and ultimately closure of Devizes).

Initial tests of the new short-wave system proved outstandingly successful, and it became necessary to construct a brand new transmitting station. This station was to be located at Portishead, near Bristol, and thus in 1927 Portishead Radio was born. Three long-wave transmitters were installed, followed in 1929 by a new short-wave transmitter. Existence of the Portishead site ultimately resulted in the closure of the Devizes station. Long-wave transmissions ceased from Portishead in 1959. In 1970 radiotelephony service transferred from Baldock to Portishead. The Portishead transmitting site was closed in 1978, leaving the sites at Leafield and Ongar, operating alongside the main transmitting site at Rugby. However, the famous name of 'Portishead Radio' was maintained to provide the maritime community with a familiar and well-known service.

Other sites - Rugby, Ongar, Leafield
The GPO had transmitter sites at a number of locations around the UK which provided point-to-point transmission facilities for long-range international telephone calls. At undersea cables came into use followed by satellite communications, some of the powerful transmitters at these sites became redundant, opening the way for them to be transferred for maritime use (and contributing to the demise of the Portishead transmitter site with its older, less powerful transmitters. These sites also provided service for other users (such as Reuters) and, as use of short-wave declined, so more transmitter capability became available at Rugby and the sites at Ongar and then Leafield became redundant, eventually closing. Another site associated with maritime communications was Baldock Radio which provided the maritime world with it's HF radiotelephony links until 1970. Today Rugby provides the entire HF maritime transmitter capability.

Rugby Radio/GBR
A Special mention is warranted for GBR. Opened in 1926 on 16kc/s, GBR's purpose was for long-range broadcasts to ships. More recent Radio Officer's remember the station for it's time signals. GBR still continues but it's transmissions are no longer connected with those who sail on the oceans surfaces. And the famous keying of the GBR callsign in Morse no longer causes the lights in the vicinity of the radio station to illuminate in time to the keying, the transmissions now being various forms of teletype.