Rampisham Down

Rampisham Down
Rampisham Down from the north
Highest point
Elevation	221 m (725 ft)
Prominence	5 m (16 ft)
Geography
Location	Dorset Downs, England
OS grid	ST544014
Topo map	OS Landranger 194

Rampisham Down is a chalk hill in the Dorset Downs, eight miles north west of Dorchester in west Dorset, England. The highest part of the hill is 221 metres (720 feet). To the north east of the hill is the Frome valley and the village of Rampisham, to the south west is the Hooke valley and the village of Hooke. The A356 road between Dorchester and Crewkerne cuts across the down.

Rampisham Down was the location of one of the main transmitters of the BBC World Service in Europe until it was shut in 2011. There were 26 transmitter pylons on the down.

The 189-acre site was acquired by the BBC in November 1939 and the station, known as Overseas Extension 3 (OSE3), was equipped with four Marconi type SWB 18, 100 kW short-wave transmitters. The transmitter halls, each containing a pair of these transmitters, were separated by heavy blast walls. A comprehensive aerial system was installed consisting of 29 arrays supported between 15 masts of heights varying between l00 ft and 325 ft. Full world coverage was given by this aerial system, although the transmissions were primarily intended for areas outside Europe. This was the first of the BBC's short-wave stations to be provided with 4-wire transmission lines, following tests made at Daventry (OSE1). A remotely controlled switching tower was used for connecting any transmitter to any aerial array (antenna).

OSE3 was provided with an emergency power supply consisting of two 750-bhp diesel alternator sets. The diesel engines, which had been designed for railway locomotives abroad, were equipped with battery starting facilities instead of the compressed-air starting arrangements that were conventional for diesel engines of this size. The station came into service on 16 February 1941 and during May of that year a number of tests were carried out using a captive balloon to measure the performance of the horizontal dipole arrays and to determine the effect of the contour of the ground close to the station on their vertical radiation pattern.