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Photos by BT Heritage (commentary by Dan Glover) Page last updated: 2016-05-27

London to Birmingham 900 MHz link

Initial field trials for the London to Birmingham television link were carried out in December 1946 with further tests from the chosen sites in 1947. The requirement was to provide a link from Museum exchange in London to the central Birmingham exchange (both locations later gained concrete towers as part of the subsequent GPO microwave network, of course). In "Stage 1" the link was intended to be reversible but this proved troublesome in practice - "Stage 2" provided a permanent link in both directions. See "Tales from a Cold Field" for the BBC transmitter site's experience and apparent relief that there was also a cable route between London and Birmingham (link below)

The intermediate sites chosen were Harrow Weald, Dunstable (Zouches Farm), Charwelton and Turners Hill. All except Turners Hill continued to be used by the Post Office and BT as SHF link sites. Initially a single dish was used with the transmitters and receivers switched when the link was reversed. The dishes were a 14 ft paraoblic reflector - but reduced to 10 ft horizontally to allow a more compact mounting. A dipole and reflector were mounted at the focus and electrically heated to avoid ice forming. Conventional coax cable was used. Two frequencies were used in each direction, alternating for each section of the route. From London 870 MHz was used, then 890 MHz at Harrow Weald, 870 MHz at Dunstable, and so on. The return path started with a 917 MHz transmission from Birmingham, changing to 937 MHz at Turners Hill

Creative Commons LicenceThese images are Copyright BT Heritage, licensed under a Creative Commons License and reproduced under the following terms

December 1949 - for "Stage 1" a single antenna was used in each direction, mounted on a guyed mast

[TCB 417/E 16253]

"Dunstable intermediate repeater station view of transmitter side door open"

[TCB 417/E 16256]

"Dunstable transmitter and receiver"

[TCB 417/E 16257]

1962 - in "Stage 2" separate antennas were provided to allow independent links in each direction. Self-supporting towers were constructed and the equipment was housed in a cabin at the top

[TCB 417/E 27791]

By 1965 the 900 MHz antennas had given way to SHF dishes, probably operating at 4 GHz, but the new tower had been completed and equipped with horn antennas able to operate at 4 GHz and 6 GHz simultaneously. The original TV link building can just be seen to the right of its much larger successor

[TCB 417/E 31337]

There is something slightly sinister about the new tower which may be why it was used as a location for Dr Who in 1970 (see link below)

[TCB 417/E 31341]

Zouches Farm index

BT Tower | Turners Hill

Zouches Farm as Dr Who location
Tales from a Cold Field: The Pictures

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