History

This page documents a group of links set up for television destribution in south and west Wales. The first site to be established was at Mynydd Pencarreg in 1957: the BBC transmitter at Blaenplwyf used a "direct pickup" link, receiving the Wenvoe transmitter off-air with a short microwave link.

For ITV two separate franchises were created. Wales (West and North), operated as Teledu Cymru would serve the coastal region. Television Wales and the West covered south Wales and the west of England, initially from a single transmitter at St Hilary, near Cardiff. The first transmitter for WWN would be at Preseli but the studios were in Cardiff (TWW region) requiring a new "vision circuit" from the Post Office. The PO and Intependent Television Authority (ITA) agreed that onward links to WWN's other transmitters would be provided by the ITA. WWN first broadcast on 14 September 1962, this being the final ITA franchise to launch.

Parts of the WWN link were initially of an interim nature. Around the same time the PO had agreed to provide a fully-engineered link for the BBC, including a spur to a new transmitter at Haverfordwest. Contract 23515 was awarded to GEC in November 1961, described as "Wenallt - Tall Drysch and Blaen Plwyf". The completion date was to be "1 December 1963, subject to access to buildings & towers by 1 August 1963".

GEC's bid of £117,459 for a L6 GHz system was accepted, Marconi was unable to bid "due to present production position" and STC's offer of £174,030 was ruled out. The revised price at April 1966 was £133,984. The link required new sites at Wenallt, near Cardiff, Werfa and Llanllawddog which would become a hub with local spur links. All three sites were provided with varying forms of the "Standard Tower" including platforms for horn antennas. The ITA site at Preseli (Tall Drysch) was equipped with a dish on the broadcast mast and the existing BBC link from Mynydd Pencarreg incorporated into the overall scheme.

Photos of the sites show dishes installed on short towers or telegraph poles and "temporary equipment" providing the initial link for Preseli. The first extension to the system was addition of a link for the BBC transmitter at Haverfordwest. Contract 23543 was issued in November 1962 for "Llanllawddog - Woodstock" - a 2 GHz link: "The equipment to be ready for service by 1 May 1964...". GEC's bid of £25,254 was accepted, STC were unable to quote (they did not produce 2 GHz equipment) and Marconi made a higher offer of £28,130. The link to Haverfordwest required a dish at high level on the tower at Llanllawddog which has a tall centre section for this purpose.

The Haverfordwest transmitter provided a VHF 405-line service from February 1964, closing in January 1985, however the PO link had been replaced by a "self-provided" BBC link some time after 1972. Blaen Plwf became a UHF transmitter site for BBC2 from December 1970. BBC1 was added in February 1972 and ITV in May 1973. 625-line UHF television, with provision for colour, required links to a higher standard and these became available progressively during the early 1970s. A new UHF transmitter was added by the BBC at Carmel with BBC2 in-service from July 1971 - again the programme feed was a spur from Llanllawddog. Carmel carried BBC1 from August 1972 and ITV from May 1973 with all three UHF services added to Preseli in August 1973. These dates are likely to be influenced by the availability of new links from Cardiff as well as the local spurs.

Due to the original ownership of the transmitter sites only the BBC 625-line BBC feeds were provided to Carmel and only ITV to Preseli although all three were available at Blaen Plwyf. This BBC/IBA split between Carmel and Preseli continued into the 1980s. Feeds for the "missing" BBC services were received off-air at Preseli and it's likely a similar arrangement was made at Carmel for ITV.

Prior to the addition of Channel 4 (S4C) and a new link to support BBC FM stereo broadcasts from Blaen Plwyf it seems the entire scheme was fully re-engineered. In 1976 a new site had been added at Swansea - assumed initially for telephony purposes. This was added as an extra intermediate site between Werfa and Llanllawddog. A 1980s diagram shows the vision circuits had sequential numbers throughout. The links remained essentially one-way: five circuits (BBC1, BBC2, IBA1, IBA2 and BBC stereo) from Cardiff to Llanllawddog, contining to Blaen Plwyf; BBC1 and BBC2 were carried over the Carmel spur with IBA1 and IBA2 on the Preseli spur. Each branch was provided with audio circuits - these carried programme sound for the IBA together with switching and "supervisory" functions. Return audio circuits for control purposes were also provided from all transmitter sites. No return vision ("contribution") circuits are shown on the diagram. Shared "protection" circuits were used on a 5 + 1 basis for the main route, 2 + 1 for the spurs and 1 + 1 for the audio circuits returning from the transmitter sites.

By the mid 1990s BBC and C4/S4C links had migrated to Energis and BT-provided fibre links respectively - it is likely the remaining links to Blaen Plwyf and Preseli would have been transferred soon after. All sites were retained.

There is little information about telephony traffic west of Cardiff and the original configuration appears to be designed purely for television requirements. An article in the Post Office Electrical Engineers' Journal, January 1977, suggests a new site at Swansea initially had a single dish, presumably to provide telephony circuits. Diagrams of proposed digital links in the 1980s show a microwave link between the Digital Main Switching Unit sites at Cardiff and Swansea. This continued to a site near Carmarthen, believed to be Llanllawddog. Google Street View in 2009 shows Llanllawddog with just three large dishes apparently facing Swansea. Photos of the other two main sites confirm dishes were still present in the early 2000s with the dishes at Werfa facing Swansea rather than Llanllawddog.