The Kilvey Hill transmitting station was originally built at the summit of Kilvey Hill in Swansea, Wales, by the BBC in 1967 as a relay for VHF and UHF television. VHF television came on air a few months before the UHF services. As built, the station did not radiate VHF FM radio, this was added later. Currently, the hill's transmitters cater for the entire network of digital terrestrial and digital radio subscribers in the city and county of Swansea, Neath Port Talbot and possibly even further. The transmission station located on top of Kilvey Hill is owned and operated by Arqiva.
Freeview digital terrestrial TV was already available at low power from this transmitter before the digital switchover process began, with the first stage taking place on Wednesday 12 August 2009. The second stage was completed on Wednesday 9 September 2009, with the transmitter becoming the first in Wales to complete digital switchover. After the switchover process, analogue channels ceased broadcasting permanently and the Freeview power increased from 383 W ERP to 2 kW ERP, a 7dB power increase.
Kilvey Hill provided BBC 405-line VHF television to the Neath and Port Talbot area which is strongly shielded by local hills from the Wenvoe transmitter just to the west of Cardiff. Kilvey Hill was a relay of the Wenvoe transmitter. Despite being sited at Swansea, no effort was made to provide the VHF TV signal to Swansea itself - the town was already deemed to be well served by Wenvoe.
A BBC R&D report details the coming of 625-line UHF television to the Kilvey Hill site. This again was with the station acting as an off-air relay of Wenvoe, which was (at that point) only transmitting BBC 2 (in colour) on 625-lines. This time, the northern parts of Swansea were intended to be covered by the signal as local hills (including Kilvey Hill itself) shielded those parts of the town from the UHF signal from Wenvoe.
During 1997, Channel 5 gained an analogue channel from some transmitters and Kilvey Hill was one of them. The site radiated all five UK terrestrial analogue television services at 10 kW until digital switchover was completed on 9 September 2009.
The initial rollout of digital television in the UK involved radiating the signals at low power in between the existing analogue channels. The apparent use of channels "21" and "22-" for muxes "C" and "2" respectively might look like a mistake, but is confirmed by OFCOM's site.
The UK's digital switchover commenced with Kilvey Hill on 12 August 2009. Analogue BBC Two Wales on channel 26 was first to close, and ITV Wales was moved from channel 23 to channel 26 for its last month of service. With it went Mux 1 from channel 25- to be replaced by the new BBC A mux which started up in 64-QAM and at full power (i.e. 2 kW) on channel 23 which had just been vacated in the shuffle.
Swansea Sound changed frequency to 96.4 MHz as required by a new bandplan for Band II broadcasting which placed BBC stations below 96 MHz and Independent Local Radio stations above that. The band limit was 98 MHz at that point. BBC Radio 2, BBC Radio 3 and BBC Radio Cymru commenced from the site sometime before 1988 as the BBC's Service Area map of 1988 shows.