The Mendip transmitting station is a broadcasting and telecommunications facility on the summit of Pen Hill, part of the Mendip Hills range in Somerset, England, at above sea level. The station is in St Cuthbert Out civil parish, approximately north-east of Wells. Its mast, high, was built in 1967 and is the tallest structure in South West England. The mast broadcasts digital television, FM analogue radio and DAB digital radio, and had broadcast analogue colour television from 1967 until 2010.
Description
The station is owned and operated by Arqiva (which acquired National Grid Wireless, previously Crown Castle).
Until 2008 a GRP aerial cylinder, containing the analogue television transmitting antennas, was mounted at the top of the mast, bringing the total height of the structure to . With a mean height of above sea level, these antennas were among the highest in the UK. They were removed in 2010, the antenna cylinder being replaced with a new antenna assembly, ready for digital switchover later that year. The present assembly is slightly shorter than the previous cylinder, causing the overall mast height to be reduced from to .
There are red aircraft warning lamps (six sets of two lights) on the mast and two lights on top. The lights were upgraded in February 2007 to comply with CAA 2000 Air Navigation Order, designed to prevent low flying aircraft from hitting the mast. The mast was repainted during 2007.
The mast can be seen from as far away as Puriton during the day and the red aircraft warning lights make it visible at night from pretty much anywhere on the Somerset Levels and areas of South Wales, such as the high ground near the Wenvoe Transmitting Station.
Television
Mendip was configured as a C/D group transmitter when it entered service with analogue PAL transmissions. In July 2007, Ofcom confirmed that it would remain a C/D group transmitter at digital switchover. The mast broadcasts digital television over a large area of the west of England, including Somerset, Wiltshire, North Somerset, Bath and North-East Somerset, Bristol, southern Gloucestershire, northern Dorset and East Devon.
Cardiff and other parts of southeast Wales were also able to receive the analogue TV transmissions from Mendip, and many households used it in preference to their more local Wenvoe transmitter which carries the Wales variations of BBC One, BBC Two, and ITV. This was originally because the Wenvoe transmitter broadcast S4C (with programmes in Welsh and some prime-time English programmes from Channel 4 scheduled at much later times) rather than Channel 4 itself. Even after digital switchover when transmitters in Wales also began to broadcast Channel 4 in addition to S4C, some households continued with their preference for the West variations of BBC One, BBC Two, and ITV, and having Channel 4 (not S4C) as number 4 on the electronic programme guide.
Power on analogue transmissions was 500 kW (ERP) for BBC 1, BBC2, HTV West, Channel 4, and 126 kW (ERP) for Channel 5. The latter was transmitted outside of the original C/D grouping of the transmitter but most homes in reasonable signal areas for the C/D group could receive it with their C/D group aerial. All six digital multiplexes were transmitted at 10 kW until switchover in 2010 when the power on the "BBC A", "BBC B/HD" and "D3&4" multiplexes was boosted to 100 kW. In 2011, SDN was boosted to 50 kW and in 2012 the remaining two Arqiva multiplexes were boosted to 50 kW too.
In June 2019, as part of the 700MHz clearance programme, Mendip became K group (excluding muxes 7 and 8, which are due to be switched off between 2020 and 2022). This means that homes in poor signal areas which still have a C/D group aerial may have difficulty in receiving all multiplexes.
Mendip's population coverage is around 1.5 million, although some homes in the immediate vicinity, such as those in Cheddar, are unable to receive a signal due to being in the shadow of the Mendip Hills and therefore depend on local relays.
Radio
Mendip broadcasts FM (analogue VHF) radio for BBC Radio Somerset and the Severn Estuary regional service Kiss 101. Mendip also transmits high power Digital Audio Broadcasting (DAB) signals for the Digital One, Sound Digital and BBC National DAB multiplexes. An additional DAB multiplex, MuxCo Somerset, was awarded a licence in 2008 to broadcast local and national services to Somerset, and began transmission in 2014. After the closure of the Severn Estuary digital radio multiplex, the equipment from Mendip was reused to improve coverage on the Welsh coastline for the Cardiff & Newport, now South East Wales, mulitplex.