The Caerhendy television relay station was sited at Caerhendy in the Afan Valley, a few kilometres north of Junction 40 on the M4 motorway at Port Talbot. It was originally built in the 1980s as a fill-in relay for UHF analogue television. It was sited at the clubhouse of the soccer ground at Ynys Park and consisted of a mere 3 m aluminium mast carrying a vertically stacked yagi array. The transmitter served about 50 houses in Caerhendy, about 500 m across the valley to the east, which for reasons of geography couldn't get a signal from Mynydd Emroch transmitter just to the south.