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.
Alltwen transmitter re-radiated a signal received off-air from Cwmafan about 2 km farther to the northeast, itself a relay of Wenvoe. It was possibly the lowest ERP officially provided TV relay in the UK, radiating just 0.5 W on each of its four UHF channels.
When it came, the digital switchover process rendered Caerhendy redundant. It is no longer in service.
| Frequency | UHF | kW | Service |
|---|---|---|---|
| 471.25 MHz | 21 | 0.0005 | BBC One Wales |
| 495.25 MHz | 24 | 0.0005 | ITV1 Wales |
| 519.25 MHz | 27 | 0.0005 | BBC Two Wales |
| 551.25 MHz | 31 | 0.0005 | S4C |
Transmitter sites in Wales | |
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| Transmitter stations | |
