It was originally built in the 1980s as a fill-in relay for UHF analogue television covering the communities of Rhayader and St. Harmon.

It consists of a 45 m self-supporting lattice steel mast standing on a hillside which is itself about 345 m above sea level.

After the switchover process, analogue channels had ceased broadcasting permanently and the Freeview digital TV services were radiated at an ERP of 20 W each.

The UK's digital switchover commenced at Carmel (and therefore at Rhayader and all its other relays) on 26 August 2009.

Channel 23 was replaced by the new digital BBC A mux which started up in 64-QAM and at full power (i.e. 20 W).