It consists of a 25 m self-supporting lattice mast standing on a hillside which is itself about 230 m above sea level.

Builth Wells transmitter is classed as an indirect off-air relay of Carmel.

After the switchover process, analogue channels had ceased broadcasting permanently and the Freeview digital TV services were radiated at an ERP of 5 W each.

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

Channel 25 was replaced by the new digital BBC A mux which started up in 64-QAM and at full power (i.e. 5 W).