It consists of a 17 m self-supporting lattice mast standing on Craig Glyn Meirch, a hillside which is itself about 140 m above sea level (about 90 m above the valley floor).

Alltwen transmitter re-radiates the signal received off-air from Kilvey Hill about 12 km to the southwest.

When it came, the digital switchover process for Alltwen duplicated the timing at the parent station, with the first stage taking place on Wednesday 12 August 2009 and the second stage was completed on Wednesday 9 September 2009, with the Kilvey Hill transmitter-group becoming the first in Wales to complete digital switchover.

After the switchover process, analogue channels had ceased broadcasting permanently and the Freeview digital TV services were radiated at an ERP of 2 W each.

The UK's digital switchover commenced at Kilvey Hill (and therefore at Alltwen and all its other relays) on 12 August 2009.