Deri is a village hidden away in the bottom of the Darran Valley in South Wales. The valley is quite deep so the area requires its own fairly substantial relay despite being almost adjacent to both Bargoed and Rhymney.

Transmission is from two pairs of panel antennas, with a vertically polarised signal to the east towards Deri itself and to the north towards Pentwyn and Pen-y-Bank. The receive aerial is a trough antenna pointing south west at Wenvoe.