It was originally built by the BBC,[1] entering service just before Christmas 1966 transmitting the now-defunct 405-line VHF television system.

[3] When digital television was introduced in 2009, the site formally became a relay of Long Mountain which had now become classed as a main transmitter in its own right.

BBC 405-line television started up with the site acting as an off-air relay transmitter of Llandrindod Wells about 25 km to the south.

The direct line-of-sight to Blaenplwyf is heavily obstructed and so Llanidloes rebroadcast the off-air signal from Llandinam's relay transmitter about 10 km to the east.

When the UK's digital switchover commenced at Llanidloes it therefore mirrored the changes taking place at Long Mountain.

From the outset, Llanidloes radiated the BBC's three FM radio services, acting as an off-air relay of Llandrindod Wells.