ITV 405 line VHF TV TRANSMITTERS
|Channel / Polarisation||9 H||8 V||13 H|
|Max. Vision ERP||100 kW||100 kW||0.1 kW|
|Site ASL||987 ft||900 ft||492 ft|
|Aerial ASL||1687 ft||1867 ft||606 ft|
|Location (NGR)||J 278727||H 393947||D 077423|
A large part of Northern Ireland was provided with an Independent Television service in the Autumn of 1959 by the construction of the Black Mountain station near Belfast, close to the BBC's existing Band I station at Divis.
The Black Mountain station overlooks Belfast and is 987 ft above sea level. A 750 ft mast, the highest which could be permitted owing to the proximity of the airport, was erected. It supported a moderately directional aerial radiating about 100 kW to both the north-west and the south-west, 70 kW to the west and 20 kW to the east. This power-radiation pattern ensures the optimum coverage of the area whilst avoiding harmful interference to the service areas of other stations using Channel 9, notably Winter Hill.
West Ulster, which includes the districts of Londonderry and Enniskillen, could not be covered by the Black Mountain station and it was clear that at least one additional station was needed. A study of the topography of West Ulster revealed that the unserved area could be covered economically by a single station if a high site near Strabane could be obtained. A site 900 ft above sea level was found four miles south-east of Strabane and here a station using a 1,000 ft mast was constructed. It has a highly-directional aerial radiating about 90 kW in two main lobes to the north and to the south. 10 kW only is radiated to the east and west, but this suffices to cover the areas not served by the Black Mountain transmitter and, at the same time, prevents unnecessary radiation into the territory of the Irish Republic to the west. The Strabane station is a semi-automatic satellite of Black Mountain.
The Black Mountain station went into service on 13th October 1959, Strabane on 18th February 1963.
A small relay station at Ballycastle provided an improved service in the north-east of the area. This entered service on 6th July 1970, and was the penultimate 405-line transmitter to be constructed by the ITA.