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Photos by Brian Hutchison and Jordy Lyons Page last updated: 2012-04-10

Original photos

The unusual and distinctive diamond shaped mast at Lisnagarvey is known after its designers and manufacturers as a Blaw-Knox radiator and is now the only surviving example in Western Europe. As built, at its original size it was almost 145m (475 feet) tall but when its main operating frequency was changed to 1341kHz its top section was removed.

Thanks to Aub McKibben for the picture below of the mast in its original state at the BBC's historic Lisnagarvey site - also known locally, at the time, as Blaris and also, as you can see, as Lisburn. The photo was originally printed in the BBC Annual of 1936.

Brian Hutchison took the next two photos. He says: "While this mast is very efficient it also causes a lot of problems for the computer networks in the neighbouring car dealers. It is rumoured that this mast will be dismantled in the next year or so, and either moved or replaced by another mast elsewhere."

The top section of the mast was removed many years ago and now stops at the third platform up. Some services (R4 and R Ulster?) are radiated by the mast itself while other services are radiated by more conventional wire antennas suspended from adjacent supports.

It may be the size and shape of the mast which make Radio Ulster audible over a wide area, including parts of England sometimes as far south as London!

The extensive old transmitter halls at this site and offices are the main base for NGW's maintenance operations in N.I.

There are now two conventional lattice masts supporting a wire aerial at the site.

But rumours that the Blaw-Knox mast's days are numbered are apparently untrue.

Lisnagarvey entered service on 20th March 1936 with the N.Ireland regional programme on 977 kHz.

1st September 1939 this was replaced with the Home Service on 767 kHz.

29th July 1945 N.Ireland Home Service on 1050 kHz. Also a transmitter for the new Light programme entered service on 1149 kHz.

15th March 1950, these frequencies were changed to Home Service,1151 kHz and Light Programme, 1214 kHz.

7th January 1963, N.Ireland Home Service frequency changed to 1340 kHz.

30th September 1967, 1214 kHz re-assigned to Radio 1.

23rd November 1978, R.Ulster frequency changed to 1341 kHz, Radio 3 re-assigned to 1215 kHz. New transmitters brought into service for Radio 1, 1089 kHz, Radio 2, 909 kHz and Radio 4, 720 kHz.

27th August 1990, 909 kHz re-assigned to Radio 5

28th February 1992, Radio 3 on 1215 kHz closed.

30th April 1993, INR 2 (Virgin Radio) launches on 1215 kHz.

30th June 1994, Radio 1 on 1089 kHz closed.

14th February 1995, INR 3 (Talk Radio) launches on 1089 kHz.

Lisnagarvey index

Black Mountain | Divis A

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