This picture shows one of the 500khz transmitters used at Malin Head Radio. With a maximum output power of 1.2kilowatts. These transmitters used a pair of 4 x 500 valves, with a plate voltage of 3kv. A cabinet of the same size housed the modulator stage, which was common to all the W/T transmitters at the station, i.e. 500khz, 512khz, and 421khz. The modulator used a pair of triode valves type 4212e in push pull, developing 600 watts of audio power to plate and screen modulate the 500khz carrier, producing the required MCW (modulated carrier wave) signal required on this distress frequency.

All W/T transmitters were fed to a "Tee" type wire antenna strung between the two 150ft towers on the station. As the antennas natural resonant frequency was 920khz, it was brought to resonance on 500khz with a coil of 95uH. With a clear take off and the sea on two sides of te station, Malin Head Radio's signal on 500khz could be heard over large areas of the atlantic, whilst also covering the Irish Sea.

Click on the photo to listen to the last morse message sent from Malin Head Radio on 31st December 1988.  

This is sound of the final broadcast to all stations on 500khz announcing the close down of 500khz service at Malin Head Radio, callsign EJM, followed by the replies from ships and other coast radio stations, sending best wishes and good luck. This transmission was sent using a straight key, by F. O'Connor R/O.