Terror by satellite

Tony Hale, skilled engineer and amateur radio ham, smuggles a home-made transceiver on board an Earth-orbiting satellite during his tour of duty. This proves invaluable as the commander of the satellite, Hendriks, is a megalomaniac and demands to be made 'Dictator of the World'. To back up this demand, he begins destroying swathes of the Earth's surface using a radiation beam. The only secure link between the Earth and the satellite is Tony's radio.