Space Qualification of the Radioastron 22 GHz Receiver

The Radioastron space VLBI satellite, expected to be launched in 1995, will have on board four sensitive two-channel radiometers. Finland is responsible for the 22 GHz receiver. The most important properties of the receiver are sensitivity, phase stability and gain stability. To reach maximum sensitivity, a modern space qualified low noise HEMT amplifier has been designed. The measured receiver noise temperature is 140 K. For maximum phase and amplitude stabilities, temperature stabilisation and a high Q dielectric resonator oscillator design have been utilized. The measured phase stability is better than 3 o/h. The main aspects of the space qualification tests and the reliability analysis are described.