A dual-channel cooled GaAsFET receiver for the Dominion Radio Astrophysical Observatory 26-metre radio telescope covering 1.35 to 1.75 GHz

A low-noise receiver for a radio telescope is described. Two identical three-stage GaAsFET amplifiers were built which give excess noise temperatures of less than 28 K with at least 34 dB gain between 1.35 and 1.75 GHz when operated at a physical temperature of 12 K. This noise temperature is measured at the cryostat input connectors. The physical temperature is maintained by a closed cycle helium refrigerator. Source-inductance feedback is used to allow optimum noise performance combined with good input match. Return loss is better than 15 dB across the band. Construction details of the amplifiers and their mounting in the cryostat are provided. Sample observational results are presented.