THE PARKES RADIO TELESCOPE MODIFIED FOR RAPID RECEIVER CHANGES

This paper describes recent improvements to the Parkes 64 m radio tele scope, now 33 years old. It is being upgraded to allow rapid switching between receivers, and to track the best-fitting focus as the elevati on angle changes. Carried out under contract on behalf of NASA, the up grade included installing a low-noise 2.3 GHz receiver for tracking th e spacecraft Galileo in 1997. We explain the mechanical and structural aspects of the upgrade, including the need to replace the existing fo cus cabin with a larger unit, and the effect of the increased weight a t the prime focus on the focusing characteristics and reflector accura cy. Finally, we summarize the designs of the feed and receiver to opti mize the antenna-efficiency/temperature ratio at 2.3 GHz for the Galil eo mission.