In-orbit performance of Comstar TWTAs

The first Comstar satellite was launched in May of 1976, while the last of the Comstar satellites was launched in February of 1981. There are four Comstar satellites in orbit with a total of eight driver traveling wave-tube amplifiers (TWTA) working and 96 final TWTAs. A description is provided ou the Comsat General's Comstar RF performance measurement system, and some of the recorded findings are presented. The Communications Subsystem is designed to relay telephone or television signals from point-to-point within the continental U.S. or offshore areas including Alaska, Hawaii, and Puerto Rico. Attention is given to the wideband receiver section, the input multiplexer assembly, high-level TWTA, the output multiplexer assembly, the in-orbit RF performance monitor system, the tests which can be performed, and the Comstar TWTAs.