Power subsystem for Skylab radiometer/scatterometer/altimer experiment

Spacecraft electrical systems must satisfy a demand for short duration pulses and long term or dc levels as the spacecrafts electronic equipment is operated. During these operational periods, the spacecraft bus undergoes wide variations in power demand which can cause voltage fluctuations and out of specification conditions to occur if adequate design provisions are not incorporated. This paper describes the power subsystem of the Radiometer/Scatterometer/Altimeter Experiment for Skylab 1, and the design implemented to provide a high quality bus to supply widely varying power demands. Some of the load conditions considered include initial turn-on of power and the associated inrush current; low frequency operation of a traveling wave tube; bursts of calibration pulses; periodic high power radar pulsing; waveguide switch operation; antenna gimbal slewing; and heater control circuitry to provide constant temperature. Power processing circuits are also discussed, including a pulse-width modulated voltage regulator, dc-to-dc conversion for isolation, and additional converters to provide various voltage levels.