Communications & Power Industries, Inc.

Communication and Power Industries, Inc.

Communications and Power Industries, Inc., Satcom Division

Eric Oiesen

Michael J Cascone

Edward L Wright

Richard J Dobbs

A klystron tube for amplifying signals at microwave radio frequencies utilizes an electron source for emitting electrons through a field focused by a high energy magnet in the RF section of the tube. After the electrons have passed through the active area of the tube, the electrons strike the collector which, in this case, is a multistage depressed collector. The multistages of the depressed collector are connected to high energy voltage sources of different potentials. The klystron tube with the multistage depressed collector is uniquely used here for the first time in a ground based satellite or terrestrial communications system.

Multiple stage depressed collector (MSDC) klystron based amplifier for ground based satellite and terrestrial communications

An adaptive heater voltage algorithm and control system for setting and maintaining a vacuum electron device (VED) heater voltage, such as that of a klystron. An algorithm and control system are disclosed that sets and maintains the VED's cathode at the lowest temperature required for 98% of the beam current that corresponds to a fully space charge limited (FSCL) operation. VED lifetime is dependent upon cathode temperature, and in general, a cooler cathode will last longer. The optimum heater voltage corresponds to the beam current that is 98% of the beam current during FSCL operation. As the VED ages and the cathode becomes depleted, the heater voltage will need to be gradually increased to maintain the 98% FSCL value. There are, therefore, two stages to the adaptive heater voltage algorithm&mdash;(1) initial determination of the heater voltage and (2) the determination of the heater voltage during amplifier operation.

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Ben Lomand, CA, United States of America

Eric Oiesen