High efficiency, C-band, 10-kilowatt CW transmitter tube for troposcatter applications

The design and performance characteristics of a coupled-cavity traveling-wave tube are described. This tube provides power output of greater than 10 kW over an instantaneous bandwidth from 4.4 to 5.0 GHz with up to 57 percent overall efficiency, including solenoid and cooling power. High efficiency is obtained by use of the voltage-jump technique, wherein the beam voltage is increased in the output section of the slow-wave structure, in conjunction with circuit phase velocity tapering and two-stage collector depression. The tube uses a novel, self-contained vapor-phase cooling system that includes an air-cooled heat exchanger. This system eliminates the need for coolant pumps and provides excellent heat transfer and high cooling efficiency.