Modern medium-power travelling-wave-tube amplifiers for communications

Over the past decade or so, travelling-wave-tube amplifiers for communications have advanced from field replaceable glass bodies to packaged metal ceramic tube construction and from large, fully adjustable, linear power supplies to miniature, highly efficient, preset switched mode units. The principal features of modern tube design are based on metal ceramic technology, dispenser cathodes, two-stage depressed collectors and samarium cobalt magnets. Equally important, though often neglected in the literature, is the design and construction of the power supply and in particular the interface between tube and supply. These problems and their solutions in development and manufacture are discussed in this paper and a case is presented for a more integrated design approach.