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The purpose of this program was to develop two advanced development model high power amplifier tubes specifically for troposcatter communication application. Varian Associates was awarded a single contract to develop a klystron model tube and a klystrode model tube. Critical elements of the specification for the two tubes were (a) power output l0xw, (b) 10 MHz electronics bandwidth, (c) 750-980 MHz tuning range and (d) efficiency 50%. The challenge for the klystron design was to be able to maintain efficiency in excess of 50% over the full 10 MHz bandwidth. This was accomplished with an eight cavity design. The klystrode challenge required designing a new grid shape that integrates a converging electron beam with a cavity with a minimal magnetic field focusing. Results of the program were that basically most of the performance specifications were demonstrated. However, the klystron showed a sharp drop-off in power at 840 MHz due to a second harmonic cavity mode. The klystrode has considerably less gain than the existing klystron and thus additional RF drive is required.