Design and development of a novel 1,250 watt KU-band CW helix traveling wave tube

Communication and Power Industries (CPI), USA has designed, and developed a novel 1,250 Watt high power, high efficiency, compact, conduction-cooled continuous wave Helix Traveling Wave tube VTU6397J4 for Satcom application. This paper presents the test results of the two initial TWT prototypes produced. Both units were tested in a light-weight conduction-cooled baseplate, used SMA female coaxial input and WR-75 waveguide output connections as designed. Both prototypes measured over 1,300 watts of average CW output power, over 51 dB of small signal gain across the extended Ku-band from 12.75GHz through 14.80 GHz. TWT's demonstrated good linearity and third-order intermodulation performances at 4 dB and 7 dB back-offs from rated power (61.0 dBm). TWT design includes a standard proven electron Gun assembly with FE turn-on and isolated anode, a two stage multi-stage depressed collector assembly, and a novel slow wave structure. Test results are in agreement with the design goals. The predicted and measured performance data are compared.