Development of a klystron for satellite operation in the 12 GHz frequency band

The development of a 12 GHz klystron for operation in TV-broadcasting satellites with an RF output power of 800 W is described. The development makes use of technological and operational experience gained with a klystron presently in operation in terrestrial 12 GHz TV transmitters with amplitude modulation. A klystron was realized with a lightweight PPM focusing system. It operated uncritically over a wide range of voltage and power. Using a 3-stage depressed collector the efficiency could be increased to more than 50%. The bandwidth of 30 MHz as required for a FM TV transmission and the linearity performance (AM-PM conversion, AM-PM transfer and cross modulation) were obtained. The variations of group delay time are given by the characteristic of a 4-stage bandpass filter with a bandwidth of 30 MHz. The investigated concept of a PPM-focused klystron is seen as the basis for the design of a spaceborne klystron with a direct radiating collector, an efficiency of more than 50%, and a total mass of approximately 1.5 kg.