Abstract: A klystron comprises a plurality of resonant cavities, the frequency of which is defined by a piston within each cavity. In order to change the frequency of the klystron, each piston is provided with a rod applied against an adjusting screw under the pressure of a spring. In order to reduce the bulk of the springs, the distance between a screw head and the plate on which the springs are applied remains constant irrespective of the length of the adjusting screws. This is obtained by means of a set of switches which are fixed on the movable plate and control the compression of the springs by checking the position of a cup in which each spring exerts its force on the corresponding piston rod.

Abstract: A multi-cavity klystron device having a plurality of resonance cavities, comprising a plurality of movable elements, each of which is mounted on each of said resonance cavities and which is adapted to change the resonance frequency in each cavity, a plurality of tuning means for giving a reciprocal movement to each movable element against a resilient member provided therefor, a plurality of pulse motors coupled to the tuning means, and a preset means for controlling pulse supply to each pulse motor, wherein a predetermined number of pulses stored in the memory units of the preset means are selectively applied to the pulse motors to rotate each pulse motor in correspondence with the number of pulses, thereby changing each resonance frequency of each cavity.