GB756235A - Electron discharge devices utilising velocity modulation - Google Patents

Abstract

756,235. Velocity-modulated tubes. GENERAL ELECTRIC CO. March 24, 1954 [March 27, 1953], No. 8626/54. Class 39 (1). A high-frequency electrondischarge device for providing two output signals of the same frequency comprises an input resonator 9 for applying an input signal between cathode 2 and grid 4 so as to density modulate the beam, the density-modulated beam exciting resonator 10 at the same frequency as the input and the resonator 10 both giving an external output and reacting back on the beam to velocity-modulate it a drift space 6 in which bunching occurs, the initial density-modulation and the bunching produced by velocity modulation being cumulative, and a second output resonator 22 excited by the finally bunched beam. Outputs are taken capacitively from resonators 10 and 22, and may be used separately or combined, e.g. by a " diplexer." Feedback from either output to the input may be employed to increase the gain. The resonators are preferably of the concentric line type but the input resonator could be a hollow cavity resonator. Impedancematching stubs 15, 16 have movable plungers for tuning and their outer conductors are capaci-. tively coupled to the outer conductor of the input resonator 9 to allow different D.C. potentials to be applied to the cathode and grid 4; 17 is a heater lead. The input resonator is tapered at 18 for matching to a feeder line. Resonators 10, 22 are also tuned by plungers, plunger 20 having two sets of fingers with an intermediate mica ring to enable grids 4, 5 to be at different D.C. potentials. The grids 4, 5, 7 are supported from disc seals. Specification 766,236 is referred to.