GB680597A - Improvements in or relating to high frequency electron-discharge tube apparatus - Google Patents

Abstract

680,597. Velocity-modulated tubes. SPERRY CORPORATION. Nov. 17, 1950 [Dec. 30, 1949], No. 28183/50. Class 39(i) An electron-discharger tube apparatus of the reflex-velocity modulation type comprises a plurality of resonant-space resonators of different resonant frequencies and means for varying the circuit, parameters e.g. voltage applied to the reflector electrode so that any one of the resonators may be excited selectively to oscillate at its resonant frequency. As shown the apparatus comprises resonant spaces 38, 39 of different frequencies constituted by metallic laminations 46 to 50 and a separating wall 49 supported by a tube 37 mounted on a shell 23 which forms the enclosure for the cathode button 12 and its heater 13. The electrons emanating from the cathode 12 and under the influence of an accelerating potential provided by battery 69, accelerate toward a "smoother" grid 35 and traverse the tube 57 after which they pass through gaps defined by grids 41 to 44 to be reflected back by the reflector electrode 57, the potential on which may be varied, for example by switch 76, to excite selectively one of the resonators. Energy is extracted from the resonators in the arrangement shown, by a wave-guide 79 the end of which is closed by a window 82 mounted in a frame 81 the configuration of which provides a relatively long heat path and minimises cracking of the window; alternatively energy may be extracted from the resonators by co-axial transmission lines (not shown). To ensure maximum output from the resonator 38 the length of the "drift" space 54 between the pairs of grids 41 to 44 is kept to a minimum. The arrangement is also such that the modes of oscillation of the resonators 38, 39, do not coincide or overlap. The use of laminations 46 to 50 facilitates the ready construction of resonators of different dimensions; if desired tuning mechanisms may also be employed in conjunction with the resonators. Selective operation may also be effected by altering the accelerating voltage as applied to the " smoother " grid 35 and the cathode voltage in addition to or alternatively to the reflector voltages. The apparatus may be used as a switching mechanism in which H.F. signals of different frequencies are generated in responses to pulses of different magnitudes.