GB592930A - Improvements in or relating to electronic discharge devices for producing ultra-highfrequency electrical oscillations - Google Patents

Abstract

592,930. Velocity-modulated tubes. WESTERN ELECTRIC. CO., Inc. Sept. 2, 1943, No. 14383. Convention date, April 4, 1941. [Class 39 (i)] In a velocity modulated tube of the kind in which two gaps 18, 19 are formed within a single resonator by a drift tube 17, the entrance and,exit apertures are formed in discs 13, 14 sealed through the envelope and engaging a two-part casing 21, 22 forming the remainder of the resonator. Preferably the parts 21, 22 are semi-cylinders clamped together and to the discs by rings 27, 28 which also clamp cylindrical magnetic polepieces 25, 26 cradled in recesses 46, 47 in the permanent focussing magnet 45. The electron gun 11 focuses the beam in the input gap 18, and the magnetic field re-focusses it in the output gap 19, the drift tube 17 being made barrel-shaped to follow closely the shape of the beam in between. The D.C. connection of drift tube to resonator is made by lead 20, flexible lead 30 and a clamping screw. Adjustable tuning screw-plugs are provided. In modifications the single lead 20 is replaced by three equally-spaced leads or by a disc. Casing 22 is screwed at 48 to magnet 45. The electron gun comprises a concave cathode 49, Fig. 3, heated by coil 50, focussing sheath 51 at cathode potential, and cylindrical anode 52 with a frusto-conical aperture 52a ; spaces 52c are left for assembly purposes. The potentials are supplied by a battery shunted by potential dividers and where high output is required the collector 12 is connected directly to the positive pole of the battery to keep collector current out of the dividers.