GB495843A - Electron multipliers - Google Patents

Abstract

495,843. Electron multipliers and circuits therefor. STANDARD TELEPHONES & CABLES, Ltd. May 21, 1937, No. 6854/38. Convention date, July 31, 1936. Divided out of 495,839. [Classes 39 (i) and 40 (v)] Modulation is effected in an electron-multiplier tube by applying one set of currents to the cathode and a control grid and the other set to a secondary-emitting electrode part of which is emissive and part non-emissive, so as to vary the number of electrons falling upon the emitting part. In one arrangement, Fig. 1, low-frequency modulating currents are applied between two of the secondary-emitting electrodes SE4, SE5, the latter having a depressed portion 52 which is non-emissive and on to which about half of the electrons fall when no modulating voltages are applied. In a second arrangement, Fig. 2 (not shown), one terminal of the modulating source is connected to a secondary emitter and the other to a point on the biassing potentiometer. The preceding secondary-emitting electrode is made emissive only over a small central strip (similar to SE2, Fig. 2A), to give a sharp, narrow beam. The high and low frequency circuits may be interchanged or both sources may be of high frequency for heterodyning or detecting purposes. Part of a secondary-emitting electrode may be rendered non-emissive by coating with carbon or by covering with parallel wires 55, Fig. 2A. Specification 495,839 is referred to. The Specification as open to inspection under Sect. 91 comprises also another arrangement, Fig. 3 (Cancelled), in which the modulating potentials are applied to two metal electrodes 57, 58 extending across the electron stream. This subject-matter does not appear in the Specification as accepted.