GB531247A - High frequency electron tubes and a method of reducing grid loss therein - Google Patents

Abstract

531,247. Thermionic valves. LELAND STANFORD JUNIOR UNIVERSITY, BOARD OF TRUSTEES OF. April 27, 1939, No. 12636. Convention date, May 24, 1938. [Class 39 (i)] In a high frequency valve active grid loss is prevented by using a pair of spaced grid sections 2, 15, the section 15 nearer the anode 3 being spaced from the cathode a distance approximately equal to the travel of an electron during threequarters of a cycle ; the section 2 is spaced from the cathode at such a distance that at least as much or more energy is transferred from the electrons to the grid sections during travel from the sections to the anode as is given to the electrons during their travel from the cathode to the sections. The two grids are coupled by the condenser 17, 18 and the section 15 is at a higher d.c. potential than the section 2 and is positive with respect to the cathode ; a choke 16 is included in the circuit to the section 2. A.c. is imposed from the source 14 and the coil 11 is coupled to the circuit 9, 10 for feed back. If more energy is given by the electrons to the grid sections than is received by the electrons the valve will self oscillate without the necessity of external feed back. A suppressor grid may surround the anode. In a modification the grids 2, 15, Fig. 5, are connected together and a third grid 35 is placed between them and maintained at a higher positive potential. In another form two grids 2, 15, Fig. 4, connected together are used in a hollow resonator containing standing waves. The resonator comprises two separated sections 23, 24 capacity coupled by the flanges 28, 29; the emitter is formed on a face 21 independently heated. The grids are excited from a loop 26 within the resonator and a grid leak 27 is connected to the section 24. Energy is removed by a loop 32. A mathematical exposition and an explanation of the grid action is given in the Specification.