GB292218A - Improvements in or relating to thermionic valves for transmitting and receiving wireless signals and for other purposes - Google Patents

Abstract

292,218. Midgley, A. H. March 11, 1927. Vacuum tubes.-A valve has a central anode surrounded in turn by a grid, a cathode, and a second grid and anode. The spacing and size of the electrodes are preferably such that the first grid and central anode have a greater effect on the electron stream passing to the central anode than that of the second grid and anode. The valve may be used as a detector, amplifier, or as an oscillation generator as described in Specification 289,999, [Class 40 (v), Wireless signalling &c.]. As shown in Fig. 1, the receiving input circuit is connected between the grid G<1> and cathode, and the central anode A<1>, in the form of a. rod or cylinder, is joined through a resistance R with the positive terminal of the high tension battery, which is also connected through a telephone receiver T with the outer anode A<2>. A blocking condenser C<2> connects the anode A<1> and grid G<2>. The cathode may consist of one or more straight filaments in series or parallel, or of a straight or zig-zag filament wound to form a cylinder of circular or oval section. The central anode may be in the form of a plate and the other electrodes of oval section, or the inner anode and grid may be of circular section, and the other electrodes of oval section. The inner anode and grid mav be shorter than the other electrodes. In order to provide another stage of amplification two further grids with an interposed cathode and surrounded by a third anode, may be mounted around the second anode. In the receiving circuit shown in Fig. 3, the valve has a central anode A<1>, a grid G<1>, a cathode K, and two outer grids G<2>, G', and anodes A<2>, A<3>. The aerial is connected through an inductance I<1> and condenser C' between the grid G<2> and cathode K, which is earthed. The anodes A', A<2> are connected through resistances with the high tension batterv, and the anode A<2> is connected through an inductance I<2> and condenser C<3> to earth, the inductances being coupled. A blocking condenser C<2> connects the anode A<2> and grid G<1>. Specifications 267,198 and 280,981 also are referred to.