GB450280A - High frequency electric wave apparatus - Google Patents

Abstract

450,280. Tuned circuits ; wireless transmitting and receiving apparatus; thermionic valves. STANDARD TELEPHONES & CABLES, Ltd., 63, Aldwych, London.-(Assignees of Potter, R. K. ; 5, Pine Avenue, Madison, Morris, New Jersey, U.S.A.) Aug. 2, 1935, No. 21954. Convention date, Oct. 4, 1934. [Classes 39 (i), 40 (iii), and 40 (v)] The tuned circuit of a short-wave generator or amplifier consists of a tank-like structure formed as a re-entrant surface of revolution, e.g. a toroid, which is broken to form a circular gap with adjacent opposed flanges constituting capacity elements. A modified form of tank structure completely encloses the amplifying or generating valve. Fig. 5a shows two tanks A, B arranged as grid and plate circuits respectively of a generator, back-coupling being provided by a condenser connected between plate and grid. When used in a Colpitts oscillator circuit, the tank has a third insulated plate d, Fig. 6a, interposed between the capacity elements a, b, the three elements being connected to plate, grid, and cathode respectively. For a Hartley oscillator, the filament connection is taken to an intermediate point M, Fig. 7a, of the inductive part of the circuit by radial wires or by a disc. The tank may be entirely disconnected from the valve, and may be coupled to the grid and plate circuits by wire loops extending through the gap into the tank interior, Fig. 8a (not shown). The valve may be housed within the tank, Fig. 9a (not shown). In Fig. 9c, the tank is of cylindrical form with tubular axial openings X1, X2 through which leads are taken from the bias and plate batteries to the valve which is housed within the tank. The cathode is connected to the tank and its leads are taken through a tubular opening X3 in the curved wall. The tuning-condenser C3 is also within the tank and is connected between the axial tubes X1, X2. The circuit shown is of the Hartley type, but may be of Colpitts or other type, Fig. 9b (not shown). In Fig. 11a, the tank is divided by a partition x parallel to its end-plates, and its central portion G forms the grid of the valve. The cathode F and anode P arc connected to axial rods which carry the supply current and project into the tubular openings X1, X2 in the tank walls. The electrodes are enclosed in a glass envelope E. One half of the tank forms a tuned grid circuit, and the other a tuned circuit between anode and grid, and tuning is effected by making the tank of telescopic form, or by sliding adjustment of hemispherical shells S1, S2. The circuit may be employed as an amplifier with concentric conductor transmission lines TL1, TL2 used as input and output circuits. The grid and anode may be of cylindrical form. When the arrangement of Fig. 11a is used as an oscillator, back coupling may be effected by providing apertures a, a<1>, Fig. 13b, in the partition X and by mounting the grid in a disc I which is adjustable relatively to the partition X to afford variation in capacity back-coupling.