GB295079A - Improvements in and relating to thermionic valves - Google Patents

Abstract

295,079. British Thomson-Houston Co., Ltd., Kinman, T. H., and Davies, L. J. May 19, 1927. Vacuum tubes.-A thermionic valve comprises a V-shaped cathode 1, Fig. 1, having one limb longer than the other, a grid G<1> and on anode A<1> associated with the extended limb and a larger grid G<2> and anode A<2> associated with the remainder of the cathode. The electrodes may be supported from a pinch and may be parallel to the plane of the pinch, or the electrodes G<1>, A<1> may be at right angles to this plane. Additional small sets of electrodes may be arranged around the extended limb. A standard cap 9 with four pins 10 may have the pins connected two to the cathode, one to the grid G<1> and the remaining one to the anode A<2>, the grid G<2> and anode A<1> being connected to side terminals 11, 12, for connection to additional components when the valve is plugged into an existing socket in a radio receiver to introduce an extra stage of amplification. The electrodes G', A<1> are adapted for detection or amplification and the electrodes G<2>, A<2> for power amplification. Interaction between the electrode sets may be avoided by spacing the sets or by metal grills or screens connected to earth or to the positive or negative filament terminal. With a 2-volt filament, the extended limb is connected to the positive terminal and the return lead for the grid G<1> is connected to the negative terminal to produce grid bias for detection, the grid G<2> being connected to an external bias. With a 6-volt filament, the extended limb is negative and the return leads for the grids G<1>, G<2> are connected to the negative terminal to produce the correct bias on both. Resistance-capacity couplings may be provided between the electrode sets and a reaction circuit may be connected to the anode A<1>. When a high resistance is included in the circuit of the anode A<1>, an auxiliary anode in the set A<1>, G<1> may be connected to a reaction coil. Interaction between the electrode sets may be produced by extending the grid G<1> towards the anode A<2> or by the circuit shown in Fig. <2>. The anode A<1> is connected through a high resistance R<1> to the positive high tension terminal H and through a condenser to the grid G<2>. whilst the anode A is connected to the terminal H through a high-frequency choke C and lond-speaker L. and also to the negative filament terminal F<2> through a reaction coil 13.