GB426082A - Improvements in or relating to radio and like modulated carrier wave receivers and thermionic valves suitable for use therein - Google Patents

Abstract

426,082. Thermionic valves. TELEFUNKEN GES. FUR DRAHTLOSE TELEGRAPHIE, 12, Hallesches Ufer, Berlin. Jan. 9, 1934, No. 837. Convention date, Jan. 9, 1933. [Classes 39 (i) and 40 (v)] A screen-grid valve, such as one adapted for the dual purpose of carrier frequency amplification and rectification of the amplified carrier energy, comprises, in addition to the normal cathode, anode and control and screen grids therebetween, an additional probe-like electrode of wire, strip or the like placed on the anode side of the screen grid. In the receiver circuit shown in Fig. 1, the additional electrode S is placed between the anode A and the screen grid G2, modulated carrier wave voltage being applied between the control grid G1 and cathode K. Highfrequency voltage set up across an oscillating circuit L, C2, in the anode current circuit and tuned to the input high frequency, is applied to the electrode S through a capacity coupling R, C3. The low frequency voltage produced by rectifier action across the resistance R may be applied to the next valve, e.g. through a high frequency choke filter. The invention may be applied to valves with more than two grids. In the valve shown in section in Fig. 3, a cathode K is surrounded in turn by a control grid G1, a screen grid G2, a "retarding" grid G3 and an anode A. A small auxiliary anode S is provided in the form of a strip placed between the grids G2 and G3. In order that the anode S shall disturb the potential distribution as little as possible, it is placed in the plane of the supports for the electrodes, where the potential distribution is already disturbed by the presence of the supports. In a modification, the cathode is surrounded by a control grid and a screen grid and has two anodes on opposite sides of the cathode. A small auxiliary anode is placed near each of these two anodes.