GB280550A - Improvements in or relating to incandescent cathode rectifiers - Google Patents

Abstract

280,550. Meyer, F., and Spanner, H. J. Nov. 15, 1926, [Convention date]. Addition to 276,303. Vacuum tubes.- In incandescent - cathode rectifiers with conductive shielding plates between the anodes as in the parent Specification, the plates are connected to the cathode through an auxiliary source of potential so that they are negative with respect to the cathode during the parts of the cycle when the corresponding anodes are negative. The plates may comprise grids wholly or partly surrounding the electrodes. At high voltages, the potential applied to the plates by the source deflects or neutralizes rapidly moving positive ions and prevents destruction of the electrodes. At low voltages, particularly with large currents, destruction of the electrodes due to heat produced by ionic currents is prevented. In a rectifier with shielding grids 7, 7<1>-, Fig. 1, around the anodes 4, 4<1>, the anodes are connected to one secondary 5 of the supply transformer, the cathode is heated by a second secondary 2 and the grids 7, 7<1> are connected to the ends of a third secondary 8, the centres of the secondaries 2, 8 being connected. Resistances 10, 10<1> reduce grid currents. The grids may comprise semicircular slotted plates or flat plates with punchedout, bent tongues. In a modification with a single shielding grid around the cathode between the anodes, this grid is made negative by a battery connected between it and the cathode. The cathode may be divided as in Specification 279,024.