GB420886A - Improvements in and relating to means for reducing static electrical effects - Google Patents

Abstract

420,886. Wireless receiving systems ; thermionic valves. BRITISH THOMSONHOUSTON CO., Ltd., Crown House, Aldwych, London.-(Saxton, H. L. ; 106, East College Avenue, State College, Pennsylvania, U.S.A.) March 3, 1933, No. 6537. Void [Abridged as open to inspection under Sect. 91 of the Acts, Sept. 30, 1933]. [Classes 39 (i) and 40 (v)] A limiting valve is interposed between an aerial circuit and the input circuit of a radio receiver to reduce the amplitude of atmospheric and other disturbances. In one embodiment, the aerial circuit 1, 2, Fig. 1, feeds the control coil 3 of a magnetically controlled valve 4 whose polarizing field is produced by a coil 5 and adjusted to such a value that signals of above a predetermined amplitude do not produce any increase of anode current. The anode circuit is coupled by a transformer 8 to the receiver 9, the effects of the interelectrode capacity of the valve being balanced out by connecting the earthed cathode to a properly chosen intermediate point 6 on the coil 3. In other embodiments a neutralized triode or screen grid valve is given a characteristic of the form B or C, Fig. 6, by the inclusion of resistances such as 12, 14, Fig. 5, in the anode and control grid circuits respectively and /or reducing the cathode heating current. The characteristic may be varied at will between arbitrary limits such as B and C, Fig. 6, by varying the position of a tapping on a potentiometer 17, Fig. 6, supplying a resistance 19 from which are tapped anode and grid potentials.