GB445763A - Improvements in arrangements for eliminating disturbances in radio receiving sets - Google Patents

Abstract

445,763. Wireless receiving systems. NAAMLOOZE VENNOOTSCHAP PHILIPS' GLOEILAMPENFABRIEKEN, Emmasingel, Eindhoven, Holland. Dec. 13, 1935, No. 34653. Convention date, Feb. 1. [Class 40 (v)] In order to eliminate the effect of disturbances in a radio receiver, a switching device disables the low frequency amplifier upon receipt of a disturbance, the impulse produced by said device being neutralized by a compensating circuit. In one embodiment, an anode bend detector D, Fig. 1, feeds a low frequency amplifier V through transformer T1 and an auxiliary rectifier G fed from a coil W coupled to the detector input circuit T operates a relay R to open a contact S in the detector anode circuit when a disturbance of above a predetermined amplitude is applied to the valve G. The said amplitude is determined by the grid biassing source Eg2 of the valve G. The impulse produced in the grid circuit of valve V by the switching operation is neutralized by a compensating circuit comprising a transformer T2 whose secondary S2 is in the grid circuit of valve V and whose primary circuit containing a resistance R1 and anode source Ea is opened by the contact S. In a further embodiment, Fig. 2 (not shown), the auxiliary rectifier produces a disabling grid bias for a low frequency amplifier which is also applied to a compensating valve the output circuit of which is connected in push-pull with the disabled valve. In a third embodiment, a low frequency coupling transformer, Fig. 3, comprises a primary 1, 1 split secondary 2, 2 and a saturating winding 3, 3 controlled by the auxiliary rectifier to lower the efficiency of the transformer upon receipt of a disturbance. The two halves of the secondary 2, 2 have equal and neutralizing impulses induced by the sudden change in magnetization. The auxiliary rectifier may be fed from an auxiliary receiver tuned to a channel other than that being received by the main apparatus or from an aperiodic receiver.