Improvements relating to radio-telephonic systems

摘要

341,832. Wireless receivers. BRUNI, R., 36, Via XX Settembre, Genoa, Italy. May 28, 1930, No. 16421. Convention date, May 28, 1929. Addition to 314,092, [Class 40 (v), Wireless signalling &c.]. [Class 40 (v).] In order to eliminate residual interference, a heterodyne receiver for signals transmitted in the form of an intermediately-modulated carrier-wave, as described in the parent Specification, is characterized by the provision of a second valve 25, arranged in parallel with the first detector valve 24. The output currents from the two valves flow in opposition through coils 91, 911, whereby high-frequency parasitic currents are balanced out across the input 12 to the final stage of the receiver. The coils. 91, 911 are tuned by the series condenser 10 to the intermediate modulation frequency of the carrier wave. The coupling between the coils 91, 911, and 11 is adjustable. The coils 161, 1611 serve, as in the parent case, to reduce interference, and, together with the coils 91, 911 and 11, are screened as shown in dotted lines at 17 and 18.