GB423673A - Improvements relating to systems for relaying and distributing radio programmes - Google Patents

Abstract

423,673. Wired wireless systems. ECKERSLEY, P. P., 82, Swan Court, Chelsea, and CARPENTER, R. E. H., 11, Garrick Street, Covent Garden, both in London. Aug. 1, 1933, No. 21602. [Classes 40 (iii) and 40 (v)] In a system in which programmes on different carrier frequencies are distributed over a power network &c., each amplifier output circuit comprises, in addition to a matching transformer 6 or matching network, circuits such as 12, 13 designed to reject the frequencies of the other channels and so prevent cross-modulation in the amplifier, a band-pass filter 7-10, the reactances of which are in part composed of the effective reactances of the rejector circuits, the leakage inductance of transformer 5 and the inductance of the network, and preferably a low-pass filter 4 designed to prevent harmonics generated in the amplifier from reaching the line. In certain cases the whole of the inductive reactance of the band-pass filter may be provided by the transformer, the rejector circuits and the feeders. The rejector circuits are preferably of the form shown in Fig. 2, which is more suitable for rejecting a band of frequencies than a simple tuned circuit. Transformer 5 is designed to give bad regulation and its ratio is somewhat less than that required for optimum impedance matching. The bandpass filter may be wholly or in part on the amplifier side of the transformer and is preferably grounded at a nodal point for, e.g. the carrier frequency through condenser 11. The feeders to the network may be single core cables in which case the coupling condensers 25-28 are at the network ends of the feeders. Instead of separate feeders a low-impedance common feeder may be used. Specification 325,833, [Class 40 (v)], is referred to.