GB347431A - Improvements in or relating to radio frequency distributing systems for use in connection with broadcast and like receivers - Google Patents

Abstract

347,431. Wireless and wired-wireless signalling. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., Marconi House, Strand, London.-(Assignees of Weinberger, J. ; 31, Mosholu Parkway, New York, U.S.A.) March 28, 1930, No. 10022. Convention date, March 29, 1929. [Class 40 (v).] The pick-up from an outside aerial 1 is distributed aperiodically to a number of radio receivers 3, located for instance in the various rooms of an apartment house, through a series of two-wire aperiodic transmission lines 5, each fitted with a terminal " surge " impedance and with series loading-coils 37, Fig. 2, so as to minimize interaction between the various channels. Each line 5 is coupled to the aerial 1 through a separate amplifier 7, whilst each individual receiver 3 is coupled to the feed-line through an amplifier 19. A common electric source 11, either battery or mains, supplies the entire equipment, whilst a central volume-control 9 allows an overall supervision. As shown in Fig. 2, the volume control comprises a resistance 23 in the aerial with adjustable tappings to the input of the first valve 27 of each of the amplifiers 7. A resistance 45, Fig. 2, inserted across the grid and filament of the first valve of each amplifier 19, also serves to reduce interaction between the sets. Reception may also be improved by inserting a series-tuned " dummy " aerial in the leads between the amplifiers 19 and receivers 3. In an alternative arrangement, an outside T-aerial is coupled through filter circuit and transformer directly to the distributing lines 5, the aperiodic character of the coupling helping to prevent interaction.