GB444881A - Television method and arrangement - Google Patents

Abstract

444,881. Television. RADIOAKT.-GES. D. S. LOEWE, 10, Wiesenweg, Steglitz, Berlin. June 30, 1934, No. 19361. Convention date, July 1, 1933. [Class 40 (v)] Television and telephone signals, transmitted on independent ultra-short carrier waves, are mixed at a receiver by a local oscillator 12 having a frequency between those of the vision and sound carriers, and are separated by a forked circuit 2. The oscillator is a screening - grid valve with reactive coupling through the internal capacities. The aerial 8 is coupled to the anode through an auto-transformer 10 and a small coupling condenser 11. The valve is adjusted to the lower bend of its anode - current characteristic by grid current through a resistance 14. According to a modification, Fig. 2 (not shown), the aerial is coupled inductively to the cathode circuit and the inner grid is earthed through a large condenser. The telephone signals are selected by a tuned circuit 18, 19 damped by a resistance 20 which also acts as a volume control. The television intermediate frequency is amplified by an amplifier 4 with screened coupling resistances 26, Fig. 3 (not shown). A choke 30 tuned to the highest side-band frequency is in series with the anode resistance 29. The amplifier is transformer coupled to a push-pull detector 36. Fading is compensated by a separate screening-grid valve 35, which also acts as an amplitude filter for separating the synchronizing signals.