GB527602A - Improvements in apparatus for receiving television and like signals - Google Patents

Abstract

527,602. Wireless signalling. GENERAL ELECTRIC CO., Ltd., ALDOUS, W. H., and EDWARDS, G. W. April 17, 1939, No. 11582. [Class 40 (v)] A television receiver for separating sound signals centred on a frequency f(1 + #) from vision signals having a band width αf and centred on frequency f, where # is slightly greater than a, comprises input terminals 1, 2 for the combined signals which are amplified in valve 3, the anode of which is connected to HT+ through the primaries of transformers 4 and 5 in series. The primary of transformer 4 is shunted by resistance 6 and the secondary is shunted by resistance 20 and connected across vision output terminals 8, 9. A variable condenser 7 is shunted across the primary of transformer 5 while the secondary is shunted by variable condenser 10 and connected across sound output terminals 11, 12. Transformer 4 is tuned to frequency f by the stray capacities 15, 16 of the valves while transformer 5 is tuned by condensers 7, 10 to a frequency f(1 + #). The live end of transformer primary 5 is connected by a blocking condenser 17 to the secondary of transformer 4 so as to add the voltage across primary 5 to that developed across secondary 4 at terminals 8, 9. Otherwise the vision gain-frequency curve shows a minimum at a frequency between f(1 + #) and f which reduces the width of the vision frequency band. The secondary 4 may be connected to a tapping on primary 5 or to a tapping on a condenser potentiometer connected across primary 5 when a part only of the voltage across primary 5 is to be added to that across secondary 4.