GB188707A - Improvements in and relating to electron discharge apparatus - Google Patents

Abstract

188,707. British Thomson - Houston Co., Ltd., (General Electric Co.). June 18, 1921. Vacuum tubes.-A thermionic valve having a cathode, an anode at a high positive potential, and an interposed grid at an intermediate potential, is so arranged that the grid circuit has a negative resistance characteristic due to secondary emission from the grid being attracted to the more positive anode. The control or input circuit of the valve is connected between the filament and a second grid nearer to the filament than the first, and the output circuit is coupled to the plate circuit. The valve may also be adjusted to operate independently of the negative resistance characteristic. The connections for amplifying currents of audible or radio frequency are shown in Fig. 1, in which the plate circuit includes a direct-current source 6 and an output transformer 9. The grid 4 is given a potential lower than the plate 3 by means of a potentiometer 7 across the source 6 or by other means, and its circuit includes a resistance 18 shunted by a condenser 11. The input transformer 8 is connected between the cathode 2 and control grid 5. When using the valve as a detector a series condenser is connected in the circuit of the control grid 5 shunted by a high resistance; and the grid 4 may be connected through the resistance 18 to the positive side of the source 6. The presence of the grid 4 prevents electrostatic effects between the control grid 5 and the plate, thus preventing self-oscillation and increasing the pcssible amplification for high frequencies.