GB326922A - Improvements in or relating to thermionic valve amplifiers - Google Patents

Abstract

326,922. Turner, P. K. Jan. 18. 1929. Thermionic amplifiers.-Relates to an amplifying system of the kind in which two valves v1, v2 are connected plate to filament in series across a common high-tension supply. The input voltage is applied in phase opposition and is preferably divided in inverse ratio to the respective amplification factors of the valves. The output will then be in straight-line relation to the input. irrespective of the form of the valve characteristics, whilst the current taken from the hightension source is maintained constant so that it is unnecessary to use either smoothing or decoupling devices even in the case of a high-' impedance source common to several valves. As: shown in Fig. 1. the output is fed from' reversely-wound coils p1, p2 in series with condensers c1, c2 to a secondary winding s. In the modified arrangement shown in Fig. 2 the load circuit L is connected between two series condensers c3, c4 and the filament of the valve v1. In Fig. 3 the input is fed to the valve v2 only, the grid of the valve v1 being retroactively coupled to the output transformer t3. Grid bias for both valves may be taken from resistances such as RA, Fig. 4, in the filament circuit, or it may be derived from a resistance RB in the direct-current high-tension path.