GB271222A - Improvements in thermionic valve amplifying systems - Google Patents

Abstract

271,222. British Thomson-Houston Co., Ltd., Clinker, R. C., and Lucas, G. S. C. April 14, 1926. Thermionic amplifiers. - In valve amplifiers operating in push-pull or in parallel, the filaments being fed in series, provision is made for separately adjusting the grid and plate voltages in order to maintain symmetry in operation. As shown in Fig. 1, the filaments of two push-pull amplifiers V<a>, V<b> are fed from any suitable source, such as the house mains in series with resistances Rp, Rg, from the latter of which separate tappings are taken to the two grids through the split windings a, b of the input transformer Ti. Fig. 2 shows a similar pushpull arrangement in which the plate potentials are also separately divided from a resistance Rp through the divided windings a<1>, b<1> of the output transformer T<o>. Fig. 3 illustrates two valves V<a>, V<b> operating in parallel. The filaments are fed in series from a suitable source, whilst the grid impulses are supplied in parallel through two separate coupling condensers A, B. The grid leaks A<1>, B<1> are separately tapped to a common biasing battery Bg. The plate voltages are equalized through the two sections of the split output transformer To.