GB355670A - Improvements in or relating to thermionic valve circuits - Google Patents

Abstract

355,670. Valve circuits. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., Alarconi House, Strand, and GREEN, E., 24, Church Road, Hendon, both in London. May 23, 1930, No. 15935. [Class 40 (v).] In a circuit comprising a plurality of valves 1 .. 4 in parallel, in which parasitic oscillations due to the transfer of energy through the grid-anode self-capacities of the valves is reduced by a low-reactance path L1<SP>11>.. L2<SP>111 >for the desired oscillations with a high reactance to the parasitic oscillations, the path is shunted by a damping resistance r<11>, r<111> connected between points which are at substantially the same potential as regards the main oscillations but at different potentials as regards the parasitic oscillations, in order to avoid damping the main oscillations. The inductances L1<SP>11> .. L2<SP>111>, which may be closely coupled, are connected in the grid circuits of the valves, and the damping resistance r<11>, r<111> is connected between the grids of the valves. Particularly if the inductances are not closely coupled, the effect of the reactance opposed to the main oscillation by the inductances is compensated by a circuit Cg, Lg, rg. Devices L1 .. L<1>2, r, r1 to suppress parasitic oscillations are inserted in the output circuits in addition to, or in place of those in the input circuits. According to a modification, two sets of four valves in parallel are arranged in push-pull, Fig. 7 (not shown).