GB270800A - Improvements in or relating to circuit arrangements for use with high frequency currents - Google Patents

Abstract

270,800. Green, E. Feb. 11, 1926. Thermionic amplifiers.- One or more of the leads connected to a, thermionic valve has its inherent inductance neutralized, at the working frequency, by means of a series condendenser of appropriate capacity, in order that the two ends of the lead may be at the same " A.C. potential." Thus in the leads shown in Fig. 1 are inserted condensers C1 - - C4 adapted to neutralize the natural inductances of the respective leads. The condensers may be shunted by chokes L1 - - L4 which pass direct current : or comparatively small inductances may be used, in which case each combination, comprising a condenser and an inductance in shunt, is so dimensioned that its resultant reactance neutralizes the inductance of the lead. In order to prevent self-oscillation a resistance may be included in series with the inductance or with the combination. The invention may be applied to the two forms of anti-coupling bridge described in Specification 241,289, a condenser shunted by a choke being inserted in each grid lead in order to prevent disturbance of the bridge balance at high frequencies. In the modification of one of these bridges shown in Fig. 3, the condenser K is inserted in the grid lead, and a passage for direct current is provided by the choke M in series with a damping resistance such as a lamp S and with a battery B which is shunted by a condenser Z<1>. The arrangement is identical with that shown in Fig. 1 of Specification 241,289. except that the parts B, S. M, Z', E have been added. Instead of the inductance of the leads being exactly neutralized, the net reactance may be dimensioned so as to give a controlled degree of reaction.