GB437671A - Improvements in or relating to thermionic oscillation generators - Google Patents

Abstract

437,671. Valve generating circuits. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., Electra House, Victoria Embankment, London, and MOULLIN, E. B., 189, Morrell Avenue, Oxford. May 4, 1934, No. 13557. [Class 40 (v)] A back-coupled oscillator is so arranged that exact anti-phase is produced between grid and anode voltages with consequent frequency stability. The resonant frequencydetermining circuit comprises two arms connected in parallel between anode A and cathode K, one arm including inductance LI, resistance R1, and condenser C1, the other arm including condenser C2, inductance L2, and resistance R2, each in the order named. The resistances may be inherent in the inductance coils. At the resonant frequency one arm has inductive reactance, the other capacitative. The resistances are equal and the ratio of L2 to L1 is the same as the ratio of C2 to Cl. A high resistance B is connected between the junction y of C2 and L2 and a tapping x on the resistance R1, the tapping x being so chosen that the voltage across xy is in phase quadrature with that across the anode and cathode. The mid-point M of the resistance B is connected to the grid through a condenser BC, a grid leak GL being provided. A large condenser may be connected between the tap x and the resistance B, and the grid-leak and condenser BC may then be omitted. The anode battery may be connected through a choke CH to a point below the resistance R1, or to the tap x on R1, or to the anode. If the oscillation frequency is to be varied, the condensers C1, C2 and/or the coils L1, L2 may be made variable and gang-controlled, but the ratio of C1 to C2 must be maintained equal to the ratio of L1 to L2. Specification 415,716 is referred to.