GB428581A - Improvements in or relating to electrical oscillation generators - Google Patents

Abstract

428,581. Valve generating circuits. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., Electra House, Victoria Embankment, London.-(Assignees of Finch, J. L. ; Patchogue, Long Island, New York, U.S.A.) Oct. 1, 1934, No. 28076. Convention date, Oct. 19, 1933. [Class 40 (v)] A crystal - controlled valve oscillator is arranged to generate an harmonic of the crystal frequency by including the crystal 16 in series in the feed-back connection 30 from the plate coil 14 to the tuned grid circuit 38 which latter is tuned to the desired harmonic. The plate coil tapping 32 is at a point of low oscillatory potential, and the grid coil tapping 36 is also at a point of low oscillatory potential opposite to that of the grid, on account of the intermediate connection to the cathode. The crystal electrode-capacity is balanced by the capacity 15. The screen-grid is kept at earth potential by a condenser 12, which may with the inductance of the screen-grid lead constitute an acceptor circuit for the desired harmonic. The plate tapping may be at a point beyond the cathode connection of the coil 14, and the grid tapping at a point on the grid side of the coil 38 (Fig. 2 not shown). The grid coil tapping may be omitted and the lead 30 may include a coil inductively coupled to the coil 38, an electrostatic screen being interposed (Fig. 3 not shown).