GB415504A - Improvements relating to the reception of high frequency oscillators - Google Patents

Abstract

415,504. Valve circuits for wireless reception. HAZELTINE CORPORATION, 15, Exchange Place, Jersey City, New Jersey, U.S.A.-(Assignees of Whitman, V. E.; 703, Randolph Street, Washington, U.S.A.) March 25, 1933, No. 9062. Convention date, April 9, 1932. [Class 40 (v).] An oscillator-modulator, suitable for use as the frequency-changer of a heterodyne or superheterodyne receiver, and producing local oscillations of constant amplitude over the tuning range, has the inherent grid-cathode capacity neutralized. It is shown in the Specification that this results in a constant amplitude of local oscillations being applied between grid and cathode. As applied to a super-heterodyne, the combined detector-oscillator valve 11, Fig. 2, is back-coupled over circuit 28 to produce local oscillations. The circuit 28 includes a resistance 29 to produce a constant amplitude of oscillation over the tuning range. The gridcathode capacity is neutralized by the condenser 35, the mid-point of the inductance 23 being earthed. In a modification, the valve 11, Fig. 3, is back coupled over inductances 20, 28, 23, the coupling between inductances 20, 28 being augmented by a condenser 31 to maintain a uniform oscillation voltage over the frequency range. British Specification 248,311, [Class 40 (v)], and U.S.A. Specification 1,820,809 are referred to.