GB414836A - Improvements in or relating to thermionic oscillation-generators and the like - Google Patents

Abstract

414,836. Valve circuits for wireless reception. RADIOAKT.-GES., D. S. LOEWE, 10, Wiesenweg, Steglitz, and SCHLESINGER, K., 39, Friedrichstrasse, Friedrichshagen, both in Berlin. April 12, 1933, No. 10906. Convention date, April 15, 1932. [Class 40 (v).] In order to facilitate wave-band switching, and the use of a tuning-condenser marked with an exact frequency-scale, particularly in shortwave working, a valve generator or amplifier is characterized by a reactive arrangement in which condensers 3, 4, Fig. 2, are shunted across the main oscillatory circuit 1, 2 and a threepoint connection is made to the valve so that the cathode 14 is at HF potential and the grid 15 is earthed through the signal input circuit 19. The circuit can also be used to apply the local and signal frequencies to the first detector of a superhet receiver, the signal input being between grid and earth, and the local oscillations between cathode and earth. The H.T. supply is taken from terminals 8, 9 through chokes 7, 6. The effect of the valve interelectrode capacity on the main oscillatory circuit is minimized by the screening-grid 16, and by the inclusion of small series condensers 20, 21. As applied to a superhet circuit, Fig. 3, the beat frequency is built up in a tuned anode circuit 24, 25, in series with the choke 7 which excludes the heterodyne frequency. In Fig. 4 the beat frequency is collected in a circuit 4, 26, 27 located between the cathode 14 and earth, the local heterodyne circuit consisting of the coil 2 and condensers 1, 4, 21. The condenser 20, for reducing the effect of valve capacity, is in this circuit shunted by a high resistance 28 designed to pass the necessary plate current.