GB428956A - Improvements in wireless receiving systems of the super-heterodyne type - Google Patents

Abstract

428,956. Valve circuits for wireless reception. PEYTON, L. A., 4, Thirlmere Place, Northlands, Durban North, Durban, South Africa. Jan. 29, 1934, No. 2944. Convention date, Feb. 22, 1933. [Class 40 (v)] [See also Group XXXVI] The output circuit of a combined detector oscillator valve P, Fig. 1, comprises three paths. viz. the condensers Cl, C2 to earth, having a low impedance for high-frequency oscillations ; the resistance R1 and the condenser C6, having a low impedance for the intermediate frequency oscillations ; and the condenser C3 and feed-back coil L3, having a low impedance for the local oscillations, the coil L3 being earthed through condensers C4, C5. The feed-back coil L3 is coupled to a grid coil L2 which is tuned by a condenser TC. The feed-back coil L3 is tuned by the condenser TC over the coupling L2, L3 to the frequency of the local oscillations. A switch S allows the tuning condenser TC to be connected across various portions of the grid coil L2 and various points of the grid coil to be earthed. The coils L1, L2, Fig. 2, are wound on the outside of a rectangular frame, the coil L3 being movably mounted within the frame. The coils are secured in position on the frame F by external and internal clips CS1, CS2, Fig. 3, which are disposed at diametrically opposed points and which are chamfered to reduce the area of contact between the coils and the frame. In a modification, the coil assembly is provided with an additional coil having an iron dust core, Figs. 6 ... 9, (not shown). Specification 382,286 is referred to.