GB370768A - Coupling system for thermionic valve circuits - Google Patents

Abstract

370,768. Wireless receiving apparatus. HAZELTINE CORPORATION, 15, Exchange Place, Jersey City, New Jersey, U.S.A.-(Assignees of Wheeler, H. A. ; 18, Melbourne Road, Great Neck, Long Island, New York, U.S.A.) July 10, 1931, No. 19879. Convention date, Aug. 19, 1930. [Class 40 (v).] A transformer coupling adapted for use as an input coupling or as an intervalve coupling and to give a wireless receiver a constant amplification throughout the tuning range comprises a tunable secondary circuit LC and two primary circuits in parallel one comprising a large inductance L2 resonant at a frequency slightly lower than the lowest operating frequency and the other comprising a small coil L1 in series with a condenser C1. Fig. 3 shows the application to a neutralized receiver in which the coil L1 also serves as the neutralizing winding. In a modification, Fig. 2 (not shown), applied to a screen-grid valve receiver the winding L1 is arranged adjacent winding L as shown in Fig. 4 and is open circuited at one end since the capacity between the windings forms the condenser C1. In a modified coil construction the winding L1 is interposed between coils L and L2. Specifications 273,639, 315,399, [both in Class 40 (v), Wireless signalling &c.], 358,054, [Group XXXV], and 359,890 are referred to.