GB392411A - Intermediate frequency coupling systems for a superheterodyne receiver for wireless signalling - Google Patents

Abstract

392,411. Valve circuits for wireless reception. HAZELTINE CORPORATION, 13, Exchange Place, Jersey City, New Jersey, U.S.A.-(Assignees of Macdonald, W. A. ; Little Neck, New York, U.S.A.) Nov. 21, 1931, No. 26290/32. Convention date, Feb. 13, 1931. Divided on 391,521. [Class 40 (v).] An intermediate frequency amplifier for a superheterodyne receiver, has one intervalve transformer coupling designed to give a double resonance and one or more succeeding transformer couplings designed for single resonance, the overall response being substantially uniform over the side-band range. As shown in Fig. 1, the output from the first detector of a superheterodyne circuit, is passed to the amplifier 41 through tuned circuits 43, 44 so coupled as to give resonance peaks at the limits of the side-bands as shown by curve a of Fig. 2. The couplings 49, 55 between the valve 41 and the succeeding amplifier 42, and between that amplifier and the second detector 60, have only one coil tuned, preferably the anode coil, so giving a single resonance (curve b of Fig. 2). The combination gives a curve c of substantially uniform gain over the side-band range. The secondary coil 52 is designed to have a natural resonance at a frequency lower than the lowest received frequency. A volume control is afforded by a tapped resistance 53 across the secondary 52 of the coupling 49 ; whilst the coupling 55 is designed to step down to suit the low impedance of the detector 60. The Specification also describes the remainder of the receiving circuit disclosed in Specification 391,521 ; and an automatic volume control arrangement of the kind described in Specification 293,462, [Class 40 (v), Wireless signalling &c.], also is referred to.