GB551045A - Improvements in selective high frequency resonant systems - Google Patents

Abstract

551,045. Valve amplifying circuits. JOHNSON LABORATORIES, Inc. May 30, 1941, No. 6958. Convention date, June 10, 1940. [Class 40 (v)] In a permeability tuned receiver an electron discharge tube is regeneratively associated with an amplifier tuned circuit the plate of the tube being directly connected to the high potential terminal of the circuit and the grid being connected to the low potential end of the circuit. Fig. 3 shows a tuned circuit 40 providing the anode load to amplifying value 25 and having its damping reduced by regeneratively coupled triode valve 28. In a supersonic heterodyne receiver a resistance condenser combination may be associated with the aerial in place of the tuned circuit shown. In a modification, Fig. 4, the output is taken from the suppressor grid 88 of the pentode 25 instead of directly through condenser 58. Instead of the tuned circuit being tapped by condensers 44, 45 an autotransformer may be used, Fig. 6 (not shown) or a two-coil transformer the untuned winding 94 of which is in the cathode connection, Fig. 5. The movable core may be so constructed that the ratio of inductance to resistance of the circuit will remain constant throughout the tuning range. The winding may be varied in pitch or the core material may have higher losses per unit volume at the end last entering the coil to produce an inverse proportionality between the mutual inductance and the square of the frequency. Specifications 366,475 and 455,573, [Group XXXVI], are referred to. The Specification as open to inspection under Sect. 91 comprises also an arrangement in which the high potential side of the tuned circuit is connected to the grid instead of the latter being earthed, Fig. 5 (Cancelled and not shown). This subject-matter does not appear in the Specification as accepted.