Intermediate-frequency neutralisation of self-oscillating mixer stages

摘要

939,285. Valve frequency changing circuits. STANDARD TELEPHONES & CABLES Ltd. Aug. 4, 1961 [Aug. 11, 1960], No. 28470/61. Class 40 (6). In a grounded-grid triode self oscillating mixer stage, feedback at I.F. from the output circuit ZF to the input between grid and cathode is neutralised by completing the network between grid, cathode and anode and the I.F. circuit ZF to form a double bridge network including a resistor R KF and capacitor C KF , Fig. 2, connected between cathode 5 and point 4. Alternatively, Fig. 3, if the grid is not at earth potential at I.F. frequency, but is connected to earth via a capacitance Cgm the connection between 4, 5 may be omitted, the balance of the bridge then involving the inductance Ltg4 and the grid-earth capacitance Cgm.