GB530936A - Improvements in or relating to electron discharge tube amplifiers - Google Patents

Abstract

530,936. Valve generating circuits. TELEFUNKEN GES FUR DRAHTLOSE TELEGRAPHIE. July 6, 1939, Nos. 19737 and 19738. Convention dates, July 6, 1938 and Nov. 18, 1938. [Class 40 (v)] A neutralized amplifier, particularly for ultra short waves and adapted for frequency doubling, comprises a pair of valves, one of which may be replaced by an impedance simulation, with the anodes connected together and the input applied in push-pull and with an impedance connected between the anodes and the mid-point of the input circuit and having a tapping connected to through impedance to the cathode circuits. Fig. 1 shows a frequency doubling arrangement having an input circuit 3 and an output circuit 4 with a tapping connected to the junction of cathode impedances 5, 51. If the second valve is unheated or replaced by an impedance frequency doubling is not effected. Fig. 3 shows an inductance 2 as the valve simulation with the output taken from a coupled coil 6. In a modification, Fig. 2 (not shown) the valve cathodes are connected by an inductance to a tapping on which a variable common cathode impedance, connected to a tapping on the output circuit, is connected. The cathode circuit impedances may be constituted by Lecher wires. The grid and anode circuits may be interchanged so that the latter is the input circuit. In a further modification the effect of the inductance of the anode and cathode leads may be overcome by subdividing the output impedances into parallel paths 4a, 4b, Fig. 5, with the ends connected by a variable capacity Cu. A tuning capacity Ca may be connected to the mid-point of the input circuit for tuning the output circuit.