GB483504A - Improvements in thermionic valve circuits employing reaction - Google Patents

Abstract

483,504. Valve circuits. MURPHY RADIO, Ltd., and BALEAN, J. H. Oct. 28, 1936, No. 29349. [Class 40 (v)] To maintain reaction substantially constant over a wide range of frequencies, the reaction coil or reaction circuit is shunted by a reactance of which the accoptance varies with frequency in the same manner as the reaction of the valve would vary with frequency in the absence of the shunt. In Fig. 1, reaction is obtained by inductance 5 and is controlled by condenser 6. The circuit 5, 6 is shunted by the compensator 7, 8, 9 which comprises two tuned circuits which present two minima of impedance with a maximum between them. The valves of the components are chosen so that the minima occur at or near the high frequency end of the two ranges of wave length for which the receiver is tunable and the maximum is at the low frequency end of the short or medium wave range. High tension may be applied at any convenient point and is connected through high impedance 10 so that the compensator is not shunted by condenser 11 and transformer 12 which supply the next stage. Several arrangements of compensator are shown connected between anode and cathode or between grid and cathode as shown in Fig. 7. If the shunt is to be used in a circuit which is tuned over a number of wave ranges, the notwork should have one fewer rejector resonances than the number of ranges with an acceptor resonance on each side of each rejector resonance. The effect of the compensator may be enhanced by the provision of an additional impedance such as inductance 21, Fig. 7. The invention can be used to cause an oscillator to give constant voltage at all frequencies.