GB616261A - Improvements in and relating to pulse generating circuits - Google Patents

Abstract

616,261. Pulse amplifying circuits. BRITISH THOMSON-HOUSTON CO., Ltd. June 19, 1945, No. 15650. Convention date, June 19, 1944. [Class 40 (vi)] In a pulse amplifying circuit in which a valve, feeding an inductive load is rendered conducting for the duration of a pulse, means are provided for suppressing the oscillations generated at the termination of the pulse by a feedback arrangement between the load and the valve. Positive pulses applied to the grid of normally biassed-off valve 3, Fig. 1, cause the anode potential to fall suddenly, thereby applying a negative potential to the cathode of the magnetron 9, shunted by the inductor 8 and stray capacity 17. At the termination of the pulse, due to the resonant circuits 8, 17 and 7, 8 the potential of the cathode of magnetron 9 commences to oscillate, Fig. 4 (not shown), and as it rises above earth potential, diode 18 conducts, causing the grid potential of valve 3 to rise and the valve to pass anode current and stop the oscillation. In a modification, Fig. 3, positive pulses are fed to valve 28, to cause it to conduct, the output being applied over transformer 31 as positive pulses to valve 35 feeding the auto-transformer 41 connected to the magnetron 42. The grids of the valves 28, 35 a.re biassed beyond cut-off, conducting only during the pulses. When the valve 35 conducts, the potential of the autotransformer input is driven negative, the diode 45 conducting and maintaining the cathode near earth potential. Upon the pulse ceasing the potential of the input of the auto-transformer 41 rises, and due to the oscillatory circuit the potential tends to become positive, the diode 45 then ceasing to conduct, so that a rise in potential is applied over condenser 47 and resistance 32 to cause the valve 28 to recommence conducting. Valve 35 is thus rendered conducting to reduce the amplitude of the undesired oscillations.