GB541120A - Improvements relating to the modulation of magnetron oscillators - Google Patents

Abstract

541,120. Magnetrons and circuits therefor. MARCONI'S WIRELESS TELEGRAPH CO., Ltd. May 24, 1940, No. 9217. Convention date, May 24, 1939. [Classes 39 (i) and 40 (v)] Magnetron oscillators are modulated in amplitude or in frequency by applying the signal voltage to two similar electrodes in such manner that the undesired kind of modulation is compensated out. As shown in Fig. 3 the anode is divided transversely to the axis forming in effect two separate split-anode magnetrons 9, 11. Lecher-pairs 21, 23 secured to each lie closely adjacent to each other and are coupled to the aerial circuit 27. The signal source 29, Fig. 5, is connected through an amplifier 35, two potentiometers 31, 33 and two separate amplifiers 37, 45 and transformers 41, 49 to the anode supply circuits of the respective magnetron sections 9, 11. Potentiometers 53, 55 across the anode source 51 are so adjusted that the magnetrons act on opposite slopes of the curve indicating output amplitude as a function of anode voltage, and the reversing-switch 43 is placed so that the signals reach the anodes in opposite phase. Under these conditions, amplitude modulation is effected without frequency modulation. With the switch 43 in its other position, frequency modulation without change of amplitude is effected. In a modification (Fig. 6 not shown), the same results are achieved by applying the signal voltage to end-plates of the magnetron, a reversing switch being provided in one of the circuits. In a further modification, the signal voltage is applied to the divided anodes, which are biased equally, and the end-plates are differently biased.