GB413961A - Improvements in or relating to frequency modulated carrier wave apparatus - Google Patents

Abstract

413,961. Wireless transmitting- systems. MARCONI'S WIRELESS TELEGRAPH CO., Ltd., Electra House, Victoria Embankment, London.-(Assignees of Conklin, J. W. ; Rocky Point, Long Island, New York, U.S.A.) Dec. 18, 1933, No. 35621. Convention date, Dec. 17, 1932. [Class 40 (v).] A magnetron oscillator is modulated in frequency by varying the anode voltage, or the magnetic field strength, or both, and amplitude modulation is eliminated either by a limiting- device or by a suitable relation between the modulating potentials applied respectively to the anode and to the field coil. As shown in Fig. 3, signals are applied through a transformer 12, potentiometer 22, and amplifier 14, thus varying the voltage across a resistance or coil 16 which is in the anode circuit of the magnetron 4. The steady anode voltage and the field created by the coil 8 are so adjusted that variations of anode voltage or of the coil current do not affect the amplitude but only the frequency of oscillation. The modulated wave may be fed to an aerial 30 through amplifiers, frequency multipliers, and limiters. The modulating signal may be applied to the main field coil 8 or to an auxiliary field coil either directly or after amplification. As shown in Fig. 8, a split-anode magnetron is employed, and the signal is applied jointly to the field coil 50 through a transformer 58 and to the anode supply lead 54 through a transformer 48.