Patent GB-683941-A (GB)
Title: Improvements in or relating to the tuning of resonant circuits for high-frequency generators
IPC: H03L7/04
Filed: 1947-07-04
Abstract: 683,941. Velocity-modulated tubes. SPERRY GYROSCOPE CO., Inc. July 4, 1947 [May 19, 1942], No. 17713/47. Class 39(i) [Also in Groups XXXV and XXXVI] The Specification as open to in'spection under Sect. 91, comprises the following subject-matter. In Fig. 5, (Cancelled), the two resonators 71, 72 of an oscillator 70 are maintained at a common frequency by rectifying at 80, 80<SP>1</SP> the outputs from the resonators, comparing the resulting D.C. voltages in the valves 81, 81<SP>1</SP> and utilizing their difference to control a reversible motor 32. This operates a vane 86 projecting through the wall separating the resonators, and acts differentially on the tuning of the resonators. A desired ratio between the excitation of the respective resonators may be obtained by adjustment of the tappings 78, 78<SP>1</SP>. An arrangement for automatically tuning a receiver to an incoming wave, which bears a frequency modulation at an auxiliary frequency f, is shown in Fig. 14, (Cancelled), here the received carrier is fed to the buncher resonator 124 of a multi-resonator amplifier. The frequency modulation at frequency f present in the received carrier results in the development of amplitude modulation if the receiver is mistuned, and this amplitude modulation, the phase sense of which depends on the sense of the mistuning, is detected at 128 and fed through a tuned amplifier 129 to a mixer or phase comparator 130. To detect the frequency modulation, the electron beam is branched by interposing a wedge plate 131 at cathode potential. The branch beams pass into two resonators 132, 132<SP>1</SP> tuned respectively above and below the frequency to which the receiver should be tuned. Grids 133, 1331 at cathode voltage, and collector plates 134. 134<SP>1</SP> are placed in the electron stream beyond the resonators. The plates 134, 1341 are grounded through resistors 135, 136 across which the detected FM signal of frequency f is passed to a tuned amplifier 139 and constitutes the second input to the phase comparator 130. The D.C. output controls a reversible motor 32 adjusting the tuning- plugs of the resonators 124, 126. In the receiver shown in Fig. 16, (Cancelled), the incoming wave is applied to the buncher resonator 162 of a three-resonator tube 161, similar to that described in Specification 602,164. A local source 170 of frequency f feeds a grid 166 in the main electron stream, and also a grid 173 in a perpendicular electron stream emanating from a cathode 172. In this way, the resonant frequency of the receiver is varied at frequency f without producing serious amplitude modulation. The intermediate frequency appearing on the plate 1701 is frequency-modulated at the frequency f, and this frequency is selected by a tuned amplifier 178 and applied to a phase comparator 179 which also receives the frequency f from the source 170 through a phase-adjuster 180. The D.C. output from the phase comparator 179 is fed to a reversible motor 32 which adjusts the tuning plugs of the tube 161 to bring the receiver in tune. This subject-matter does not appear in the Specification as accepted.