| 摘要 |
<p>1,180,773. Adjusting tuning element; automatic frequency control systems; modulator systems. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. 14 Nov., 1967 [17 Nov., 1966], No. 51756/67. Headings H3A, H3Q, H3R and H4L. In a tuning arrangement for an oscillator providing a predetermined fixed frequency comprising a rotor 2 rotatably supported in a stator portion and driven by a reversible motor 1, the rotor is rotated in a certain direction to continuously vary the tuning frequency of the oscillator and an arrestor arrangement is provided which is rendered ineffective when the tuning body is rotated to provide the continuously varying tuning frequency but which functions when the rotor is rotated in the opposite direction by the motor so as to arrest the rotor in a position which corresponds to the predetermined oscillator frequency. The rotor shaft 2 of the motor 1 of a tunable magnetron, is attached to a disc 3 such that when the disc is rotated clockwise, the tuning of the magnetron is continuously varied and a catch lever 7 is moved by springs 14, 15, which are in frictional contact with the disc 3, against a stop 12. If the direction of the motor is reversed the disc 3 moves anticlockwise until the lever 7 moves against a projection 4 and the tuning of the magnetron is then fixed. The pre-set frequency may be varied by rotating a shaft 18 and screw 16 which meshes with teeth or a rack 17 on the ring 9, on which the catch lever 7 is mounted. The locking and adjusting arrangements are protected by a lid 23 which is hermetically connected to the arrangement. The motor may be of two-phase type connected to provide forward and reverse under control of a switch (27, Fig. 3, not shown). Automatic frequency control (Fig. 4).-The output from the magnetron is passed to the aerial via a waveguide 28 which is coupled via a directional coupler 29 to a further waveguide 30. Two cavity resonators 31, 32 tuned to different frequencies are coupled to the waveguide 30 and feed detectors 35, 36 which give outputs in opposite directions. The outputs from the detectors are added in an amplifier 37 which gives an output error voltage. This is fed via a peak rectifier 39 to control a servomotor 40 which is coupled to the shaft 18 of the tuning arrangement so as to maintain the predetermined frequency half way between the frequencies (f 1 , f 2 , Fig. 5, not shown), of the cavity resonators 31, 32. An attenuator 38 may be provided so that the output voltage from the detectors can be adjusted to be equal.</p> |
