| 摘要 |
An arrangement for transmission of a predetermined fixed frequency by means of a tunable high frequency transmitter tube, such as a magnetron, the tuning of which can be varied periodically by means of a rotatable tuning body driven by a motor. The arrangement comprises a locking hook (22) which is pivotably mounted on a part connected to the rotatable tuning body and cooperates with a stationary locking disc (11), having a locking notch (14) with a stop surface (15). The locking hook (22) cooperates with spring means (28, 30) urging the active end of the locking hook towards the stationary locking disc (11). The locking hook (22) has furthermore a counterweight (35) situated at the opposite side of its rotation axis (23) as compared with the active end. When the tuning is varied, the tuning body is rotated in its normal rotation direction, in which case the counterweight (35) will overcome the force from the spring means (28, 30) so that the locking hook (22) is swung to a position in which it is free from the locking disc (11). When a predetermined fixed frequency is to be transmitted the motor is reversed, whereby the locking hook (22) under influence of the spring means (28, 30) is swung with its active end towards the stationary locking disc (11) with the locking notch (14). After reversion of the rotation direction the locking hook (22) engages the locking notch (14) and locks the tuning body in a position determined by the angular position of the locking notch (14). |
