| 摘要 |
<p>In a magnetron a spinner (22), rotatable on a longitudinal axis (x) has a number of evenly spaced markings formed circumferentially on an exterior surface. The markings are sensed, as the spinner rotates, by a photo sensitive transistor (PT) coupled to window (26) in the vacuum envelope of the magnetron by a fibre optic pipe (FP1). The periodicity of pulses, generated by the transistor in response to movement of markings past the window, is divided in a network (43) to generate a succession of further pulses. The further pulses are then counted in circuit (44) and the instantaneous count compared with reference frequency values stored in memory (46) to generate an output signal O/P(1) related to the instantaneous magnetron frequency.</p> |
