| 摘要 |
A duty cycle power control circuit for a magnetron including a power transformer having a primary winding, a secondary anode winding for supplying anode voltage to the magnetron and a secondary filament winding for energizing the filament of the magnetron. In the illustrative embodiment the power transformer primary winding comprises a main winding and a serially connected standby winding. Duty cycle controlled switching devices are effective in a standby state to connect the main winding in series with the standby winding across an external power supply and are effective in the power on state to disconnect the standby winding and connect the main winding directly across the external power supply. The ratio of the standby winding turns to main winding turns is selected such that when the standby winding is serially connected to the main winding the anode voltage supplied at the secondary of the power transformer is below the minimum anode voltage level for microwave energy generation and when the standby winding is disconnected from the main winding the secondary anode voltage is greater than this minimum anode voltage level; in either instance the filament voltage is sufficient to maintain the filament temperature high enough to avoid moding in the magnetron.
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