Wide range cavity tuning for high-power X-band magnetrons

Use of a simple external cavity to tune a magnetron over wide frequency ranges (10 per cent or greater) imposes performance limitations with respect to electronic efficiency, moding, cathode-temperature variation, and coupling change. This paper discusses the use of more than one external tuning cavity to improve magnetron performance. A demountable laboratory design which tunes over a range of 17 per cent is described, as well as a sealed-off tube having electronic efficiency, cathode temperature, and power output constant over a range of 10 per cent. The multiple-cavity method of tuning permits the use of much higher frequency ranges and power outputs.