A frequency locked grid-controlled magnetron for amplitude and frequency modulation

An 800 mc continuous-wave magnetron will be described which utilizes a cathode-grid structure on which a standing wave may be set up around the cathode close to the source of the emission to introduce a locking wave in the electron stream. An experimental magnetron has been locked in frequency over a range up to and exceeding 10 mcs. The frequency locking range varies as a function of the locking power and also of the reciprocal of the output power. The output power of the experimental magnetron has been anode-voltage modulated from virtually zero power to several hundred watts without attendant frequency modulation and with negligible phase modulation. However, load conditions, especially in the case of phase modulation, are critical. The locking power is from 5 to 30% of the output power depending upon the percent modulation and the frequency locking range. The efficiency of the magnetron, utilizing the cathode-grid structure, was found to be slightly less than that of a magnetron having a normal cathode.