KU-BAND TRIODE AND CAVITY COMBINATION CW OSCILLATOR.
GENERAL ELECTRIC CO OWENSBORO KY TUBE DEPT
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Two-hundred and sixty-eight triodes of eighteen different designs were assembled for testing at Ku-Band. Ten basically different cavity designs were evaluated during this same period. The original objective of CW operation required an anode input power of four watts. Consideration of foreshortening grid-to-anode capacitance limited the anode diameter to 0.060 in. resulting in a power density of 210 wattssq cm. It was necessary to limit the duty to 25 in order to prevent thermal runaway conditions at 25 duty, 15 milliwatts were obtained at 16.4 GHz. Single knob tuning provided operation over a range of 400 MHz around this center frequency. A change in objectives to accomplish dual function transmitreceive operation required a very high cathode current density 30 Asq cm capability for transmit operation. Different cathode materials, primarily coated-powder carbonates, were evaluated with negative results because of inadequate emission levels. Dispenser type cathodes were also evaluated but were prone to give excessive sublimation. Highest power output in the transmit mode was 7.5 watts highest power output in the local oscillator or function was 150 milliwatts with a useful band-width of 400 MHz. Simultaneous optimization of transmit and local oscillator functions was not feasible. Best operational life achieved under local oscillator conditions was 70 hours. Author
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