X-BAND HIGH POWER CW AMPLIFIER AND AMPLIFIER CONSOLE.

Efforts to develop a 12.5 kilowatt CW traveling-wave tube covering the frequency range from 7.7 Gc to 8.4 Gc are described. The tube is designed to be used in ground stations for satellite communications. The major effort during this quarter was directed at incorporating the efficiency taper into a CW tube. Results indicate that efficiency can indeed be improved by the use of tapering, however it was not possible to solve the oscillation problem and none of the tubes constructed during this period could be operated CW because of the oscillation difficulties. This problem arises from the fact that the coupled cavity structure is not a continuous structure but is composed of discrete elements. The impedance for the cavities in the tapered region differs from the impedance of the normal circuit and thus a mismatch occurs at this point. Because of this mismatch, and due to the high impedance, at the edge of the passband the tapered tubes have shown oscillations at all voltages. By driving the tubes these oscillations have been controlled, and useful test data has been obtained. These measurements show that efficiency has been improved by a factor of 1.3 to 1.5 and the oscillation problem can be solved. Thus, the tapering technique should be very useful. Author