The report describes the work performed and the results obtained on a program to improve the operational performance of a basic ICEM coaxial magnetron. In addition, manufacturing methods were to be established which would allow volume manufacture of the device at reasonable costs. Minimum peak power of 500 kw at X-band, tunable over the band from 8.6 GHz to 9.6 GHz, and a life time in excess of 10,000 hours were required. The starting point for this program was the SFD-328 ICEM coaxial magnetron. While still a laboratory test vehicle, this tube had demonstrated performance which confirmed that the objectives of this program were realistic and achievable. The program consisted of two elements, following a basic manufacturing methods approach. Through refinement, the device progressed from the laboratory test stage to a production device. The device was then placed in a life test program. The final device which resulted from this program is discussed together with its advantages and limitations.