2.5 watt traveling wave tube amplifier for the MACS program

This paper will describe the development of an X-Band TWTA (Traveling Wave Tube Amplifier). The 2.5 watt PPM focussed TWT and its accompanying solid state dc-dc convertor have been developed for use in MACS, a Medium Altitude Satellite Communication System. The significant design parameters with their inter-relationships with the design specifications will be discussed. Experimental results will be presented as curves of power output, gain, noise figure, and phase characteristics. Of particular significance in this program are the requirements for a high MTTFF (50,000 hours) and also a high overall efficiency and therefore of major interest will be the aspects to be discussed, of the design which are expected to provide both the required reliability and of the overall efficiency which will be above 22%. The life test program which will yield the proof of the required reliability will also be described in some detail.