Abstract:This paper presents observed results of spurious spectrum of TWTA used for satel-lite. The rnechanism of spurious spectrum formation is analysed and the rnethods of its sup-pression are discussed. It is shown from the study that in order to obtain pure spectrum, the measures rnust be taken for both design of TWT and EPC circuit. Based on this study, the aruplitude of spurious spectrum of spaceborne TWTA has been reduced 10-15dB