what is the upper freq of the band you are interested in? %0 100Khz? 50 - 1Mhz, or what? The reason for asking is that if you run a smps above the frequency where you don't want interference you are unlikely to have problems. George -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics