Original poster: "R Lunsford by way of Terry Fritz <twftesla-at-uswest-dot-net>" <Millipede-at-carolina.rr-dot-com> Ok, here is a question that requies a lot more theory than I have at my command... Why are the majority of primary coils built flat or conical in relation to the secondary? Wouldn't a cylindrical primary work best? _Robert Lunsford