> > > If a high-permeability core goes around both conductors, > > > then the fields cancel out pretty well > cancellation seems to be >99.6%. Oh, I see what you mean. I thought you were referring to a shield in the wire itself -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist