Original poster: "D&M's High Voltage by way of Terry Fritz <twftesla-at-qwest-dot-net>" <DMsHV.DavMcKin-at-verizon-dot-net> Terry, Could you also test them using 5 turns of the main line through them (vs. just 1 turn). This will increase the coupling, lower the turns ratio, and may flatten their response. Also, what type of signal were you using (pure sinewave? TC? etc.)? Thanks. David L. McKinnon