Original poster: "Resonance Research Corp. by way of Terry Fritz <teslalist@qwest.net>" <resonance@jvlnet.com> Set the base separation at 3/16 inch and the top at 41/2 inch. We have VDGRF's on our website at www.Resonanceresearch.com Dr. Resonance Resonance Research Corp. E11870 Shadylane Rd. Baraboo, WI 53913