Hi Everyone - the HV cable we use to make the short connection is RG316. It has a 0.1 inch OD. Curtis -- Prof. Curtis A. Meyer Department of Physics Phone: (412) 268-2745 Carnegie Mellon University Fax: (412) 681-0648 Pittsburgh PA 15213-3890 cmeyer at ernest.phys.cmu.edu http://www.curtismeyer.com/