Chapter 4. Radial Dirod #8

4.1. Principles

Model #8 is an updated and improved version of Model #6. The principles of operation are identical to those described in Section 2.1 and the reader is encouraged to read that section before proceeding. The disk diameter has been enlarged from 10 inches to 11.5 inches and the collectors have been moved farther apart, increasing the spark length and top voltage for Model 8. The aluminum rods have been replaced with foil strips and metallic beads, eliminating the tedious finishing of the rod ends. The beads are larger and smoother than the old rod ends and so they suffer less corona loss. The foil strips would suffer significant corona loss were it not for the beads. In addition to these improvements, the collector tees are now supported by the legs rather than by the corona shield, the upper bearing is now on the corona shield, and the neutral connection is through a foil strip underneath the base. Crowning all of these improvements, the corona shield is now quickly and easily removed, easing the replacement of brushes and belt. With a capacitor, Model #8 will produce hot 5-inch sparks across the corona shield and nearly 2-inch sparks with a ball gap. The construction of Model #8 differs significantly from that of the previous models and so it will be given in detail.