Hi Will, If Mr. Harper had a (1937 or 1943) Terman book in his references it would have saved him considerable research. 73 & Good afternoon, Marv WC6W http://wc6w.50webs.com/ -- "Will Matney" wrote: Pay close attention when reading this about the only possible way a control grid could become positive. It's under the portion about how a triode works. The control grid has to be heated hot enough to emit electrons. Under normal operation, a tube will be at cathode potential Vg = OV, or under Vg = -10 Vdc, etc. This is a very long article, but a good one. "Tubes 201" - How Vacuum Tubes Really Work; http://www.john-a-harper.com/tubes201/ Best, Will _______________________________________________ Amps mailing list Amps@contesting.com http://lists.contesting.com/mailman/listinfo/amps ________________________________________________________________________ Try Juno Platinum for Free! Then, only $9.95/month! Unlimited Internet Access with 1GB of Email Storage. Visit http://www.juno.com/value to sign up today!