Hi Guys, I noticed that some tubes with oxide cathodes (3cpx5000a7 ex.) have data sheets that say "no class C operation"...How come? 73 Jay W7CW 1AB Ranch Gillette, Wyoming -- FAQ on WWW: http://www.contesting.com/ampfaq.html Submissions: amps@contesting.com Administrative requests: amps-REQUEST@contesting.com Problems: owner-amps@contesting.com Search: http://www.contesting.com/km9p/search.htm