In a message dated 1/21/2007 12:19:36 P.M. Eastern Standard Time, k7rdx at charter.net writes: It took me a long time to "let go" of my old 4-1000`s(HF ) and move on to newer ceramic tubes...I`ll never look back but the old guys did have a cool glow! 73,Jim K7RDX.. Jim, I found that out early in my amplifier building days and went to ceramic tubes. Lou