Posted by Damir [ 213.202.98.120 ] on December 31, 2005 at 08:49:30:
In Reply to: Small HV caps, and pentodes driving power triodes posted by PakProtector on December 30, 2005 at 18:48:53:
Hi, first thing (when I find a little time) is to try CCS parallel to Ra with cascode and pentode, and use a Mu-out.
Some of those pentodes are fantastic on paper (P. Millett`s measurements), say 12BY7, 7054, D3a, ... even EF184. Even distortion profile isn`t bad, the only think I don`t like is rel. low bias (say 1-2V) for the most of those high-gm tubes. With common triodes, PP driver/splitter with more then 2 x 40Vrms clean "swing" and only 300V supply isn`t easy. 
Do you think about (pentode) driver and ct choke as a splitter, or...?
And yes, I can`t find small values HV poly caps, "Wima" has 33pF and more...
Happy New Year - and lot of interesting projects!
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