Let me throw my experience(s) into this. Not God's word, just my own personal
experience.
Svetlana made the GU-74B (I don't want to fuss with Cyrillic letters here)
which was
used in some commercially built amps. Svetlana USA offered the tube as a
4CX800A, not 4CX800, not 4CX800A7. I used a 4CX800A in my Dentron MLA-
2500B conversion (QST, May 1996). I may still have a tube or two around. I
have
the data sheet (Svetlana) for the 4CX800A which has been posted on :
http://www.g8wrb.org/tetrodes/
Since Svetlana USA got out of the business, and the Svetlana (St. Petersburg)
quit
making them, the 4CX1600B (which I also used in an amplifier. See ARRL
handbooks 1999-2004. Since publication, the 4CX1600B is unobtanium. The
4CX800A may have the same status. There are a few (fewer and fewer!) GU-74B's
around, and prices are climbing.
Moral: if K6GT wrote about it, it's about to become extinct!
73,
George T Daughters, K6GT
CU in the California QSO Party (CQP)
October 2-3, 2010
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