Expanding a bit on what Paul Christensen wrote - going to the review of 3 amps
in QST, Sept 1997, and 4 others in July 1992:
Alpha 91b GU-74B/4CX800A AB1 3d/5th ord IMD: 45/49 dB
Ameritron 800H 3CX800 AB2 " " " " : 49/55 dB
QRO HF-2500DX GU-74B/4CX800A AB1 " " " " : 43/40 dB
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
Ameritron AL-82 3-500Z " " " " : 38/54 dB
Commander HF-1250 3CX800A7 " " " " : 48/44 dB
Kenwood TL-922A 3-500Z " " " " : 38/54 dB
Ten-Tec Centurion 3-500Z " " " " : 38/50 dB
Looks like there is much more involved in the variation than whether a
grounded-grid triode or a tetrode design is used. I won't venture guesses as
I'm not that conversant in amp design and the many tradeoffs. Reflecting on
the list, though, maybe ceramic is better than glass - nah, I won't go there!
hi!
73, Duane
"Tom Rauch" <w8ji@akorn.net> wrote:
Hi All,
Does anyone have any idea why tetrode amps like the one just
reviewed in QST seem to have such poor IMD performance?
... etc....
Duane Calvin, AC5AA
Austin, Texas
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