On Wed, 25 Oct 2000 20:23:11 -0400 "Tom Rauch" <w8ji@contesting.com>
writes:
>
>
>Just because the exciter is -30dB on third order, it doesn't mean an
>amplifier that is -35dB will not add noticeable extra bandwidth.
Of course it will, in fact the combination, without running through
the math, will likely produce an overall 3rd order product in the
vicinity of -25 dB.
>
>I hear similar reasoning from people trying to pass off -20 and -30
>dB 3rd order IMD amplifiers as "acceptable" because some rigs are
>that poor on low order distortion products at full power on the worse
>bands.
Worse is worse; And it is all additive. I suggested using a reallllly
clean exciter so as to make straightforward unambiguous distortion
measurements on the amp. Eimac describes (in "Care & Feeding of Power
Grid Tubes") a 4CX5000A operated in Class A as the signal source for such
purposes.
73,
Marv WC6W
*
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