> actually measured the difference in IMD for a single tube run
> at 400mA and 550mA? Has anyone actually measured the IMD
> from an AL-80B at various levels of anode current?
I'm not sure why this stuff always gets so drawn out and personal or
emotional, but of course IM has been tested Mike.
When operated according to the manual, IM3 in the 80A was typically
about -38 to -44dB below PEP for third order and about 5-6 dB better for
IM5. This is considerably better than most radios produce. The tube actually
can do about -50dB (PEP) or better IM3 when operated easier.
Naturally some IM products go up while some go down as power level is
changed.
All of this stuff was always tested in prototype stages while manuals are
being written. Back then the test was with two radios through a combiner, a
simple two-tone test.
73 Tom
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