Hello All,
In fairness to the DAF design, wouldn't it be more appropriate to tell us
WHAT tube(s) were employed in the amps for which the IMD was quoted and
what was the IMD of the exciter? Many years ago, I was privileged to see
IMD test data on the 813 tube that was taken by a major manufacturer of
power tubes. I was surprised to learn, it was coincidentally a relatively
good tube for the time of the test and far ahead of those in its time.
That was apparently strictly a product of some fortunate geometry in its
construction. The IMD figures, taken on a very elaborate test set, were
in the low 30dB region with reference to ONE tone!
That IMD performance may have accounted for Thornley's results although
he also used the 4-125 tube. Recently, I had some contacts with ZS
stations, still using the DAF and I would have to say that they sounded
pretty good but how they would look on an analyzer is a good question.
Certainly, they couldn't compete with the 3CX800s etc.
73,
Marv, W6FR
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