>
>"Does the fact you measured one bad sweep tube amp suddenly mean the DAF is
>considered good engineering? (I don't think so.)"
>
>I simply stated that some grounded grid amps, which happen to use sweep
>tubes, have poor imd performance, yet that does not mean that all sweep tube
>amps are unacceptable. Rich measured one bastardized "DAF" amp for imd and
>feels qualified to condemn all of them.
>
>I do not object to a conclusion based upon either empirical knowledge or
>logic - even if I might disagree with it. I do object to a conclusion based
>upon faulty logic and/or no empirical testing - even if I agree with the
>conclusion.
>
>Two tone testing of amplifiers will not show a possible defect in the "DAF "
>circuit. In particular, the screen voltage will be held high. Norm's
>bastardized "DAF" hung a large electrolytic cap. on the screen, which would
>destroy it as a linear amp - yet it could have passed a 2 tone test. But,
>the fact that a "DAF" circuit passes 2 tone testing does not mean it will
>fail. Other tests can be used to determine the qualities of the "DAF"
>circuit. I understand tests have been done and posted to a website, yet no
>one seems interested in looking at empirical results. The attitude of a few
>is "it cannot work, therefore any results which tend to indicate that it
>does are flawed".
The DAF works. The splatter level of c. -22db is FCC-legal because it
does not usually go outside the amateur radio band in use.
>
>At least a few "modified" DAF circuits are in daily use in Sweden. Tests
>have been made and posted, and other hams who seem competent, have listened
>and not heard objectionable splatter. That may not prove that the "DAF"
>circuit is the best circuit to use, but it may cause one interested in
>scientific investigation to at least come up with a test acceptable to them
>to further investigate the amplifiers that are in daily operation.
>
Testimonials about the wonderfulness of DAF amplifiers from users reminds
me of a religious cult. Members give positive testimonies supporting
the founder of the cult - even though he practiced polyandry with the
wives of 11 cult members.
>To dismiss an idea for the wrong reason, or because of a lack of adequate
>testing or understanding, is perhaps as objectionable as listening to a lot
>of splatter. In fact, it is much worse. I have a neighbor who runs a
>4-1000 grounded grid, driven by a SB-200. He overdrives everything and has
>horrendous buckshot. But, even though I operate in the same dx window as
>he, it does not bother me that much.
>
>For me, splatter is less objectionable than a closed mind!
>
How do you feel about tetrode users who close their minds to the 3/2
Power Law, Colin?
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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