As Schiller/Beethoven said; " An die FREUD (-e) .......". de KI
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>Från: measures <measures@vcnet.com>
>Till: <nospam4me@juno.com>, "AMPS" <amps@contesting.com>
>Ämne: Re: [AMPS] drive derived screen potential
>Datum: sön 19 dec 1999 16.46
>
>
>>
>>hello,
>>
>>I want to thank Ian and Colin for your quick replies about eh DAF
>>circuit. Reminds me of a circuit used by Norm (w6edd) in his two 4cx250b
>>amplifier. He controlled the screen voltage with drive, although I
>>believe he did use a negative bias on the control grid. Norm labeled the
>>amplifier as using "class C linear operation." Opinions of the amplifiers
>>performance were mixed "up and down the band."
>
>Norm's DAF amplifier was one of the two amplifiers I measured. He
>eventually converted the amplifier to conventional Class AB1.
>>
>>Next question... Less the requirement of a bias and "large" screen
>>supply,
>
>A conventional screen supply for the 4cx250Bs is hardly large. Since
>screen current is typically around zero mA when the amplifier is heavily
>loaded, the screen's shunt regulator can be fed from the HV bleeder R.
>
>> why would one want to use this type of circuit?
>
>? I have a theory on this. /// Those who are revulsed by psychohistory
>should probably not read beyond this point. /// If an amplifier
>builder constructs a conventional tetrode AB1 amplifier, efficiency is a
>Snoresville 60%. . . Norm claimed that his DAF "linear" amplifier was
>c. 80% efficient. Norm's DAF amp. was a hot topic. For those who
>bought Norm's story, he came across as way Smarter than those who built
>ordinary linear amplifiers. Getting Norm to acknowledge that his
>voice-modulation distortion products were in the -20db to -23db region,
>depending on grid current, took months of effort by myself and several
>others. In my opinion, some guys use the DAF config. as an
>attention-getter and ego-builder. According to phychologist Dr. Phyllis
>Greenacre, some men use such tools to promote male-competence. . . .
>"The sense of reality is characterized by a peculiarly sharp, quick
>perceptiveness, extraordinarily immediate keenness and responsiveness,
>especially in the area or the imposture. The sense of reality is,
>however, impaired."
> [Phyllis Greenacre: "The Impostor" Psychoanalytic Quarterly, 27:359 -
>382 (1958)]
>
>
>> Are there
>>stated advantages by users or builders?
>>
>But of course.
>
>Cheers, Skip.
>
>- Rich..., 805.386.3734, www.vcnet.com/measures.
>
>
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