----- Original Message -----
From: Bob Duckworth <wb4mnf@atl.org>
To: AMPS <amps@contesting.com>
Sent: Monday, December 27, 1999 1:08 PM
Subject: Re: SV: SV: [AMPS] daf on-air amplifier testing
>
> Inexperienced amp builder has some questions.
>
> What are design goals of this DAF amp? I tried
> web site but my DNS says no such name.
What web site? www.pocab.se/amp/g2daf.htm should work...
About goals, I guess Dick´s goal was simplicity in amp design with tetrodes...
> Does this DAF amp employ any feedback?
Nope.
> How much?
-
> What class does it run for SSB? A? AB? B?
All the above. It operates with floating class of operation.
> Amps in general.
>
> What's are the differences between the screen having a
> constant potential over a period that is long relative
> to the modulation period and the screen staying at
> a constant potential the entire time the amp is 'keyed'
> and the screen staying at a constant potential the
> entire time the amp is powered on? Or, maybe the
> broader question. What difference does it make if
> everything changes over a period that is long relative to
> the modulation, so long as HiFi is maintained in the
> window.
>
> Difference meaning, does it make any significant (X db
> where X matters) difference to the fidelity.
Good questions! I do not have the answers...
> And this grid current stuff. What's it matter if there is
> some grid current if there is enough feedback? What's
> reasonable feedback and grid current for a tube
> based amp? Why not sample the output of a SSB
> amp like my friend does with his AM TX and use the
> difference between input and output to improve fidelity?
>
> Why don't folks wire a relay into the PTT or VOX and
> rebias the amp so that it is idling with little or no plate current
> until it's time to yak? If I can OOK the amp at CW speeds,
> shouldn't I be able to OOK it with the PTT or VOX (introducing
> some small delay prior to excitation)?
There is no problem with grid current as long as the tube can handle it and the
amp still is on the "linear operating line" , thereby dont get saturated.
73 de Lars/SM3BDZ
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