There's really not much need for regulation on the plate supply on a PA.
Look at the characteristic curves as shown at
http://www.nd2x.net/gu84b.html
Particularly the "Averaged Anode Characteristic Curves" It shows plate
current vs plate voltage with 400V on the screen and various grid bias.
Note the curves for high plate voltage are nearly flat. That's because the
plate current is determined by the screena and grid voltages...the plate
voltage is shielded from affecting the tube by the screen.
This greatly reduces the effect of variations in plate voltage from
affecting the output of the tube. There's some variation in output
impedance and match and some variation in peak power capability but nothing
dramatic.
Amateur amplifiers, even the best ones, commonly use a capacitor filter with
10% or more sag between no load and full load without negative affect on
intermods or overall performance.
jeff, wa1hco
----- Original Message -----
From: "Frank Goenninger" <frank_goenninger@t-online.de>
To: <amps@contesting.com>
Sent: Sunday, December 28, 2003 3:55 PM
Subject: RE: [Amps] 3.5 kV 2A REGULATED Power Supply: Schematic ?
> Thx for quick response.
>
> Referring to your question:
>
> On Sun, 2003-12-28 at 21:35, Dr. William J. Schmidt, II wrote:
> > <<I'm looking for a regulated power supply design where output voltage
does not
> > drop more than 1% on load. I will be using a 3-phase 400V mains line.>>
> >
> > What is the point of this???
> >
>
> I think I should re-phrase my question:
>
> Considering a grounded-cathode circuit for a tetrode (like GU-84b),
> what is the requirement for the plate supply concerning voltage
> stability and ripple? (I also would like to know "Why", if you
> could please explain...)
>
> Thx again.
>
> > Sincerely,
> >
> > Dr. William J. Schmidt, II K9HZ
> > Trustee of the North American QRO - Central Division Club - K9ZC
> >
> > "Collector of Edison Wind-up Phonographs... Do you have one for me?"
> > Email: bill@wjschmidt.com
> > Alternate Email: wmschmidt@charter.net
> > WebPage: www.wjschmidt.com
> >
>
> Regards & 73
>
> Frank DG1SBG
>
> > -----Original Message-----
> > From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com]
On Behalf
> > Of Frank Goenninger
> > Sent: Sunday, December 28, 2003 1:55 PM
> > To: amps@contesting.com
> > Subject: [Amps] 3.5 kV 2A REGULATED Power Supply: Schematic ?
> >
> > Hi all on the list:
> >
> > I have now tried to find (for several days) a design that builds a power
supply
> > for about 3.5kV and 2A.
> >
> > I'm looking for a regulated power supply design where output voltage
does not
> > drop more than 1% on load. I will be using a 3-phase 400V mains line.
> >
> > The objective is to have a "standard" power supply for various amps I
have in
> > the pipeline - starting with a GU-84b based grounded-cathode project.
Next, I
> > want to build one with a 4CX3500A (boy, what a piece of electronic
device, wow).
> >
> > So, all the "surrounding" modules should be as much adjustable as
possible...
> >
> > Hm, I wonder if you guys have something to look at and to start from.
>
>
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