Let us get the arithmetic right:
Assuming we are talking, say, 3kV @ 1A peak power for the anode, then the
screen load is trivial by comparison.
If building from iron collected from surplus sources, then making a 400V or
whatever supply and tapping off for the screen, and then seriesing this with
2.6kV to make up 3kV is no big deal.
The resting anode current gives a bleed and helps stabilise standing volts.
Sure, this is dearer than making a separate lighter screen supply and then
electronically stabilising it if parts are bought new, but may be very cheap
if parts are acquired surplus.
In effect the screen contribution becomes part of the anode supply, gratis.
Just seems to me to be crude, simple, and likely highly effective.
I would certainly sense the screen current and incorporate protective
circuitry, regardless of where tha screen volts came from.
73
end
Barry Kirkwood PhD ZL1DD
Signal Hill Homestay
66 Cory Road
Palm Beach
Waiheke Island 1240
NEW ZEALAND
www.waiheke.co.nz/signal.htm
----- Original Message -----
From: rich <2@mail.vcnet.com>
To: Barry Kirkwood <bjk@ihug.co.nz>; AMPS <amps@contesting.com>
Sent: Wednesday, January 30, 2002 7:17 PM
Subject: Re: [AMPS] Iron regulated screen supply?
>
>
>
> >
> >Contemplating building a tetrode linear from the accumulated treasures of
> >years.
> >Thinking back on the 30S-1 approach, and amateur as opposed to production
> >budgeting.
> >Thoughts:
> >If one is starting from scratch with things accumulated from junk sales
> >(with an aging ham population used equipment seems to be a buyer's
market!)
> >then a power supply made by stacking a frinstance 400V @ 1A peak with say
> >3kV@ 1A peak is not such a bad concept :
>
> // An anode PS sourced shunt 400v screen regulator is cheaper, less
> complex, more RF immune, and more accident resistant than a 1A screen
> supply.
>
> >the screen load is trivial, one is
> >basically making a slightly unorthodox anode supply.
>
> Screen dissipation is not trivial.
>
> >Again, tuned chokes are not such a big deal, and maybe plain choke input
> >with a generous reservoir capacity and generous bleed current might show
> >almost as good dynamic regulation.
>
> When an old timer [W6SDM] recommended againt such because of a transient
> regulation problem, I went home, fired up my DC oscilloscope and saw for
> myself. When the load current decreased, there was a substantial
> V-spike. When the load current increased, there was a substantial V dip.
> On a meter, I could not see the problem.
>
> >After all tetrode high fi audio amps run
> >low distortion (albeit with negative feedback) ...
>
> // Bingo
>
> good luck, Barry
>
> - R. L. Measures, a.k.a. Rich..., 805.386.3734,AG6K,
> www.vcnet.com/measures.
> end
>
>
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