You missed my point. My design receiver consisted of a
switching power supply _and_ associated digital logic with
wideband A/D running with high dynamic range an a
-110 dBm received signal. This shielding and filtering
requirements include all the switching energy _and_ all the
digital logic, a more difficult problem than just power
supply alone.
By the way, since this monster just runs the PA, it seems
that to kill receiver noise, JUST TURN IT OFF...should
have thought of that before.
On the subject of 240 vs 120.
The suggestion was to use the 240 power mains transformer
as 120-0-120 to generate 150 (really 170 peak). The
alternative uses a full wave bridge on 240 and generates
340 peak. That changes the step down ratio from 170/50
to 340/50 and makes the regulator a bit more difficult.
The current pulses on the mains wires run 50 A peak
either way.
Power factor is important. Capacitor input supplies
pull current from the line over a very small portion of
the cycle...in huge pulses. Ham's live with this, maybe
they like to see the lights dim? The proposed switcher
will pull current whenever the input line is greater than
the output voltage. The suggestion was to put enough C
on the primary filter to keep the DC from dropping below
60-70V. That means that after line rectification, the C
need to reduce ripple from 170V (full line) to 100V.
That seemed like enough improvement. No need for a
complicated crest factor controller. The switcher will
pull 50A from the line over virtually the entire cycle.
I don't have a working design at 50A, just a suggestion
that the technology is ready for this and a desire to help
push the state of the ham art.
----- Original Message -----
From: Alex Von Yonkers <avy@qwestonline.com>
To: jeff millar <jeff@wa1hco.mv.com>; <amps@contesting.com>
Sent: Sunday, March 25, 2001 11:27 AM
Subject: RE: [AMPS] Transformer ++
> Dear Jeff...
>
> A PS dedicated for Logic circuits has total different requirements than
one
> dedicated to SSB transmissions. For one, the Logic Power Supply works
> usually under a constant load(more or less) while this SSB PS must cope
with
> power demands in order of 50-100A ramps per 1mS on a repetitive basis.
Thus
> the transient response must be VERY, VERY good. That usually costs a lot.
I
> have discussed this with 6 (SIX) application Engineers from the major
Power
> Supply Manufacturers and none of them could guaranty this level of
> performance.
>
> Also for these power demands, the 110VAC line is not recommended (as you
> suggested) but the 240. More over, it is imperative to have a Power
> Crest-Factor Controller incorporated to raises the DC voltage to 500-600V.
> This where the Power Supply extracts the necessary instantaneous power
when
> there is a demand for a 50-100A step.
> As usually the Power Factor Controller must be rated to twice, at least,
of
> the PS output power, so here we are speaking of a 4 - 8KW Power Factor
> Controller.
>
> And not to forget the EMI:)
>
>
> As I said, not a trivial task.
>
> However, if you have a proven design, I am willing to give it a try :)
>
>
> Alex
>
>
> > -----Original Message-----
> > From: owner-amps@contesting.com [mailto:owner-amps@contesting.com]On
> > Behalf Of jeff millar
> > Sent: Sunday, March 25, 2001 10:48 AM
> > To: avy@qwestonline.com; amps@contesting.com
> > Subject: Re: [AMPS] Transformer ++
> >
> >
> >
> > 5 KW switcher? no. But switching power supply to power digital logic
> > in communication receivers, yes. It's not a trivial task, that's true,
but
> > it's
> > not magic either, design works. The primary drivers on design consist
> > of FET's,Choke, shielded package, and input/output filtering
> > components.
> >
> > Moving the switching frequency around saves money on shielding
> > and fitering, it's just the cheap way out.
> >
> > jeff, wa1hco
> >
> > ----- Original Message -----
> > From: Alex Von Yonkers <avy@qwestonline.com>
> > To: jeff millar <jeff@wa1hco.mv.com>; <amps@contesting.com>
> > Sent: Sunday, March 25, 2001 6:55 AM
> > Subject: RE: [AMPS] Transformer ++
> >
> >
> > > Hmmm....Have you ever designed such a monster before Jeff?
> > > You realize you have to have variable Oscillator Frequency to be able
to
> > > move eventual EMI from the Rx frequency. And this under
> > Receiver Control.
> > > Unless you can design a real quiet (-100dBm EMI) 2-4KW switcher in the
> > > frequency bands of interest. This is not a trivial task :)
> > >
> > > Alex
> > >
> > >
> > >
> > >
> > >
> > > > -----Original Message-----
> > > > From: jeff millar [mailto:jeff@wa1hco.mv.com]
> > > > Sent: Saturday, March 24, 2001 9:57 PM
> > > > To: avy@qwestonline.com; amps@contesting.com
> > > > Subject: Re: [AMPS] Transformer ++
> > > >
> > > >
> > > > How about a switch mode power supply that drops 120-0-120 full wave
> > > > rectified down to 50 volts? This will require a switcher chip, some
> > hefty
> > > > FET's and a high frequency, high power choke but no transformer.
> > > > Using the
> > > > 240 feed as a 120 each side of center and two big diodes to
> > > > rectifiy it will
> > > > produce about 150V. The switcher chip will track the 120 Hz power
> > ripple
> > > > fairly well, just use enough filter C to hold the voltage to
> > about 60-70
> > V
> > > > minimum.
> > > >
> > > > If you're interested, I can help with figuring the values and
> > selecting
> > > > parts.
> > > >
> > > > jeff, wa1hco
> > > >
> > > >
> > > > ----- Original Message -----
> > > > From: Alex Von Yonkers <avy@qwestonline.com>
> > > > To: <amps@contesting.com>
> > > > Sent: Saturday, March 24, 2001 5:07 PM
> > > > Subject: RE: [AMPS] Transformer ++
> > > >
> > > >
> > > > >
> > > > >
> > > > > Speaking of transformers. I'm building an amp based on four MRF157
> > > > > Transistors from Motorola.
> > > > > I need to build an Power Supply able to deliver 50A at 100A
> > or two of
> > > > > 50V/50A. I have called several transformer manufacturers
> > but I almost
> > > > > had an hearth attack when told about the prices.
> > > > >
> > > > > Any good idea?
> > > > > Alex
> > > > >
> > > > > PS. Do you think that there could be a market for a 2KW+ solid
> > > > state amp?
> > > > >
> > > > >
> > > > > --
> > > > > FAQ on WWW: http://www.contesting.com/FAQ/amps
> > > > > Submissions: amps@contesting.com
> > > > > Administrative requests: amps-REQUEST@contesting.com
> > > > > Problems: owner-amps@contesting.com
> > > > >
> > > > >
> > > >
> > > >
> > >
> > >
> >
> >
> > --
> > FAQ on WWW: http://www.contesting.com/FAQ/amps
> > Submissions: amps@contesting.com
> > Administrative requests: amps-REQUEST@contesting.com
> > Problems: owner-amps@contesting.com
> >
> >
>
>
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