[Amps] [ham_amplifiers] RE: The power of an oversized electrolytic capacitor /howmuch PS filter C is enough?
Bill Fuqua
wlfuqu00 at uky.edu
Fri May 11 08:31:08 PDT 2012
even active feedback systems have a damping factor.
If it is under damped it exhibits a resonant peak just before the
roll off frequency.
73
Bill wa4lav
At 02:46 AM 5/11/2012 -0400, Roger (K8RI) wrote:
>On 5/10/2012 3:21 PM, Carl wrote:
> >
> > Incorrect, it can be either active or passive.
>I think we are running into semantics, but the way I see it(depending
>on how active feedback is defined) if the math is done for either the
>flywheel or the caps they do see what I would call an active feedback.
>. In both cases when the energy storage device (which contains potential
>energy) sees less energy in the system it transfers energy into the
>system, or more correctly energy transfers or flows from the higher
>potential to the lower.
>
>Unless active feedback is defined as from an external device the system
>itself senses potential energy on both sides and attempts to equalize
>the energy by transferring from the higher potential to the lower and
>would stop if they became equal. In both cases the storage device is
>recharged when the system contains more energy than the storage device.
>
>73
>
>Roger (K8RI)
> > Carl
> > KM1H
> >
> > ----- Original Message -----
> > *From:* Al Kozakiewicz <mailto:akozak at hourglass.com>
> > *To:* garyschafer at comcast.net <mailto:garyschafer at comcast.net> ;
> > amps at contesting.com <mailto:amps at contesting.com>
> > *Cc:* ham_amplifiers at yahoogroups.com
> > <mailto:ham_amplifiers at yahoogroups.com>
> > *Sent:* Thursday, May 10, 2012 11:46 AM
> > *Subject:* [ham_amplifiers] RE: [Amps] The power of an oversized
> > electrolytic capacitor /howmuch PS filter C is enough?
> >
> > To continue the physical analogy, you're describing damping, not
> > regulation. Adding mass to increase inertia may mimic the results
> > of regulation, but only if the time interval of the measurement is
> > relatively short.
> >
> > For the purpose of the amplifier power supply discussion, I get
> > the point. But regulation is an active process, not passive, and
> > requires feedback.
> >
> > Al
> > AB2ZY
> >
> > ________________________________________
> > From: Gary Schafer [garyschafer at comcast.net
> > <mailto:garyschafer at comcast.net>]
> > Sent: Thursday, May 10, 2012 11:21 AM
> > To: Al Kozakiewicz; amps at contesting.com <mailto:amps%40contesting.com>
> > Cc: ham_amplifiers at yahoogroups.com
> > <mailto:ham_amplifiers%40yahoogroups.com>
> > Subject: RE: [Amps] The power of an oversized electrolytic
> > capacitor /how much PS filter C is enough?
> >
> > Think about this: if you place a resistor between the transformer
> > and the
> > filter capacitor your dynamic regulation will deteriorate. Thus
> > the need for
> > low resistance transformer windings and heavy primary lines. This
> > is just as
> > much "regulation" as is an active regulator, although not with the
> > same
> > precision.
> >
> > A flywheel on an engine does provide dynamic regulation as well.
> > It keeps
> > sudden loads from dragging the rpm down instantaneously as well as
> > smoothing
> > the "ripple" of the firing cylinders.
> >
> > 73
> > Gary K4FMX
> >
> > > -----Original Message-----
> > > From: amps-bounces at contesting.com
> > <mailto:amps-bounces%40contesting.com>
> > [mailto:amps-bounces at contesting.com
> > <mailto:amps-bounces%40contesting.com>]
> > > On Behalf Of Al Kozakiewicz
> > > Sent: Thursday, May 10, 2012 9:29 AM
> > > To: amps at contesting.com <mailto:amps%40contesting.com>
> > > Cc: ham_amplifiers at yahoogroups.com
> > <mailto:ham_amplifiers%40yahoogroups.com>
> > > Subject: Re: [Amps] The power of an oversized electrolytic capacitor
> > > /how much PS filter C is enough?
> > >
> > > Although I understand the point being made, filter capacitors,
> > no matter
> > > how large, do not provide "regulation" any more than a big flywheel
> > > takes the place of a governor on an engine. Regulation requires
> > active
> > > circuitry and feedback.
> > >
> > > OK, back to nuclear weapons design.
> > >
> > > Al
> > > AB2ZY
> > >
> > > ________________________________________
> > > From: amps-bounces at contesting.com
> > <mailto:amps-bounces%40contesting.com>
> > [amps-bounces at contesting.com
> > <mailto:amps-bounces%40contesting.com>] On
> > > Behalf Of Leigh Turner [invertech at frontierisp.net.au
> > <mailto:invertech%40frontierisp.net.au>]
> > > Sent: Thursday, May 10, 2012 7:19 AM
> > > To: 'Jim Thomson'; amps at contesting.com
> > <mailto:amps%40contesting.com>
> > > Cc: ham_amplifiers at yahoogroups.com
> > <mailto:ham_amplifiers%40yahoogroups.com>
> > > Subject: Re: [Amps] The power of an oversized electrolytic
> > capacitor /
> > > how much PS filter C is enough?
> > >
> > > Hi Jim,
> > >
> > > There are two aspects to consider here; the static and dynamic
> > voltage
> > > regulation, and the amount of ripple on the B+ plate supply.
> > >
> > > In CW and SSB amplifier service the keyed and syllabic
> > fluctuation of
> > > load
> > > defines the requisite dynamic regulation capability of the HV power
> > > supply.
> > > Achieving static and dynamic regulation under 5 percent would be
> > good
> > > design
> > > practice. As for rms ripple voltage, a target of less than 2 to 5
> > > percent of
> > > the DC supply voltage under full load current would be
> > considered good
> > > engineering practice.
> > >
> > > A large energy storage capacitance on the HV rail makes sense
> > from the
> > > point
> > > of view the amplifier load current requirements have a large
> > peak-to-
> > > average
> > > ratio in SSB service. A stiff B+ voltage also helps with
> > minimising IMD.
> > >
> > > For common 3 kV @ 1A amplifier power supplies, i.e. a load
> > resistance of
> > > circa 3000 Ohms, a reservoir capacitance of about 60 uF would be
> > > sufficient
> > > to yield the above respectable regulation and ripple objectives. One
> > > might
> > > double the filter capacitance to circa 100 uF for good measure; but
> > > going
> > > beyond that amount of capacitance would be a futile exercise in
> > > diminished
> > > returns.
> > >
> > > Now your 7 kV B+ supply corresponds to a PS load resistance of circa
> > > 7000
> > > Ohms, so there is an associated relaxation in the capacitance
> > required
> > > to
> > > meet a given percentage ripple voltage objective.
> > >
> > > The tolerable ripple level superimposed on the HV plate supply above
> > > which
> > > incidental AM hum sidebands appear on the radiated signal is an
> > > interesting
> > > question; the anecdotal experience of Rich's friend with only 2
> > uF of
> > > filter
> > > capacitance suggests there's a large tolerance to ripple on the
> > plate
> > > supply
> > > with the tube and tank circuit exhibiting a good PSRR.
> > >
> > > We can note the amplifier in question here uses a 4-1000
> > tetrode, and
> > > that
> > > such tubes exhibit a plate current virtually independent of plate
> > > voltage,
> > > i.e. tetrodes are a constant current device. Such a
> > characteristic would
> > > make it more immune to ripple and noise on the B+ plate supply.
> > >
> > > Leigh
> > > VK5KLT
> > >
> > >
> > > -----Original Message-----
> > > From: amps-bounces at contesting.com
> > <mailto:amps-bounces%40contesting.com>
> > [mailto:amps-bounces at contesting.com
> > <mailto:amps-bounces%40contesting.com>]
> > > On
> > > Behalf Of Jim Thomson
> > > Sent: Tuesday, 8 May 2012 5:19 PM
> > > To: amps at contesting.com <mailto:amps%40contesting.com>
> > > Subject: [Amps] The power of an oversized electrolytic capacitor /
> > >
> > > Date: Sat, 5 May 2012 20:59:29 +0930
> > > From: "Leigh Turner" <invertech at frontierisp.net.au
> > <mailto:invertech%40frontierisp.net.au>>
> > > Subject: Re: [Amps] The power of an oversized electrolytic
> > capacitor /
> > > overkill
> > >
> > >
> > > I agree Rob; a fraction of that massive HV PS capacitance would
> > create
> > > an
> > > unperceivable difference in the Tx performance and signal at a
> > distant
> > > Rx
> > > station :-)
> > >
> > > Leigh
> > > VK5KLT
> > >
> > > ### Leigh, how many uF in your opinion, do you suggest I use on
> > a 7.7 kv
> > > No
> > > load B+ supply.
> > > What is the bare minimum I could get away with. I'm being
> > serious here.
> > > Rich Measures has a friend with a 4-1000 amp...and he only uses
> > 2 uf for
> > > a
> > > filter cap...and No choke anywhere. Nobody hears any hum.
> > >
> > > On a similar note, a friend was on one night, toggling between
> > his SB-
> > > 220
> > > and his Alpha 9500. Nobody could tell the difference between the
> > 1200w
> > > of
> > > the SB-220.....and the 1500w of the Alpha 9500.
> > >
> > >
> > > -----Original Message-----
> > > From: amps-bounces at contesting.com
> > <mailto:amps-bounces%40contesting.com>
> > [mailto:amps-bounces at contesting.com
> > <mailto:amps-bounces%40contesting.com>]
> > > On
> > > Behalf Of Rob Atkinson
> > > Sent: Saturday, 5 May 2012 8:53 PM
> > > To: Jim Thomson
> > > Cc: amps at contesting.com <mailto:amps%40contesting.com>
> > > Subject: Re: [Amps] The power of an oversized electrolytic capacitor
> > >
> > > 832 uF at 7.7 KV. No offense, but that's a waste of capacitors.
> > >
> > > Rob
> > > K5UJ
> > >
> > > On Fri, May 4, 2012 at 9:28 AM, Jim Thomson <jim.thom at telus.net
> > <mailto:jim.thom%40telus.net>> wrote:
> > >
> > > > ### BTW, My latest creation uses 24 x 10,000 uf @ 450 vdc
> > caps, all
> > > in
> > > > series... and charged up to 7700 vdc. That's one bank. I built
> > a 2nd
> > > > identical bank of 24, and parallel the 2 x banks together...
> > onto a
> > > common
> > > > buss....
> > >
> > > ### I got them for dirt cheap. There is No way I would build
> > something
> > > like this by paying full price for new caps. I wouldn't buy a
> > brand new
> > > vac
> > > cap from Jenning's either, they are cost prohibitive. But I have
> > > managed to
> > > buy surplus, nib, sealed in the box, Jennings ceramic vac caps. They
> > > come
> > > encased in a metal foil bag which has been vac sealed. You poke
> > a pen
> > > knife
> > > into it, and whoosh, the air rushes into the bag. Once bag is
> > removed,
> > > then
> > > you unseal the box...and the new vac cap is inside a box, lined with
> > > foam
> > > rubber on all 6 x sides.
> > >
> > > later... Jim VE7RF
> > >
> > >
> > > _______________________________________________
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