[Amps] [ham_amplifiers] RE: The power of an oversized electrolytic capacitor /howmuch PS filter C is enough?
Roger (K8RI)
k8ri at rogerhalstead.com
Thu May 10 23:46:55 PDT 2012
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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> > Amps at contesting.com <mailto:Amps%40contesting.com>
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> >
> >
> >
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