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@comcast.net]
Sent: Thursday, May 10, 2012 11:21 AM
To: Al Kozakiewicz; amps@contesting.com
Cc: ham_amplifiers@yahoogroups.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@contesting.com [mailto:amps-bounces@contesting.com]
> On Behalf Of Al Kozakiewicz
> Sent: Thursday, May 10, 2012 9:29 AM
> To: amps@contesting.com
> Cc: ham_amplifiers@yahoogroups.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@contesting.com [amps-bounces@contesting.com] On
> Behalf Of Leigh Turner [invertech@frontierisp.net.au]
> Sent: Thursday, May 10, 2012 7:19 AM
> To: 'Jim Thomson'; amps@contesting.com
> Cc: ham_amplifiers@yahoogroups.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@contesting.com [mailto:amps-bounces@contesting.com]
> On
> Behalf Of Jim Thomson
> Sent: Tuesday, 8 May 2012 5:19 PM
> To: amps@contesting.com
> Subject: [Amps] The power of an oversized electrolytic capacitor /
>
> Date: Sat, 5 May 2012 20:59:29 +0930
> From: "Leigh Turner" <invertech@frontierisp.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@contesting.com [mailto:amps-bounces@contesting.com]
> On
> Behalf Of Rob Atkinson
> Sent: Saturday, 5 May 2012 8:53 PM
> To: Jim Thomson
> Cc: amps@contesting.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@telus.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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