[AMRadio] Screen Regulator Circuits, 20a, etc.

[John Coleman, ARS WA5BXO]

You have to type this address in or cut and paste it back together
because it wraps to the next line and doesn't complete when you click on
it or cut and paste only the first line.

John,
WA5BXO


-----Original Message-----
From: amradio-admin at mailman.qth.net
[mailto:amradio-admin at mailman.qth.net] On Behalf Of David Knepper
Sent: Wednesday, November 19, 2003 5:02 AM
To: amradio at mailman.qth.net
Subject: Re: [AMRadio] Screen Regulator Circuits, 20a, etc.

Jim, the websites that you gave cannot be downloaded.

Thank you.

Dave, W3ST
Secretary to the Collins Radio Association
Publisher of the Collins Journal
www.collinsra.com
----- Original Message -----
From: "Jim candela" <jcandela at prodigy.net>
To: <amradio at mailman.qth.net>
Sent: Wednesday, November 19, 2003 12:26 AM
Subject: [AMRadio] Screen Regulator Circuits, 20a, etc.


>
>
> Hi Guys,
>
> I have been working on two HV regulator circuits in the past year
where I
> needed +375 volts at up to 100 ma. In the first case I had 600 volts
to
> start with, so I used a tube circuit. In the second case, all I had
was
> about +430 which dips to about 390 at maximum output, and reduced AC
line
> voltage, so I went solid state.
>
> My two circuits are here:
>
> Tube version:
>
>
http://pages.prodigy.net/jcandela/CentralElectronics20AModifications/CE_
20A_
> QRO_Power_Supply.jpg
>
> Solid State version:
>
>
http://pages.prodigy.net/jcandela/Sherwood_S8000/HV_REG/SS_HV_VOLTAGE_RE
GULA
> TOR.jpg
>
> The first circuit shows my complete power supply in my Central
Electronics
> 20A QRO #2 rig. I used a pair of 7591's in the RF final to make up to
12.5
> watts AM output, or about 55 watts PEP SSB output. I ended up with a
6W6
in
> the series regulator as it had more emission than a 5V6, even though
the
6W6
> only had 5 1/2 volts on the filament. This regulator is always at
+374,
hot,
> cold, month after month. The ripple from it is unmeasurable (with my
> equipment), and dynamic load response is excellent, although I cannot
> remember exactly what the results were, as that was last winter. The
rest
of
> my 20a info on the web is at:
>
> http://pages.prodigy.net/jcandela/CentralElectronics20AModifications/
>
>
> The second regulator circuit is much simpler, and cheaper to build,
and
the
> performance is similar with one big exception. The regulator only
needs a
15
> volt delta input to output, whereas a 6W6 at zero bias triode
connected
> needs closer to 100 volts (and that is saturated, i.e. no
regulation)to
pass
> 100 ma. The main drawback is that the solid state circuit is not
adjustable.
> You have to get a string of zeners to add up to the desired output
voltage.
> This is no big deal though. You can buy from Mouser (www.mouser.com)
the 1
> watt zeners series (1n47xx) for about 15 cents each in packs of 10,
and
they
> carry them up to 200 volts, although I prefer to go no more than 100
volts
> per zener for power dissipation reasons. For folk with higher input
> voltages, there are higher voltage fets that can pass 900 volts or
more,
so
> that isn't a big problem. The one I use is rated at 500 volts, and can
be
> had for about one dollar. To keep the power dissipation down, add as
much
> series "R" into the regulator input so that you have slightly greater
than
> 15 volts across the regulator circuit shown at maximum load current,
and
> minimum ac (brownout) voltage. The opto coupler in this circuit has a
> Darlington transistor, and the CTR (current transfer ratio) is very
high,
> hence the excellent closed loop regulation. Reduction of power line
ripple
> is > 40 db. With only 1 ma through the zeners, the zener warm-up drift
is
> about 1-2 volts rise. Keep in mind that this solid state regulator is
still
> a work in progress, and still populates a proto-board on top of my
Sherwood
> 30+30watt stereo amplifier with 4 X 7868 output tubes. I designed the
> circuit to be short circuit proof with the intention that if the
output
were
> shorted, the Sherwood fuse would pop before anything fried too bad. I
have
> been way "too-chicken" to try this feature out. Maybe one of you brave
souls
> can perform this test using components bought from your very own
checking
> account!
>
> These circuits can find there way into all sorts of AM equipment...I
hope
> that somebody tries one of these circuits and then asks me "why didn't
you
> do this _____ instead"
>
> Regards,
> Jim Candela
> WD5JKO
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