[ARC5] ARC5 Digest, Vol 193, Issue 39

Tue Feb 11 11:52:55 EST 2020

I am modifying the PS-23 to full-wave to reduce the supply voltages. Not
because there is a problem
with the original design.

Cascading the two supplies, with full wave rectification and filtering,
will yield about
150 volts for the receivers.  Adding that the high voltage should provide
around 500 volts
for the transmitters.  I don't want to push them to their limits for a few
extra watts.
Also, I may want to plate modulate them someday, and I don't think they
were designed for those peak voltages.

12.6 winding will used with half-wave doublers for each transmitter's.
filament and relays.  Receivers will be
modified (all of mine were hacked previously) for 12.6 volts.

Pete

On Tue, Feb 11, 2020 at 11:07 AM <arc5-request at mailman.qth.net> wrote:

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> Today's Topics:
>
>    1. Re: Army/Navy transmitters from a NON COLLECTOR viewpoint,
>       the ham version... (Brian Clarke)
>    2. Question about posting for sale (Bill KA8VIT)
>    3. Re: Army/Navy transmitters from a NON COLLECTOR viewpoint,
>       the ham version... (Kenneth G. Gordon)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 11 Feb 2020 21:13:33 +1100
> From: "Brian Clarke" <brianclarke01 at optusnet.com.au>
> To: "'Dennis Monticelli'" <dennis.monticelli at gmail.com>
> Cc: 'Peter Bertini' <radioconnection at gmail.com>,        'ARC-5 List'
>         <arc5 at mailman.qth.net>
> Subject: Re: [ARC5] Army/Navy transmitters from a NON COLLECTOR
>         viewpoint,      the ham version...
> Message-ID: <[email protected]>
> Content-Type: text/plain; charset="utf-8"
>
> Thank you, Dennis,
>
>
>
> Yes, your image came through. This is one of the simpler Cockcroft-Walton
> designs. And it is full wave. The DC output is actually at 2.8 times Vin,
> assuming that Vin across the transformer secondary is stated in RMS terms.
>
>
>
> With this design, the dotted end of the secondary winding is alternately
> at the highest and the lowest Voltage of the output, less one diode drop.
> So, insulation needs to be good for 2.8 times Vin.
>
>
>
> Cheers, Brian
>
>
>
> On Tuesday, 11 February 2020 6:58 PM, Dennis said:
>
>
>
> The full wave voltage doubler commonly used in transmitter power supplies
> since the 70's is a good design.  It utilizes the core well, does not
> impose DC on the mains or transformer, and inherently allows use of
> capacitor stacking.  I believe this is one to which Ken is referring.  It's
> only real disadvantage is that the flying secondary is not ground referred.
>
>
>
> It is true that oversized lytics increase I squared R losses, which is not
> a kind thing to do to a tired old transformer used to small lytics and/or
> chokes input filters. When the full wave doubler was applied to
> factory-built transmitters the vendor used transformers with a lower
> winding resistance than the plate transformers of old, thus minimizing the
> issue.
>
>
>
> Hopefully, this low res image came through.
>
>
>
> Dennis AE6C
>
>
>
>
>
>
>
>
>
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> ------------------------------
>
> Message: 2
> Date: Tue, 11 Feb 2020 08:12:36 -0500 (EST)
> From: Bill KA8VIT <ka8vit at ka8vit.com>
> To: ARC-5 List <arc5 at mailman.qth.net>
> Subject: [ARC5] Question about posting for sale
> Message-ID: <67939124.348332.1581426756783 at email.ionos.com>
> Content-Type: text/plain; charset=UTF-8
>
> Is it ok to post here if we have an T-21/ARC-5  to sell ?
>
> If not please please delete.
>
> If so, I will post details.
>
> Also, does the list accept pictures ?
>
> Thanks.
>
> 73 - Bill KA8VIT
>
>
> ====================================
> Bill Chaikin, KA8VIT
> USS COD Amateur Radio Club - W8COD
> WW2 Submarine USS COD SS-224 (NECO)
>
> ka8vit at ka8vit.com
> http://ka8vit.com
> http://www.usscod.org
> ====================================
>
>
> ------------------------------
>
> Message: 3
> Date: Tue, 11 Feb 2020 08:06:38 -0800
> From: "Kenneth G. Gordon" <kgordon2006 at frontier.com>
> To: "Brian Clarke" <brianclarke01 at optusnet.com.au>
> Cc: 'ARC-5 List' <arc5 at mailman.qth.net>
> Subject: Re: [ARC5] Army/Navy transmitters from a NON COLLECTOR
>         viewpoint,      the ham version...
> Message-ID: <5E42D10E.13812.171925 at kgordon2006.frontier.com>
> Content-Type: text/plain; charset=ISO-8859-1
>
> On 11 Feb 2020 at 17:01, Brian Clarke wrote:
>
> >
> >     Hello Kenneth,
> >     ?
> >     Not just transformer-less power supplies. Most Voltage doublers are
> effectively half
> >     wave; some Cockcroft-Walton designs are full-wave - but they are
> quite complex.
>
> In fact, that is exactly the design I am using. I don't consider them
> complex to wire, although
> they may be a bit complex to understand.
>
> > With
> >     consumer-level Voltage doublers, DC does get back through the mains
> transformer
> >     because with half-wave rectification, only one half of the mains
> cycles are loaded. So,
> >     the transformer core is compromised, too.
>
> I don't use half-wave designs. Never have. Don't like half-wave rectifier
> circuits. In fact, I
> usually replace half-wave circuits which show up in any of my equipment
> with full-wave
> designs. I could never understand the "economy" of half-wave.
>
> >     ?
> >     The mains distribution board fuse or circuit breaker is unlikely to
> trip. Its main purpose is
> >     to prevent fire in the wiring hidden inside the walls that services
> the power outlets.? You
> >     probably have 60 A fuses / circuit breakers
>
> No. 20 amp for all new (#12) wiring I installed (I am an electrician), and
> 15 amp on those old
> circuits with #14 wire I couldn't reach to change. In our home, we still
> have "knob-and-tube"
> wiring to at least one circuit, but it is safe.
>
> I do have one 30 amp circuit to my SB-220 amp, and of course there are two
> larger circuits
> for the electric range and for the dryer.
>
> > for each mains circuit with NEMA-code
> >     wiring, and a 200 A fuse on the phase wire incoming from your local
> pole pig.
>
> Yes. The panel is a 200-amp panel, so the main-breaker is a 200 amp.
>
> >     However, equipment fuses are there for a different purpose -to
> protect the equipment -
> >     and hence, should be selected for their time vs current performance
> for each piece of
> >     equipment, with perhaps a 20% continuous overload. As you have
> bumped your
> >     smoothing filter capacitor from 150 to 640 uF, you have more than
> quadrupled the
> >     start-up surge load. And if you have used modern, low-ESR
> capacitors, all the rage
> >     these days, the start-up surge may be even higher. One hidden effect
> of such surge
> >     loading is that the turns inside the transformer starts to jump
>
> ...unless the transformer was designed for it...
>
> > about and may hit the
> >     laminations, especially if an accountant has designed the
> transformer, giving intermittent
> >     shorted turns.
> >     ?
> >     Actually, the average load does increase with Voltage doubling. The
> rectification
> >     efficiency is lower than with full-wave rectification.
>
> Which is only ONE reason I never use half-wave rectifier circuits.
>
> >     When I have made changes to increase the filtering, rather than rely
> on the resistance of
> >     the transformer primary, I use a very simple soft-start circuit; I
> use a mains Voltage rated
> >     SPST relay, its solenoid across the transformer primary, with a
> resistor (select on test -
> >     usually about 10 Ohm) across the NO contacts in series with the
> incoming mains. If you
> >     don?t have mains rated relays, use a lower Voltage one across one of
> the lower Voltage
> >     secondaries, eg, a heater winding.
>
> Yes. That is a good, un-complicated, reliable, soft-start circuit and one
> of my
> favorites....when I use one.
>
> >     ?
> >     Cheers es 73 de Brian, VK2GCE
>
> And vy 73 to you, Brian.
>
> Ken W7EKB
>
>
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> End of ARC5 Digest, Vol 193, Issue 39
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