Well.... I mentioned "shield". That takes care of radiated if the shield is
complete and well grounded. We had a problem at work where the supply was
powering a sensitive printing system. Didn't have time to get another
supply and had to run the system tests. It worked well. One of many times
that Ham radio came in handy at work.
73 de Gary, AA2IZ
----- Original Message -----
From: "Robert & Linda McGraw K4TAX" <RMcGraw@blomand.net>
To: <tentec@contesting.com>
Sent: Monday, March 10, 2003 6:31 PM
Subject: Re: [TenTec] Radio Shack 25 amp switching supply?
> OK, that takes care of conducted noise on the output, now what about
> radiated noise? That is usually a significant part of the problem.
>
> 73
> Bob, K4TAX
>
> ----- Original Message -----
> From: "Gary Hoffman" <ghoffman@spacetech.com>
> To: <tentec@contesting.com>
> Sent: Monday, March 10, 2003 4:21 PM
> Subject: Re: [TenTec] Radio Shack 25 amp switching supply?
>
>
> > Hasn't anyone tried to ground/shield/filter these things ? We used them
> at
> > the place I used to work, and I got them quieted down to the point where
I
> > couldn't measure any noise with a scope hooked directly to the output of
> the
> > supply.
> >
> > 73 de Gary, AA2IZ
> >
> >
> > ----- Original Message -----
> > From: <al_lorona@agilent.com>
> > To: <tentec@contesting.com>
> > Sent: Monday, March 10, 2003 4:17 PM
> > Subject: RE: [TenTec] Radio Shack 25 amp switching supply?
> >
> >
> > >
> > > I have posted on this topic here before. You may cringe at such a
> blanket
> > statement, but *all* switching mode power supplies generate noise. As
> users
> > of extremely sensitive RF receiving equipment, we must be prepared to
> > tolerate at least a small amount of RFI from these devices. Show me any
> SMPS
> > of any size from any manufacturer and give me a good receiver, and I
will
> > let you hear the noise coming out of the supply. It's just a fact of
life.
> > >
> > > The noise you hear will be greater with unbalanced antenna systems
> nearer
> > the SMPS. Operate from a hotel room with a random wire and an SMPS one
of
> > these days and you'll see what I mean.
> > >
> > > The advantages of a SMPS are small size and light weight, but the
> > advantages of a linear power supply are its quiet-- if not nonexistent--
> RFI
> > spectrum.
> > >
> > >
> > >
> > > > -----Original Message-----
> > > > From: Paul Christensen, Esq. [mailto:w9ac@arrl.net]
> > > > Sent: Sunday, 09 March 2003 8:18 AM
> > > > To: tentec@contesting.com
> > > > Subject: Re: [TenTec] Radio Shack 25 amp switching supply?
> > > >
> > > >
> > > > > Mine is going back to the store today. If I lived in a
> > > > place where the
> > > > > noise level was always S5 to S8 it would be fine, but it is
> > > > not the case
> > > > > at this QTH. I hear the noise on 20 meters, now, since the band
is
> > > > > mostly quiet this morning. Give me back my linear supply.
> > > >
> > > > I generally stay far away from switching power supplies: My main
shack
> > > > supply is centered around an Astron RS-35 linear supply and power is
> > > > distributed to many devices via a RigRunner DC distribution
> > > > panel (which
> > > > btw, is a fantastic product).
> > > >
> > > > However, about a year ago, I was looking for a lightweight
> > > > supply that could
> > > > handle my Triton IV at full 100W output power for portable
> > > > operation. I
> > > > sheepishly purchased the Astron SS-25 after reading a QST
> > > > product review of
> > > > a similar Astron SS supply.
> > > > As I recall, there was essentially no measured noise from the
> > > > Astron SS.
> > > >
> > > > The SS-25 is very light in weight, takes up a relatively
> > > > small footprint and
> > > > doesn't even blush when pushed to 25 amps over extended
> > > > periods of time.
> > > > There's a small thermostatically-engaged whisper fan on the
> > > > rear panel that
> > > > produces nearly no audible noise. I absolutely love the
> > > > Astron SS amp.
> > > > However, I still would not consider it for the main station
> > > > where I leave
> > > > the RS-35 linear supply on 24/7. I simply never want to have
> > > > to consider
> > > > whether or not a spur that I'm hearing is being generated by
> > > > the supply.
> > > > It's difficult enough in trying to localize shack noise
> > > > problems without
> > > > having to examine the supply and rule that out as a potential
> > > > noise source.
> > > > But for intermittent and portable operation, I couldn't be
> > > > more pleased with
> > > > the Astron SS.
> > > >
> > > > Also, Ten Tec makes some nice switching supplies and I would
> > > > bet that theirs
> > > > is at least as clean as the Astron. I know in my previous
> > > > dealings with Ten
> > > > Tec, that they have been very sensitive to the user's power supply
and
> > > > potential noise generation.
> > > >
> > > > -Paul, W9AC
> > > >
> > > > _______________________________________________
> > > > TenTec mailing list
> > > > TenTec@contesting.com
> > > > http://lists.contesting.com/mailman/listinfo/tentec
> > > >
> > > _______________________________________________
> > > TenTec mailing list
> > > TenTec@contesting.com
> > > http://lists.contesting.com/mailman/listinfo/tentec
> > >
> >
> >
> > _______________________________________________
> > TenTec mailing list
> > TenTec@contesting.com
> > http://lists.contesting.com/mailman/listinfo/tentec
> >
>
>
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