----- Original Message -----
From: "K2DBK" <dkozinn@gmail.com>
To: <towertalk@contesting.com>
Sent: Friday, November 26, 2004 11:47 AM
Subject: Re: [TowerTalk] Halogen Bulbs - 1.8 Mhz RFI
> I discovered that I've got one of the "bad" types of LV power supplies
> for some of my lights, which, unfortunately, does a really nice job
> of generating RFI over a very broad spectrum. (I don't think it
> actually makes it as far as the 2m band, but it does show up on 50mHz
> and lower.) Fortunately, the lights it powers aren't the primary
> lighting for any of the rooms that they are in, so we try to keep them
> turned off when I'm at the radio.
>
> The power supply itself is in an easily accessible location in the
> basement, and I wouldn't mind replacing it myself. Has anyone had any
> experiences with non-noisy supplies like this that they'd recommend?
>
> 73,
> David, K2DBK
More to the point, David, what's the make and model of the noisy supply (and
is there a FCC sticker/label on it)?
I've noticed that my laptop cranks out a LOT more RFI when plugged in than
when running on batteries (discovered this when sweeping for noise with a
PCR1000). It's a DELL PA-5 putting out 19V at 3.16 A.
>
> On Fri, 26 Nov 2004 11:41:59 -0700, Bill VanAlstyne, W5WVO
> <w5wvo@cybermesa.net> wrote:
> > FWIW, my experience with switching LV power supplies of various kinds
has been
> > that the RFI they generate is common-mode. I've had no luck suppressing
any
> > noise from them with differential filters. That's just an anecdotal data
point,
> > nothing more -- not a theoretical opinion. :-)
> >
> > I've also had the experience with LV halogen lights that some of the
switcher
> > PSes clearly do not meet any standard for RFI, generating S9+ hash over
the
> > entire HF-VHF spectrum, while many others are completely clean. The
difference
> > is always huge -- they either do it or they don't. Makes me think that
some
> > manufacturers simply figure to get away with it and save big money on
filtering
> > components -- and apparently do so with relative impunity, since the
devices are
> > on the shelves and people buy them. After all, what percentage of
typical
> > consumers would even know or care about HF-VHF RFI from halogen PSes?
Much less
> > than 1%, probably much less than 0.1%, is my guess. The cost of
refunding to
> > their retailers for the occasional return is probably far less than the
NRE and
> > component costs of doing it right would have been.
> >
> > Bill / W5WVO
> >
> >
> >
> >
> > Jim Lux wrote:
> > > ----- Original Message -----
> > > From: "Jim Brown" <jim@audiosystemsgroup.com>
> > > To: <towertalk@contesting.com>
> > > Sent: Thursday, November 25, 2004 12:16 PM
> > > Subject: Re: [TowerTalk] Halogen Bulbs - 1.8 Mhz RFI
> > >
> > >
> > >> On Thu, 25 Nov 2004 14:46:07 -0500, Floyd Sense wrote:
> > >>
> > >>> I doubt that there is much you can do to silence them.
> > >>
> > >> I agree that there are probably switching supplies causing the
> > >> problem, but I wouldn't give up on fixing the problem without trying.
> > >>
> > >> There are three basic ways the RF can get out -- on the power line
> > >> wiring, on the low voltage wiring to the lamps, and direct radiation
> > >> from the power supply if it is unshielded. Direct radiation you
> > >> probably can't fix except by replacing the supply. A standard, good
> > >> power line filter should eliminate what is coming via the power
> > >> line, and a multi-turn choke around a big ferrite, possibly in
> > >> combination with a capacitive
> > > filter
> > >> should be able to kill what is on the low voltage wiring.
> > >>
> > >> You will need at least 8 turns around the typical big toroids to
> > >> make an effective choke for 1.8 MHz. That choke should also work on
> > >> 80 meters, but may be running out of effectiveness by 40 meters and
> > >> above.
> > >>
> > >> 73,
> > >>
> > >> Jim Brown K9YC
> > >>
> > >>
> > >
> > > Depending on where the noise is coming from, a common mode filter
> > > (i.e.running a bunch of turns of the twoconductor wire through a
> > > ferrite)
> > > might not help a lot. You might need a decent differential mode
> > > choke/capacitor filter on the output of the low voltage supply. Put
> > > the
> > > choke first (so the capacitive load doesn't screw up the switching
> > > regulator).
> > >
> > > Also, if you have a LV halogen scheme with the two "rails" from which
> > > the
> > > lamps hang, the rails can serve as a nice radiator of differential
> > > mode
> > > noise.
> > >
> > > By the way, if the halogen power supply is a low voltage device, it
> > > would
> > > need to comply with EN55011 (the EU equivalent of Part 15). Perhaps
> > > the
> > > problem is really that the halogen supply isn't working to spec?
> > >
> > >
> > > _______________________________________________
> > >
> > > See: http://www.mscomputer.com for "Self Supporting Towers",
> > > "Wireless Weather Stations", and lot's more. Call Toll Free,
> > > 1-800-333-9041 with any questions and ask for Sherman, W2FLA.
> > >
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> >
> > _______________________________________________
> >
> > See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
> >
> > _______________________________________________
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> >
> _______________________________________________
>
> See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless
Weather Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any
questions and ask for Sherman, W2FLA.
>
> _______________________________________________
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_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
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