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Re: [RFI] New switching wallwarts - RFI potential?

To: k3lr@k3lr.com
Subject: Re: [RFI] New switching wallwarts - RFI potential?
From: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Tue, 12 Jan 2010 17:28:09 -0500
List-post: <rfi@contesting.com">mailto:rfi@contesting.com>

Tim Duffy K3LR wrote:
> Hi Pete!
> Here is a great paper on wallwarts.
> http://www.kongsfjord.no/dl/Antennas/Low%20Noise%20Active%20Antennas%20AC-DC
> %20Power%20Supplies%20II.pdf
> <snip>
> Recently, I have begun receiving a new type of wall-wart with various 
> pieces of consumer equipment and, most recently, with my QS1R SDR.  Ones 
> I've seen have generally been for 5 volts at 1 amp, are much lighter 
> than the old ones, and I even got one that said Switching Adapter on the 
> side.
> It also claimed, of course, to be FCC approved and UL listed, but no CE.
With the computer system and network, plus assorted scanners and 
printers, I have quite a few of these "narrow" "wall warts". 
Unfortunately when they get rid of in width the make up for in length 
(in spades) and although I can use more of them on a UPS and fill up all 
recepticals...some times.  I have some that have the length in line with 
the terminals when means they mount the "wrong way" and take up 3 spots 
instead of one. With the polarized plug many of them mount pointed out 
which makes the UPs a good 4 to 6" wider. They also have the output 
wires pointed out which puts them in a position designed for damage and 
adds to the width required.

But to answer the question of testing them: I've not swept the output of 
any, but being close to networks, rigs, coax, and within 20 feet (give 
or take) of several antennas I've not noticed any interference. It'd be 
interesting to put a spectrum analyzer  antenna next to one.


Roger (K8RI)
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