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Re: [RFI] 10m RFI "white noise hiss"

To: "'Patrick Dyer'" <pjdyer@swbell.net>, <rfi@contesting.com>,<w1mg@arrl.net>, <w3otc@amsat.org>
Subject: Re: [RFI] 10m RFI "white noise hiss"
From: "Tim Duffy K3LR" <k3lr@k3lr.com>
Reply-to: k3lr@k3lr.com
Date: Sat, 10 Nov 2007 14:13:28 -0600
List-post: <mailto:rfi@contesting.com>
I have found that the W3NQN AC line filter can fix this kind of problem. 

By simply inserting the W3NQN filter in series with the AC line feeds of TVs
and computers, I have cleaned up several RFI generation problems that affect
the HF band (both my own and nearby neighbors).

The W3NQN filter is available from WX0B - Array Solutions.

Tim K3LR

The K3LR DX spotting cluster is available by Telnet dx.k3lr.com

-----Original Message-----
From: rfi-bounces@contesting.com [mailto:rfi-bounces@contesting.com] On
Behalf Of Patrick Dyer
Sent: Saturday, November 10, 2007 1:37 PM
To: rfi@contesting.com; w1mg@arrl.net; w3otc@amsat.org
Subject: [RFI] 10m RFI "white noise hiss"

With a VERY cooperative neighbor I just located the device doing this -
an Aug 2006 production of a Durabrand (Walmart) STS92D DVD-Home Theatre
item.  Apparently it is the switcher PS as copious RFI is produced when
it is plugged in and not in use.  They think that they have had it about
a year, but I've only noted the 28-MHz RFI lately (I surely would have
encountered such RFI during the Mar 2007 ARRL DX test).  So, then it
could be a PS component failure vs just faulty OEM design/build.

Now, what do I do about it ?

I first was going to offer, in trade, a Samsung (2004) DVD player, but
that lacks all those extra speaker outputs for their "surround sound"
that the Durabrand provided.  So much for that "simple solution".

I was given the Durabrand "to look at/in", but without a service manual
(or experience in servicing switchers) that has its limitations!  I did
manage (with effort) to get the (totally plastic) top cover off to see
its gross innards.  There is an internal token toroid with the line cord
looped twice thru it.  There are also a couple of "vacant" component
outlines (one C and one R) in the PS region.

If they (or I) obtained another such similar unit, it would have to be
"pre-tested" in order to ensure that it is not also a gross source of

73, Pat - WA5IYX

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