You could also try winding the coax cable through a ferrite toroid a few
times. (and position it close to the DVD player).
RP

On 25/12/2007, Sean Breheny <shb7@cornell.edu> wrote:
>
> Hi all,
>
> Recently my mom was complaining about lots of buzzing noises on the AM
> broadcast band when listening from her house so when I came to visit
> for Christmas, I checked it out.
>
> It turns out that the source of the noise seems to be a Philips
> DVP3140 DVD player I bought her a few months ago. When I unplugged it,
> ALL of the buzzing noises went away. They were astoundingly strong -
> so much that even with stations which give almost full-scale S meter
> on my Icom IC-R20, depending upon where you are in the house, you can
> still hear the buzz in the background. The noise seemed to be
> emanating from the AC mains house wiring, as it would get much louder
> when the receiver was brought near an outlet or a power cord which was
> plugged into an outlet.
>
> Now for the most interesting point - the noise was only audible when
> the DVD player was plugged in to the AC outlet (2 prong plug) AND
> grounded via the coax of the cable TV feed. If I ground the player
> directly to the outlet (regardless of whether the cable TV coax is
> connected), the noise almost completely goes away.
>
> As a side-note for accuracy's sake, the coax actually goes directly to
> the TV and the player is attached by composite video and audio cables
> to the TV. However, the noise is still present even if I eliminate the
> TV entirely and touch the coax shield to the shield of the output
> signal connectors on the player.
>
> So, I've directly grounded the DVD player to the outlet and all is
> well now. I did some googling for this model of DVD player and didn't
> find anything about RFI problems. I suppose that what was happening
> was that the fact that the DVD player case was floating with respect
> to AC ground (and probably internally generating switching power
> supply noise), allowed the coax shield to become an antenna which
> somehow also coupled into the AC power lines.
>
> Anyone seen something like this before?
>
> Thanks,
>
> Sean
>
> P.S. Merry Christmas!
> --
> http://www.piclist.com PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist