On 17 Jun 2007 at 22:14, Alan Melia wrote:
> I have neighbours either side with broadband and I am not aware of any
> problems on 500k, but what I did notice was a horrendous noise in the
> middle of the band when the video recorder was sitting on timed record
> and the TV was switched to AV. I often do this to avoid missing
> programs or missing them due to a phone call in the middle. It would
> seem that whilst not receiving a signal, but producing a raster (blank
> screen with an "AV" legend) there is a large comb of frequencies at
> about 502. I am guessing that without a signal to lock it, the line
> oscillator free-runs a little above 15.625kHz. Putting my TV on
> standby or OFF kills the noise.
Alan, those sorts of problems are certainly due to dodgey switch mode
psus in equipment and fairly common. You and Mike should be looking
in that direction and not blaming ADSL. I would not expect problems
from ADSL as it is a balanced system and should not radiate very far
at all. You would only get any radiation if there is a dodgey
telephone connection somewhere, say in the overhead lines, where the
twin pairs have been accidentally split between two separate pairs so
the two lines do not run parallel - very rare but has been known to
happen. It most certainly will not be a dodgey ADSL filter as the
broadband signal is not filtered at all in those, only the telephone
side is filtered (and I doubt whether they ever fail despite all the
suggestions to change them when you have a fault, as passive devices
there is nothing inside them to fail...).
So look very seriously at those smpsu's, wallwarts etc.
73 Dave G3YMC
http://www.davesergeant.com
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