RE: Mains Noise - any truth in solutions

["Keith Doxey" <ukha@xxxxxxxxxxx>]

Hi Chris


> Quoting christopher purves (CHRIS_PURVES@xxxxxxx):
>
> > I am getting noise on my POTS phone system which is terminated
> in node 0
> > which is due I am sure to the large ammount of electrical
equipment in
> > there.
> >
> > Has anyone tried one of these ?
> >
> > http://www.stoneaudio.co.uk/stoneaudio/products/details.asp?product=999
> >
> > or something similar ?
>

You dont say what type of noise you are getting but I very much doubt that
it is anything in Node 0 causing it.

The filters you posted a link for are for killing noise on the mains
wiring.
I hope you dont use X10 because  that works by SENDING noise on the mains
and the device you linked to will probably stop X10 stone dead!

Interesting that they dont actually give any information about the
frequency
of noise it attenuates or the amount of attenuation :(

> The last BT engineer to visit me suggested that the simplest thing to
try
> first was an in-line RFI filter on the phone line.
>

The inline RFI filters are intended to remove interference from AM radio
transmissions and do a very good job but I dont know what would happen if
one was used on an ADSL line unless it was after a filter.

Chris, do you have ADSL ?

If so, have you correctly filtered the line?

The most foolproof way is to have the line feed stright into an NTE5 fitted
with a proper ADSL faceplate. You then wire the ADSL connection away to
your
modem/router and use the filtered phone terminals for feeding  the
phones/PBX

I notice you say "POTS Phone System" so I assume you are using a
PBX, in
which case what type ?
Have you correctly wired the extensions with the right type of sockets/RJ45
adapters?
Have you correctly assigned pairs of wires as appropriate for example many
analogue key systems have a speech pair and a data pair, if you mix up the
pairing you will overhear the data being data sent back and forth. This can
be a constant hiss (as is the case with improperly filtered ADSL) or a
"dit"
"dit" "dit" type noise.

More info on the type of noise would be helpful

Regards

Keith (still troubleshooting phones 9 years after I stoped being a
telephone
engineer!)