[TowerTalk] Re: RFI filter for DSL line?

[Paul McInnish - K4BET]

I, too have DSL (from Bellsouth.net) and I was able to get a whole house
filter from Bellsouth.net.  I 
installed it on the outside where the underground line from the street
pedestal comes into house at the 
interface box.  I separated the DSL line from the phone line via this
filter and ran the separate DSL line 
(CAT 5 cable) from this filter to the DSL modem in the office/ham
shack.  This also allowed me to remove 
each of the individual filters from each phone throughout the house....
the biggest plus with this (in addition to 
stopping RF problems with a 1.5 kw amplifier on low bands) was my
digital telephone answering machine 
worked better!  I still have a standard phone line in the shack for
telephone and fax use. (DO NOT use one 
of the unused pairs in the DSL CAT 5 cable for the phone line!!!
Potential "cross talk" - experienced 
this!!  Use a separate cable!)

73, 

Paul - K4BET


dick@pobox.com wrote:
> 
> 25 NOV, 2000 - 1030 CST
> 
> I have had a DSL connection for over 11 months and I have no known RFI
> problem on the line.  However, both my 100 Base T computer network and
> the analog phone lines in my house use shielded CAT 5 cable.  It was not
> cheap or easy to make the changeover last December, but I'm glad I spent
> the money.  Anyone building a new home, or remodeling (opening up the
> walls), can specify this type of cable and the installation labor should
> be about the same as the typical unshielded twisted pair wiring.
> 
> As for RFI filtering of a DSL line, the typical analog telephone line
> filter will not work because it will also block the higher frequency
> DSL signal.  DSL operates well above the analog voice frequency at 2 to
> 3 Mhz.  Therefore, a filter would have to be designed to pass everything
> below this band and this would probably allow some ham band-generated RFI
> to ride the DSL line.  Of course, this might not be a big problem if
> one were to only operate 20 meters and higher at very low power levels.
> 
> There may be some (expensive?) electronic notch-type filter on the market
> that would protect a DSL line.  If there is, I would like to know about it
> just in case I develop a problem later on.  But the cheap analog voice
> line filters now available will block both the RFI and the DSL signal.
> 
> - Dick Isely, W9GIG
> 
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