Radio Frequency Interference on Residential Line

Radio Frequency Interference on Residential Line

Post by Dale R. Worl » Thu, 19 May 1994 04:51:59

Quote:Kobb) writes:
> The FCC has been very clear on its position about telephone interference.
> The agency says that "filters cannot be relied upon to eliminate tele-
> phone interference."

Though I've had luck trying to get rid of interference on my line by
using a filter.  However, it was a strange sort of interference: It
was only present when my modem was off-hook.  It turns out that the
problem was a strong local radio station was coupling RF into the
line, which went into the modem (when it was off-hook), was *rectified
into audio*, and sent back out the line.  Really ugly.

People have asked me about this before, and only now have I found the
information I wanted to tell them: The filter I used was from K-COM.
They have 1-line (RJ-11, $14.95) and 2-line (RJ-12, I think, 19.95)
models.  Their phone number is 216-325-2110.


1. Radio Frequency Interference on Residential Telephone Line

Please help me if you can.

My home is wired for two residential telephone lines.  Because of my
proximity to an am radio transmitter (am 1550khz), many of my audio
and telephone devices suffer from "radio noise", from that one station
only though.  Some days it is worse than others, some days there is no
interference at all.

I have had all of the affected telephone devices modified by their
respective manufacturers ... the problem persist on a recently puchased
Panasonic KXT3175, two-line, Easa-Phone.

The local telco has installed several blue capacitors(?) at the demark box
on my house.

I have tried to eliminate the Panasonic telephone as the culprit by
putting it in a metal breadbox (really!!!), with no success.

I believe that the noise is entering the line via a TP four-conductor
cable strung along the outside of my home.

At this point I am open to suggestions.  Might I be able to install a
filter (to filter out mainly 1550khz) right at the telephone?  (I use
one of my lines for voice and modem.)  A commercially available inline
filter (#Z100B1), besides being a single line device, did not have any

Any help would be greatly appreciated.  I am fairly technically and
mechanically competent and could handle minor electrical modifications
with limited instructions.

Thank you!

Dirk Menzel

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