[RFI] AC line noise

[Jim P]

Terry,

Twenty years ago I used to have a quite QTH, from
AM Broadcast band through six meters; this changed
substantially since then, predominantly owing to the
myriad of electronic devices (using switching power
supplies, computer monitors, etc) which are connected
to the AC line.

Currently, the noisiest place on the AM Broadcast band
in my house is near the AC meter as well!

I, to, have underground power lines. They seem to conduct
'noise' from all my neighbors houses quite effectively. I can
easily locate the underground lines through the use of
an AM broadcast receiver near the ground too.

One of the 'offenders' a few years back that was producing
a 'carrier' on a 50 KW blowtorch station's signal was a
computer monitor at a woman's house across the
alley; an AC line filter offered to her cured the problem.

The filter was one of the rugged Tripplite cast aluminum housed
series - a $60 dollar solution to the problem.

Okay - back to the movie 'Minority Report'.

Jim P  /  WB5WPA  /


----- Original Message -----
From: <n6cw at aol.com>
To: <rfi at contesting.com>
Sent: Saturday, March 12, 2005 6:44 PM
Subject: [RFI] AC line noise


> Hi All,
>
> In my quest to eliminate RFI in my Qth, I have also been working on some
AC line noise problems. This is mostly an annoyance to my XYL who listens to
AM radio on our stereo set that has a constant hum in the radio, 24/7. I
have tracked the noise to both my AC power meter and a light pole across the
street. I have underground power lines. I can take the portable and follow
the noise, with the radio 6 inches off the ground from the AC meter, to a
junction box at the street (which supposedly has the cable TV cable only),
and across the street to the light pole. There are a couple of ground
mounted power transformers (?) on either side of the light pole but they do
not seem to be radiating any noise. This noise does not normally bother my
amateur radio receiving capabilities, but I am thinking it might be the
source of some flareups that do bother me. Turning off the mains of my house
does not reduce the noise. The radio that is being bothered is directly on
the wall on the other
>   side of the AC meter. And I can take the portable anywhere on the AC
meter side of the house and get the noise.
>
> My question is, should I be getting this kind of noise using a portable
radio within 1-2 feet of the AC meter or the power pole. Would this be
normal? Should there be any kind of line noise in this situation? I know I
can move the stereo system to the other side of the house and eliminate the
problem but it is perfect where it is.
>
> Terry Baxter/N6CW
>
>