Hi Joe,
> After a year of living with it, and a few weeks (all too brief) respite, my
> neighborhood RFI FROM HELL is back.
I'm sorry to hear that you noise problem is back. If you're like me then
you're probably now considering moving out into the country and get off
the grid. :-)
> The outdoor TV cable drop radiates this signal VERY strongly. By using a
> portable SW receiver and touching the antenna to shield of the TV cable, I
> can get
> spurs up to 60 mHz. But nothing above that.
>
> It also appears to radiate from cold water pipes, as well as house wiring.
One of the things I realized when using a portable shortwave receiver to
track down RFI is that if you hold the whip antenna next to anything
conducting, it will act as an extension of your antenna. Often it will
sound as if you found where it's coming from, while you really just
increased the receiving capabilities of your radio.
Now I use a Sony ICF-SC1(PC) Wavehawk scanner that can tune down as low
as 20 kHz (through a painful keypad-power up trick) and up to 1.3 GHz
and use attenuators (3-30db) that I place between the scanner and the
rubber duck when I get closer to the source. I start out by tuning to
the highest frequency I can hear the noise on and then go through the
neighborhood while increasing the frequency. When I think I get closer
to the source I start using the attenuators.
You have to be careful though using just a shortwave receiver. I have
some bad power line noise that has been hard to track down because it's
not always there (some would call that a blessing :) ). One time I drove
though the whole neighborhood using just the car's AM radio. I thought I
had it pegged at some point because the noise got really strong at some
pole two streets over. Using a shortwave radio in the car hooked to the
2 meter antenna on the car confirmed my suspicions. Well, so I thought.
Last week the noise was back and tracked it on foot with the scanner and
attennuators and found that the source is really somewhere on the pole
in my next door neighbors front yard! Neither the AM radio nor the
shortwave radio test would lead me to suspect that pole. Maybe it's
because the power line terminates there(?). I live on the corner and get
my power from a different power line. I also found two other poles that
have what I would consider minor problems using this method.
> To review:
>
> -RFI is 24/7, fundamental frequency on 3-4 Mhz.
> -Only abated (temporarily) by HEAVY RAIN
I wonder if it's an automatic outdoor light with a dirty or badly
positioned light sensor.
73,
--Alex KR1ST
http://www.kr1st.com
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