[RFI] Locating Noise - Radiated or Conducted and then radiated

Wendell Wyly W5FL wendell@wyly.org
Sun, 2 Jun 2002 18:14:31 -0500

Based on the inputs received, I proceeded to connect the radio with an
extension cord to the washer outlet (which had nothing else on it) and then
methodically shut down every other circuit breaker.  The noise was unchanged
throughout shutting down in order all 37 or the 38 breakers in the panel
leaving only the one powering the 1000MP.  I turned off each of the 4 UPS's
in the house, all portable telephones, leaving only the smoke detectors and
a couple of battery operated clocks.

Looks like the problem is indeed outside.  I started to attach the antenna
patterns in an html formmatted message or as an attachment, but was not sure
this group allowed that.  It is about 18k in size.

Now to find someone in Fort Worth Texas with an MFJ-852 noise receiver to
hunt further with.  Has anyone used this device ($99) from MFJ or found it
useful?  How close to an arcing pole hardware do you have to get to hear
it - or conversely how far away can you hear arcing pole hardware at 136
Mhz?  My AM radio hears things for way too long a distance to be very useful

-----Original Message-----
From: rfi-admin@contesting.com [mailto:rfi-admin@contesting.com]On
Behalf Of Wendell Wyly W5FL
Sent: Saturday, June 01, 2002 9:21 PM
To: rfi@contesting.com
Subject: [RFI] Locating Noise - Radiated or Conducted and then radiated

I have very loud received noise that is about 10 db over S9 on 10,12,15,17,
and 20 meters.  When I plot the pattern using the noise as a constant source
from the 10 meter antenna, 15 meter antenna, and 20 meter antenna, I get
three similar overlaid patterns corresponding to the actual antenna patterns
but all three pointing exactly to 210 degrees and all with almost the same
maximum S meter reading on these five bands.

I am on a rural hilltop location with 20 mile line of sight from a 64 foot
tower. Most houses are on 5 acre or larger sites here.  I assume the noise
is line noise, but have not confirmed that either. Am I looking at the noise
source directly with the antenna or can the exact direction be camouflaged
if the noise is conducted for a long ways and then re-radiated?  Is there an
easy way to determine whether the noise is primarily radiated or conducted.

The noise blanker on the Yaesu 1000MP knocks the noise way down (6 or 7 S
Units)as the noise has a very high peak to average ratio (arc?).

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