Topband: RFI

[K4SAV]

Power pole noise can be difficult to find with a portable receiver that 
is not directional.  It's also difficult to find when all you have is an 
ultrasonic detector because those have to be pointed right at the source 
to hear anything..  Power lines make a good antenna for radiating power 
pole noise.  Often the wires act like a long wire antenna and that can 
sent the noise for a long distance in the direction the line runs.  My 
record for that with S9 noise at home on 160 has been 3 miles to the 
source.  The source was very big.

To get started searching in the right direction try locating the 
direction with a rotatable antenna from home.  A 6 meter Yagi does well 
usually. Then when you head off in the right direction, you need an AM 
receiver with a directional antenna, something like the MFJ-856 which is 
a 135 MHz AM receiver with a 3 element Yagi. That will get you within a 
pole or two.   Other receivers can work too but it really needs to be on 
AM.  Then an ultrasonic detector can be used to identify the part on the 
pole that is the source. I use a homebrew one but MFJ also makes one, 
the MFJ-5008.

After you think you have found the source, try to verify its 
characteristics with what you are hearing at home.  You don't want to 
send the power company to fix something that is not your problem.  I 
often find lots of noise sources that I don't hear at home.

Jerry, K4SAV