[Wswss] [NC9RS] How far can noise carry via power lines?

[CATFISHTWO at aol.com]

I am certainly not an expert, but if you have noise from the broken  
insulator area, and there is wires going to the other stuff, it seems to be a  
good possibility... Did you try the old sledge hammer to the power poll trick 
to  see if the noise changes?  good luck  
 
tom n6ajr
 
 
In a message dated 9/12/2013 3:31:25 P.M. Pacific Daylight Time,  
kj6ko at innercite.com writes:

 
 
 
Hello to all
  Sorry to bombard all the groups with this,  but this is someting I havn't 
seen before and am just looking for  help/advice.  
 
Including some broadcast guys in this  also.
 
  I have been working with the Bishop  Amateur Radio club on finding an 
interference issue that is a bit odd..Here  are the symptoms and what we found 
so far.....
 
.. Broadband VHF (140-170) noise, about an 18db  degredation in receiver 
sensitivity.  
 
.. No "obvious" source.   Traced it a  while back to a small low power FM 
station building next toor...coming out of  the building, not the antennas.
 
.. This last trip, we found it seems to be coming  from all the buildings 
on the hilltop!  The broadcasters shut down ALL  their transmitters, and 
noise was still present coming from the building,  around -100dbm 20' from the 
building...or now, ANY of the buildings on the  mountaintop.
 
 
..  Getting closer to any of the buildings  really doesn't seem to get much 
stronger, pretty much about -100dbm 20' from  any of the buildings, always 
pointing at the building, with the exception of  the building that houses So 
Cal Edison's MW systems, it is much stronger  inside (the only one we could 
really get inside of) , about -80 when very  close to the XFER panel, but 
they have a LOT of power in the building and a  generator.  Everything was 
VERY well grounded in that building  also!  You can never find that one device 
the should really "light up"  when you get close to it!

 
.. We went further to the main power meter panel  and small building, that 
houses the step down XFRMR, that is 150' away  from any of the TX buildings, 
and it has the same noise level coming  from that building!  No 
transmitters on site!
 
.. We "listened" to the noise, and it is not just  white noise, it has some 
"component" in it that sounds 60Hz.
 
.. After determining that it is most likely NOT  an RF issue, we began a 
search along the power system.  We found an  extreemly noisy pole about 1/3mi 
away with an obviously broken insulator on it  just a couple poles from the 
"mini sub station" that converts 60KV down to ??  for the underground run to 
the site.
 
So my question to you all is,
  Has anyone seen this or something similar  before, where noise from a bad 
power line will travel 1/3mi through  an underground power feed to a site 
and pollute every power panel in  every building on a mountaintop and cause 
the noise floor to  raise??
  To me, it seems possible, but sort of  "unlikely"?
 
  This is not an extreemly big site from an  RF point of view, 4 low power 
FM stations (<5KW) one digital UHF TV station  (<5KW) a cell site, local 
PD/Fire etc.  Mt Wilson, it is  NOT!
 
  Looking for any ideas, experiences or  comments!  It is difficult to 
trace as you need a good BPF on your  instrument to keep all the other broadcast 
etc from overloading your front  end, but we had a pretty good one.
 
The club is purchasing a DCI 2M filter for future  noise hunts and to put 
on the repeater full time, but we should have found  something that lit up 
the analyzer with noise, but never did!
 
Thanks and 73 de  Greg


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