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[TowerTalk] power line noise

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Subject: [TowerTalk] power line noise
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Date: Wed, 14 May 1997 08:45:30 -0500
>Have any of you ever had a noise case that seemed to "propagate" down a line 
>to show up at another spot?  
>Is this one for the X Files, or is it common for noise to propagate down a 
>line in a similar fashion to a transmission line and peak at a point that is 
>some distance away from its source?  
Yes Will, it is indeed possible.  That's why the utilities call them 
transmission lines!  You'll find standing waves up and down the line from the 
noise sources,  and if it peaks in the vertical plane, the noise is null in 
the horizontal and vice versa.  It can drive you nuts!  Great book to check 
out is "Interference Handbook" by William R. Nelson, WA6FQG who was an RFI 
Investigator for Southern Cal Edison Co.  The power line stuff is still 
current since power systems change slowly and most lines are old.  The TVI 
stuff in this book is a little dated though. 
>Another very noticeable sysmptom - The noise almost goes away completely in 
>high humidity / wet conditions, and is strong in dry conditions. I would 
>think that this would suggest problems with insulators, but the tech. says 
>it's not necessarily so.  
>Their "fixes" so far have been to "tighten the hell out of everything" which 
>seems to last anywhere from a couple days to a month. 
I'd suspect loose hardware or a loose ground staple on a wood pole somewhere.  
Make damn sure when they tighten everything up that it's during VERY DRY wx.  
Otherwise the noise will return once it drys out and everything's loose again. 
 Also, if it's a pretty new pole, it may be going thru a drying process for 
quite a while yet, and will require numerous periodic trips to keep it quiet 
for you. 
>It is a major chore getting the interference tech. out here, and even harder 
to >get the line crew scheduled. Keep in mind I work for the utility and I 
think I'm >getting "preferential" treatment. I pity the service that outsiders 
probably >get... 
Yes, it is getting more difficult to justify this service in the deregulated 
power industry environment, and it's only going to get worse in the near 
future.  Sort of like right after the Bell break-up.  Service went way down in 
some ways.  We're still lucky here in Nebraska being the only state totally 
served by Public Power Districts.  But that'll probably change soon!  In Iowa 
they're telling hams that it costs too much to solve interference problems: 
"Just go away" is their response now.  They know the FCC won't touch them!  
We'll all be there soon. 
I'm curious what utility you work for and what you do there.  You can e-mail 
me direct if you want. 
>Thanks - CU at Dayton, 
I wish I was going, but it's being held on my wedding anniversary now! 8^( 
de ed -- K-zero-IL 

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