Is AC line noise affected by humidity?

JoshuaHufford

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I've been battling what I'm pretty sure is AC line noise at my receive site which is located in my Father-In-Law's shop. Since it is located at his location I got his permission before I called the utility company, and he told me he had seen arcing at times near the transformer that supplies power to the shop, I figured that is probably the cause right there. I called the utility company, they sent me to a few different people and then finally said they would send someone out. I asked them if I could PLEASE be notified when they were going to come so I could be there, but of course they didn't. I did get a call from the guy that was sent out, he said he could certainly see evidence of arcing at the transformer and that he repaired the problem. He also said the pole was in bad shape (it is totally rotted out at the top), and he would put in an order to have it replaced, this was back in early March, the pole still has not been replaced. I also asked if they had done any testing in the area to see if there were any other problem spots and he said no.

Well at the time the problem did seem to go away, every once in a while I would hear interference but it only lasted for a short time so it couldn't assume that was line noise. Well now that we are getting into fall and humidity levels around here are dropping. On dry days the noise is back, sometimes to the point it destroys all but the strongest nearby signals. I can pretty much gauge outside humidity levels by the level of noise I hear, the lower the ambient humidity the worse it is, the higher the better it is, if it rains, it completely goes away. Also on windy days I can hear the noise go from strong to not there at all then back again in just seconds, I'm guessing there is some movement in the lines causing this.

I've also heard the line noise in my car using a roof mount antenna, although not nearly as strong.

I called the utility company back again and got the run around, basically saying we already sent someone out, it should be fixed. While I'm not going to give up on them, I'd like to arm myself with better information before I call back again.

From what I've described does this sound like AC line noise?

If so how can I pinpoint the location? The noise only affects the VHF band from what I can tell, is there a small directional VHF antenna I can hook up to a handheld scanner? I figure if I can give them an exact location of the source maybe they will at least come back out and check it.

Any suggestions as to how to deal with this would be greatly appreciated. I keep hoping whatever failing component that is causing this will just destroy itself and the power company will then have to come fix it.
 

mmckenna

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Might be arcing. Could be a loose connection, dirty insulator, etc. A rotting pole indicates some ignored maintenance.

I used to work with a lady who previously was employed by the local electric utility. One of her jobs was to go out with a crew and wash high voltage insulators. They'd use deionized water sprayed from a cannon in the cherry picker. Dirty insulators will cause noise, but I'm not sure if dry air or damp air is worse. My gut would say damp air is likely to cause more issues with that. I know out here on the coast, foggy weather will result in hearing crackling coming from some poles.
 

bobruzzo

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I had a similar problem when I was a kid. I was into medium wave dx'ing and there was a time where the static was really bad. I noticed a pattern that on dry days it was worse. When it rained the problem went away. I tried an experiment with a small battery transistor radio. I walked up the street past my house in one direction, then in the other. Both times the noise slowly decreased, so I guessed it must have been coming from a line or pole close to our house. I had my Father call the electric company. They surprisingly came down within a few days and from what I remember there was a bad wire or something. The lineman said when it rained, it provided a path on the wire where in dry weather there was a gap or bad spot. So they did replace a section of wire way up on top between 2 poles.
 

n1das

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You could try hitting poles with a sledgehammer?
An easier method would be to grab one of the guy wires and yank it back and forth a few times to get the top of the pole slightly moving back and forth at its natural resonant frequency. I've heard of this being done at a 2m repeater site that was experiencing the exact same kind of problem. After tugging on one of the guy wires a few times to jiggle the top of the pole around, the problem was solved.
 

JoshuaHufford

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Thanks everyone, good suggestions.

If anyone has a good idea for a small directional VHF antenna at least that would help me narrow down the direction. I don't really want to buy a VHF yagi for this.
 

DJ11DLN

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Had the same issue years back when I was into CB. Just constant bacon fry on dry days, less when it was humid and at night, goes away completely when it rains. I located the issue with a transistor AM radio and used the sledge hammer trick to confirm it. They had a spur coming off of the line and rather than set a guyed pole across the road and connect it to support the pole where the spur came off, they just set the first pole of the spur fairly close and made very short runs to it without enough tension on the insulators for them to work properly. I never was able to get them to fix it.
 

JoshuaHufford

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Had the same issue years back when I was into CB. Just constant bacon fry on dry days, less when it was humid and at night, goes away completely when it rains. I located the issue with a transistor AM radio and used the sledge hammer trick to confirm it. They had a spur coming off of the line and rather than set a guyed pole across the road and connect it to support the pole where the spur came off, they just set the first pole of the spur fairly close and made very short runs to it without enough tension on the insulators for them to work properly. I never was able to get them to fix it.

You know there is a short spur coming off the main line to supply power to this shop, and I doubt there is much tension on the line, probably the same exact thing.
 

WB9YBM

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I've been battling what I'm pretty sure is AC line noise at my receive site which is located in my Father-In-Law's shop. I called the utility company, they sent me to a few different people and then finally said they would send someone out. I asked them if I could PLEASE be notified when they were going to come so I could be there, but of course they didn't. I did get a call from the guy that was sent out, he said he could certainly see evidence of arcing at the transformer and that he repaired the problem. He also said the pole was in bad shape (it is totally rotted out at the top), and he would put in an order to have it replaced, this was back in early March, the pole still has not been replaced. I also asked if they had done any testing in the area to see if there were any other problem spots and he said no.
I've had a similar problem in the past: about two houses north of me, the power company has a telephone pole mounted transformer which I suspected was going bad; every time humidity would increase here, the noise on my "S" meter would go up--the higher the humidity, the higher the noise. I called the power company several times but was ignored every time. After a few months of this the transformer blew out (nice big bang, fire shooting out of the top). Problem solved. The only down side is if the power company would've paid attention to me in the first place, maybe they could've saved the transformer (and spared me a few months of having to fight the noise!). Bureaucracy at it's best!
 

jwt873

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