Noise-again

Discussion in 'Ham Radio Discussions' started by N7WR, Jul 28, 2021.

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  1. N7WR

    N7WR Premium Subscriber QRZ Page

    I have posted before about noise making my use of HF very difficult/impossible at certain times. Briefly, I have eliminated anything on our property as the noise source. the local power company used their sniffer on all of their lines and poles for a mile in every direction from our rural property. I have "sniffed" my closest neighbor's property. The power company rebuilt 3 power poles (all equipment on each pole) because they were emitting "a little" noise.

    The problem, however, persists and only occurs when the weather is hot and dry. Any moisture at all (rain or high humidity days) and the noise is gone. Can't figure it out as it is 180 degrees opposite of any noise issues I have ever had in the past.

    Drone overflights (with video) show no solar systems visible within 2 miles of here. Anyone have any ideas? On a no noise day the noise level (all bands and modes) is maybe an S 2. On high noise days it is 10 db over 9 at best.

    I am not in an urban area with close by neighbors. Very rural with few neighbors the closest (and only) neighbor being 1/4 mile from me.
     
  2. US7IGN

    US7IGN Ham Member QRZ Page

    Is there any dependence on the wind? It could be static electricity.
     
    K0UO, W7UUU, W0PV and 1 other person like this.
  3. N4OGW

    N4OGW Ham Member QRZ Page

    Being weather related, it sounds like power-line noise to me. I had a similar problem which turned out to be a bad power line insulator. I was able to identify it using a 70 cm HT in AM mode and a small yagi. Trying to find these on HF is harder as the noise can be conducted along the lines making it harder to pinpoint.

    Tor N4OGW
     
    N2OTG and W5INC like this.
  4. NK7Z

    NK7Z XML Subscriber QRZ Page

    What type of equipment did the Power Company use? Was a dish of any kind involved? A yagi of some sort, both?
     
  5. K3EY

    K3EY Premium Subscriber QRZ Page

    I had the exact same problem which took 5 long years to resolve. It was absent with rain or any moisture. It turned out to be a ground cable arching only when it was a dry day. The potential it’s so high in those powerlines that what looks like a safe distance for the ground cable away from any high voltage is NOT distance enough to prevent arcing, and wrecking havoc with radio receivers.

    I feel your pain I truly do, good luck!!
     
    WN1MB, NL7W, W5INC and 2 others like this.
  6. W0AEW

    W0AEW Ham Member QRZ Page

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    NL7W, N2EY, KA3CTQ and 6 others like this.
  7. N7WR

    N7WR Premium Subscriber QRZ Page

    Both
     
  8. N0TZU

    N0TZU Platinum Subscriber Platinum Subscriber QRZ Page

    The only way I know to locate it is by using your own DF equipment when it’s noisy - and oodles of patience. Start by going around your house because it could be something close, and widen out. Keep notes so you can begin where you left off when the noise starts again.

    I also had annoying power pole noise that was intermittent and at least partially weather dependent. It took a while to locate because other poles in the area are also intermittent (but far enough away not to be worth a crew fixing, yet).

    I used a home made HF loop with a portable SW receiver, my HT with AM aircraft band and simple homemade wire 135 MHz and 335 MHz Yagis, and finally a home made ultrasonic dish, in that order to zero in on the exact location of the noise. It took a long time to pin down.

    If you know it’s nearby start with the VHF or even UHF. Otherwise use the HF to get a general bearing - you’ve already done that it seems. Then start walking. Then VHF will get to a pole or group of them, UHF for the pole, even portion of the pole, and ultrasonic will locate the hardware item.

    My noise turned out to be a cut off pigtail of ground wire left about 6 inches from the top insulator mount on one of the poles for a neighborhood line that cuts through my property. The REA lineman said he could hear it buzzing when he got close. He eliminated the pigtail and made a new clamped connection to the neutral just in case the old one was bad. End of problem.

    According to the lineman, decades ago they did the pigtail as a sort of spark gap for lightning. Not sure I buy that explanation, but all the older poles in the neighborhood have the same darn pigtail, and I know some are similarly intermittently noisy because I’ve DF’d them.
     
    Last edited: Jul 28, 2021
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  9. NK7Z

    NK7Z XML Subscriber QRZ Page

    Thanks for the update, that helps me understand what the power company checked for, and how. I asked because the dish is listening for sparks, using ultrasonic sound, and that can happen due to dirty insulators.

    Having the RFI go away when dampness sure sounds like power line noise to me. If they have rebuilt a few poles, then they located something, and made it go away, too bad it is not your RFI source. Some questions:

    1. What is the highest frequency you hear this on?
    2. Have you performed a full power off test of your property?
     
    WN1MB likes this.
  10. N7WR

    N7WR Premium Subscriber QRZ Page

    The highest frequency (in the ham bands) is 10 meters. No noise on V/UHF. The worst noise in on the low bands (160/75/40) My mobile HF picks up the noise up to a mile from the house
     

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