Noise

Discussion in 'General Technical Questions and Answers' started by W4GOV, Dec 27, 2020.

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  1. W4GOV

    W4GOV Premium Subscriber QRZ Page

    Hello all.

    I am now experiencing some impressive noise that my antenna is picking up. Here is what I have found.

    1. my station is normally relatively quiet (s1-2 noise) on any band
    2. After hearing this new noise, which is about s6-8, I tried unplugging stuff at the house and nothing changed
    3. I unplugged the antenna from my 2:1 switch and all noise was gone. Plug the antenna back in and the noise is back
    4. Using my waterfall display, I spanned the display from 2.5khz to 250 kHz and identified a pattern in the signal.

    can anyone tell what this could be from based on how it looks? It sounds like rapid pulsing and other wise electrical noise of sorts. I didn’t change anything in my station or home to generate such noise. I thinking it’s something new from the power lines or something from a neighbors house. It’s affecting all bands but worse on the lower bands.

    many assistance is appreciated in identifying the possible source type of the noise.

    Thanks
    Adam
     

    Attached Files:

  2. N7WR

    N7WR Premium Subscriber QRZ Page

    Looking at the sat view of your QTH it appears your closest neighbor is aways from you. Don't know what the environment is like there but last winter I began to have the same sort of noise. We also live on rural land with only one neighbor and his closest structure is about 350 yards from my shack. I did what you did. Shut off all circuits on our place one by one and was satisfied the noise source was not on our property. I then took my AM air band hand held receiver and went looking. Finally found the source on the neighbor's property. He had just purchased a battery charger for his ATV/snow plow. Cheap one bought on Amazon. When I got near it I knew that was the source. Went and got a spare I had, explained the problem to the neighbor and gave him mine with the one he bought going in the dumpster. Problem solved. That battery charger was at least 350 yards from my shack and even further from my antennas. It was a noise radiator
     
    KI4ZUQ and W4GOV like this.
  3. W4GOV

    W4GOV Premium Subscriber QRZ Page

    Thanks. I am sure it is either something that someone got for Christmas, or the power lines have gone whacko. At this point, all I know is it is not at my house, its loud and killing my HF ears, and it looks pretty on the waterfall display LOL
     
    KP4SX likes this.
  4. NK7Z

    NK7Z XML Subscriber QRZ Page

  5. W4GOV

    W4GOV Premium Subscriber QRZ Page

    Thanks. I've actually performed all of these steps and like I mentioned, This just started this evening. I've been running this station for years without noise like this. I am sure it is not originating from my home. I have a TS-990 on house power and a TS-480 on battery. They both pick up the noise equally.
     
    KI4ZUQ likes this.
  6. W4GOV

    W4GOV Premium Subscriber QRZ Page

    Well I woke up this morning and much to my dismay, the new noise is still there. It’s the worst between 12.5 MHz to 15 MHz but seems to cover between 6 MHz to 28 MHz.

    I shut down all power to the home and had both radios running off UPS (TS-990) and battery (TS-480). They both pick up this oppressive noise. I know it’s not located in my home.

    the question is, from the way it repeats and looks on the waterfall, can anyone have a possible opinion on the source? If not, any suggestions on how to find it? I have a small AM radio I could use as a cheap And dirty DF tool.
     
  7. W4GOV

    W4GOV Premium Subscriber QRZ Page

  8. N0TZU

    N0TZU Platinum Subscriber Platinum Subscriber QRZ Page

    A few years ago I had a similar problem as N7WR did and it was a cheap Harbor Freight battery charger that my neighbor began using. I took it apart and the RFI filter parts were not installed - typical of cheap-a@@ companies saving a couple of pennies per unit in production after getting their certification to FCC requirements. Or they don’t even bother with that subterfuge and do whatever they want from the start.

    It may be easier for people here to help identify the noise if you show a waterfall in the 80m band or lower since that’s closer to the fundamentals, and also post a video with a sound recording of the noise using AM mode.

    As was mentioned, it’s time to walk around the neighborhood with a portable radio to find the source. If you can hear the same noise on AM broadcast band, use that radio. If not, use a portable SW radio. These days every ham should own one because the need to track down noise happens frequently, often on your own property. (There are much more sophisticated was of doing it with directional antennas and such, but walking around can work surprisingly well).
     
    Last edited: Dec 27, 2020
  9. W4GOV

    W4GOV Premium Subscriber QRZ Page

    thanks for the info! I’m hoping to go knock on some doors today and ask if anyone got a charger or plugged one in for Christmas lol.

    160-80m is not affected. It is mainly covering 6-28 MHz (40-10 meters).

    As of this post, the noise disappeared for about 20 minutes then came back on. When it’s gone, I’m back to S zero noise. When it’s on, it’s S9!

    i posted a pic of it on and off.
     

    Attached Files:

  10. N0TZU

    N0TZU Platinum Subscriber Platinum Subscriber QRZ Page

    Ok just use the lowest band it appears on. It looks very broadband if I’m understanding your waterfall correctly. Is the spectrum above the waterfall some normal signals, or is that the noise? Those don’t seem to agree with the waterfall below them.

    Lots of horizontal lines or bars through the waterfall are often caused by power pole noise, or other such arcing type sources. Switching power supplies such as from most modern devices and chargers will usually create vertical lines or bars spaced at regular intervals (the switching frequency).

    Before you go knocking on doors, you really should be very sure of what you’re hearing and have located the noise down to a particular house or location. It’s fraught with issues of neighborly relations and should be your last step. Read the NK7Z guide posted above, and also go to the ARRL website and read all about RFI.
     
    Last edited: Dec 27, 2020
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