Why?

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by N5YPJ, Oct 26, 2020.

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  1. N5YPJ

    N5YPJ QRZ Moderator QRZ Page

    My receiver TS-590S connected to a Mosley Pr0-57B antenna pointed same direction, same time of day, etc. doing a check of noise (no signal) levels - 20 meters is S-9
    17 meters is S-5
    15 meters is just over S-1. I made a few qsos in to Europe this AM
    12 meters is S-6
    10 meters is s-9 /+10 DB.

    Anyone know why there is such a difference in noise levels?
    After getting what I had coming from the PoCo :( and ARRL :( now I am using a phaser and magnetic loop for receive 20, 30 & 40 time being, it works well but really wish I could use the Mosley on all bands TX & RX.

    73

    Richard / N5YPJ
     
  2. N5YPJ

    N5YPJ QRZ Moderator QRZ Page

    All bands 20 - 10 that is. :) :)
     
  3. N1IPU

    N1IPU Premium Subscriber QRZ Page

    Hard to say, Solar storms, Local noise, etc. Twenty is always noisy on the horizontal, Using a vertical helps a great deal with that. but again no real way of knowing whats causing it while horizontally polarized.
     
  4. KH6AQ

    KH6AQ Ham Member QRZ Page

    I suspect a switching power supply that just happens to have switching harmonics fall in the 20 and 10 meter bands. You can tune around -- say 10 - 30 MHz -- and record the frequencies. If the noise occurs at a set spacing, such as 200 kHz, it is a switching power supply.

    Have you checked that the noise source is not in your home? To do that the TS-590 can be powered by a 12V battery and the AC power to the entire house is shut off. If the noise goes away the source is in your house and it's then a matter of locating it, which is easy.
     
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  5. N0TZU

    N0TZU Platinum Subscriber Platinum Subscriber QRZ Page

    What sort of noise?

    It’s impossible to even take a guess without more information. Normally all the upper HF bands are pretty quiet for atmospheric noise.

    Is it broadband noise, or only on certain frequencies through the band?
    Does it vary with time?
    Is it constant when it’s occurring or does it have a tone, buzz, or rhythm?

    A video posted so we can hear it (and see it on a band scope of available) would be helpful.
     
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  6. N5YPJ

    N5YPJ QRZ Moderator QRZ Page

    We powered the TS-590S with a battery with AC power off, noise levels did not change. Sweep of the house with AC on turned up a nasty cell phone charger that was replaced.
     
  7. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Time to go snooping (I mean, "RF sniffing") around the neighborhood.

    If it's not your own home, it could be a neighbor's. Years ago I had band-specific RFI ("noise") that I confirmed wasn't coming from our home so took a drive, just using the AM broadcast radio in my car. Half mile away the noise peaked badly and "sounded" about the same as I was receiving on some ham bands. This was right at a horse property, about 5 acres, that had an electric fence. But using a portable radio, I could tell it wasn't the fence; but it was something at that property.

    Long story short, it turns out that while they had disconnected the wiring to the fence years ago, they never unplugged the high voltage transformer, which was in a barn. Found it, unplugged it...no more noise.

    Definitely took some snooping and a cooperative neighbor to find this, but once the neighbor agreed to let me look around, took ten minutes.
     
  8. WB5YUZ

    WB5YUZ Ham Member QRZ Page

    Arcing transformer near hay? What could go wrong?

    You did them a solid. Hope they realized that.
     
    AK5B likes this.
  9. AE1N

    AE1N Ham Member QRZ Page

    TRYING TO PULL HIM OUT OF THE NOISE!
    B.TRYING TO PULL HIM OUT OF THE NOISE.jpeg

    B.FINALLY FIXED THAT NOISE PROBLEM.jpg

    ---Layne AE1N
     
  10. KF8RM

    KF8RM Ham Member QRZ Page

    The easy answer is that the noise source will have different propagation characteristics at different frequencies thus the different levels on various bands. Another theory is that the noise source is also narrow band and is strongest on the frequencies it is being generated at.
     

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