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Power line noise.



  • WA2ZKD , the local times for the noise is around 8:55 PM - 1:55 AM. QTH is Carlow, Ireland.
  • Powernumpty,

    LW performance of emerald is seriously effected by emerald1 SMP, but, don't ask me how in the Hell it does not effect emerald1 is beyond me the one it's actually plugged into. I'm using this SMP while I'm waiting for my Linear PSU.

    I suspect that emerald using the MD300DX is being effected further along the spectrum too.

    Try your recordings again tonight as I've now sorted the networking issues pointing the different URL's to the one Kiwi.
  • They were definitely different SDR's, I even checked users in case I was tying it up when busy, there was myself and one Italian IP on the first, only me on the second.

    In the screen shot above it is possible to tell one is showing more electrical crashes (left), neither bad but one it showed more visibly.
    The new one I'd say seems smoother and the older more lively and if anything slightly more sensitive for the stations I was copying.

    I'll have another look as long as I don't lock any serious users out,
  • what is that large complex to the Northwest of you? Not the first place but the larger second?
  • Go to both Kiwi's and check out 75 meter broadcast, and look over to 80 meter Ham, zoom in/out until you can see the two bands and look at 3.9 Mhz, this is the QRM I'm talking about , now compare to the Loop, it's almost non visible. Nice to be able to compare antennas.
  • Powernumpty, work away, there's people using it for 5 hrs at a time , not that I approve but I don't want to impose limits but it might have to come to that.
  • WA2ZKD, the large complex , which is 2 properties to the left ? that's another Farm.
  • Noise is a problem I'm fighting, too It is possible to reduce the noise quite a bit by rotating the Pixel RF Pro-1B mag loop 90°, but I've yet to find a way to eliminate it. (Ha ha, like that will happen.) Anyway, here is the video: 2018-10-29 07-02-43-425.mp4?dl=0

  • Mike, is your loop outside? That looks to me like a switch mode PSU but unless it is really close to the loop it would have to be a plastic cased charger/supply without any filtering often "replacement" laptop power supplies from Ebay/Amazon.
    I picked up a couple for an older HP laptop, the 90W produced this sort of noise.
  • I note the OV (overload) is on, what signal is causing that? That and your noise may be related. Is the OV on continuously?
  • It appears that something >30 MHz is killing you. Try 10-20 dB attenuation at the antenna connector and see if it changes.
    Glenn n6gn
  • Powernumpty, the loop is mounted outside about 10m from the house. The one power company that has some high voltage lines running through the neighborhood had a tree trimming crew come through about 4 weeks ago. They were trimming trees and branches for a planned current increase in the line ... they've doubled the current. This occurred just before the noise jumped. I'm prettys sure I know the source.

  • Ah that is a difficult one, power here is underground so although I've found some hot spots with a GQ EMF meter most radiated EMI is from homes (which are close together).
    I'd be temped to pick up an emf meter as it pays to have a feel for the levels and types of fields where we spend a lot of time (he said while specifically sat in the narrow part of this room with the least field from the supply input below).
    The balance at the houses and grounding obviously also affects radaited so you may still be able to reduce it if you can identify the worst locations.
  • Mike, Is your kiwi public? Is it the same on both the Pixel and the Wellbrook?
  • WA2ZKD, not public yet. Hope to finalize that in the next couple of days. As for the antenna, it is whichever one is connected at the time.
  • WA2ZKD: Not registered, but online at
  • Other nosey parker here..

    That is not as bad as mine on a normal Mag loop, It sounds like switchmode but not as harsh as the gaming rigs...
    How close is the nearest PC? LED lights?
    With the spectrum on there are obvious repeating peaks like squarewave switching noise.
    The dips in the spectrum don't seem to tie up with the ham bands so it doesn't look too much like mains networking, I didn't get the feel of data passing (though there is some horizontnal banding).

    I'd start with a bunch of ferrite clip on beads and while watching the display (done on a tablet here) add/remove ferrite to everything from DC lead to GPS coax watching the full spectrum and background noise to see if you can find where it is getting in.

  • I think the Pixel Loop uses the amplifier described below. If it does, I don't see provision to filter frequencies above 30MHz. I see the OV light on the receiver but there isn't a signal appearing on the waterfall to explain it. So I suspect the strong signal is up higher in frequency but within the KiwiSDR passband. If you could connect a receiver that covers above 30MHz, the signal should become apparent and you could then design a filter to attenuate it ahead of the KiwiSDR or the Pixel loop to stop the OV condition. The OV condition is likely the total cause of the interference.
    Ron - KA7U

  • I've actually had ethernet noise, usb noise, you can even get electrical noise when your furnace turns on and off. Do you have a sump pump? It could be the "phase" of the electrical line your device is plugged into? Separate power plugs?
  • Also if you have a smart meter they broadcast your stats to local towers regularly. Some are cellular some are 900Mhz. Cellular being around 700Mhz
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