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Noise on 20m.

Hi, What can be the origin of this type of noise on 20m.
This is a screenshot taken two hours after local sunset.
Left and right of the FT8 signals and up to S9 and seem to shift up an down the band.
Terrible if it gets on top of the FT8 signals.

Eddy ON5UQ.


  • KL4QGKL4QG Member ✭✭
    edited May 16
    Has be The Russians ****
  • Bob K8RCBob K8RC Old Guy Member ✭✭
    edited September 2019
    I've seen similar from a variable speed motor drive in an HVAC air handler.
  • Ray SylvesterRay Sylvester Member
    edited September 2019
    looks like a solar panel inverter
  • edited September 2019
    Looks just like what I am getting in my shack. It's on more than 20 meters for me. I think it is coming from my router or modem. Need to shut down everything, put my SDRPlay on a laptop and chase it down.
  • Jim GilliamJim Gilliam Member
    edited September 2019

    Does this noise repeat itself every 50 to 100 kHz? If it does, it is more than likely from some type of electronic switching device.
  • EddyEddy Member
    edited September 2019
    Thanks for your reply.
    I get terrible noise from a solar panel installation in my neighbourhood but only during daylight hours.
    This noise disappears as soon as it is dark but the noise of the screenshot remains all night.
    Is it possbile that string inverters or optimisers on each solar panel cause this RF noise during night hours ?

    Eddy ON5UQ.

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