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Flex Net Noise: Any Ideas?

Alan
Alan Member ✭✭✭
edited August 2020 in Amateur Radio Interests
While on the Flex Net today, a noise signal frequency-shifted through 14.329.  Any ideas of its origin?

Here are some photos.

Alan
WA9WUD



Answers

  • Roy - W5TKZ
    Roy - W5TKZ Member
    edited April 2020
    Alan, I traced one of those to a noisy wall wart. It drifted with the heat in my home. I also have a neighbor with one but it doesn't bother me.

    Roy - W5TKZ
  • Martin AA6E
    Martin AA6E Member ✭✭
    edited April 2020
    Yes, it's likely to be something quite nearby you.  The thing to do is to start switching off your AC circuit breakers one by one (excluding your shack!) until the noise stops, then track down the devices you have plugged into that circuit.  It looks like a cheap switched power supply - or wall wart.

    73 Martin AA6E
  • Alan
    Alan Member ✭✭✭
    edited June 2020
    Thanks, Martin.  I thought it could be a noisy switching power supply but was not sure due to the frequency moving around.

    Alan
  • Patrick
    Patrick WH6HI KauaiMember ✭✭✭
    edited April 2020
    One way to check is to zoom out on your display to show more screen bandwidth.  If you see those same noise spikes evenly spaced multiple times.  That is a good indication of switching power supply interference.  Wall warts are basically switching power supplies.  Using #75 and/or #31 ferrite on output and/or input can lower the emissions.  Or do like I did and use an appropriate new supply of better quality.  I use a small Meanwell product like 5v or 12v power supplies and I common up all the devices needing appropriate voltage supply.  Reduces number of wall worts and I do some some #31 ferrite to reducing Ingres of RF from station transmitter.  This method reduced the **** by a large margin.  

    Use the power of the radios built in spectrum analyzer to help trouble shooting interference problems.
  • Patrick
    Patrick WH6HI KauaiMember ✭✭✭
    edited April 2020
    Switching power supplies use none crystal control, so temp or load can change the switching frequency, thus the drift you see.
  • Alan
    Alan Member ✭✭✭
    edited April 2020
    Thanks, Pat.   Your input will help me find and fix the source of the noise.

    Alan
    WA9WUD

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