Weird interference, every 66 Khz

Discussion in 'General Technical Questions and Answers' started by N1LOU, Oct 18, 2021.

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  1. N1LOU

    N1LOU Premium Subscriber QRZ Page

    I am noticing this interference on all bands from 10-160. it seems to recur every 66 Khz. It is noticeably absent above 35 Mhz. The amplitude of the interference differs among the bands being more noticeable on some. On 60 Meters it is the worse, and I actually see two different signals on the band, one spaced at 66 Khz and one very square shaped wave every 62 Khz. If I tune one of these signals it comes across as a soft white noise. It's not the worst interference as I can easily tune signals that are not right on top of one of these spikes, and they are actually quite far apart compared to the bandwidth of a typical SSB signal. Has anyone seen this and if so, what is it and how do I get rid of it

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  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Switchmode power supply, converter or regulator operating at about 66 kHz?
    WE4E, KH6AQ, KA0HCP and 1 other person like this.
  3. K8CCA

    K8CCA Ham Member QRZ Page

    Yeah, I agree, switchmode power supply. I got rid of mine (Alinco DX-330) and got a linear supply (Astron RS-35M) and that interference went away on my IC-7300.
    KI4ZUQ likes this.
  4. KI4ZUQ

    KI4ZUQ Ham Member QRZ Page

    Same here except every 75 khz. Was from 55 amp RV converter I thought was so quiet! Similar was the 30 china 12 volt adjustable from Amazon. Repetitive noise spikes 60 to 75 khz moving down freq slowly.

    Going AGM batteries for a while...
  5. SM0GLD

    SM0GLD Ham Member QRZ Page

    This is very common for various LED-lightning using switching led-driver.

    Have a look in the datasheet.
    W4HWD, N1LOU and KA0HCP like this.
  6. N1LOU

    N1LOU Premium Subscriber QRZ Page

    Well its definitely not my switching mode power supply. I ran from a battery and still had the same RFI. I will have to turn the mains off and see if it is even coming from my home or a neighbor's house.
    N0TZU likes this.
  7. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Excellent tip!

    The RFI causer is likely exactly that.
    N1LOU likes this.
  8. N0TZU

    N0TZU Platinum Subscriber Platinum Subscriber QRZ Page

    That is always step one.

    Any new or recently replaced devices in your house? Anything obviously new in the neighborhood?


    Scope the mains in FFT mode. Any odd noise there?
    Caution with scope on mains.
  10. K8XG

    K8XG XML Subscriber QRZ Page

    Make sure to remove batteries out of your computers, or shut them down and also remove the backup battery in your cable modem if you have one. Remove "float chargers" off any batteries you keep "topped off". The battery will back feed the charger and still cause RFI. My "tender" has some of that 60kz bands when I used to use it to top off. Now I keep them topped off with solar controllers.

    So if you have any solar you need to shut the controllers off also when you kill the mains.
    N0TZU likes this.

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