Welcome to the new FlexRadio Community! Please review the new Community Rules and other important new Community information on the Message Board.
If you are having a problem, please refer to the product documentation or check the Help Center for known solutions.
Need technical support from FlexRadio? It's as simple as Creating a HelpDesk ticket.

Noise Floor - FLEX 6400

I purchased a FLEX 6400 at the 2023 Dayton Hamvention with SmartSDR v3.4.23 using a GAP Titan DX vertical antenna mounted on the ground. Compared to a fellow ham, he seems to think: 1) I have a high noise floor, 2) that the spikes and ripple peaks may be generated by "wall warts," 3) the noise floor decreases with increasing frequency. The attached png files are from the afternoon in the Dayton Ohio area (roughly 4PM) with sunny/calm weather. My radio and amp are grounded. I use Belden (not sure of the coax number) with a run of approximately 40 feet or so.

I have attached 3 bands; 80, 20, 10m. 10m shows the ripple the best.

Has anyone seen the 10m ripple before? Any thoughts on what is generating the noise? remedies? Could it be my Dell XPS desktop computer (since that is the radio, I cannot turn it off) which is 6 years old?



  • Erika - KØDD
    Erika - KØDD Member ✭✭✭

    Doubtfull its the dell. But holy moly thats a lot of noise. The only time I see that is with tstorms overhead. Thats got to be making a real racket in the audio. Where's the agc t set?

  • KD0RC
    KD0RC Member, Super Elmer Moderator

    Hi Tom, you can start turning things off until you find the culprit. If you have the capability, run the radio and computer from batteries and shut off power to the house. If you still have the noise, it is probably from someone else's house. If not, start turning things on one by one until you find it.

    Do you or a neighbor have solar? That is a common source of noise like this.

  • ad4vxtom
    ad4vxtom Member
    All my AGC Ts are set in the 30s (10m is at 16) and don't seem to visually change much, but does make a huge difference audibly. I took another screen shot of the whole 10m band to demonstrate the peaks and valleys by freq more clearly. Thanks for the input!
  • ad4vxtom
    ad4vxtom Member
    KD0RC, thanks for the input, there is at least one house with solar, but it is maybe at least 100 yards away if not more. Now, my next door neighbor has a hybrid car which he charges the batteries when not in use. In addition, I will try your suggestion on unplugging wall warts and other equipment. I've ruled out the washer and dryer. Between wife, daughter and myself, we have roughly 30 wifi "things," so the trial and error may take awhile. BTW, I see that I show up as AD4VX which is an older call sign of mine, but I've kept the e-mail address because that's whateveryone knows me by. Tom-W9TO
  • Erika - KØDD
    Erika - KØDD Member ✭✭✭
    edited June 11

    I believe he was suggesting go to the panel and flip all the breakers off... see if you still have the noise... hope you can find it in your house it a real hassle getting neighbors to cooperate. I had a devil of a time silencing a 5 square mile area of electric fences at our farm. I had a 130ft tall broadcast style vertical with 14000 ft of radials.. between powerlines and cattle confinement we had a Dickens of a time. But don't rule out the solar system even at that distance. Without hearing the audio powerline noise can look like that too. Good luck with troubleshooting DD.

  • ad4vxtom
    ad4vxtom Member
    Thank you for your suggestions. Sounds like the place to start is inside the house, turn off everything but shack power and see what I have.
  • Ha Gei
    Ha Gei Member ✭✭✭

    Well, this is not Flex Problem...you just can SEE the noise.

    When searching, keep in mind :

    Solar optimizers can send their RFI over loooong distances

    We saw a problem with a SONOS transmitter , even creating RFI with non switched PSU over 4 house away !

    so walk around with some reciever to locate the beast and , wehn switching off.. leave off a while, not just few seconds.



Leave a Comment

Rich Text Editor. To edit a paragraph's style, hit tab to get to the paragraph menu. From there you will be able to pick one style. Nothing defaults to paragraph. An inline formatting menu will show up when you select text. Hit tab to get into that menu. Some elements, such as rich link embeds, images, loading indicators, and error messages may get inserted into the editor. You may navigate to these using the arrow keys inside of the editor and delete them with the delete or backspace key.