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Not boat related, but might be EMI

Discussion in 'SSB and Ham Operators' started by Brian D, Sep 21, 2016. Add this thread to a FAQ

  1. Brian D

    Brian D Moderator

    Joined Feb 17, 2006
    3,481 posts, 325 likes
    Lancer 27PS
    US Oceanside, Ca MCB Camp Pendleton, Ca KF6BL
    I have a Yaesu 857D, MFJ-929 Auto Tuner, SingnaLinks, and an Acer Aspire 5517 Laptop. Connecting the laptop to the SignaLinks is a USB printer cable (unshielded I believe). Connecting the SignaLinks to the 857D is a purchased control/data cable. The software I am using is WSJT for data.

    My issue is a tone appearing at 831 hz, 1831 Hz, and 2831 Hz on the WSJT waterfall display. My primary frequency is 14076 KHz. So these tones are 14076.831 KHz, 14077.831 KHz and 14078.831 KHz. I do not believe these tones are being transmitted, at least I hope they are not.

    When I touch the radio or the tuner the amplitude of the signals and the three tones reduces. Not much so even though my system is grounded via all the cables there might be a minor ground loop somewhere. But I don't think that is causing those three tones to appear.

    If I move the connection to the PC the tones reduce greatly but are still visible. Removing the cable locks up the program (as expected). Moving the connections at the SignaLinks does nothing, so I appears to be the PC/Cable connection. Also turning off the SignaLinks does nothing. But it appears the tones are being passed along the cables between the PC and the radio. If I listen real carefully, it sounds like the tones are clocking at 2000ms.

    I have applied Snap-on Ferrite beads/cores (whatever you want to call them) and this is not doing anything at all to the tones. The ferrites are on both ends of the USB cable, both ends of the control/data cable, and the PC end of the PC power cable.

    Can anyone think of what might be causing the tones? I don't think it is interfering with data reception, but it seems to be more annoying than anything else. I normally keep the radio's audio volume at zero when working data.
     


  2. woodster

    woodster

    Joined Sep 15, 2009
    6,240 posts, 262 likes
    S2 9.2a
    US Fairhope Al
    i don't know any thing about all this but what comes to mind for me is ....a direct ground hookup between the two might clear that up ....just wag but i thought it might help
     


  3. Brian D

    Brian D Moderator

    Joined Feb 17, 2006
    3,481 posts, 325 likes
    Lancer 27PS
    US Oceanside, Ca MCB Camp Pendleton, Ca KF6BL
    A common ground point exist already. There are two AC connections; the power supply for the laptop and the power supply for the radio. Both AC cables share the same outlet so the ground is common. The radio supplies the power for the antenna tuner and the laptop powers the Signalinks box.
     


  4. Gene S

    Gene S

    Joined Nov 29, 2015
    92 posts, 11 likes
    Delphia 37
    US Washington Tacoma
    How is the 857D powered? 12V? Do you get the signals with just the radio on? Laptop p/s are switching types and can put out harmonics. What else is on when you hear the signals?
     


  5. Brian D

    Brian D Moderator

    Joined Feb 17, 2006
    3,481 posts, 325 likes
    Lancer 27PS
    US Oceanside, Ca MCB Camp Pendleton, Ca KF6BL
    The 857D is power with an MFJ 25 amp power supply. With the PC off, the tones are not present. So it appears to be associated with the laptop. That is the only thing that seems to be producing the tones. Turn off the PC or remove the USB cable and the tones go away.

    Just to be sure, I have disables all my wifi equipment both near the PC/Radio and downstairs. There was no change. Removing the control/data cable between the radio and the SignaLinks did not change anything except the tones moved up to the 1000 Hz, 2000 Hz, and 3000 Hz marks. Replacing the cable moved the tones back down to 831, 1831, and 2831.

    One thing I notice is the amplitude changes when I wiggle the USB cable at the PC. I know, don't wiggle the cable. LOL So I am starting to point to a connection issue there. I am wondering if the USB outer flange is too small. I will look for another USB Printer cable and see if that solves the issue.
     


  6. Justin_NSA

    Justin_NSA

    Joined Jul 7, 2004
    3,909 posts, 366 likes
    Hunter 30T
    US Wichita, KS
    Where does beer fit into this thread? :biggrin:
     


  7. Brian D

    Brian D Moderator

    Joined Feb 17, 2006
    3,481 posts, 325 likes
    Lancer 27PS
    US Oceanside, Ca MCB Camp Pendleton, Ca KF6BL
    Right after I figure out what is going on. Once solved, the beer will flow. :clap:
     


  8. Brian D

    Brian D Moderator

    Joined Feb 17, 2006
    3,481 posts, 325 likes
    Lancer 27PS
    US Oceanside, Ca MCB Camp Pendleton, Ca KF6BL
    SOLVED!

    The issue was the cable between the laptop and the SignaLinks. Two problems; first the cable was not shielded and second, the physical connection was loose. I purchased a Belkin shielded cable from Walmart. Although the physical connection is better, it is still a little loose. However, when connection is good, there are no tones present. I can live with that just by being careful not to hit that connection.

    Thanks guys for your suggestions.
     


    Rick D likes this.
  9. Rick D

    Rick D

    Joined Jun 14, 2008
    6,298 posts, 108 likes
    Hunter Legend 40.5
    US Long Beach, Shoreline Marina, CA
    Geesh, I was proud of myself for just changing from a J-pole to a Diamond x300 at home. This thread reminds me how far I have to go.... :yikes:
     



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