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Re: Re: [softrock40] band-specific reception problem

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  • Alan
    ... Subject: RE: Re: [softrock40] band-specific reception problem ... Rob, I thought it was my ancient Outlook Express but saw the same on the Group page.
    Message 1 of 4 , Sep 16, 2013
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      ----- Original Message -----
      Subject: RE: Re: [softrock40] band-specific reception problem


      > >
      > My apologies for the HTML junk. That was courtesy of the yahoo "new topic" dialog. Perhaps a bug from attaching the images?
      > Anyway...
      >

      Rob,

      I thought it was my ancient "Outlook Express" but saw the same on the Group page.

      >
      > I'm setting the frequency using Rocky, but I also have the "Softrock Configuration Tool" open to verify the frequency. The tuning
      > is definitely working. The 5mhz wwv was coming in clear and I was able to monitor several QSOs on 40m.

      It is best not to have both running, sometimes it may work. Try turning off Rocky's Si570 control and just use CFGSR. Check with the
      "Test" tab that "Get" shows no error.

      >
      > If I change frequencies the blob of noise stays at the same place (centered at the tuned frequency wherever that might be). The
      > blob slowly gets bigger as I tune to 20meters. As you said, I can't imagine a ground loop causing the problem since it's
      > frequency specific.
      > > Is it possible that the receiver was somehow getting overloaded?
      >

      The spectrum display will show signal strength. I doubt whether it is overload, that usually fills the spectrum with spurious
      signals. And it would stop when the antenna is removed.
      Do you actually see and hear signals on 40m?
      If you do then I still cannot see how you do not receive anything on 20m apart from no propagation.
      And I'm not familiar with the Rocky waterfall, what does the spectrum display show? Does that vary greatly in the centre?

      73 Alan G4ZFQ
    • physicsrob2
      I spent some time this evening verifying the problem. Basically I think my previous description was accurate, but let me add a few details: The problem is
      Message 2 of 4 , Sep 17, 2013
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        I spent some time this evening verifying the problem.  Basically I think my previous description was accurate, but let me add a few details:


        The problem is definitely only around 20m, and my antenna is cut for 20m.  I'm thinking this can't be a coincidence -- there must be some sort of overloading going on.


        Here's the spectrum for 20 meters with no antenna attached (sufficiently blank to my eye):

        http://picpaste.com/pics/20m_blank-37DMcRNI.1379405047.png


        Here's the spectrum for 20 meters with my antenna attached:

        http://picpaste.com/pics/20m_noise-vIMdNYU9.1379405215.png


        With this zoom you can see the quality of the noise a bit better.  It appears that there is noise peak at roughly every multiple of 100hz.  Weird, huh?  


        Here's the spectrum for 30 meters with my antenna attached:

        http://picpaste.com/pics/30m_clean-n6XHXIvv.1379405458.png


        As you can see the noise problem is nonexistent on 30 meters.


        If this is indeed some sort of overloading problem would that point to a particular component?  Any debugging suggestions?


        Thanks so much for the help.


        73,

        Rob

        NE6U

         



        --- In softrock40@yahoogroups.com, <alan4alan@...> wrote:

        ----- Original Message -----
        Subject: RE: Re: [softrock40] band-specific reception problem


        > >
        > My apologies for the HTML junk. That was courtesy of the yahoo "new topic" dialog. Perhaps a bug from attaching the images?
        > Anyway...
        >

        Rob,

        I thought it was my ancient "Outlook Express" but saw the same on the Group page.

        >
        > I'm setting the frequency using Rocky, but I also have the "Softrock Configuration Tool" open to verify the frequency. The tuning
        > is definitely working. The 5mhz wwv was coming in clear and I was able to monitor several QSOs on 40m.

        It is best not to have both running, sometimes it may work. Try turning off Rocky's Si570 control and just use CFGSR. Check with the
        "Test" tab that "Get" shows no error.

        >
        > If I change frequencies the blob of noise stays at the same place (centered at the tuned frequency wherever that might be). The
        > blob slowly gets bigger as I tune to 20meters. As you said, I can't imagine a ground loop causing the problem since it's
        > frequency specific.
        > > Is it possible that the receiver was somehow getting overloaded?
        >

        The spectrum display will show signal strength. I doubt whether it is overload, that usually fills the spectrum with spurious
        signals. And it would stop when the antenna is removed.
        Do you actually see and hear signals on 40m?
        If you do then I still cannot see how you do not receive anything on 20m apart from no propagation.
        And I'm not familiar with the Rocky waterfall, what does the spectrum display show? Does that vary greatly in the centre?

        73 Alan G4ZFQ
      • Alan
        ... Subject: [softrock40] RE: band-specific reception problem ... Rob, Yes, you are picking up something, maybe from your monitor or other device. Maybe some
        Message 3 of 4 , Sep 17, 2013
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          ----- Original Message -----
          Subject: [softrock40] RE: band-specific reception problem


          >
          > The problem is definitely only around 20m, and my antenna is cut for 20m. I'm thinking this can't be a coincidence -- there must
          > be some sort of overloading going on.
          > Here's the spectrum for 20 meters with my antenna attached:
          >
          > http://picpaste.com/pics/20m_noise-vIMdNYU9.1379405215.png


          Rob,

          Yes, you are picking up something, maybe from your monitor or other device. Maybe some sort of ground loop, although I've never
          noticed a frequency dependent loop. If it is 120Hz spacing it could point to powerline harmonics.
          But there is no sign of overloading.

          > Here's the spectrum for 30 meters with my antenna attached:
          >
          > http://picpaste.com/pics/30m_clean-n6XHXIvv.1379405458.png
          >

          From what I've seen so far I'd be more worried about signals that are not seen. What were the two signals on 30m?
          I guess you are showing the bands when they are closed?
          You do get good results on 40m?

          I'd say just forget the 20m noise in the centre if it is the only problem. Try it in the weekend when there are definitely signals
          there. Find out what the noise is later if it is otherwise working properly. If the Softrock is receiving properly then I do not
          think it is a fault in the hardware.

          73 Alan G4ZFQ
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