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Strange V9.0 problem

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  • dldietmeyer
    I put together a V9.0 recently, and have been developing a QUISK extension. I jump around the bands, from 0.88 MHz to above 33 MHz. I seldom spend time on 10
    Message 1 of 6 , Aug 1, 2009
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      I put together a V9.0 recently, and have been developing a QUISK
      extension. I jump around the bands, from 0.88 MHz to above 33 MHz. I
      seldom spend time on 10 meters because it seemed to have excessive
      noise. Then the other day I switched to 10, and the tuning happened to
      be on the center (LO) frequency, with USB demodulation. Hey, I could
      understand the noise. It looked like an AM signal, but AM modulation
      was not understandable, perhaps because the carrier was being killed by
      being at zero Hertz audio. I listened to the station. It turned out to
      be WIBA (1310 KHz). Its there when my LO is set in the range 25 MHz to
      33+ MHz. I have no idea how this can happen, or why WIBA is so
      special. (Another local station at 970 KHx shows up at 1940 in the
      160 meter band, but that is understandable.) I just tried again running
      Rocky under XP. Same thing, so it is probably something in my
      hardware.

      Do you have any idea what is happening or how to fix my V9.0? Tnx in
      advance.

      Don
    • g8voip
      Hi Don, The AM MW broadcast image problem at the top of 160m, above 1.90MHz is common with the v9.0 RX, and I do see it here on my two. The other problem
      Message 2 of 6 , Aug 1, 2009
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        Hi Don,

        The AM MW broadcast image problem at the top of 160m, above 1.90MHz is common with the v9.0 RX, and I do see it here on my two.

        The other problem between 25 and 33MHz is much more strange. If it always happens exactly at the zero point and at any different LO frequency, then it surely cannot be any mixing or image problems, as it would more around as you change the LO.

        How close are you to that particular AM broadcast station, and how strong is the signal you are seeing on the SoftRock?

        I wonder if you have a problem with direct pick-up on your soundcard leads, or even inside the PC itself?

        Maybe the problem is present all the time, but at the higher frequencies, the band noise is lower, so it starts to show up?

        You could try running the SDR programs without the v9.0 soundcard leads connected at the RX end, but still plugged into the soundcard and see if it is still present, if it is, its not the SoftRock to blame (you will need to keep the USB lead connected to stop any error).

        It its pick up on the leads, try the usual ferrite beads or clip on chokes etc to remove it.

        I guess if it is pick-up, it will be common to both the I & Q signals, so one would be shifted 90 degrees in the SDR program, not sure what it would sound like.

        Good luck,

        73, Bob G8VOI




        --- In softrock40@yahoogroups.com, "dldietmeyer" <dld@...> wrote:
        >
        > I put together a V9.0 recently, and have been developing a QUISK
        > extension. I jump around the bands, from 0.88 MHz to above 33 MHz. I
        > seldom spend time on 10 meters because it seemed to have excessive
        > noise. Then the other day I switched to 10, and the tuning happened to
        > be on the center (LO) frequency, with USB demodulation. Hey, I could
        > understand the noise. It looked like an AM signal, but AM modulation
        > was not understandable, perhaps because the carrier was being killed by
        > being at zero Hertz audio. I listened to the station. It turned out to
        > be WIBA (1310 KHz). Its there when my LO is set in the range 25 MHz to
        > 33+ MHz. I have no idea how this can happen, or why WIBA is so
        > special. (Another local station at 970 KHx shows up at 1940 in the
        > 160 meter band, but that is understandable.) I just tried again running
        > Rocky under XP. Same thing, so it is probably something in my
        > hardware.
        >
        > Do you have any idea what is happening or how to fix my V9.0? Tnx in
        > advance.
        >
        > Don
        >
      • Donald L. Dietmeyer
        Bob, I pulled the audio line: no more WIBA on 10 meters. Then I put it back and pulled the antenna from the V9.0. Again no more WIBA. I just used
        Message 3 of 6 , Aug 2, 2009
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          Bob,
          I pulled the audio line: no more WIBA on 10 meters. Then I put it
          back and
          pulled the antenna from the V9.0. Again no more WIBA. I just used
          Travelquest
          to find that I am about 6 miles from the transmitter. It seems to me
          that the
          problem is in my V9.0, perhaps the BPF?
          Don

          --

          Donald L. Dietmeyer
          2211 Waunona Way
          Madison, WI 53713-1619
          (608) 222-3663
          dld@...
        • g8voip
          Hi Don, Are you using the switched BPF module with the v9.0 RX or the manual plug-in ones? If you are using the switched BPF module, which version of the
          Message 4 of 6 , Aug 3, 2009
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            Hi Don,

            Are you using the switched BPF module with the v9.0 RX or the manual plug-in ones?

            If you are using the switched BPF module, which version of the firmware are you using to control the filter module?

            If you are using Fred's v15.10, the 'ABPF' mode is the best one to use as it is compatible with all of the SDR software. Check the three filter cross over points are set to 4, 8 and 16MHz, which is their default state.

            One test you could do is to disconnect the lead linking the main board J3 to the connector on the filter module, and without any jumpers fitted to JP1 or JP2, that will select the band 4, 16 - 30MHz BPF correctly.

            I cannot really think of anything actually with the filter that could allow the MW broadcast through, except perhaps if L11 was open circuit, but even then I find that very unlikely.

            Its the fact that you say it is always at the exact centre frequency, and not affected if you move the LO frequency that makes be believe it is direct pick-up, and not a result of an image or mixing process.

            I suppose it could be pick up in the op-amp part of the main board, but the capacitors C29 / C30 should cause the frequency response to roll off well before the MW broadcast frequency.

            Last comment, do you have your v9.0 in a screened metal box, or is it just running open on the bench?

            73, Bob G8VOI


            --- In softrock40@yahoogroups.com, "Donald L. Dietmeyer" <dld@...> wrote:
            >
            > Bob,
            > I pulled the audio line: no more WIBA on 10 meters. Then I put it
            > back and
            > pulled the antenna from the V9.0. Again no more WIBA. I just used
            > Travelquest
            > to find that I am about 6 miles from the transmitter. It seems to me
            > that the
            > problem is in my V9.0, perhaps the BPF?
            > Don
            >
            > --
            >
            > Donald L. Dietmeyer
            > 2211 Waunona Way
            > Madison, WI 53713-1619
            > (608) 222-3663
            > dld@...
            >
          • dldietmeyer
            Bob, and all, A local friend who has been informed of my problem and attempts to fix it, suggested put up a folded dipole, or if you want to keep the bow tie,
            Message 5 of 6 , Aug 25, 2009
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              Bob, and all,

              A local friend who has been informed of my problem and attempts to
              fix it, suggested "put up a folded dipole, or if you want to keep
              the bow tie, replace the coax feed line with a balanced transmission
              line. Could even try zip cord." I did replace the coax with zip
              cord, and the appearance of WIBA (1310 kHz) at the LO frequency from
              25 t0 33 MHz was gone!! There is a local 10 meter beacon so I know
              the V9 is working on 10 meters.

              I don't have a good understanding of what was going on, but the
              shield of the coax was acting as part of the antenna and brining a
              very strong signal to the V9. It may have been strong enough to
              couple to the op amps bypassing the BPF and mixer, as you suggested
              all along.

              Thanks for your help,
              Don

              --- In softrock40@yahoogroups.com, "g8voip" <g8voi.reeves59@...> wrote:
              >
              > Hi Don,
              >
              > Are you using the switched BPF module with the v9.0 RX or the manual plug-in ones?
              >
              > If you are using the switched BPF module, which version of the firmware are you using to control the filter module?
              >
              > If you are using Fred's v15.10, the 'ABPF' mode is the best one to use as it is compatible with all of the SDR software. Check the three filter cross over points are set to 4, 8 and 16MHz, which is their default state.
              >
              > One test you could do is to disconnect the lead linking the main board J3 to the connector on the filter module, and without any jumpers fitted to JP1 or JP2, that will select the band 4, 16 - 30MHz BPF correctly.
              >
              > I cannot really think of anything actually with the filter that could allow the MW broadcast through, except perhaps if L11 was open circuit, but even then I find that very unlikely.
              >
              > Its the fact that you say it is always at the exact centre frequency, and not affected if you move the LO frequency that makes be believe it is direct pick-up, and not a result of an image or mixing process.
              >
              > I suppose it could be pick up in the op-amp part of the main board, but the capacitors C29 / C30 should cause the frequency response to roll off well before the MW broadcast frequency.
              >
              > Last comment, do you have your v9.0 in a screened metal box, or is it just running open on the bench?
              >
              > 73, Bob G8VOI
              >
              >
              > --- In softrock40@yahoogroups.com, "Donald L. Dietmeyer" <dld@> wrote:
              > >
              > > Bob,
              > > I pulled the audio line: no more WIBA on 10 meters. Then I put it
              > > back and
              > > pulled the antenna from the V9.0. Again no more WIBA. I just used
              > > Travelquest
              > > to find that I am about 6 miles from the transmitter. It seems to me
              > > that the
              > > problem is in my V9.0, perhaps the BPF?
              > > Don
              > >
              > > --
              > >
              > > Donald L. Dietmeyer
              > > 2211 Waunona Way
              > > Madison, WI 53713-1619
              > > (608) 222-3663
              > > dld@
              > >
              >
            • g8voip
              Hi Don, Thanks for the update, good to hear you have finally got to the bottom of it. Sometimes these things do defy logic or reason. 73, Bob G8VOI
              Message 6 of 6 , Aug 25, 2009
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                Hi Don,

                Thanks for the update, good to hear you have finally got to the bottom of it. Sometimes these things do defy logic or reason.

                73, Bob G8VOI

                --- In softrock40@yahoogroups.com, "dldietmeyer" <dld@...> wrote:
                >
                > Bob, and all,
                >
                > A local friend who has been informed of my problem and attempts to
                > fix it, suggested "put up a folded dipole, or if you want to keep
                > the bow tie, replace the coax feed line with a balanced transmission
                > line. Could even try zip cord." I did replace the coax with zip
                > cord, and the appearance of WIBA (1310 kHz) at the LO frequency from
                > 25 t0 33 MHz was gone!! There is a local 10 meter beacon so I know
                > the V9 is working on 10 meters.
                >
                > I don't have a good understanding of what was going on, but the
                > shield of the coax was acting as part of the antenna and brining a
                > very strong signal to the V9. It may have been strong enough to
                > couple to the op amps bypassing the BPF and mixer, as you suggested
                > all along.
                >
                > Thanks for your help,
                > Don
                >
                > --- In softrock40@yahoogroups.com, "g8voip" <g8voi.reeves59@> wrote:
                > >
                > > Hi Don,
                > >
                > > Are you using the switched BPF module with the v9.0 RX or the manual plug-in ones?
                > >
                > > If you are using the switched BPF module, which version of the firmware are you using to control the filter module?
                > >
                > > If you are using Fred's v15.10, the 'ABPF' mode is the best one to use as it is compatible with all of the SDR software. Check the three filter cross over points are set to 4, 8 and 16MHz, which is their default state.
                > >
                > > One test you could do is to disconnect the lead linking the main board J3 to the connector on the filter module, and without any jumpers fitted to JP1 or JP2, that will select the band 4, 16 - 30MHz BPF correctly.
                > >
                > > I cannot really think of anything actually with the filter that could allow the MW broadcast through, except perhaps if L11 was open circuit, but even then I find that very unlikely.
                > >
                > > Its the fact that you say it is always at the exact centre frequency, and not affected if you move the LO frequency that makes be believe it is direct pick-up, and not a result of an image or mixing process.
                > >
                > > I suppose it could be pick up in the op-amp part of the main board, but the capacitors C29 / C30 should cause the frequency response to roll off well before the MW broadcast frequency.
                > >
                > > Last comment, do you have your v9.0 in a screened metal box, or is it just running open on the bench?
                > >
                > > 73, Bob G8VOI
                > >
                > >
                > > --- In softrock40@yahoogroups.com, "Donald L. Dietmeyer" <dld@> wrote:
                > > >
                > > > Bob,
                > > > I pulled the audio line: no more WIBA on 10 meters. Then I put it
                > > > back and
                > > > pulled the antenna from the V9.0. Again no more WIBA. I just used
                > > > Travelquest
                > > > to find that I am about 6 miles from the transmitter. It seems to me
                > > > that the
                > > > problem is in my V9.0, perhaps the BPF?
                > > > Don
                > > >
                > > > --
                > > >
                > > > Donald L. Dietmeyer
                > > > 2211 Waunona Way
                > > > Madison, WI 53713-1619
                > > > (608) 222-3663
                > > > dld@
                > > >
                > >
                >
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