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Re: SoftRock V6 with AD9951

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  • n3hkn
    John, You seem to have a lot of experience with the DDS60 as a VFO driving the SoftRock series. My experience has been with the V5 where I found the amount of
    Message 1 of 14 , Jul 4, 2006
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      John,
      You seem to have a lot of experience with the DDS60 as a VFO driving
      the SoftRock series. My experience has been with the V5 where I found
      the amount of spurs in the bandpass to be high (amount) enough to set
      the DDS60 aside as a VFO. Do you find the number and amplitude of the
      spurs excessive (used as a VFO) in your experience?

      The one thing I did not do was to put 50ohms across the DDS60. I would
      guess that the resistor should be placed before the 47pf cap??

      Dick N3HKN

      --- In softrock40@yahoogroups.com, John Melton <john.melton@...> wrote:
      >
      > Hi Ben,
      >
      > In all cases I have not populated Xtal/2n3904 oscillator circuit and I
      > have also put a 50 ohm termination across the input from the DDS-60.
      >
      > V4 - DDS-60 input to C8.
      > V5 - DDS-60 input to pin 4 of J1 on QSD board with 47pF cap in series.
      > V6 - DDS-60 input to C7
      > V7 - DDS-60 input to C6
      >
      > Hope that helps,
      >
      > Regards,
      >
      > John g0orx/n6lyt
      >
      > Ben Hall wrote On 07/03/06 23:12,:
      >
      > > Hi John,
      > >
      > > How/where do you connect the DDS-60 to your various versions of the
      > > softrock?
      > >
      > > thanks and 73,
      > > ben, KD5BYB
      > >
      > > John Melton wrote:
      > > > I have a DDS-60 from AMQRP
      > > http://www.amqrp.org/kits/dds60/index.html
      > > <http://www.amqrp.org/kits/dds60/index.html>
      > > > <http://www.amqrp.org/kits/dds60/index.html
      > > <http://www.amqrp.org/kits/dds60/index.html>>
      > > > that I use with several different versions of the SoftRock.
      Apart from
      > > > some spurs, which can be avoided, it works well. Just make sure that
      > > > you have a good 50 ohm termination.
      > > >
      > > > Regards,
      > > >
      > > > John g0orx/n6lyt
      > >
      > >
      >
      >
      > --
      > --
      > John Melton
      > Sun IT CTO
      > Office: +44 1252 421708 (ext 21708)
      > Mobile: +44 7714 708861
      >
    • John Melton
      The 50 ohm termination does help somewhat and, yes, it is before the 47pf cap. There are still frequencies where there are many spurs across the 48/96 KHz
      Message 2 of 14 , Jul 4, 2006
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        The 50 ohm termination does help somewhat and, yes, it is before the
        47pf cap. There are still frequencies where there are many spurs across
        the 48/96 KHz bandwidth but you can easily offset the DDS-60 to a
        frequency that has none or minimal spurs and use the software to tune
        the required frequency.

        I have been experimenting with some code for a version of my Java GUI
        for DttSP that is similar to the spur reduction code in PowerSDR but
        modified for the AD9951. I plan on making that code part of the release
        for DttSP2.

        John

        n3hkn wrote On 07/04/06 14:41,:

        > John,
        > You seem to have a lot of experience with the DDS60 as a VFO driving
        > the SoftRock series. My experience has been with the V5 where I found
        > the amount of spurs in the bandpass to be high (amount) enough to set
        > the DDS60 aside as a VFO. Do you find the number and amplitude of the
        > spurs excessive (used as a VFO) in your experience?
        >
        > The one thing I did not do was to put 50ohms across the DDS60. I would
        > guess that the resistor should be placed before the 47pf cap??
        >
        > Dick N3HKN
        >
        > --- In softrock40@yahoogroups.com
        > <mailto:softrock40%40yahoogroups.com>, John Melton <john.melton@...>
        > wrote:
        > >
        > > Hi Ben,
        > >
        > > In all cases I have not populated Xtal/2n3904 oscillator circuit and I
        > > have also put a 50 ohm termination across the input from the DDS-60.
        > >
        > > V4 - DDS-60 input to C8.
        > > V5 - DDS-60 input to pin 4 of J1 on QSD board with 47pF cap in series.
        > > V6 - DDS-60 input to C7
        > > V7 - DDS-60 input to C6
        > >
        > > Hope that helps,
        > >
        > > Regards,
        > >
        > > John g0orx/n6lyt
        > >
        > > Ben Hall wrote On 07/03/06 23:12,:
        > >
        > > > Hi John,
        > > >
        > > > How/where do you connect the DDS-60 to your various versions of the
        > > > softrock?
        > > >
        > > > thanks and 73,
        > > > ben, KD5BYB
        > > >
        > > > John Melton wrote:
        > > > > I have a DDS-60 from AMQRP
        > > > http://www.amqrp.org/kits/dds60/index.html
        > <http://www.amqrp.org/kits/dds60/index.html>
        > > > <http://www.amqrp.org/kits/dds60/index.html
        > <http://www.amqrp.org/kits/dds60/index.html>>
        > > > > <http://www.amqrp.org/kits/dds60/index.html
        > <http://www.amqrp.org/kits/dds60/index.html>
        > > > <http://www.amqrp.org/kits/dds60/index.html
        > <http://www.amqrp.org/kits/dds60/index.html>>>
        > > > > that I use with several different versions of the SoftRock.
        > Apart from
        > > > > some spurs, which can be avoided, it works well. Just make sure that
        > > > > you have a good 50 ohm termination.
        > > > >
        > > > > Regards,
        > > > >
        > > > > John g0orx/n6lyt
        > > >
        > > >
        > >
        > >
        > > --
        > > --
        > > John Melton
        > > Sun IT CTO
        > > Office: +44 1252 421708 (ext 21708)
        > > Mobile: +44 7714 708861
        > >
        >
        >


        --
        --
        John Melton
        Sun IT CTO
        Office: +44 1252 421708 (ext 21708)
        Mobile: +44 7714 708861
      • datosa2001
        John, I have idea to design I/Q generator with 2 AD9951 or AD9954 to avoid the X4 factor, I have some doubt about the internal AD9954 comparator, did you
        Message 3 of 14 , Jul 4, 2006
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          John,
          I have idea to design I/Q generator with 2 AD9951 or AD9954 to avoid
          the X4 factor, I have some doubt about the internal AD9954
          comparator, did you already try that one? any advantage?

          Davide

          --- In softrock40@yahoogroups.com, John Melton <john.melton@...>
          wrote:
          >
          > The 50 ohm termination does help somewhat and, yes, it is before
          the
          > 47pf cap. There are still frequencies where there are many spurs
          across
          > the 48/96 KHz bandwidth but you can easily offset the DDS-60 to a
          > frequency that has none or minimal spurs and use the software to
          tune
          > the required frequency.
          >
          > I have been experimenting with some code for a version of my Java
          GUI
          > for DttSP that is similar to the spur reduction code in PowerSDR
          but
          > modified for the AD9951. I plan on making that code part of the
          release
          > for DttSP2.
          >
          > John
          >
          > n3hkn wrote On 07/04/06 14:41,:
          >
          > > John,
          > > You seem to have a lot of experience with the DDS60 as a VFO
          driving
          > > the SoftRock series. My experience has been with the V5 where I
          found
          > > the amount of spurs in the bandpass to be high (amount) enough to
          set
          > > the DDS60 aside as a VFO. Do you find the number and amplitude of
          the
          > > spurs excessive (used as a VFO) in your experience?
          > >
          > > The one thing I did not do was to put 50ohms across the DDS60. I
          would
          > > guess that the resistor should be placed before the 47pf cap??
          > >
          > > Dick N3HKN
          > >
          > > --- In softrock40@yahoogroups.com
          > > <mailto:softrock40%40yahoogroups.com>, John Melton <john.melton@>
          > > wrote:
          > > >
          > > > Hi Ben,
          > > >
          > > > In all cases I have not populated Xtal/2n3904 oscillator
          circuit and I
          > > > have also put a 50 ohm termination across the input from the
          DDS-60.
          > > >
          > > > V4 - DDS-60 input to C8.
          > > > V5 - DDS-60 input to pin 4 of J1 on QSD board with 47pF cap in
          series.
          > > > V6 - DDS-60 input to C7
          > > > V7 - DDS-60 input to C6
          > > >
          > > > Hope that helps,
          > > >
          > > > Regards,
          > > >
          > > > John g0orx/n6lyt
          > > >
          > > > Ben Hall wrote On 07/03/06 23:12,:
          > > >
          > > > > Hi John,
          > > > >
          > > > > How/where do you connect the DDS-60 to your various versions
          of the
          > > > > softrock?
          > > > >
          > > > > thanks and 73,
          > > > > ben, KD5BYB
          > > > >
          > > > > John Melton wrote:
          > > > > > I have a DDS-60 from AMQRP
          > > > > http://www.amqrp.org/kits/dds60/index.html
          > > <http://www.amqrp.org/kits/dds60/index.html>
          > > > > <http://www.amqrp.org/kits/dds60/index.html
          > > <http://www.amqrp.org/kits/dds60/index.html>>
          > > > > > <http://www.amqrp.org/kits/dds60/index.html
          > > <http://www.amqrp.org/kits/dds60/index.html>
          > > > > <http://www.amqrp.org/kits/dds60/index.html
          > > <http://www.amqrp.org/kits/dds60/index.html>>>
          > > > > > that I use with several different versions of the SoftRock.
          > > Apart from
          > > > > > some spurs, which can be avoided, it works well. Just make
          sure that
          > > > > > you have a good 50 ohm termination.
          > > > > >
          > > > > > Regards,
          > > > > >
          > > > > > John g0orx/n6lyt
          > > > >
          > > > >
          > > >
          > > >
          > > > --
          > > > --
          > > > John Melton
          > > > Sun IT CTO
          > > > Office: +44 1252 421708 (ext 21708)
          > > > Mobile: +44 7714 708861
          > > >
          > >
          > >
          >
          >
          > --
          > --
          > John Melton
          > Sun IT CTO
          > Office: +44 1252 421708 (ext 21708)
          > Mobile: +44 7714 708861
          >
        • n3hkn
          The first low value resistor I came across was 42 ohms so installed that across the DDS60 output. The spur population is now much less. I do not think that you
          Message 4 of 14 , Jul 5, 2006
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            The first low value resistor I came across was 42 ohms so installed
            that across the DDS60 output. The spur population is now much less.
            I do not think that you could ever simply set your SDR at a place in
            the 48/96khz bandwidth and simply tune the DD60 as you would
            a "normal" VFO. While the spurs are less numerous, such tuning
            produces constant low level audible birdies that could be signals
            (perhaps CW).

            However, as John noted, you can select a region of a band (48 or
            96khz) and tune the DDS to produce minimum/acceptable spurs. Then
            tune as you would if the SDR was xtal controlled. As an example if
            you were interested in PSK you can easily find a setting with spur
            free operation in the 14.070 area. The same for CW (more 48/96khz
            segments) or SSB (many more 48khz/96khz segments). However, for SSB
            some software has notch filtering which allows more general tuning
            with good results even if a spur is setting within the selected
            passband.

            Dick N3HKN



            --- In softrock40@yahoogroups.com, John Melton <john.melton@...>
            wrote:
            >
            > The 50 ohm termination does help somewhat and, yes, it is before
            the
            > 47pf cap. There are still frequencies where there are many spurs
            across
            > the 48/96 KHz bandwidth but you can easily offset the DDS-60 to a
            > frequency that has none or minimal spurs and use the software to
            tune
            > the required frequency.
            >
            > I have been experimenting with some code for a version of my Java
            GUI
            > for DttSP that is similar to the spur reduction code in PowerSDR
            but
            > modified for the AD9951. I plan on making that code part of the
            release
            > for DttSP2.
            >
            > John
            >
            > n3hkn wrote On 07/04/06 14:41,:
            >
            > > John,
            > > You seem to have a lot of experience with the DDS60 as a VFO
            driving
            > > the SoftRock series. My experience has been with the V5 where I
            found
            > > the amount of spurs in the bandpass to be high (amount) enough
            to set
            > > the DDS60 aside as a VFO. Do you find the number and amplitude
            of the
            > > spurs excessive (used as a VFO) in your experience?
            > >
            > > The one thing I did not do was to put 50ohms across the DDS60. I
            would
            > > guess that the resistor should be placed before the 47pf cap??
            > >
            > > Dick N3HKN
            > >
            > > --- In softrock40@yahoogroups.com
            > > <mailto:softrock40%40yahoogroups.com>, John Melton
            <john.melton@>
            > > wrote:
            > > >
            > > > Hi Ben,
            > > >
            > > > In all cases I have not populated Xtal/2n3904 oscillator
            circuit and I
            > > > have also put a 50 ohm termination across the input from the
            DDS-60.
            > > >
            > > > V4 - DDS-60 input to C8.
            > > > V5 - DDS-60 input to pin 4 of J1 on QSD board with 47pF cap in
            series.
            > > > V6 - DDS-60 input to C7
            > > > V7 - DDS-60 input to C6
            > > >
            > > > Hope that helps,
            > > >
            > > > Regards,
            > > >
            > > > John g0orx/n6lyt
            > > >
            > > > Ben Hall wrote On 07/03/06 23:12,:
            > > >
            > > > > Hi John,
            > > > >
            > > > > How/where do you connect the DDS-60 to your various versions
            of the
            > > > > softrock?
            > > > >
            > > > > thanks and 73,
            > > > > ben, KD5BYB
            > > > >
            > > > > John Melton wrote:
            > > > > > I have a DDS-60 from AMQRP
            > > > > http://www.amqrp.org/kits/dds60/index.html
            > > <http://www.amqrp.org/kits/dds60/index.html>
            > > > > <http://www.amqrp.org/kits/dds60/index.html
            > > <http://www.amqrp.org/kits/dds60/index.html>>
            > > > > > <http://www.amqrp.org/kits/dds60/index.html
            > > <http://www.amqrp.org/kits/dds60/index.html>
            > > > > <http://www.amqrp.org/kits/dds60/index.html
            > > <http://www.amqrp.org/kits/dds60/index.html>>>
            > > > > > that I use with several different versions of the SoftRock.
            > > Apart from
            > > > > > some spurs, which can be avoided, it works well. Just make
            sure that
            > > > > > you have a good 50 ohm termination.
            > > > > >
            > > > > > Regards,
            > > > > >
            > > > > > John g0orx/n6lyt
            > > > >
            > > > >
            > > >
            > > >
            > > > --
            > > > --
            > > > John Melton
            > > > Sun IT CTO
            > > > Office: +44 1252 421708 (ext 21708)
            > > > Mobile: +44 7714 708861
            > > >
            > >
            > >
            >
            >
            > --
            > --
            > John Melton
            > Sun IT CTO
            > Office: +44 1252 421708 (ext 21708)
            > Mobile: +44 7714 708861
            >
          • gack.brkkarter
            Hi all, A quick update for the new users with V6.2 RX/TX: Depopulate the Xtal/2n3904 oscillator circuit and interface the DDS-60 input to C45, use the
            Message 5 of 14 , Dec 15, 2007
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              Hi all,

              A quick update for the new users with V6.2 RX/TX:

              Depopulate the Xtal/2n3904 oscillator circuit and interface the DDS-60
              input to C45, use the unpopulated emitter solder point for Q13.

              Todd
              KV1M

              --- In softrock40@yahoogroups.com, John Melton <john.melton@...> wrote:
              >
              > Hi Ben,
              >
              > In all cases I have not populated Xtal/2n3904 oscillator circuit and I
              > have also put a 50 ohm termination across the input from the DDS-60.
              >
              > V4 - DDS-60 input to C8.
              > V5 - DDS-60 input to pin 4 of J1 on QSD board with 47pF cap in series.
              > V6 - DDS-60 input to C7
              > V7 - DDS-60 input to C6
              >
              > Hope that helps,
              >
              > Regards,
              >
              > John g0orx/n6lyt
              >
              > Ben Hall wrote On 07/03/06 23:12,:
              >
              > > Hi John,
              > >
              > > How/where do you connect the DDS-60 to your various versions of the
              > > softrock?
              > >
              > > thanks and 73,
              > > ben, KD5BYB
              > >
              > > John Melton wrote:
              > > > I have a DDS-60 from AMQRP
              > > http://www.amqrp.org/kits/dds60/index.html
              > > <http://www.amqrp.org/kits/dds60/index.html>
              > > > <http://www.amqrp.org/kits/dds60/index.html
              > > <http://www.amqrp.org/kits/dds60/index.html>>
              > > > that I use with several different versions of the SoftRock.
              Apart from
              > > > some spurs, which can be avoided, it works well. Just make sure that
              > > > you have a good 50 ohm termination.
              > > >
              > > > Regards,
              > > >
              > > > John g0orx/n6lyt
              > >
              > >
              >
              >
              > --
              > --
              > John Melton
              > Sun IT CTO
              > Office: +44 1252 421708 (ext 21708)
              > Mobile: +44 7714 708861
              >
            • Alan
              ... From: gack.brkkarter ... What I have done is remove JP2 and JP1. Then a DDS60 (or whatever) can be connected to the centre pin of JP1. Quick and simple
              Message 6 of 14 , Dec 16, 2007
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                ----- Original Message -----
                From: "gack.brkkarter"
                >
                > Depopulate the Xtal/2n3904 oscillator circuit and interface the DDS-60
                > input to C45, use the unpopulated emitter solder point for Q13.

                What I have done is remove JP2 and JP1.
                Then a DDS60 (or whatever) can be connected to the centre pin of JP1.
                Quick and simple to revert to the crystals.

                73 Alan G4ZFQ
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