Loading ...
Sorry, an error occurred while loading the content.

Re: SoftRock V6 with AD9951

Expand Messages
  • 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 1 of 14 , Jul 4, 2006
    • 0 Attachment
      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 2 of 14 , Jul 5, 2006
      • 0 Attachment
        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 3 of 14 , Dec 15, 2007
        • 0 Attachment
          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 4 of 14 , Dec 16, 2007
          • 0 Attachment
            ----- 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
          Your message has been successfully submitted and would be delivered to recipients shortly.