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Re: [softrock40] KX3 and Si570 tuneing step noise

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  • Alan
    ... Subject: Re: [softrock40] KX3 and Si570 tuneing step noise ... Sid, The current data sheet says Note that changing the DCO frequency outside of the ±3500
    Message 1 of 34 , Dec 7, 2012
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      ----- Original Message -----
      Subject: Re: [softrock40] KX3 and Si570 tuneing step noise


      >
      > There is a signal that is used to hold off the si570 lock until some
      > period after it settles, this signal was missing from the early si570's.
      >

      Sid,

      The current data sheet says
      "Note that changing the DCO frequency
      outside of the ±3500 ppm window will cause the output
      to momentarily stop and restart at any arbitrary point in
      a clock cycle. Devices sensitive to glitches or runt
      pulses may have to be reset once reconfiguration is
      complete."

      Which seems to say that the switch is not likely to be completely smooth.

      I was under the impression that Fred uses the lock code but I still see/hear jumps when large changes are made.
      Don't you?

      73 Alan G4ZFQ
    • Alan
      ... Subject: [softrock40] Re: KX3 and Si570 tuneing step noise ... Paul, Please let us know when you have tested this. And may I remind anyone with a recent
      Message 34 of 34 , Jan 4, 2013
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        ----- Original Message -----
        Subject: [softrock40] Re: KX3 and Si570 tuneing step noise


        > I have built some three standalone SI570 based oscillators and they all suffer from tuning noise, as you claim.
        >
        > I have built another one who claimS to have eliminated this noise, but I have not tested it yet. He claims to have adjusted the
        > Freeze M DCO:
        >

        Paul,

        Please let us know when you have tested this.

        And may I remind anyone with a recent Softrock with a Si570 manufactured since the beginning of 2011 that an AVR USB controller with
        V 15.15 firmware has the Freeze_M feature. The AVR would need replacing because Tony still uses V 15.12. Fred would be very
        interested if this could be tested.

        73 Alan G4ZFQ

        > http://cbjohn.com/aa0zz/index.html
        >

        >>
        >> Yes that's what got me thinking, looking at the block diagram of the KX3
        >> Hi Fred,
        >> which can be downloaded at the address below
        >> http://www.elecraft.com/manual/KX3%20Manual%20Block%20Diagram.pdf is
        >>
        >> It looks almost like a softrock rx from the front end filters to the
        >> opamp before the DSP,
        >> I have searched for the schematic but no luck so far. If anyone has a
        >> KX3 can you please
        >> verify that on large tuning steps there is no chuffing . hickups ?
        >>
        >> Kelvin
        >>
        >> > I don't think the Freeze-M bit will remove the hick-up of the
        >> receiver,
        >> > for changing freq. (at TX (fsk) it is mandatory!), it can make the
        >> time a
        >> > little smaller, maybe.
        >> > At the block schema the mixing of the KX3 looks like the softrock,
        >> even
        >> > with the 2m osc signal from the si570. I expect there is no detail
        >> internal
        >> > schema available. When using the I&Q outputs on a PC with HDSDR it
        >> > maybe easier to see on the screen.
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