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Re: [softrock40] KX3 and Si570 tuneing step noise

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  • Alan
    ... Sid, Yes, I always thought that the early Kees controller did not use the smooth tuning . I only have the early version. I m not sure if this was
    Message 1 of 34 , Dec 10, 2012
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      >
      > With the SDR-Widget it was horrible enough to mask audio when tuning
      > with the rotary encoder, same on the SR v6.3 when used with the K5BCQ
      > si570 Controller but back then I thought it was just noise generated by
      > the rotary encoder.

      Sid,

      Yes, I always thought that the early Kees controller did not use the "smooth tuning". I only have the early version.
      I'm not sure if this was something that SiLabs did not document in their first data sheet. Maybe Fred can comment on that.

      But with today's AVR dragging the scale in HDSDR so the LO changes continuously? Yes the noise floor does rise 10dB or so. Difficult
      to be sure why. Now, this could be what you mean.
      And stepping 10Hz at a time sometimes causes a noise rise. "Even relatively small changes in output frequency may require writing
      more than 1 RFREQ register"

      This is with AVR with V 15.15 and an old Si570.

      OK, Sid, you have convinced me. I obviously operate a glitch filter. Although most of my interest is at LF when antenna noise
      probably masks this.

      But what does the KX3 do on large changes?

      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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