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Re: [softrock40] SI570 Question

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  • Alan
    ... Subject: [softrock40] SI570 Question ... It seems as if what you see is normal. There will always be harmonics of the Si570 signal. So 3 x 2.34 = 7.02 and
    Message 1 of 11 , Feb 16, 2013
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      ----- Original Message -----
      Subject: [softrock40] SI570 Question


      >I just got the receiver going on my 30/20/17 Ensemble RxTx.
      > The SI570 is driving me crazy.
      >
      > I couldn't find the 30m band so I started dialing around on the TUNE tab of CFGSR. I finally found some signals on 40m by dialing
      > a Requested frequency of either 1.406666 or 2.34.
      >
      > I can hear the local oscillator on about 7.02 when I dial in 2.34 on the tune tab. Like it's multiplying by 3.
      >
      > I can also hear the local oscillator on about 7.033 when I dial in 1.406666 like it's multiplying by 5.
      >

      It seems as if what you see is normal.
      There will always be harmonics of the Si570 signal. So 3 x 2.34 = 7.02 and you will hear signals centred on 7.02.
      And Softrocks will hear outside their expected range.

      Why you do not hear signals on 30m IS possibly a problem. How about the other bands? Make sure they are open, sometimes signals are
      just not there.

      Have you put the DLL in HDSDR? You should be able to tune exactly the same as CFGSR.

      73 Alan G4ZFQ
    • John
      I had the same divide by 3 instead of 4 on my Softrock RXTX 6.3. At a certain frequency (around about 6 MHz) the division jumped from 3 to 4 (or 4 to 3
      Message 2 of 11 , Feb 16, 2013
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        I had the same divide by 3 instead of 4 on my Softrock RXTX 6.3.   At a certain frequency (around about 6 MHz) the division jumped from 3 to 4 (or 4 to 3 depending on tuning direction) This was confirmed by observing the divider outputs using an HP 8560A spectrum analyzer.  The culprit was a leaky C34 the 0.01uF capacitor.  Check the voltage at pin 3 of U9 the divider input (and voltages of other pins of U9 while you are at it)   This info relates to the Softrock RXTX 6.3 not the Ensemble.
         
        John G3UGY
         

        Sent: Saturday, February 16, 2013 7:42 AM
        Subject: [softrock40] SI570 Question

         

        I just got the receiver going on my 30/20/17 Ensemble RxTx.

        BUT BUT

        The SI570 is driving me crazy.

        I couldn't find the 30m band so I started dialing around on the TUNE tab of CFGSR. I finally found some signals on 40m by dialing a Requested frequency of either 1.406666 or 2.34.

        I can hear the local oscillator on about 7.02 when I dial in 2.34 on the tune tab. Like it's multiplying by 3.

        I can also hear the local oscillator on about 7.033 when I dial in 1.406666 like it's multiplying by 5.

        I'm listening using HDSDR but I'm controlling the SI570 using CFGSR.

        Can anyone help me????? THANKS!!!!

        Thanks! N9MS

      • Alan
        ... Subject: Re: [softrock40] SI570 Question I had the same divide by 3 instead of 4 on my Softrock RXTX 6.3. At a certain frequency (around about 6 MHz) the
        Message 3 of 11 , Feb 16, 2013
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          ----- Original Message -----
          Subject: Re: [softrock40] SI570 Question


          I had the same divide by 3 instead of 4 on my Softrock RXTX 6.3. At a certain frequency (around about 6 MHz) the division jumped
          from 3 to 4 (or 4 to 3 depending on tuning direction) This was confirmed by observing the divider outputs using an HP 8560A spectrum
          analyzer. The culprit was a leaky C34 the 0.01uF capacitor.

          John,

          Interesting fault.
          But this "fault" is multiply by 3. It happens because we are dealing with square waves and has been reffered to as "sub harmonic"
          mixing. Used in crystal controlled Softrocks. As an example, using round figures, a 20MHz crystal is divided by 4 and the 3rd
          harmonic of this division appears at the mixer and may be used for 15MHz reception.

          I have presumed that N9MS could have heard the Si570 true fundamental and other harmonics? Unless CFGSR has been misconfigured the
          Si570 will oscillate where CFGSR sets it.

          73 Alan G4ZFQ
        • John
          John, Interesting fault. But this fault is multiply by 3. It happens because we are dealing with square waves and has been reffered to as sub harmonic
          Message 4 of 11 , Feb 16, 2013
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            John,

            Interesting fault.
            But this "fault" is multiply by 3. It happens because we are dealing with square waves and has been reffered to as "sub harmonic"
            mixing. Used in crystal controlled Softrocks. As an example, using round figures, a 20MHz crystal is divided by 4 and the 3rd
            harmonic of this division appears at the mixer and may be used for 15MHz reception.

            I have presumed that N9MS could have heard the Si570 true fundamental and other harmonics? Unless CFGSR has been misconfigured the
            Si570 will oscillate where CFGSR sets it.

            73 Alan G4ZFQ
             
             
             
            Hello Alan,
             
            Yes, looking at the divider outputs on a spectrum analyzer and varying the Si570 frequency reveals a lot.
            At some frequencies the amplitude of harmonics is not far off the amplitude of the wanted frequency.
             
            73 John G3UGY
          • Alan
            ... Subject: Re: [softrock40] SI570 Question John, I m not sure if you understood. To put it bluntly I m saying you are wrong. N9MS has not got a divide by 3
            Message 5 of 11 , Feb 16, 2013
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              ----- Original Message -----
              Subject: Re: [softrock40] SI570 Question


              John,

              I'm not sure if you understood.
              To put it bluntly I'm saying you are wrong.
              N9MS has not got a divide by 3 fault. I do not see how his figures confirm that.
              The reception he gets at 7.02MHz when 2.34MHz tune is set is due to the 3rd harmonic of 2.34MHz = 7.02. The Si570 output will be
              2.34 x 4 =9.36MHz.
              Similarly 1.406666 x 5 = 7.033.

              73 Alan G4ZFQ


              >Interesting fault.
              But this "fault" is multiply by 3. It happens because we are dealing with square waves and has been reffered to as "sub harmonic"
              mixing. Used in crystal controlled Softrocks. As an example, using round figures, a 20MHz crystal is divided by 4 and the 3rd
              harmonic of this division appears at the mixer and may be used for 15MHz reception.

              I have presumed that N9MS could have heard the Si570 true fundamental and other harmonics? Unless CFGSR has been misconfigured the
              Si570 will oscillate where CFGSR sets it.



              Hello Alan,

              Yes, looking at the divider outputs on a spectrum analyzer and varying the Si570 frequency reveals a lot.
              At some frequencies the amplitude of harmonics is not far off the amplitude of the wanted frequency.

              73 John G3UGY
            • John
              Interesting to calculate permutations to see how those frequencies can be arrived at ... I cant look at it until Monday. Not difficult just time consuming.
              Message 6 of 11 , Feb 16, 2013
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                Interesting to calculate permutations to see how those frequencies can be arrived at ... I cant look at it until Monday.
                Not difficult just time consuming.
                 
                John

                From: Alan
                Sent: Saturday, February 16, 2013 2:17 PM
                Subject: Re: [softrock40] SI570 Question

                 


                ----- Original Message -----
                Subject: Re: [softrock40] SI570 Question

                John,

                I'm not sure if you understood.
                To put it bluntly I'm saying you are wrong.
                N9MS has not got a divide by 3 fault. I do not see how his figures confirm that.
                The reception he gets at 7.02MHz when 2.34MHz tune is set is due to the 3rd harmonic of 2.34MHz = 7.02. The Si570 output will be
                2.34 x 4 =9.36MHz.
                Similarly 1.406666 x 5 = 7.033.

                73 Alan G4ZFQ

                >Interesting fault.
                But this "fault" is multiply by 3. It happens because we are dealing with square waves and has been reffered to as "sub harmonic"
                mixing. Used in crystal controlled Softrocks. As an example, using round figures, a 20MHz crystal is divided by 4 and the 3rd
                harmonic of this division appears at the mixer and may be used for 15MHz reception.

                I have presumed that N9MS could have heard the Si570 true fundamental and other harmonics? Unless CFGSR has been misconfigured the
                Si570 will oscillate where CFGSR sets it.

                Hello Alan,

                Yes, looking at the divider outputs on a spectrum analyzer and varying the Si570 frequency reveals a lot.
                At some frequencies the amplitude of harmonics is not far off the amplitude of the wanted frequency.

                73 John G3UGY

              • Zack Widup
                I ve been playing around with my Ensemble II a lot. Although the frequency range is specified to be 1.5 to 30 MHz, I find I can tune the AM band down to 800
                Message 7 of 11 , Feb 16, 2013
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                  I've been playing around with my Ensemble II a lot. Although the
                  frequency range is specified to be 1.5 to 30 MHz, I find I can tune
                  the AM band down to 800 kHz. The filters are probably the limiting
                  factor here, but it seems they don't attenuate that much all the way
                  down to 800 kHz. I can still hear broadcast band stations and DX in
                  that band at night.

                  I can also tune up to 35 MHz or so with it, but there isn't anything
                  to hear up there. :-)

                  73, Zack W9SZ


                  On 2/16/13, Alan <alan4alan@...> wrote:
                  >
                  > ----- Original Message -----
                  > Subject: [softrock40] SI570 Question
                  >
                  >
                  >>I just got the receiver going on my 30/20/17 Ensemble RxTx.
                  >> The SI570 is driving me crazy.
                  >>
                  >> I couldn't find the 30m band so I started dialing around on the TUNE tab
                  >> of CFGSR. I finally found some signals on 40m by dialing
                  >> a Requested frequency of either 1.406666 or 2.34.
                  >>
                  >> I can hear the local oscillator on about 7.02 when I dial in 2.34 on the
                  >> tune tab. Like it's multiplying by 3.
                  >>
                  >> I can also hear the local oscillator on about 7.033 when I dial in
                  >> 1.406666 like it's multiplying by 5.
                  >>
                  >
                  > It seems as if what you see is normal.
                  > There will always be harmonics of the Si570 signal. So 3 x 2.34 = 7.02 and
                  > you will hear signals centred on 7.02.
                  > And Softrocks will hear outside their expected range.
                  >
                  > Why you do not hear signals on 30m IS possibly a problem. How about the
                  > other bands? Make sure they are open, sometimes signals are
                  > just not there.
                  >
                  > Have you put the DLL in HDSDR? You should be able to tune exactly the same
                  > as CFGSR.
                  >
                  > 73 Alan G4ZFQ
                  >
                  >
                • Alan
                  ... Subject: Re: [softrock40] SI570 Question ... Zack, Yes, others have said the receivers work well down to the lowest frequency. You may find a few signals 3
                  Message 8 of 11 , Feb 16, 2013
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                    ----- Original Message -----
                    Subject: Re: [softrock40] SI570 Question


                    > I've been playing around with my Ensemble II a lot. Although the
                    > frequency range is specified to be 1.5 to 30 MHz, I find I can tune
                    > the AM band down to 800 kHz. The filters are probably the limiting
                    > factor here, but it seems they don't attenuate that much all the way
                    > down to 800 kHz. I can still hear broadcast band stations and DX in
                    > that band at night.
                    >

                    Zack,

                    Yes, others have said the receivers work well down to the lowest frequency.
                    You may find a few signals 3 times or maybe 5 times the tuned frequency coming through but usually you have to look carefully.

                    But RXTXs should not be used on transmit outside their design frequency.

                    73 Alan G4ZFQ


                    > I can also tune up to 35 MHz or so with it, but there isn't anything
                    > to hear up there. :-)
                    >
                  • Mike Saeger
                    It s fixed. Too embarrassed to tell the group what I did wrong. Missed reading one paragraph of the Si570 setup. Starting to build the TX portion now. N9MS
                    Message 9 of 11 , Feb 16, 2013
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                      It's fixed. Too embarrassed to tell the group what I did wrong. Missed reading one paragraph of the Si570 setup.

                      Starting to build the TX portion now.

                      N9MS
                    • Alan
                      ... Subject: [softrock40] Re: SI570 Question ... Sorry Mike, you ll have to tell! John and I are both wrong, save us a lengthy discussion of what you might
                      Message 10 of 11 , Feb 17, 2013
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                        ----- Original Message -----
                        Subject: [softrock40] Re: SI570 Question


                        > It's fixed. Too embarrassed to tell the group what I did wrong. Missed reading one paragraph of the Si570 setup.
                        >

                        Sorry Mike, you'll have to tell!
                        John and I are both wrong, save us a lengthy discussion of what you might have missed.
                        Private if you really are that embarrassed:)

                        73 Alan G4ZFQ
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