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LO Question

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  • wa1vta01452
    Hi, Just completed the 80/40 SR. Using Rocky to attempt troubleshooting. When the center freq is set to 7046, the actual signal is about 34 khz higher. If I
    Message 1 of 12 , Jan 2, 2010
      Hi,

      Just completed the 80/40 SR. Using Rocky to attempt troubleshooting.
      When the center freq is set to 7046, the actual signal is about 34 khz
      higher. If I generate a signal on 7046 with my IC746pro, it shows up
      on 7080 +/- on the Rocky display. I measured the LO and LO x 4
      frequencies and get the following values:

      DIP SW LO base freq Actual read

      0000 1846 1826 (-20)
      0001 1892 1872 (-20)
      0010 3546 3507 (-39)
      0011 3846 3804 (-42)
      0100 7046 6967 (-79)
      0101 7138 7221 (-83)
      0110 10029 10146 (-117)

      DIP SW LO x 4 Actual read

      0000 7384 7298 (-86)
      0001 7568 7483 (-85)
      0010 14184 14024 (-160)
      0011 15384 15210 (-174)
      0100 28184 27863 (-321)
      0101 28884 28550 (-334)
      0110 40584 40114 (-470)

      What could I look at to see why the frequency seems shifted? Also the 746 signal is way down in signal strength on Rocky. I have
      symmetry around the center frequency as well, seeing at least two, if
      not 4 signal mirror images. What controls the sensitivity of the
      receiver? Can the receiver FULLY function independently if I unplug
      the xmit board and jumper P2 pins 1-5?

      Thanks for any assistance,

      Tom
    • g8voip
      Hi Tom, Those LO frequencies seem to be pretty close to the programmed values. The differences are due to the tolerance of the Si570 master oscillator. The PIC
      Message 2 of 12 , Jan 2, 2010
        Hi Tom,

        Those LO frequencies seem to be pretty close to the programmed values. The differences are due to the tolerance of the Si570 master oscillator.

        The PIC software makes the assumption that the Si570 is running at the default 114.285MHz, where in practice there will be some small error.

        You need to carry out a calibration within Rocky to update the correction factor stored in the Rocky.ini file.

        As you are essentially using a 'fixed' frequency LO, all you need to do is go to the 'Tools' menu and select 'Si570 Calibration'. You will see there is a box to enter the 'true' frequency you are tuned to. Hopefully once you have updated that, the 'dial' frequency will tie up with what you expected.

        If you are not aware, as you have a dual band radio, select 'Multi-band' on the set up DSP tab, and then edit the Rocky.ini file to add all of your centre frequencies. When you run Rocky, you can now select the centre frequency from the pull down to the right of the frequency display. Makes changing bands a lot easier.

        It sounds like you have not optimised the image rejection, hence seeing images each side of the centre frequency. From the 'Tools' menu item, select 'RX I/Q balance'. Make sure both 'Collect Data' and Correct Balance' are checked. Best to do a reset, then the correction curves will gradually build up automatically, or if you have a signal generator, you can speed up the process by stepping a signal across the band and pausing at each step. You should see the 'image' automatically being reduced.

        If that process fails, make sure you have both the I and Q signals being output from the receiver through to the PC. You can see the relative values for the two channels on the bottom line of the Rocky display. Disconnecting either the I or Q, will remove any image rejection present.

        73, Bob G8VOI
      • wa1vta01452
        Bob, thanks for all that. I m not at all sure of what I m doing yet. As a starter, the Si570 Calibration option is grayed out in Rocky.... Tom
        Message 3 of 12 , Jan 2, 2010
          Bob, thanks for all that. I'm not at all sure of what I'm doing yet.
          As a starter, the Si570 Calibration option is grayed out in Rocky....

          Tom


          --- In softrock40@yahoogroups.com, "g8voip" <g8voi.reeves59@...> wrote:
          >
          > Hi Tom,
          >
          > Those LO frequencies seem to be pretty close to the programmed values. The differences are due to the tolerance of the Si570 master oscillator.
          >
          > The PIC software makes the assumption that the Si570 is running at the default 114.285MHz, where in practice there will be some small error.
          >
          > You need to carry out a calibration within Rocky to update the correction factor stored in the Rocky.ini file.
          >
          > As you are essentially using a 'fixed' frequency LO, all you need to do is go to the 'Tools' menu and select 'Si570 Calibration'. You will see there is a box to enter the 'true' frequency you are tuned to. Hopefully once you have updated that, the 'dial' frequency will tie up with what you expected.
          >
          > If you are not aware, as you have a dual band radio, select 'Multi-band' on the set up DSP tab, and then edit the Rocky.ini file to add all of your centre frequencies. When you run Rocky, you can now select the centre frequency from the pull down to the right of the frequency display. Makes changing bands a lot easier.
          >
          > It sounds like you have not optimised the image rejection, hence seeing images each side of the centre frequency. From the 'Tools' menu item, select 'RX I/Q balance'. Make sure both 'Collect Data' and Correct Balance' are checked. Best to do a reset, then the correction curves will gradually build up automatically, or if you have a signal generator, you can speed up the process by stepping a signal across the band and pausing at each step. You should see the 'image' automatically being reduced.
          >
          > If that process fails, make sure you have both the I and Q signals being output from the receiver through to the PC. You can see the relative values for the two channels on the bottom line of the Rocky display. Disconnecting either the I or Q, will remove any image rejection present.
          >
          > 73, Bob G8VOI
          >
        • Alan
          ... From: g8voip Subject: [softrock40] Re: LO Question ... The PIC software should compensate for the Si570 s startup frequency but only if it is 56.32MHz.
          Message 4 of 12 , Jan 2, 2010
            ----- Original Message -----
            From: "g8voip"
            Subject: [softrock40] Re: LO Question


            > Hi Tom,
            >
            > Those LO frequencies seem to be pretty close to the programmed values. The
            > differences are due to the tolerance of the Si570 master oscillator.
            >

            The PIC software should compensate for the Si570's startup frequency but
            only if it is 56.32MHz. There is no simple way to rectify this so Bob's
            remedy will have to be used. (Reprogramming the PIC is possible.)

            >
            > It sounds like you have not optimised the image rejection, hence seeing
            > images each side of the centre frequency.

            If images are very obvious, if both sides are symmetrical then it is likely
            you have a fault. You seem to say the Softrock is not very sensitive? If so,
            then maybe the input transformer is wired wrongly.

            73 Alan G4ZFQ
          • g8voip
            Hi Tom, Sorry, I just had a quick play here and the Si570 calibration is only enabled when the USB Si570 option is used, so not possible to do with the fixed
            Message 5 of 12 , Jan 2, 2010
              Hi Tom,

              Sorry, I just had a quick play here and the Si570 calibration is only enabled when the USB Si570 option is used, so not possible to do with the fixed LO.

              As your LO appears to be very close to the correct frequency, I would have expected your signal to appear in the right place.

              One test worth doing is to set the Rocky LO to 7.046 MHz, and generate a signal at 7.056MHz with your rig. See where that appears relative to the centre frequency.

              73, Bob G8VOI
            • Alan
              ... From: g8voip Subject: [softrock40] Re: LO Question ... The PIC software should compensate for the Si570 s startup frequency but only if it is 56.32MHz.
              Message 6 of 12 , Jan 2, 2010
                ----- Original Message -----
                From: "g8voip"
                Subject: [softrock40] Re: LO Question


                > Hi Tom,
                >
                > Those LO frequencies seem to be pretty close to the programmed values. The
                > differences are due to the tolerance of the Si570 master oscillator.
                >

                The PIC software should compensate for the Si570's startup frequency but
                only if it is 56.32MHz. There is no simple way to rectify this so Bob's
                remedy will have to be used. (Reprogramming the PIC is possible.)

                >
                > It sounds like you have not optimised the image rejection, hence seeing
                > images each side of the centre frequency.

                If images are very obvious, if both sides are symmetrical then it is likely
                you have a fault. You seem to say the Softrock is not very sensitive? If so,
                then maybe the input transformer is wired wrongly.

                In a subsequent post you say the calibration is greyed out. This is probably
                only relevant with USB control, you cannot adjust the frequency of the Si570
                without reprogramming the PIC. Is it a 56.32? it looks as if reprogramming
                will be necessary to get the centre frequencies correct. You will have to
                enter the true frequencies in Rocky's ini file.

                73 Alan G4ZFQ
              • wa1vta01452
                Hi Bob, Initially, I had removed the dip sw and the PIC and connected via USB/i2C adapter, but using PE0FKO CFHGSR software, the SI570 factory settings button
                Message 7 of 12 , Jan 2, 2010
                  Hi Bob,

                  Initially, I had removed the dip sw and the PIC and connected via USB/i2C adapter, but using PE0FKO CFHGSR software, the SI570 factory settings button is grayed out, so gave up. However, the LO appears to be working.

                  When I set the 746 signal to 7010. the Rocky readout is at 7019.9, so it does appear to be fairly close. However, I still have little sensitivity. I do see my 746 signal when I key in AM @ 5 watts out, but have not received any other signal to date.

                  Tom

                  --- In softrock40@yahoogroups.com, "g8voip" <g8voi.reeves59@...> wrote:
                  >
                  > Hi Tom,
                  >
                  > Sorry, I just had a quick play here and the Si570 calibration is only enabled when the USB Si570 option is used, so not possible to do with the fixed LO.
                  >
                  > As your LO appears to be very close to the correct frequency, I would have expected your signal to appear in the right place.
                  >
                  > One test worth doing is to set the Rocky LO to 7.046 MHz, and generate a signal at 7.056MHz with your rig. See where that appears relative to the centre frequency.
                  >
                  > 73, Bob G8VOI
                  >
                • wa1vta01452
                  Hi Alan, Are you speaking of the two toroids on the 80/40 board? One is just a coil, but I could have messed up the bifilar one...will check.. I assume none
                  Message 8 of 12 , Jan 2, 2010
                    Hi Alan,

                    Are you speaking of the two toroids on the 80/40 board? One is just a coil, but I could have messed up the bifilar one...will check.. I assume none of the transmit board components are used during receive.

                    Tom

                    --- In softrock40@yahoogroups.com, "Alan" <alan4alan@...> wrote:
                    >
                    >
                    > ----- Original Message -----
                    > From: "g8voip"
                    > Subject: [softrock40] Re: LO Question
                    >
                    >
                    > > Hi Tom,
                    > >
                    > > Those LO frequencies seem to be pretty close to the programmed values. The
                    > > differences are due to the tolerance of the Si570 master oscillator.
                    > >
                    >
                    > The PIC software should compensate for the Si570's startup frequency but
                    > only if it is 56.32MHz. There is no simple way to rectify this so Bob's
                    > remedy will have to be used. (Reprogramming the PIC is possible.)
                    >
                    > >
                    > > It sounds like you have not optimised the image rejection, hence seeing
                    > > images each side of the centre frequency.
                    >
                    > If images are very obvious, if both sides are symmetrical then it is likely
                    > you have a fault. You seem to say the Softrock is not very sensitive? If so,
                    > then maybe the input transformer is wired wrongly.
                    >
                    > 73 Alan G4ZFQ
                    >
                  • Alan
                    ... From: wa1vta01452 Subject: [softrock40] Re: LO Question ... Yes, the bifilar. There are some detailed instructions on one of Robby s pages. As you have a
                    Message 9 of 12 , Jan 2, 2010
                      ----- Original Message -----
                      From: "wa1vta01452"
                      Subject: [softrock40] Re: LO Question


                      > Are you speaking of the two toroids on the 80/40 board? One is just a
                      > coil, but I could have messed up the bifilar one...will check.. I assume
                      > none of the transmit board components are used during receive.
                      >

                      Yes, the bifilar. There are some detailed instructions on one of Robby's
                      pages.

                      As you have a USB controller all you have to do is use CFGSR. The PIC can be
                      forgotten.

                      73 Alan G4ZFQ
                    • tom
                      Thanks Alan, I will rewind that toroid. I wish the USB connection worked. It does not. CFGSR does not have FACTORY DEFAULT highlighted. Tried several
                      Message 10 of 12 , Jan 2, 2010
                        Thanks Alan, I will rewind that toroid. I wish the USB connection worked. It does not. CFGSR does not have FACTORY DEFAULT highlighted.  Tried several computers and am using the i2C/USB converter.
                         
                        Tom
                         
                        ----- Original Message -----
                        From: Alan
                        Sent: Saturday, January 02, 2010 2:54 PM
                        Subject: Re: [softrock40] Re: LO Question

                         


                        ----- Original Message -----
                        From: "wa1vta01452"
                        Subject: [softrock40] Re: LO Question

                        > Are you speaking of the two toroids on the 80/40 board? One is just a
                        > coil, but I could have messed up the bifilar one...will check.. I assume
                        > none of the transmit board components are used during receive.
                        >

                        Yes, the bifilar. There are some detailed instructions on one of Robby's
                        pages.

                        As you have a USB controller all you have to do is use CFGSR. The PIC can be
                        forgotten.

                        73 Alan G4ZFQ

                      • Alan
                        ... From: tom Subject: Re: [softrock40] Re: LO Question ... I should try to get that going sometime, it s far better than a PIC that is
                        Message 11 of 12 , Jan 2, 2010
                          ----- Original Message -----
                          From: "tom" <loeblt@...>
                          Subject: Re: [softrock40] Re: LO Question


                          >I wish the USB connection worked. It does not. CFGSR does not have FACTORY
                          >DEFAULT highlighted. Tried several computers and am using the i2C/USB
                          >converter.


                          I should try to get that going sometime, it's far better than a PIC that is
                          off tune!

                          73 Alan G4ZFQ
                        • g8voip
                          Hi Tom, Originally you mentioned a 80/40m TX/RX, but if you have the PIC controller, then I assume we are talking about the v6.3 TX/RX? When checking the
                          Message 12 of 12 , Jan 2, 2010
                            Hi Tom,

                            Originally you mentioned a 80/40m TX/RX, but if you have the PIC controller, then I assume we are talking about the v6.3 TX/RX?

                            When checking the receiver, do you have a PA module fitted, otherwise you will need to jumper the aerial connection across to the receive section.

                            The USB to I2C interface is a far better option to use, gives you far more flexibility. Sounds like you possibly did not have the USB driver installed if options were greyed out.

                            Looks like you are really chasing several problems.

                            At least you know the basic Si570 LO is working, as the frequencies generated were near enough spot on for the values programmed in the PIC.

                            The usual problems associated with the transformers is not cleaning off the enamel coating properly.

                            73, Bob G8VOI
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