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Need Help with Ensemble RX Build before I Throw it Away

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  • chris.kucera@ymail.com
    Hi I have been building an Ensemble RX for about a week now. I have been following the instructions and everything has been testing correctly per the
    Message 1 of 9 , May 26, 2014
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      Hi

      I have been building an Ensemble RX for about a week now.  I have been following the instructions and everything has been testing correctly per the instructions until now.  I just built the QSD stage and now I have a problem.  All my voltages on U10 are very wrong.  It seems like something is loading down the voltages but I don't know what.  I have done some research on this forum and have found a post from someone with a similar problem but it hasn't helped me with my issue.

      Here's my voltages on U10
      Pin 1, 8, 9, 10, 13, 15   0 volts
      Pin 2, 14  2.5 Volts
      Pin 3, 4, 5, 6, 7, 11, 12  .11 volts
      Pin 16   5 volts

      My voltage at the junction of R27 and R28 is .12 volts.

      At first I thought I had messed up T3 either by winding it wrong or possibly shorting the windings.  I removed it and my voltage at R27 and R28 came up to 2.5 volts.  I rewound and replaced T3 and tested again.  My voltage at R27 and R28 went back to .12 volts.  I verified correct voltage at R23 and R24 with the new transformer.

      The next thing I tried was to remove R25 and R26.  When I did that, my voltages changed.  R27 and R28 went back to 2.5 volts but U10 is still a mess.  The new voltages on U10 are

      Pin 1, 8, 9, 10, 13, 15  0 volts
      Pin 2, 14  2.5 volts
      Pin 3, 6, 11, 12  .26 volts
      Pin 4, 5, 7  2.1 volts
      Pin 16  5 volts

      I am really getting confused and do not know what to try next.  I have inspected the board for shorts and couldn't find any.  I removed U10 and made sure nothing was shorted underneath and it's fine as well.  I verified all my components are correct in case I may have put a wrong resistor in somewhere.  Everything looks fine.  I have not built the OP amps yet so I don't think R30 or R31 could be the problem.

      Has anyone had this problem?  I really could use some help.  I'm ready to pitch the radio into the bin.

      Chris


    • warrenallgyer
      Chris Let me know when trash collection day is in your neighborhood. I will be coming by...... :-) Seriously, you likely have a short to ground on the U10 side
      Message 2 of 9 , May 26, 2014
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        Chris

        Let me know when trash collection day is in your neighborhood. I will be coming by...... :-)

        Seriously, you likely have a short to ground on the U10 side of R26 and R25. With no power on the radio check the resistance from pins 3,6,11, and 12 to ground. I am betting one or more are showing zero ohms.

        You may need a strong light and a magnifier. It only takes a whisker of a trace to produce a short. If your U10 chip is indeed good then there is undoubtedly a short to ground somewhere in this vicinity.

        Warren Allgyer
        9V1TD
      • MIKE DURKIN
        Or a smart phone to take pics .. then ZOOM in to the trouble area ... you will be suprised on the resolution of those phones ... MIke KC7NOA To:
        Message 3 of 9 , May 26, 2014
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          Or a smart phone to take pics .. then ZOOM in to the trouble area ... you will be suprised on the resolution of those phones ...

          MIke KC7NOA


          To: softrock40@yahoogroups.com
          From: softrock40@yahoogroups.com
          Date: Mon, 26 May 2014 10:17:37 -0700
          Subject: [softrock40] Re: Need Help with Ensemble RX Build before I Throw it Away

           
          Chris

          Let me know when trash collection day is in your neighborhood. I will be coming by...... :-)

          Seriously, you likely have a short to ground on the U10 side of R26 and R25. With no power on the radio check the resistance from pins 3,6,11, and 12 to ground. I am betting one or more are showing zero ohms.

          You may need a strong light and a magnifier. It only takes a whisker of a trace to produce a short. If your U10 chip is indeed good then there is undoubtedly a short to ground somewhere in this vicinity.

          Warren Allgyer
          9V1TD
        • chris.kucera@ymail.com
          I found the problem. I had R30 and R31 pointed the wrong way. Guess I was a little tired last night when I was building it. I fixed the problem and all my
          Message 4 of 9 , May 26, 2014
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            I found the problem.  I had R30 and R31 pointed the wrong way.  Guess I was a little tired last night when I was building it.  I fixed the problem and all my voltages are correct now.  I completed the build and am fiddling with it using HDSDR.  My only problem now is the frequency is off.  I'm picking up WWV at 15.019 MHZ instead of 15 MHZ.

            Chris
          • MIKE DURKIN
            That s just a calibration issue ... you will find it ... To: softrock40@yahoogroups.com From: softrock40@yahoogroups.com Date: Mon, 26 May 2014 14:16:47 -0700
            Message 5 of 9 , May 26, 2014
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              That's just a calibration issue ... you will find it ...


              To: softrock40@yahoogroups.com
              From: softrock40@yahoogroups.com
              Date: Mon, 26 May 2014 14:16:47 -0700
              Subject: [softrock40] Re: Need Help with Ensemble RX Build before I Throw it Away

               
              I found the problem.  I had R30 and R31 pointed the wrong way.  Guess I was a little tired last night when I was building it.  I fixed the problem and all my voltages are correct now.  I completed the build and am fiddling with it using HDSDR.  My only problem now is the frequency is off.  I'm picking up WWV at 15.019 MHZ instead of 15 MHZ.

              Chris
            • John Williams
              Alan has a page on his site on how to calibrate it... Do it this way and it will be spot on for HDSDR, WSPR, etc. Software calibrate it in HDSDR or PSDR and it
              Message 6 of 9 , May 26, 2014
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                Alan has a page on his site on how to calibrate it... Do it this way and it will be spot on for HDSDR, WSPR, etc. Software calibrate it in HDSDR or PSDR and it will be incorrect on every other program...

                https://sites.google.com/site/g4zfqradio/calibrating-the-softrock-si570-usb-controller

                John AC9HY
                On 5/26/2014 4:16 PM, chris.kucera@... [softrock40] wrote:
                 

                I found the problem.  I had R30 and R31 pointed the wrong way.  Guess I was a little tired last night when I was building it.  I fixed the problem and all my voltages are correct now.  I completed the build and am fiddling with it using HDSDR.  My only problem now is the frequency is off.  I'm picking up WWV at 15.019 MHZ instead of 15 MHZ.

                Chris


              • chris.kucera@ymail.com
                Got the cal figured out, now I have birdies all through it about every 30 Khz.
                Message 7 of 9 , May 26, 2014
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                  Got the cal figured out, now I have birdies all through it about every 30 Khz.
                • warrenallgyer
                  Chris Regularly spaced birdies across a wide band of frequencies may be a sign of overload. There are two places in the system that can overload, the receive
                  Message 8 of 9 , May 26, 2014
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                    Chris

                    Regularly spaced birdies across a wide band of frequencies may be a sign of overload. There are two places in the system that can overload, the receive op amps and the sound card input.

                    With your VOM in the AC volts mode, measure the voltage at the hairpins of R30/31 while the birdies are in evidence. The signal here is dependent upon the level of RF signal delivered from the antenna connector, through the bandpass filters, to the mixer. 1.8 volts or higher AC at this point is an indication of op amp overload and is likely the result of a strong signal overloading the input of the receiver. Verify this by removing the antenna and the birdies should disappear.

                    If you measure less than 1.8 volts (it will often be the case that you will measure nothing at this point if no strong signals are present), and you still have birdies, the next suspect is your sound card. Make sure you are using the "Line" input and not the "Mic". Go to the sound control panel for Recording devices and reduce the input gain of the card.

                    If neither of these steps work then you have a different problem than the one I suspect.

                    Warren Allgyer
                    9V1TD
                  • Curt Carpenter
                    ... I had a problem similar to this and it turned out to be related to a switching power supply that was generating all sorts of noise. Changed to a linear
                    Message 9 of 9 , May 27, 2014
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                      On 5/26/2014 5:43 PM, chris.kucera@... [softrock40] wrote:
                       

                      Got the cal figured out, now I have birdies all through it about every 30 Khz.


                      I had a problem similar to this and it turned out to be related to a switching power supply that was generating all sorts of noise.   Changed to a linear supply and the problem went away.
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