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RXTX sparking and arcing (still having waveform issues)

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  • hawhite456
    I had a question about the completed softrock kit. I put the kit together, and found out that the waveform shown in HDSDR was uniform across all bands and
    Message 1 of 11 , Apr 10 10:10 AM
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      I had a question about the completed softrock kit.  I put the kit together, and found out that the waveform shown in HDSDR was uniform across all bands and modes.  In addition, when I go to test the components with a voltmeter, I receive arcing and sparks off the board.  I know the board is low voltage, but why is the radio doing this.
    • Alan
      Original Message ----- Subject: [softrock40] RXTX sparking and arcing (still having waveform issues) ... You must have an intermittent short circuit on the
      Message 2 of 11 , Apr 10 11:17 AM
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        Original Message -----
        Subject: [softrock40] RXTX sparking and arcing (still having waveform issues)


        > when I go to test the components with a voltmeter, I receive arcing and sparks off the board. I know the board is low voltage,
        > but why is the radio doing this.

        You must have an intermittent short circuit on the power line. Probably the 12V line.
        Look carefully with a glass, maybe a solder splash or even a badly etched track.

        73 Alan G4ZFQ
      • n5bz@ymail.com
        In order to see sparking/arcing, you need to either have considerable CURRENT flowing or a significant voltage difference between your RXTX and the voltmeter.
        Message 3 of 11 , Apr 10 4:17 PM
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          In order to see sparking/arcing, you need to either have considerable CURRENT flowing or a significant voltage difference between your RXTX and the voltmeter.

          What is connected to the RXTX? 
          What is connected to the voltmeter?

          You might have a significant RF pickup by an antenna (any nearby transmitters?), or a static electric pickup by an antenna (dust storms or wind or rain can build up a charge).
          The leads on the meter could act as an antenna for some frequencies.

          A switching supply that does NOT have a good earth ground on it can couple AC from the power line onto the 'GROUND' of the powersupply output.
          When I run my finger over the metal grill on my laptop, I can feel a small 'buzz' from ac coupled through the power supply. There is no 'earth ground' on the AC wall plug. I am careful NOT to use the laptop while near an earth ground! A voltmeter shows ~5 v ac when I touch one of the leads to the grill and stretch the other out.

          Try battery power on the TXRX.
        • H. Andrew White
          Thank you, I am doing much better now.  I am still wondering why I cannot get the wave form to come out correctly though. On Thursday, April 10, 2014 7:17 PM,
          Message 4 of 11 , Apr 11 11:47 AM
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            Thank you, I am doing much better now.  I am still wondering why I cannot get the wave form to come out correctly though.
            On Thursday, April 10, 2014 7:17 PM, "n5bz@..." <n5bz@...> wrote:
             
            In order to see sparking/arcing, you need to either have considerable CURRENT flowing or a significant voltage difference between your RXTX and the voltmeter.

            What is connected to the RXTX? 
            What is connected to the voltmeter?

            You might have a significant RF pickup by an antenna (any nearby transmitters?), or a static electric pickup by an antenna (dust storms or wind or rain can build up a charge).
            The leads on the meter could act as an antenna for some frequencies.

            A switching supply that does NOT have a good earth ground on it can couple AC from the power line onto the 'GROUND' of the powersupply output.
            When I run my finger over the metal grill on my laptop, I can feel a small 'buzz' from ac coupled through the power supply. There is no 'earth ground' on the AC wall plug. I am careful NOT to use the laptop while near an earth ground! A voltmeter shows ~5 v ac when I touch one of the leads to the grill and stretch the other out.

            Try battery power on the TXRX.


          • n5bz@ymail.com
            What did you do that made things better? What do you mean by waveform issues ? Are you using an oscilloscope to observe a waveform? If you are using a line
            Message 5 of 11 , Apr 23 1:58 AM
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              What did you do that made things better?

              What do you mean by 'waveform issues'?

              Are you using an oscilloscope to observe a waveform?
               
              If you are using a line powered scope, make sure that it is plugged into the SAME power strip as the RXTX power supply.

              Otherwise, you can have ground loop currents flowing and the scope will add those to the waveform you observe.

              If you are talking about something displayed on your computer screen by the software, please describe exactly what you are doing and observing.  Exactly what software are you using, how is the RXTX connected to your computer, and so forth.
            • hawhite456
              Not having power issues any more. Waveform issues happen in HDSDR and other SDR programs when I try to view the Waterfall image. I receive the attached image
              Message 6 of 11 , Apr 23 8:12 AM
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                Not having power issues any more.

                Waveform issues happen in HDSDR and other SDR programs when I try to view the Waterfall image.  I receive the attached image constantly, no matter what frequency I tune to in my super-band.

                I connect the usb to the computer, the power cable to the power strip the computer runs on, and two 3.5mm audio cables between the board and a creative xfi pro.

                I just want to know how to receive any signals at this point, then I will want to work on transmit!
              • hawhite456
                Here is the image I forgot to post.
                Message 7 of 11 , Apr 23 8:12 AM
                Here is the image I forgot to post.
              • Alan
                Original Message ----- Subject: [softrock40] Re: RXTX sparking and arcing (still having waveform issues) ... You are connecting the Softrock Line In to the
                Message 8 of 11 , Apr 24 12:00 AM
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                  Original Message -----
                  Subject: [softrock40] Re: RXTX sparking and arcing (still having waveform issues)


                  >
                  > I connect the usb to the computer, the power cable to the power strip the computer runs on, and two 3.5mm audio cables between the
                  > board and a creative xfi pro.
                  >

                  You are connecting the Softrock "Line In" to the soundcard Line In?
                  Have you gone over all the voltages and tests so far? "Sparking and arcing" worries me.

                  73 Alan G4ZFQ
                • H. Andrew White
                  On mine, Line in from softrock goes to line out from soundcard.  When I connected softrock to power, and tried to read voltage, on some components like U4 I
                  Message 9 of 11 , Apr 29 11:37 AM
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                    On mine, Line in from softrock goes to line out from soundcard. 

                    When I connected softrock to power, and tried to read voltage, on some components like U4 I received arcing off the board when I tried to measure voltage.
                    On Thursday, April 24, 2014 3:00 AM, Alan <alan4alan@...> wrote:
                     
                    Original Message -----
                    Subject: [softrock40] Re: RXTX sparking and arcing (still having waveform issues)

                    >
                    > I connect the usb to the computer, the power cable to the power strip the computer runs on, and two 3.5mm audio cables between the
                    > board and a creative xfi pro.
                    >

                    You are connecting the Softrock "Line In" to the soundcard Line In?
                    Have you gone over all the voltages and tests so far? "Sparking and arcing" worries me.

                    73 Alan G4ZFQ



                  • MICHAEL TALLENT
                    Then that would be wrong. The connector labeled “line in” goes to the Line in on your sound card, it is the I/Q output signal from the receiver. The
                    Message 10 of 11 , Apr 29 12:10 PM
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                      Then that would be wrong.  The connector labeled “line in” goes to the Line in on your sound card, it is the I/Q output signal from the receiver.
                       
                      The connector labeled “ line out” goes to the line out of your sound card and is the software generated transmit signal from your sound card.
                       
                      Mike  W6MXV
                       
                      Sent: Tuesday, April 29, 2014 2:37 PM
                      Subject: Re: [softrock40] Re: RXTX sparking and arcing (still having waveform issues)
                       


                      On mine, Line in from softrock goes to line out from soundcard.
                       
                      When I connected softrock to power, and tried to read voltage, on some components like U4 I received arcing off the board when I tried to measure voltage.
                      On Thursday, April 24, 2014 3:00 AM, Alan <alan4alan@...> wrote:
                       
                      Original Message -----
                      Subject: [softrock40] Re: RXTX sparking and arcing (still having waveform issues)

                      >
                      > I connect the usb to the computer, the power cable to the power strip the computer runs on, and two 3.5mm audio cables between the
                      > board and a creative xfi pro.
                      >

                      You are connecting the Softrock "Line In" to the soundcard Line In?
                      Have you gone over all the voltages and tests so far? "Sparking and arcing" worries me.

                      73 Alan G4ZFQ



                    • Steve Arntz
                      What are you using for a meter to test the voltages. If it is A/C line powered, you may want to try a meter that is battery powered. I typically used the
                      Message 11 of 11 , Apr 30 7:55 AM
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                        What are you using for a meter to test the voltages.  If it is A/C line powered, you may want to try a meter that is battery powered.  I typically used the audio jack ground for my meter except for measuring stuff in the galvanically isolated area on the first part of the build.
                         
                        73 Steve, KM5HT
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