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Troubleshooting 80/40 RXTX 6.2- Oscillator Circuit

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  • keithlebaron
    All my voltages and resistances check out fine. Nothing happened when I connected it to the sound card. Intuitively, I decided to start at the oscillator
    Message 1 of 4 , Sep 2 9:43 AM
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      All my voltages and resistances check out fine. Nothing happened when I connected it to the sound card. Intuitively, I decided to start at the oscillator circuit.
      At the emitter of Q13 I am measuring about 5 mv Peak toPeak
      At the emitter of Q14 I am measuring about 1 volt Peak to Peak but  is offset 2.2 volts above ground.

      Where to I hit the hammer (or where/what do I do to fix this)?

      I went back through the past files to early July, thinking I had read a post(s) regarding the oscillator circuit but could not find the post.

      73,
      Keith


    • Tony Parks
      Hi Keith, What DC voltage are you seeing at the base and emitter of Q13? Also, I think you must mean that the collector of Q14 is at a DC voltage of 2.2 volts
      Message 2 of 4 , Sep 2 10:27 AM
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        Hi Keith,
         
        What DC voltage are you seeing at the base and emitter of Q13?  Also, I think you must mean that the collector of Q14 is at a DC voltage of 2.2 volts since the emitter of Q14 is connected to the +5 volt supply line.
         
        The oscillator signal at the emitter of  Q13 should be much lartger than you are measuring.
         
        73,
        Tony KB9YIG
        ----- Original Message -----
        Sent: Sunday, September 02, 2007 12:43 PM
        Subject: [softrock40] Troubleshooting 80/40 RXTX 6.2- Oscillator Circuit

        All my voltages and resistances check out fine. Nothing happened when I connected it to the sound card. Intuitively, I decided to start at the oscillator circuit.
        At the emitter of Q13 I am measuring about 5 mv Peak toPeak
        At the emitter of Q14 I am measuring about 1 volt Peak to Peak but  is offset 2.2 volts above ground.

        Where to I hit the hammer (or where/what do I do to fix this)?

        I went back through the past files to early July, thinking I had read a post(s) regarding the oscillator circuit but could not find the post.

        73,
        Keith


      • keithlebaron
        Hi Tony, You are correct. It was the collector of Q14 that I should have stated. The voltage on Q13 measures C 4.87v B 2.355 v E 1.770 v 73, Keith, W9KGY
        Message 3 of 4 , Sep 2 11:54 AM
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          Hi Tony,

          You are correct. It was the collector of Q14 that I should have stated.

          The voltage on Q13 measures
          C   4.87v
          B   2.355 v
          E   1.770 v

          73,
          Keith, W9KGY

          Tony Parks wrote:

          Hi Keith,
           
          What DC voltage are you seeing at the base and emitter of Q13?  Also, I think you must mean that the collector of Q14 is at a DC voltage of 2.2 volts since the emitter of Q14 is connected to the +5 volt supply line.
           
          The oscillator signal at the emitter of  Q13 should be much lartger than you are measuring.
           
          73,
          Tony KB9YIG
          ----- Original Message -----
          Sent: Sunday, September 02, 2007 12:43 PM
          Subject: [softrock40] Troubleshooting 80/40 RXTX 6.2- Oscillator Circuit

          All my voltages and resistances check out fine. Nothing happened when I connected it to the sound card. Intuitively, I decided to start at the oscillator circuit.
          At the emitter of Q13 I am measuring about 5 mv Peak toPeak
          At the emitter of Q14 I am measuring about 1 volt Peak to Peak but  is offset 2.2 volts above ground.

          Where to I hit the hammer (or where/what do I do to fix this)?

          I went back through the past files to early July, thinking I had read a post(s) regarding the oscillator circuit but could not find the post.

          73,
          Keith



          No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.484 / Virus Database: 269.13.2/983 - Release Date: 9/1/2007 4:20 PM
        • keithlebaron
          Hi Tony, I ve remeasured some voltages and here are some observations. Q13: 550 mv P-P on emitter Q14: 1 V P-P on collector/ 2.2 volts DC offset U5: Do not
          Message 4 of 4 , Sep 5 8:38 AM
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            Hi Tony,

            I've remeasured some voltages and here are some observations.

            Q13: 550 mv P-P on emitter
            Q14: 1 V P-P on collector/ 2.2 volts DC offset

            U5: Do not understand why I was seeing 4 V P-P on pins 8 and 9.

            Please advise next step.

            73,
            Keith, W9KGY


            keithlebaron wrote:

            Hi Tony,

            You are correct. It was the collector of Q14 that I should have stated.

            The voltage on Q13 measures
            C   4.87v
            B   2.355 v
            E   1.770 v

            73,
            Keith, W9KGY

            Tony Parks wrote:

            Hi Keith,
             
            What DC voltage are you seeing at the base and emitter of Q13?  Also, I think you must mean that the collector of Q14 is at a DC voltage of 2.2 volts since the emitter of Q14 is connected to the +5 volt supply line.
             
            The oscillator signal at the emitter of  Q13 should be much lartger than you are measuring.
             
            73,
            Tony KB9YIG
            ----- Original Message -----
            Sent: Sunday, September 02, 2007 12:43 PM
            Subject: [softrock40] Troubleshooting 80/40 RXTX 6.2- Oscillator Circuit

            All my voltages and resistances check out fine. Nothing happened when I connected it to the sound card. Intuitively, I decided to start at the oscillator circuit.
            At the emitter of Q13 I am measuring about 5 mv Peak toPeak
            At the emitter of Q14 I am measuring about 1 volt Peak to Peak but  is offset 2.2 volts above ground.

            Where to I hit the hammer (or where/what do I do to fix this)?

            I went back through the past files to early July, thinking I had read a post(s) regarding the oscillator circuit but could not find the post.

            73,
            Keith



            No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.484 / Virus Database: 269.13.2/983 - Release Date: 9/1/2007 4:20 PM

            No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.484 / Virus Database: 269.13.2/983 - Release Date: 9/1/2007 4:20 PM
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