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28360Re: Troubleshooting Softrock lite RX - FIXED!!

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  • norman.billingham
    Dec 3, 2008
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      Hi Tony

      Checka all capacitor and rseitance values this afternoon and all
      seemed OK. Despite having inspected everything under 10X
      magnifcation and found no problems, I decided before yanking
      components to flux everything around the mixer and op amps and touch
      up every joint with a hot iron and it came to life - must have been a
      joint that was OK for DC but not AC as all voltages were OK.

      It's sitting on the bench putting out about 1.6V of I and Q from
      about 40mV RF in.

      Anyway - thanks again for all the help.

      Any news on when I'm likely to get the Si570 for my V9 kit? Ordered
      on October 8

      73 Norman

      --- In softrock40@yahoogroups.com, "Tony Parks" <kb9yig@...> wrote:
      > Hi Norman,
      > With DC gain of each op-amp about right, it seems that R9 has a
      larger resistance than 10 ohms, or C14 has more capacitance than 220
      pF, or there is an AC load on the pin 1 output of U5. (Also still
      the possibility there is a problem with U5.) I would suggest
      removing C16 first to see if the AC voltage at pin 1 of U5 increases
      with the RF test signal input you are using. Next, remove C14.
      > 73,
      > Tony KB9YIG
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