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Re: [softrock40] No Image rejection

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  • Albert Gerheim
    (May not be helpful...) When I put mine together, I was convinced it had image problems, because... 1) right near the local oscillator bump , everything comes
    Message 1 of 5 , Dec 29, 2011
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      (May not be helpful...)

      When I put mine together, I was convinced it had image problems, because...

      1) right near the local oscillator "bump", everything comes out symmetrically, and it looks like an image. Reduce the bandwidth of the RX audio filter as much as you can to reduce this effect. 

      2) The images were actually down 20 dB, which is plenty in this world.  However, because of the log scaling of the spectrum, they looked almost as big. 

      3) AM broadcasts came booming through in image.  Again, down 20 dB, but they started out so big...


      The hardware was in perfect health.  Also, in PSDR, there's a way to tune out the images.  I'm not sure I'm using it properly, but it's there. 

      There have been some negative comments on this, but I made a cable with the L/R channels crossed, so I can cross or uncross the jumpers without using the soldering iron.  The cable can still be used for non-studio-quality audio. 


      On Wed, Dec 28, 2011 at 9:10 PM, <ka9lhe@...> wrote:
       

      Ensemble RX/TX:
      I've checked and rechecked solder points and voltages within build instructions. Still getting mirror image using crossed jumpers (RX) and HDSDR as well as Rocky with Delta 44 soundcard. In HDSDR you can choose channel mode (left only, right only, both, I/Q. Left only gives me many signals (obviously no mirror image with one channel). Right only gives me NO signals. Both and I/Q choice results in mirror images.

      The right only: shouldn't I be getting some signal(s)?
      I do not have a scope to check I/Q.

      Any suggestions? HELP

      Mike/KA9LHE




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      Al Gerheim
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