[hpsdr] The rest of the story

[FRANCIS CARCIA]

Hi All,
  Tonight I married my sdr board running at 455 KHz to a Racal RA6830 DF front end with a 40 khz filter as the output. 
  I think my roofing filters are 20 and 25 KHz. Then I ran the MDS and dynamic range test.
  MDS= -127 dBM.
   
  DR:
  500 Hz           60 dB
  1 KHz.           70 dB
  5 KHz            90 dB
  10 KHz.         100 dB
  20 KHz          110 dB
   
  The SDR standing alone clearly worked better close in. This was due to synthesizer phase noise. Further out the roofing filters take over and were superior to the QSD stand alone.
  So now how do we get the performance of both configurations in one box. 
  I do have quieter synthesizer modules and slightly better second mixer module but the difference isn't that great. frank
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