[Premium-Rx] Racal 6793A noise

[John Reed]

  ----- Original Message ----- 
  From: Carcia, Frank A. HS 
  To: 'John Reed' ; Premium RX 
  Sent: Tuesday, March 02, 2004 9:59 AM
  Subject: RE: [Premium-Rx] Racal 6793A noise

  The synthesizer noise on the RA6793A is in line with other premium receivers and isn't the noise I'm referring to.  The bad noise is digital in nature and comes from the CPU board.  Somehow it gets into the front end or IF circuits.

  John


  John,
  I wonder if you and I were comparing synthesizer phase noise about a year ago. I thought someone measured the synthesizer
  phase noise as being acceptable. I think we compared it to the RA6830 and Harris 590A which was a bit cleaner. ????
  Digital noise is another issue. fc
    -----Original Message-----
    From: John Reed [mailto:jreed at alum.mit.edu]
    Sent: Tuesday, March 02, 2004 11:06 AM
    To: Premium RX
    Subject: Re: [Premium-Rx] Racal 6793A noise



      ----- Original Message ----- 
      From: Jeff Anderson 
      To: Premium Receivers 
      Sent: Tuesday, March 02, 2004 9:21 AM
      Subject: [Premium-Rx] Racal 6793A noise

      The RA6793A is one noisy receiver!  I think most of the noise comes from the CPU board.  I built a shield to go around this board.  That helped some, but not nearly enough.  The noise is so bad it limits the sensitivity quite a bit.  I haven't compared it to an RA6790, but compared to an old RA6772E, there is a big difference.  The RA6772E is quiet.

      John Reed


      I was recently comparing the performance of my Racal 6793A to my Racal 6790A, and I noticed that the 6793A was noticably noisier than the 6790A.

      I'm not sure what the problem is (yet).  The 6793A seemed a bit less sensitive, so it may  just be that it needs an alignment to bring up the signal level with respect to internal noise.

      Another possibility is that the synthesizer is noisier in the 6793A.

      But before I dig into it, I was wondering...

      o  Has anyone compared the 6790A to the 6793A?  If so, what were the results?

      o  Does anyone have an alignment procedure for either the 6790A or the 6793A?

      Thanks!

      - Jeff, WA6AHL




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