[eagle] Re: 70 cm Receiver - Replacing U8 made no difference

[John B. Stephensen]

That matching network has the largest impedance transformation so it may be that it is not accurate enough. I'm looking onto changing the second mixer to something that will consume less power and a mixer with an input impedance closer to 200 ohms might solve this problem. I'm considering moving the RF amplifier and first mixer to a separate box so that we can keep the SAW filters warm (at least -30 C) during eclipses.

73,

John
KD6OZH
  ----- Original Message ----- 
  From: Juan Rivera 
  To: John B. Stephensen 
  Cc: 'EAGLE' ; Bill Ress ; Dave Black (Home) ; Dave Black (Work) ; Dave hartzell ; David Smith ; Don Ferguson ; Juan. Rivera (Home) ; Juan.Rivera (Work) ; Samsonoff at Mac. Com 
  Sent: Tuesday, June 05, 2007 02:56 UTC
  Subject: 70 cm Receiver - Replacing U8 made no difference


  John,

   

  Changing the second Mixer, U8 had no affect on the passband ripple.  We've now replaced the matching network and the mixer with no change at all.  What do you suggest for the next move?

   

  Please see the Eagle Receiver page http://www.amsat.org/amsat-new/eagle/EaglePedia/index.php/U-Band_Receiver

  Under Project Status I've started a new log titled Troubleshooting Resumes.  It has before and after pictures of the passband ripple

   

  73,

   

  Juan - WA6HTP
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