[hpsdr] Mixers

[FRANCIS CARCIA]

I have a couple 8901s kicking around that came as samples. The problem with them is you are stuck with ring configuration. It will give you IP3 of near 40 dB with a lot of lo drive.
  Building a good lo amplifier is a no brainer. Square wave drive at that voltage is a different issue.
  My RA6830 uses a SD5000 in a ring and the first roofing filter falls apart before the mixer. 
  The HP8640B at full bore just starts compressing the mixer. The gates have low C so two devices could be stacked to reduce RDS on.
  I have not played with H mode yet but would like to stick one in the second mixer of my hot rod. The second mixer in a standard dual conversion is usually the weak link for close in dynamic range problems. I like the H mode because the fets are referenced to ground.
  I bet better transformer design and bigger FETs would make for impressive results. I have a few CP666s that would be cool to try. Work gets in the way of so many cool projects.
  Building a house makes it even more interesting. frank wa1gfz
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