[amsat-bb] ag-35 smoke test

Yokshs yokshs at sbcglobal.net
Wed Apr 22 20:17:49 PDT 2009

Hi all,

Well, I finally did it. I let the smoke out of my Icom AG-35 preamp!

I've read several such messages on the list over the years. Glad to know I'm 
not alone in this club.. hi hi

Before I replace the 3SK121 with an identical unit, I wonder if anyone has 
used a similar FET with better NF? The AG-35 specs I found stated 1.5 dB NF 
and 15 dB gain.

I went through my collection of new parts and found a few Agilent ATF 54143 

The NF on similar designs is more like .38 to .5 dB and gain is 19-22 dB.

I wonder if anyone else has had the wild idea of rebuilding their preamp? 
I'd like to retain the enclosure and relays, etc.

Several 54143 designs are available, such as this one:


Thanks for any help or ideas.



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