[amsat-bb] Re: ag-35 smoke test

Luc Leblanc lucleblanc6 at videotron.ca
Thu Apr 23 02:43:56 PDT 2009

On 22 Apr 2009 at 21:17, Yokshs wrote:

> 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 
> hemt..
> 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:
> http://www.qsl.net/yu1aw/atf54143eng.htm
> Thanks for any help or ideas.
> 73,
> Kyle
> K0KN
I fried my UHF one too...I order a couple from ICOM. With my very limited electronics building skills i cut the dead one leaving as much 
legs as possible and i resolder the replacement over the cut legs. Not elegant but quick and effective. Is this is achieving the same 
overall previous gain figures? that i don't know but it works.

I have another one to replace in a different type of preamp but the FET is below a lot of other components and he's flat mounted (No legs) 
i don't come up with a solution with this one?


Luc Leblanc VE2DWE
Skype VE2DWE


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