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Re: [Amps] 160m mosfet linear amplifier problem with ferrite cores

To: "sasas asasas" <tzitzikas_ee@yahoo.com>, <amps@contesting.com>
Subject: Re: [Amps] 160m mosfet linear amplifier problem with ferrite cores
From: "David Cutter" <d.cutter@ntlworld.com>
Date: Sun, 18 Apr 2010 19:25:47 +0100
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Sasas

I looked at the ARRL site for a similar power amplifier to compare notes. 
http://www.w6kan.com/ssamp.html
The devices are completely different and so is the supply voltage, but the 
push pull arrangement is comparable and in this the transformer we are 
talking about is made using type 43 material, though it uses a 2-hole balun 
type Fair-Rite part # 2643540001 beads. .  It makes interesting reading, but 
I don't feel at liberty to quote verbatim.  It could be that another 
material, perhaps the newer 31 would perform even better, but I see no 
reason to replace the type 43 or the transistors until you have found the 
real problem.  Perhaps a binocular core might work better, or 2 of your type 
side-by-side to provide more reactance at the lowest frequency.


Sasas said:
I am using 12 Siliconix's IRFP360 mosfets, but i have order and soon i will 
replace them with International Rectifier IRFP360 mosfets. Propably this is 
the reason, that the amplifier don't give many watts at outupt.
The other reason, is that the material of ferrite cores (43 material) is not 
the proper for 1-2mhz frequences. What do you think?


David
G3UNA 

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