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

[Joe Subich, W4TV]

> I'm not sure if you would call 500W 'high power'

This is not a "500W" amplifier.  This claims to be a 2KW PEP 
amplifier - in AM PEP is 4 x carrier.  In this case an amplifier 
spec'd for "500W AM" would be 4 x 500 = 2000. 

73, 

  ... Joe Subich, W4TV 



> -----Original Message-----
> From: amps-bounces at contesting.com 
> [mailto:amps-bounces at contesting.com] On Behalf Of 
> d.cutter at ntlworld.com
> Sent: Monday, April 19, 2010 8:10 AM
> To: alexeban; amps at contesting.com; 'sasas asasas'
> Subject: Re: [Amps] 160m mosfet linear amplifier problem with 
> ferrite cores
> 
> 
> Alex
> 
> I'm not sure if you would call 500W 'high power' - I would 
> from a UK perspective.  In the classic EB104 I see ordinary 
> transformers.  Perhaps I'm not understanding something, 
> you're the expert. Where is the crossover from flux coupled 
> transformers to transmission line transformers? 
> 
> David
> G3UNA
> 
> ---- alexeban <alexeban at gmail.com> wrote: 
> > Guys, the problem is more pernicious than that!
> > 
> > The problem is in the way the transformers are WOUND!
> > 
> > Efficient high power transformers are wound using transmission line 
> > coupling, not flux link coupling; they use coaxial line 
> windings, with 
> > a very specific Zo. This technique ensures very tight 
> coupling between 
> > primary and secondary, thus relieving the core from carrying high 
> > magnetic flux. The ferrite only serves to increase the reactance of 
> > the windings at the lower frequency end. Actually ferrites 
> with a Ur 
> > of about 125 are sufficient in the HF range.
> > 
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