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

[sasas asasas]

hI, AND THANK FOR YOU ANSWER. DO YOU HAVE TO PROPOSE ANY PROPER MATERIAL OF FERRITE CORES FOR FREQUENCES 1-2MHZ?
I saw AMIDON'S SITE: https://www.amidoncorp.com/categories/9
and i think 31 material is the most proper for this frequency range. What kind of these material do you think is the most proper for these frequences????
I saw an 80m band linear amplifier with mosfet witch is using 43 material ferrite cores. (but frequences are higher from 160m band)

Fron amidon's site:

43 Material Round Cable Beads
* > Round Cable Beads
Suppresses 25 to 300 MHz

31 Material Round Cable Beads
* > Round Cable Beads
31 material. Good for 1 to 300 MHz


77 Material Round Cable Beads
* > Round Cable Beads
Great for RFI in 2 to 30Mhz range


--- On Sun, 4/18/10, Alex Eban <alexeban at gmail.com> wrote:

From: Alex Eban <alexeban at gmail.com>
Subject: RE: [Amps] 160m mosfet linear amplifier problem with ferrite cores
To: "'sasas asasas'" <tzitzikas_ee at yahoo.com>, amps at contesting.com, "'David Cutter'" <d.cutter at ntlworld.com>
Date: Sunday, April 18, 2010, 1:07 AM

You get about 18 dB power gain out of it which is quite right for a FET
amplifier of this kind.
The problem lies most likely with the transformer itself: the 43 material in
the core is optimized for RFI suppression work ( a high tangent loss) and so
it's very dependent on the coupling between the windings. I shall have to
look up the material's properties and then I shall be able to recommend a
replacement and/or an alternative building method.
Alex        4Z5KS 

-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
Behalf Of sasas asasas
Sent: Sunday, April 18, 2010 10:49 AM
To: amps at contesting.com; David Cutter
Subject: Re: [Amps] 160m mosfet linear amplifier problem with ferrite cores

And how can i repair this problem???

--- On Sat, 4/17/10, David Cutter <d.cutter at ntlworld.com> wrote:

From: David Cutter <d.cutter at ntlworld.com>
Subject: Re: [Amps] 160m mosfet linear amplifier problem with ferrite cores
To: "sasas asasas" <tzitzikas_ee at yahoo.com>, amps at contesting.com
Date: Saturday, April 17, 2010, 12:15 PM

You might consider imbalance in each side of the primary which will cause a
net dc to pass, saturation and over-heating.  This may be rubbish but it
could get others thinking along a different path.

David
G3UNA


> HI. i have constructed this linear amplifier 500w rms (2kw pep) (50ohm)
with 12 mosfet irfp360, http://tzitzikas.webs.com/linear500w.jpg for 160m
band.
> When i gave 3watts of driving r.f power, it gave to output only 190w 
> at 106VDC (6A current). Two radio amateurs who have construct this linear
claim tha it gives 500w r.f power at 110vdc.
> But when i tried to give 4watts of driving r.f power the ferrite Cores 
> (43 material) of transformer T3 broken! Which do you think is the
problem??
> 



      
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