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

To: <ka4inm@tampabay.rr.com>, "'amps'" <amps@contesting.com>
Subject: Re: [Amps] 160m mosfet linear amplifier problem with ferrite cores
From: "Joe Subich, W4TV" <lists@subich.com>
Date: Sat, 17 Apr 2010 10:07:05 -0400
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Ron, 

>    I have been looking at this schematic all week.  I don't 
> get the "500w rms - 2 kW PEP" thing, that doesn't make sense 
> to me. 

This amplifier is specified for AM.  500W RMS = 500W carrier. 
500W carrier = 2 KW PEP.  

73, 

   ... Joe, W4TV 
 


> -----Original Message-----
> From: amps-bounces@contesting.com 
> [mailto:amps-bounces@contesting.com] On Behalf Of Ron Youvan
> Sent: Saturday, April 17, 2010 9:24 AM
> To: amps
> Subject: Re: [Amps] 160m mosfet linear amplifier problem with 
> ferrite cores
> 
> 
> HI  sasas asasas:
> 
> > Hi, I have constructed this linear amplifier 500w rms (2 kW 
> pep) (50 
> > Ohms) with 12 mosfet irfp360, 
> http://tzitzikas.webs.com/linear500w.jpg 
> > for 160m band. When I gave 3 Watts of driving power, it 
> gave to output 
> > only 190 W at 106VDC (6A current). Two radio amateurs who have 
> > construct this linear claim tha it gives 500w r.f power at 110vdc.
> 
>    I have been looking at this schematic all week.  I don't 
> get the "500w rms - 2 kW PEP" thing, 
> that doesn't make sense to me.  RMS isn't that different from 
> average and 2 kW PEP is about the same 
> as average.
> Also, 106 V. X 6 Amps. = 636 Watts at 50% efficiency TPO = 
> 318 Watts is all you should be looking 
> for.  (at this drive level)
> 
>    The device substitution has possibly reduced the 
> amplifier's gain and efficiency.
> 
> > But when I tried to give 4 watts of driving r.f power the ferrite 
> > Cores (43 material) of transformer T3 broken! Which do you think is 
> > the problem??
> 
>    First, type 43 is correct for the HF HAM bands, but I am 
> not sure about the top band. You need to replace the broken 
> core and test it "just for gain" (no more than 2 Watts of drive) at 7 
> MHz then compare the gain on 160 m.
> 
> 
> > http://tzitzikas.webs.com/linear20a.JPG
> > http://tzitzikas.webs.com/ferrite_broken1.JPG
> > http://tzitzikas.webs.com/ferrite_broken2.JPG
> 
>    Yup, broke.
> -- 
>     Ron  KA4INM - The next election, I know what is going to 
> happen, I'm going to help. 
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