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Re: [Amps] Real time tests to see if an RF transformer is saturating?

Subject: Re: [Amps] Real time tests to see if an RF transformer is saturating?
From: Chris Wilson <>
Reply-to: Chris Wilson <>
Date: Sun, 11 Jun 2017 19:10:51 +0100
List-post: <>

Hello Manfred,

Well,  I  have  finally  got  around  to finishing the transformer you
suggested  and  all  I can say is WOW!!I have to admit that looking at
the  difference  in  physical  size of the auto transformer on the pot
core  and  the  original  one on a ferrite toroid I thought to myself,
"Nah, this can't work, it's TINY!!". But it does, and like a champion.
Much better antenna current, negligible heating in the short amount of
time  I have been testing, and no other issues. It's not the prettiest
of  things,  I  believe  I  am  being  a bit thick and probably not
understanding  how you intended the wires to appear off the bobbin. If
I  follow your instruction verbatim, as I believe they are intended, I
would end up not being able to have full turns on the 20 turn winding,
as  bringing  them  out on opposing sides would add(or subtract a half
turn  from  one  of  them.  Let me post in a bit with a photo of a new
bobbin.  I  may  well  wind  again  as  I  have  loads of the wire you
specified.  I'll  also  put  a link to the old and the new to show the
size  difference  to  anyone reading this in the future. I can't thank
you  enough,  not  only  does  it  appear to work superbly, but I have
learnt a lot from this, which is priceless. Thanks again Manfred.

On Tuesday, May 16, 2017,  you wrote:

> Chris,

> at that low frequency, indeed you can make the individual amps for 100
> ohm and put them in parallel, or for 25 ohm and put them in series. 
> There should be no phasing problems, at such a low frequency. But you 
> have to make sure that both amplifiers have extremely similar responses,
> in terms of gain curve mainly.

> The advantage of using a combiner is that it isolates one amp from the
> other, so the system is highly tolerant to differences between the 
> individual amps, down to the point where one amp module can completely
> fail, and the other will continue limping along. Without a combiner, the
> failure of one module would probably cause the demise of the other too.

> I have been giving some thought to your transformer. First, I suggest 
> NOT buying that giant toroid. Bigger isn't always better. A huge core 
> has a lot of ferrite, that causes losses! That huge toroid has an 
> enormous space for winding, which you would never take advantage of. A
> smaller core in a better design can provide far better performance. So,
> let's start optimizing this design:

<HUGE amount of incredibly detailed advice snipped for space saving>

Best regards,

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