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,
Chris mailto:chris@chriswilson.tv
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