Fair-rite also states that multi-aperture ferrite cores (like this one)
have greater bandwidth vs. a single-hole core made of the same material. I
cannot explain that.
I can verify that the losses in any single-core transformer that I've ever
made from that core, regardless of the Z ratio, was less than 1 dB. (0.9 dB
was an extreme case.) And I've measured losses as low as 0.2 dB. ON4UN in
his latest book wound transformers on that core with even less loss, IIRC.
I used a stack of three once when I experimented with transmitting on a
Beverage. Amazingly, the core never approached the Curie temperature even
feeding it with 800 watts of CW and heavily processed SSB. Photos of that
core test are at
www.w0btu.com/files/misc/Binocular%20core%20power%20vs%20temp%20test/ .
I cannot find the measured loss on that core at the moment, but it was
certainly low enough (~0.4 dB, IIRC) that it never exceed 225 degrees F
even with 850w key-down, with no air movement and a layer of heat shrink
which reduced heat radiation. And I'm using that same transformer on the
input of my swamped-grid amplifier. It barely gets warm even with 100w CW.
My $0.02.
73, Mike
www.w0btu.com
On Fri, Nov 28, 2014 at 7:45 AM, Tom W8JI <w8ji@w8ji.com> wrote:
>
> ... This behavior makes a transformer broadband, ...
>
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