I doubt it's material with as low a permeability as #61 or #67. If you
look at the photos of the UnUn, you'll see it comprises 6 turns of coax
on a core that is significantly smaller diameter than a size 240
(probably a 140); that could never give the required winding impedances
needed at the bottom end of the HF range for a 12.5/50 transformer. My
guess is that it's #52 which I know this manufacturer uses widely - that
would give him the required winding impedances with 6 turns.
On 15/04/2012 01:08, Jim Brown wrote:
> Right. Sorry, I slept through the details of your post. It's clearly
> acting as a classic magnetically coupled transformer, so yes, I'd say
> it was a very good test, and that it demonstrates very high
> efficiency. From that, I'd guess it to be a material like Fair-Rite #61
> or #67.
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