Hi Johan & All,
I may be mistaken but I think the picture is of a very
large diameter 3E25 from the colour code like a
TL58/41/18-3E25 or TL102/66/15-3E25. A 3F3 should be
blue according to my datasheets; check the web. The 5i
(published initial permeabilty) for 3F3, 3C85, 3E25
are approx 1800, 2000, 5500, respectively.
Regardless, still TU for the data point anyways.
73 de Mike KB6WFC k ..
--- Johan Bodin <[email protected]> wrote:
Hello Rik
Ferrite (as opposed to iron powder) is best for
power transformation on LF
because of its high permeability, fewer turns = less
copper loss. Iron powder
is better for resonant circuits and filters because
of higher flux saturation point
and it has better inductance stability and low loss
/ high Q.
The best material for 136 kHz transformers, as far
as I know, is Philips 3F3
which has approximately half the core loss compared
to 3C85, and 3C85 is
good! SM6PXJ and I used a 58mm 3C85 toroid as auto
transformer for
antenna matching on our 7S6SAJ expedition. The
antenna resistance was
7..8 ohms (most of this was radiation resistance!
:o) and the transformer was
only slightly warm to the touch after running QRSS
with about 1 kW output
from Christers TX. Just a couple of watts lost, I
would guess. The winding was
made with 2.5 sq.mm flat wire (not Litz).
I have Philips ferrite data sheets in pdf format
that I can send if you are
interested.
Attached picture shows the transformer in action at
7S6SAJ. Note the full scale
deflection on the 10A thermocouple "ammeter" in the
icecream container.
Christer checked the meter later and found that 10A
indicated was actually
12A RF... (photo by SM6PXJ)
73 de Johan SM6LKM
> I am trying to make a list of toroid core material
that is suitable for
> 136kHz power applications, for impedance
transformers and low-pass filters.
> I would appreciate any information about the
material (brand-type), the
> application (transformer or filter) and the power
level it was used/tested.
>
> many thanks in advance,
>
> 73, Rik ON7YD
ATTACHMENT part 2 image/tiff name=trafo.jpg
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