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Date: Fri, 23 Aug 2002 16:45:12 -0700 (PDT)
From: "Michael Silvers" <silversmj@yahoo.com>
Subject: Re: LF: Re: toroid cores
To: rsgb_lf_group@blacksheep.org
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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 <sm6lkm.jbeab@swipnet.se> 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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