On Mon,5/15/2017 5:59 AM, Alan Ibbetson wrote:
The pros don't use designators like FT240-78. Those are numbers from
the USA reseller Amidon. You have to search on www.fair-rite.com for
the long string of digits (like 5978003801) and type that into the
Mouser or RS search box.
Right.
Finding the right part on Fair-rite is a pig. There are drop downs
under Products on the home page but it's never easy.
Actually it IS easy if you understand how ferrite materials work and
take the time to study Fair-Rite's EXCELLENT website -- indeed, their
published data is among the top five companies I've dealt with in five
decades as an engineer.
If I was in your shoes I'd try type 78 and wind on as many turns in a
5:7 ratio as will fit. As Manfred says, several strands of thinner
wire bundled together will be easier to wind and have a bit less
copper loss.
Depending on the application, #78 is not a very good material for use as
a transformer.
Nearly ten years ago, I produced a tutorial on how ferrite materials
work, and a few years later, it was incorporated into the ARRL Handbook.
k9yc.com/RFI-Ham.pdf Among other things, it shows how to view detailed
specs for individual parts and ferrite materials on the Fair-Rite
website and in their catalog.
73, Jim K9YC
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