Topband: Ferrite Cores

[Tim Shoppa]

#31 is a very nice mix for winding chokes especially at topband and lower
HF and for EMI suppression.

#61 is very common for HF transformers up to medium power levels.

#43 is also useful at HF transformers and chokes especially at upper HF.

#73 is a very nice mix for low band transformers but some of the testing
done shows typical transformers to be good 5kHz-50MHz:
http://www.cliftonlaboratories.com/imd_in_broadband_transformers.htm

I have been using #73 binocular cores for all sorts of things lately. A
little Fair-Rite 2873000202 core works excellently in isolated DC-to-DC
power converters at the several watt power level.



On Wed, Aug 6, 2014 at 11:15 AM, Ron Stordahl, AE5E via Topband <
topband at contesting.com> wrote:

> In this discussion two different ferrite mixes are mentioned:  #31 and
> #61.
>
>
> From the descriptions of these on the Fair-Rite web page, it appears that
> 31 would be more suitable for lower frequency applications.
>
>
> Is this the case?
>
> Ron, AE5E
>
>
>
> On Wednesday, August 6, 2014 4:02 AM, Charlie <
> charlie-cunningham at nc.rr.com> wrote:
>
>
>
> I agree with all those points, Jim! Over the years, professionally, we
> designed many Fair-Rite, cores into most of our electricity, gas and water
> meter and electricity load-management products and shipped millions of
> Fair-Rite products in our devices.  Fair-Rite and Kreger are excellent
> suppliers, and I still have many of their development kits around here.
> Their products are excellent and very consistent
>
> Lynne Frye, of Kreger, is a very helpful contact person, that I have worked
> with over the years!
>
> Have a good day!
>
> 73,
> Charlie Cunningham, K4OTV
>
>
>
> -----Original Message-----
> From: Topband [mailto:topband-bounces at contesting.com] On Behalf Of Jim
> Brown
> Sent: Tuesday, August 05, 2014 3:00 PM
> To: topband at contesting.com
> Subject: Re: Topband: Ferrite Cores
>
> On 8/5/2014 11:36 AM, Mike Waters wrote:
> > FT-240-61 cores. Amidon was $9/ea, Mouser (for the Fair Rite
> > equivalent)
> > >was $14/ea.
>
> The actual manufacturer of a 2.4-in o.d. #61 toroid  IS Fair-Rite. It is
> not
> an "equivalent," #61 material is Fair-Rite's mix. Other companies may make
> a
> "knock-off," but the REAL part is made by Fair-Rite.
>
> 73, Jim K9YC
>
>
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