Thanks Dave!!
73, and thanks,
Dave (NK7Z)
https://www.nk7z.net
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources
On 2/20/22 15:48, David Eckhardt wrote:
Nothing fancy. I'll attach an image of the test fixture I use. It is
not appropriate for frequencies much above 54 MHz, but works fine for HF
on downward. In determining ferrite material, one does not need
coverage above even 10 MHz.
Dave - WØ LEV
On Sun, Feb 20, 2022 at 10:48 PM Dave (NK7Z) <dave@nk7z.net
<mailto:dave@nk7z.net>> wrote:
Jim,
That is most interesting material, thank you! Will you all be
including
a test fixture description as well? I am in the process of gathering
the materials to build a test fixture, and would like to see your
designs...
73, and thanks,
Dave (NK7Z)
https://www.nk7z.net <https://www.nk7z.net>
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources
On 2/20/22 12:28, Jim Brown wrote:
> On 2/20/2022 4:13 AM, Hare, Ed, W1RFI wrote:
>> The toroids are not marked, so it will not be certain what material
>> they are."
>
> Thanks. For the next Handbook, I've given Ward details of a
method to
> identify a few MnZn ferrite materials with an ohmmeter. It was first
> suggested by W1HIS, and I fleshed it out a bit further. It's pretty
> simple. It worked with the three VOMs in my lab -- a Simpson 260, a
> Fluke 8060A, and a nice little no-name digital VOM that I bought for
> about $15 at a northwest Indiana hamfest at least 20 years ago.
>
> With the meter on a high range scale, aggressively scratch the
surface
> of the ferrite with the probes so that they get through the
coating, and
> note the reading, if there is one. #31, #75, #77, and #78 are MnZn
> mixes, and will show a reading in the range of 100K - 700K; #75,
#77,
> and #78 will be in the range of 1K - 10K. #43, #52, and #61 --
are NiZn
> materials, which have MUCH higher bulk resistivities, and will
show no
> conductivity at all. These resistivity values, as well as initial
> permeabilty (mu at low frequency) are tabulated in early pages of
the
> Fair-Rite catalog.
>
> We're also including methods to zero in on the specific material
> measuring inductance using traditional methods or studying the
shape of
> an impedance sweep with a well calibrated Vector Analyzer.
>
> These methods, of course, depend on knowing AL or ui values for the
> various materials. Fair-Rite's published data is FAR more
extensive than
> any other manufacturers; others publish little more than
marketing or
> limited applications data. For example, Laird (used to be Steward)
> publishes ui values for only two of about eight materials.
>
> 73, Jim K9YC
>
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*Dave - WØLEV*
/*Just Let Darwin Work*/
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