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It occurs to me that one could write a software application, either on a host computer, or as alternate firmware for the NanoVNA that would work as a "identify the mystery toroid".
Run a couple turns through the core, measure the S11 over a broad frequency range to get a rough idea, then run a narrower span, and you should be able to automatically compare to a collection of published materials and core dimensions. (FairRite, for example, publishes .xls files for all their materials)
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On Wed, Oct 20, 2021 at 09:05 AM, Jim Lux wrote:
It occurs to me that one could write a software application, either on a host
computer, or as alternate firmware for the NanoVNA that would work as a
"identify the mystery toroid".
Run a couple turns through the core, measure the S11 over a broad frequency
range to get a rough idea, then run a narrower span, and you should be able to
automatically compare to a collection of published materials and core
dimensions. (FairRite, for example, publishes .xls files for all their
materials)
One method is to find the frequency where R and X cross. That corresponds to where the complex permeability values ¦Ì¡ä and ¦Ì¡å cross and is unique to each ferrite Mix. Roger Roger
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There are huge variations in ferrites, parameters of the same model from different batches can vary greatly. On Wed, 20 Oct 2021 at 18:29, Roger Need via groups.io <sailtamarack= [email protected]> wrote: On Wed, Oct 20, 2021 at 09:05 AM, Jim Lux wrote:
It occurs to me that one could write a software application, either on a
host
computer, or as alternate firmware for the NanoVNA that would work as a
"identify the mystery toroid".
Run a couple turns through the core, measure the S11 over a broad frequency
range to get a rough idea, then run a narrower span, and you should be able to
automatically compare to a collection of published materials and core
dimensions. (FairRite, for example, publishes .xls files for all their
materials)
One method is to find the frequency where R and X cross. That corresponds
to where the complex permeability values ¦Ì¡ä and ¦Ì¡å cross and is unique to
each ferrite Mix.
Roger
Roger
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Yes, it's my experience too that the crossover point of reactance and resistance varies a lot between batches, also between cores of different sizes made of the same material. Determining it is also quite sensitive to measurement error. So I don't think it's a reliable way to identify the material.
What I do is simply measuring the inductance of a test coil wound on the mystery core, at a frequency low enough, where the inductance is pretty stable with frequency. That value can be used along with the core dimensions to easily calculate the material's initial permeability, with an accuracy better than the 20% tolerance most ferrite materials have. And determining the permeability is the most important step in determining what material it might be, and what it can be used for.
A quick glance at the inductance and resistance curves over frequency is useful as a confirmation, and can tell very clearly whether a material that measures ?i=40, for example, is low permeability ferrite or high permeability powdered iron. Ferrite of such permeability would remain mainly inductive throughout HF and somewhat into VHF, while iron powder of the same permeability would become very resistive well below 1MHz.
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On 10/20/21 4:20 PM, Dragan Milivojevic wrote: There are huge variations in ferrites, parameters of the same model
from different batches can vary greatly. True, but probably not so much that you can't come up with a quick way to identify them. 20% variation probably doesn't move it to confuse with a different mix. When I get some time this weekend, maybe I'll look at the FairRite data I have and see if this is an easy way.
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If you can, I have a full bin of unknown ferrites waiting for
classification ;)
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On Thu, 21 Oct 2021 at 05:31, Jim Lux <jim@...> wrote: On 10/20/21 4:20 PM, Dragan Milivojevic wrote:
There are huge variations in ferrites, parameters of the same model
from different batches can vary greatly. True, but probably not so much that you can't come up with a quick way
to identify them. 20% variation probably doesn't move it to confuse with
a different mix.
When I get some time this weekend, maybe I'll look at the FairRite data
I have and see if this is an easy way.
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On 10/20/21 8:44 PM, Dragan Milivojevic wrote: If you can, I have a full bin of unknown ferrites waiting for
classification ;) don't we all
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At one time in the not too distant past, FairRite posted a well done video
on identifying ferrite material. It was excellent and may even be in the
archives of this group. I have lost the reference to that presentation.
I'd suggest poking around on the FairRite site.
Dave - W?LEV
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On Thu, Oct 21, 2021 at 3:31 AM Jim Lux <jim@...> wrote: On 10/20/21 4:20 PM, Dragan Milivojevic wrote:
There are huge variations in ferrites, parameters of the same model
from different batches can vary greatly. True, but probably not so much that you can't come up with a quick way
to identify them. 20% variation probably doesn't move it to confuse with
a different mix.
When I get some time this weekend, maybe I'll look at the FairRite data
I have and see if this is an easy way.
--
*Dave - W?LEV*
*Just Let Darwin Work*
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NanoVNA Sorts Unknown Ferrite Suppression Beads by Fair-Rite Products Corp.
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On 10/21/2021 12:56 PM, W0LEV wrote: At one time in the not too distant past, FairRite posted a well done video
on identifying ferrite material. It was excellent and may even be in the
archives of this group. I have lost the reference to that presentation.
I'd suggest poking around on the FairRite site.
Dave - W?LEV
On Thu, Oct 21, 2021 at 3:31 AM Jim Lux <jim@...> wrote:
On 10/20/21 4:20 PM, Dragan Milivojevic wrote:
There are huge variations in ferrites, parameters of the same model
from different batches can vary greatly. True, but probably not so much that you can't come up with a quick way
to identify them. 20% variation probably doesn't move it to confuse with
a different mix.
When I get some time this weekend, maybe I'll look at the FairRite data
I have and see if this is an easy way.
--
73,
Mike, N1JEZ
"A closed mouth gathers no feet"
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**Updated post
Fair-Rite has an article on determining the Mix of a ferrite.
All the calculations to determine the initial permeability of a material can be done by measuring the toroid, winding some turns on the toroid, measuring the inductance at 10 to 100 kHz. and entering the data into this calculator.
Roger
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On 10/20/21 8:44 PM, Dragan Milivojevic wrote:
If you can, I have a full bin of unknown ferrites waiting for
classification ;)
I have 2 bins. One for non-conductive cores (ferrite) and the other for conductive (iron).
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Thank you!
73, and thanks,
Dave (NK7Z)
ARRL Volunteer Examiner
ARRL Technical Specialist, RFI
ARRL Asst. Director, NW Division, Technical Resources
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On 10/23/21 6:14 PM, §¡§ß§Õ§â§Ö§Û §¥§Ö§ß§Ú§ã§ð§Ü wrote:
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The conductive cores need not be iron powder. One quick sort:
1) Those that are not conductive are typically best applied for high
frequency work with somewhat high ?r values. They are good for baluns, RFI
suppression, RF broadband transformers, and......
2) Those which are conductive (some more than others) are usually
optimized for the lower frequencies over HF and even into audio.
Powdered iron cores (usually color coded) are best utilized for high-Q
inductors over HF frequencies. Some are good as such up to 200 MHz. They
are typically not conductive.
Dave - W?LEV
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On Fri, Oct 22, 2021 at 11:28 PM Michael <pixelwaster@...> wrote: On 10/20/21 8:44 PM, Dragan Milivojevic wrote:
If you can, I have a full bin of unknown ferrites waiting for
classification ;)
I have 2 bins. One for non-conductive cores (ferrite) and the other for
conductive (iron).
--
*Dave - W?LEV*
*Just Let Darwin Work*
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Interesting discussion and useful information.. So far, I've been able to use Fair Rite's documented method, but my small supply has limited types, (31, 43, 52)
It's surprising that Fair-Rite and others don't put an insert into the mold to mark identification somewhere on the core. Or even laser mark them.
I suppose the added cost may be the concern.
John, KB1NO
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John,
Fair-Rite does mark the cores in some of their design kits with paint, but not production parts. Micrometals seems to consistently color-code all their iron powder cores.
--John Gord
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On Sun, Oct 24, 2021 at 11:51 AM, John Nuhibian / KB1NO wrote:
Interesting discussion and useful information.. So far, I've been able to use
Fair Rite's documented method, but my small supply has limited types, (31, 43,
52)
It's surprising that Fair-Rite and others don't put an insert into the mold to
mark identification somewhere on the core. Or even laser mark them.
I suppose the added cost may be the concern.
John, KB1NO
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John. Couldn't agree more I cannot see it as a major cost ,even color coding would help.I have been supplied with one type and the difference between some was amazing.It made me think stocktaking.These are black round with a hole in the middle so must be the same into the one box they go.
Morrie
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On 25/10/2021 7:50 am, John Nuhibian / KB1NO wrote: Interesting discussion and useful information.. So far, I've been able to use Fair Rite's documented method, but my small supply has limited types, (31, 43, 52)
It's surprising that Fair-Rite and others don't put an insert into the mold to mark identification somewhere on the core. Or even laser mark them.
I suppose the added cost may be the concern.
John, KB1NO
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can this be taken off line? On Sun, Oct 24, 2021, 12:10 PM John Gord via groups.io <johngord= [email protected]> wrote: John,
Fair-Rite does mark the cores in some of their design kits with paint, but
not production parts. Micrometals seems to consistently color-code all
their iron powder cores.
--John Gord
On Sun, Oct 24, 2021 at 11:51 AM, John Nuhibian / KB1NO wrote:
Interesting discussion and useful information.. So far, I've been able
to use
Fair Rite's documented method, but my small supply has limited types, (31, 43,
52)
It's surprising that Fair-Rite and others don't put an insert into the mold to
mark identification somewhere on the core. Or even laser mark them.
I suppose the added cost may be the concern.
John, KB1NO
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Martin,
I find this an interesting topic. You can however, mute this topic if you wish. there is a button if you are reading online and a link at the bottom of the message if you are using a mail reader.
Gerald Pelanr
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nothing personal or mean.
Martin
N6QLH
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On Sun, Oct 24, 2021, 6:13 PM WD0FYF Gerald <wd0fyf@...> wrote: Martin,
I find this an interesting topic. You can however, mute this topic if you
wish. there is a button if you are reading online and a link at the bottom
of the message if you are using a mail reader.
Gerald Pelanr
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Roger Need
Mike N1JEZ
Martin Glazer