Discussion:
Trying to find out what Ferrite material this is.
(too old to reply)
m***@yahoo.com.au
2007-06-01 15:54:28 UTC
Permalink
I came across two ferrite toroids with the measurements of 35mm
diameter, the hole in the middle is 21mm and it is 13mm thick. On the
packet it says that the ferrite material is L15. Does anybody know if
L15 is equivalent to 43 or 61 ferrite material? I have searched the
net but have been unable to find any information. Any information
would be appreciated. Cheers.
charlie
2007-06-01 16:57:08 UTC
Permalink
Post by m***@yahoo.com.au
I came across two ferrite toroids with the measurements of 35mm
diameter, the hole in the middle is 21mm and it is 13mm thick. On the
packet it says that the ferrite material is L15. Does anybody know if
L15 is equivalent to 43 or 61 ferrite material? I have searched the
net but have been unable to find any information. Any information
would be appreciated. Cheers.
Where did they come from? Sounds like it may have been from a kit.


Charlie.
--
M0WYM
www.radiowymsey.org
charlie
2007-06-01 17:00:08 UTC
Permalink
Post by m***@yahoo.com.au
I came across two ferrite toroids with the measurements of 35mm
diameter, the hole in the middle is 21mm and it is 13mm thick. On the
packet it says that the ferrite material is L15. Does anybody know if
L15 is equivalent to 43 or 61 ferrite material? I have searched the
net but have been unable to find any information. Any information
would be appreciated. Cheers.
Here's how to check them:

http://www.w8pgw.org/node/303

Charlie.
--
M0WYM
www.radiowymsey.org
m***@yahoo.com.au
2007-06-01 18:03:30 UTC
Permalink
I haven't got an antenna analyser to do the above checks. The toroids
came in a box of stuff from a hamfest. They are in a packet which has
the brand name "Duratech" printed on it.
Chuck
2007-06-01 18:23:24 UTC
Permalink
Post by m***@yahoo.com.au
I haven't got an antenna analyser to do the above checks. The toroids
came in a box of stuff from a hamfest. They are in a packet which has
the brand name "Duratech" printed on it.
If you have any means at all of mesuring
inductance, you can go here:

http://en.wikipedia.org/wiki/Inductor
Inductor - Wikipedia, the free encyclopedia

Find the formula (#6) for the inductance
of a toroidal ring. Enter the
appropriate values and solve for u
(permeability of the core). Then look at
ferrites and iron power core properties
with the calculated permeability at the
test frequency. You'll probably find
several core materials that fit.

I think that's about all that can be done.

Chuck

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Richard Clark
2007-06-01 20:08:08 UTC
Permalink
Post by m***@yahoo.com.au
I haven't got an antenna analyser to do the above checks.
Do you have a SWR meter?

73's
Richard Clark, KB7QHC
h***@gmail.com
2007-06-03 19:13:50 UTC
Permalink
i do would that help me with my mess of ferrites?
Post by Richard Clark
Post by m***@yahoo.com.au
I haven't got an antenna analyser to do the above checks.
Do you have a SWR meter?
73's
Richard Clark, KB7QHC
John Smith I
2007-06-03 23:16:06 UTC
Permalink
Post by h***@gmail.com
i do would that help me with my mess of ferrites?
...
1) Is your junk drawer supply good?

2) Got a freq counter?

If you answered yes to the above, build a simple 1 transistor
oscillator. Wrap a few turns on the toroid, and shunt it with a know
capacitance. Read the freq of the oscillator, using a chart available
on the web, note the capacitive reactance of the cap value in ohms.

Since capacitive reactance = inductive reactance in ohms at resonance,
it is now a simple matter to translate in the inductive reactance of the
torrid coil into uh/mh--using the osc freq and a chart from the web ...

Warmest regards,
JS


Since
John Smith I
2007-06-04 03:51:40 UTC
Permalink
...
I should have mentioned, in case it escaped your attention, a SW
receiver will serve as freq counter (watch out for harmonics), if you
have patience to hunt the signal ... you can "rough guess" the freq by
the expectations of the expected inductance (type 43, 61, etc. and no.
of turns) and the capacitance used.

JS
Richard Clark
2007-06-04 01:20:34 UTC
Permalink
Post by h***@gmail.com
i do would that help me with my mess of ferrites?
Post by Richard Clark
Post by m***@yahoo.com.au
I haven't got an antenna analyser to do the above checks.
Do you have a SWR meter?
Hi Herbert,

Pass a wrap of wire around the material if it is a bar, or through it
if it is a toroid. Connect this to the output of the SWR meter. Hit
it with a short blip of power and note the SWR. You have the
multiple/divisor of 50 Ohms. Give it two wraps, or two passes and
repeat for more clues. Repeat at the frequencies of interest. Make a
chart.

Try to keep the power low and application short so you don't burn your
fingers.

73's
Richard Clark, KB7QHC
Roy Lewallen
2007-06-04 01:48:00 UTC
Permalink
Post by Richard Clark
Hi Herbert,
Pass a wrap of wire around the material if it is a bar, or through it
if it is a toroid. Connect this to the output of the SWR meter. Hit
it with a short blip of power and note the SWR. You have the
multiple/divisor of 50 Ohms. . .
Sorry, that's simply not true. You're almost certain to have reactance
-- possibly, a lot of it -- in which case the SWR can be vastly
different than the impedance divided by 50 ohms or its inverse.

Roy Lewallen, W7EL
Richard Clark
2007-06-04 03:32:40 UTC
Permalink
Post by Roy Lewallen
Post by Richard Clark
Hi Herbert,
Pass a wrap of wire around the material if it is a bar, or through it
if it is a toroid. Connect this to the output of the SWR meter. Hit
it with a short blip of power and note the SWR. You have the
multiple/divisor of 50 Ohms. . .
Sorry, that's simply not true. You're almost certain to have reactance
-- possibly, a lot of it -- in which case the SWR can be vastly
different than the impedance divided by 50 ohms or its inverse.
Simplicity is not to be dismissed that easily (no one needs to spend
$500 to figure out ferrite). A moment's worth of very little power
will suitably allow for heat to discriminate reactance from
resistance.

73's
Richard Clark, KB7QHC
Owen Duffy
2007-06-01 21:30:01 UTC
Permalink
Post by m***@yahoo.com.au
I came across two ferrite toroids with the measurements of 35mm
diameter, the hole in the middle is 21mm and it is 13mm thick. On the
packet it says that the ferrite material is L15. Does anybody know if
L15 is equivalent to 43 or 61 ferrite material? I have searched the
net but have been unable to find any information. Any information
would be appreciated. Cheers.
Search Jaycar's site for a LO1238. If that is what you have, you could ask
them for data.

Owen
Owen Duffy
2007-06-01 22:06:24 UTC
Permalink
Owen Duffy <***@no.where> wrote in news:***@61.9.191.5:

...
Post by Owen Duffy
Search Jaycar's site for a LO1238. If that is what you have, you could
ask them for data.
I should have added that I think it is similar to the L8 material described
in their data sheets.

I have a vague recollection of measuring the inductance of a winding on the
material, and I think the ui was around 1500 which suggests it is low loss
up to a few hundred kHz, perhaps to 1MHz or so.

Owen
m***@yahoo.com.au
2007-06-02 14:00:08 UTC
Permalink
Hello Owen,
I have tracked the product down to Jaycar but they don't know anything
about the material. The person I contacted was very vague and couldn't
steer me towards anybody that would know what material it was. All I
want to know is if the toroids would be any good for HF 1:1 baluns. I
have just made a balun using a FT-140-61 which is very close to the
same dimensions as the 2 toroids in the Duratech packet. If they can
be used they are a fair bit cheaper than sourcing FT-140-61 toroids.
In reply to Richard Clark, yes I do have a SWR meter.
Cheers
Max
Cecil Moore
2007-06-02 14:46:31 UTC
Permalink
Post by m***@yahoo.com.au
All I
want to know is if the toroids would be any good for HF 1:1 baluns.
An antenna analyzer, like the MFJ-259B, is a very
useful piece of test equipment for all types of
measurements of this kind. Using the MFJ-259B, I
discovered that the Amidon brochure, "showing typical
'Z' in ohms for one turn at 25 MHz", is misleading.
Their "one turn" goes through the core twice which
I consider as being two turns. That's bad news for
w2du baluns.

If you could gain access to an MFJ-259B, you could
run the same kind of measurement on your toroids.
Heck, if you send one to me, I will run the experiment
and send it back to you.
--
73, Cecil http://www.w5dxp.com
Danny Richardson
2007-06-02 15:57:43 UTC
Permalink
Post by Cecil Moore
Post by m***@yahoo.com.au
All I
want to know is if the toroids would be any good for HF 1:1 baluns.
An antenna analyzer, like the MFJ-259B, is a very
useful piece of test equipment for all types of
measurements of this kind. Using the MFJ-259B, I
discovered that the Amidon brochure, "showing typical
'Z' in ohms for one turn at 25 MHz", is misleading.
Their "one turn" goes through the core twice which
I consider as being two turns. That's bad news for
w2du baluns.
If you could gain access to an MFJ-259B, you could
run the same kind of measurement on your toroids.
Heck, if you send one to me, I will run the experiment
and send it back to you.
Hi Cecil,

You need to move up a notch. Check out http://w5big.com/

I've had one for several months now and won't want to be without it.

Danny, K6MHE
Cecil Moore
2007-06-02 16:22:57 UTC
Permalink
Post by Danny Richardson
You need to move up a notch. Check out http://w5big.com/
I've had one for several months now and won't want to be without it.
Thanks for the URL, Danny - didn't know about it.
--
73, Cecil http://www.w5dxp.com
Owen Duffy
2007-06-02 22:28:42 UTC
Permalink
Post by Cecil Moore
Post by m***@yahoo.com.au
All I
want to know is if the toroids would be any good for HF 1:1 baluns.
An antenna analyzer, like the MFJ-259B, is a very
useful piece of test equipment for all types of
measurements of this kind. Using the MFJ-259B, I
...

The '259B is no doubt a handy device, but very limited for measuring
components. Have you tried to measure at an inductance that has more than
250 ohms of reactance at some frequency of interest? Have you tried to
explore self resonance of a coil..., invariably it runs into the same
problem of inductive reactance going off scale way below the point at
which self resonance bites in.

When talking about ferrite or powdered iron cored inductors of reactance
over 200 ohms, where mu is frequency dependent and flux dependent, I find
the '259B nearly useless.

Owen
Roy Lewallen
2007-06-03 00:11:51 UTC
Permalink
Post by Owen Duffy
The '259B is no doubt a handy device, but very limited for measuring
components. Have you tried to measure at an inductance that has more than
250 ohms of reactance at some frequency of interest? Have you tried to
explore self resonance of a coil..., invariably it runs into the same
problem of inductive reactance going off scale way below the point at
which self resonance bites in.
When talking about ferrite or powdered iron cored inductors of reactance
over 200 ohms, where mu is frequency dependent and flux dependent, I find
the '259B nearly useless.
I've had just the opposite experience. I find the 259B to be extremely
useful in determining ferrite types and the impedances of inductors.
Generally a single "turn" (pass through the hole) is adequate for
measurement. For most toroidal inductors the impedance is closely
proportional to the square of the number of turns, so the value of
multi-turn inductors can be extrapolated with reasonable accuracy. Of
course, two or three turns can be used for measurement if the unit can't
resolve the impedance of a single turn.

The frequency dependence of the mu and loss is just why the 259B is so
useful -- I can find the impedance at the frequency or range of
frequencies it'll be used at.

I very seldom design magnetic components for applications where flux
density noticeably alters the impedance. If the signal is so large as to
permit this to happen, you'll be generating serious harmonics and, if
multiple signals are present, intermod. If the saturation is being
caused by DC, it's often possible to bias the core with the same current
while making measurements. And I've never hit a powdered iron core with
enough signal or DC to get anywhere near saturation. They tolerate much
higher flux density than ferrites.

I'd really feel handicapped in designing baluns and wideband
transformers, in particular, without my 259B or something similar.

Roy Lewallen, W7EL
Owen Duffy
2007-06-03 23:10:10 UTC
Permalink
Post by Roy Lewallen
Post by Owen Duffy
The '259B is no doubt a handy device, but very limited for measuring
components. Have you tried to measure at an inductance that has more
than 250 ohms of reactance at some frequency of interest? Have you
tried to explore self resonance of a coil..., invariably it runs into
the same problem of inductive reactance going off scale way below the
point at which self resonance bites in.
When talking about ferrite or powdered iron cored inductors of
reactance over 200 ohms, where mu is frequency dependent and flux
dependent, I find the '259B nearly useless.
I've had just the opposite experience. I find the 259B to be extremely
useful in determining ferrite types and the impedances of inductors.
Generally a single "turn" (pass through the hole) is adequate for
measurement. For most toroidal inductors the impedance is closely
proportional to the square of the number of turns, so the value of
multi-turn inductors can be extrapolated with reasonable accuracy. Of
course, two or three turns can be used for measurement if the unit
can't resolve the impedance of a single turn.
The frequency dependence of the mu and loss is just why the 259B is so
useful -- I can find the impedance at the frequency or range of
frequencies it'll be used at.
Roy, with respect, you are describing work-arounds for the inability of
the '259B to make useful measurements on inductors over about 200 ohms
reactance.

Sure, the instrument can be used to characterise a core, and that
information extrapolated to design an inductor with higher reactance, but
you cannot measure the larger inductance directly, or discover reliably,
the properties of the larger inductor like self resonance effects, or
loss.

I won't address defensive posts by others who seem to have chosen to
ignore my qualification "When talking about ferrite or powdered iron
cored inductors of reactance over 200 ohms".

An example of the traps: a chap recently confirmed to me that indeed mu
is frequency sensitive as demonstrated by the '259B measurement of the
inductance of an inductor over HF which showed inductance was highly
frequency dependent. The problem was that the inductive reactance was
over 250 ohms at most frequencies of measurement, and the '259B
calculates inductance without warning that the value is unreliable
because of the magnitude of reactance on which the inductance is
calculated. Try measuring a 30uH coil's inductance over 2-30MHz using a
'259B and you will see what I mean.

Owen
Danny Richardson
2007-06-04 01:20:35 UTC
Permalink
Post by Owen Duffy
I won't address defensive posts by others who seem to have chosen to
ignore my qualification "When talking about ferrite or powdered iron
cored inductors of reactance over 200 ohms".
Owen, are you trying to pull a Cecil or Art by changing the subject of
the thread? If you recall, this thread was about identifying an
unknown ferrite core. For that purpose *any instrument* capable of
measuring Zmag less than 200 ohms will work fine - even one that is
restricted to less than 100 ohms.

I 'm not defending the 259 as I use something else here that can
measure impedances greater that 20K, but that high range servers no
purpose if I am looking a impedances less than 100 ohms.

Danny, K6MHE
Owen Duffy
2007-06-04 01:50:55 UTC
Permalink
Post by Danny Richardson
Post by Owen Duffy
I won't address defensive posts by others who seem to have chosen to
ignore my qualification "When talking about ferrite or powdered iron
cored inductors of reactance over 200 ohms".
Owen, are you trying to pull a Cecil or Art by changing the subject of
the thread? If you recall, this thread was about identifying an
unknown ferrite core. For that purpose *any instrument* capable of
measuring Zmag less than 200 ohms will work fine - even one that is
restricted to less than 100 ohms.
A fair point Danny.

I did provide some specific information on the core if you read back
through the posts, probably more than any others!

But I still stand by my statement about the limitations of the '259B in
assessing inductors as qualified.
Post by Danny Richardson
I 'm not defending the 259 as I use something else here that can
measure impedances greater that 20K, but that high range servers no
purpose if I am looking a impedances less than 100 ohms.
I envy you, seems we always need (want?) to measure something that is
beyond the range of the instrument conveniently to hand.

Owen
Roy Lewallen
2007-06-04 01:44:14 UTC
Permalink
I agree that a 259B does not make a good general purpose instrument for
measuring inductor values over the HF range. In fact, there are very few
instruments which are. One of the few I know of is the HP 4191A vector
impedance meter, but it's not likely to be found in many amateur
workshops. Making good impedance measurements at HF is often very much
more difficult than most people realize.

The 259B is, I maintain, a very good instrument for identifying core
materials and for use in the design of inductors, transformers, and
other magnetic components. I've used mine many times for the purpose and
gotten the results I expected. That was, I thought, the subject of this
thread, but it appears to have drifted elsewhere.

Roy Lewallen, W7EL
Post by Owen Duffy
Roy, with respect, you are describing work-arounds for the inability of
the '259B to make useful measurements on inductors over about 200 ohms
reactance.
Sure, the instrument can be used to characterise a core, and that
information extrapolated to design an inductor with higher reactance, but
you cannot measure the larger inductance directly, or discover reliably,
the properties of the larger inductor like self resonance effects, or
loss.
I won't address defensive posts by others who seem to have chosen to
ignore my qualification "When talking about ferrite or powdered iron
cored inductors of reactance over 200 ohms".
An example of the traps: a chap recently confirmed to me that indeed mu
is frequency sensitive as demonstrated by the '259B measurement of the
inductance of an inductor over HF which showed inductance was highly
frequency dependent. The problem was that the inductive reactance was
over 250 ohms at most frequencies of measurement, and the '259B
calculates inductance without warning that the value is unreliable
because of the magnitude of reactance on which the inductance is
calculated. Try measuring a 30uH coil's inductance over 2-30MHz using a
'259B and you will see what I mean.
Owen
Larry Benko
2007-06-04 02:24:59 UTC
Permalink
Post by Roy Lewallen
I agree that a 259B does not make a good general purpose instrument for
measuring inductor values over the HF range. In fact, there are very few
instruments which are. One of the few I know of is the HP 4191A vector
impedance meter, but it's not likely to be found in many amateur
workshops. Making good impedance measurements at HF is often very much
more difficult than most people realize.
Look at the L/C meter from AADE (Almost All Digital Electronics)
www.aade.com which a 1 hour kit for $99. It is quite accurate and uses
a variable frequency oscillator so that smaller values of inductance and
capacitance are measures at higher frequencies. I own an 8753 HP
Network Analyzer and still use the L/C meter most of the time since it
is so convenient. It easily can tell the differences between
73/43/31/61 materials. I usually wrap 2 turns thru the torroid to do the
measurement.

73,
Larry, W0QE
Roy Lewallen
2007-06-04 03:01:31 UTC
Permalink
Post by Larry Benko
Look at the L/C meter from AADE (Almost All Digital Electronics)
www.aade.com which a 1 hour kit for $99. It is quite accurate and uses
a variable frequency oscillator so that smaller values of inductance and
capacitance are measures at higher frequencies. I own an 8753 HP
Network Analyzer and still use the L/C meter most of the time since it
is so convenient. It easily can tell the differences between
73/43/31/61 materials. I usually wrap 2 turns thru the torroid to do the
measurement.
73,
Larry, W0QE
That looks like a handy gadget. It wouldn't be very good for working
with the kinds of ferrites often used for baluns, wideband transformers,
or EMI suppression because of the very low Q encountered. Many of the
ferrites I use have a Q of one or less over at least part of the
frequency range of operation. And of course the L/C meter wouldn't be
useful in assessing the loss or Q of inductors at all. One of the unique
things about the HP unit is that it's able to resolve very small R in
the presence of large X or vice-versa, which is very difficult to do.
But then it costs a couple of orders of magnitude more.

A network analyzer is poorly suited for making measurements of
impedances which are a great deal higher or lower than 50 ohms.

The problem with any of these instruments is that they'll all happily
give you an answer, often to several decimal digits. But as Owen pointed
out for the 259B, the answer can be anywhere from good to total garbage.
The only way to know which is to understand the limitations of your test
equipment and something about the nature of the component you're trying
to measure. There just isn't any instrument which will do the thinking
for you.

Roy Lewallen, W7EL
Larry Benko
2007-06-04 03:46:05 UTC
Permalink
Post by Roy Lewallen
That looks like a handy gadget. It wouldn't be very good for working
with the kinds of ferrites often used for baluns, wideband transformers,
or EMI suppression because of the very low Q encountered. Many of the
ferrites I use have a Q of one or less over at least part of the
frequency range of operation. And of course the L/C meter wouldn't be
useful in assessing the loss or Q of inductors at all. One of the unique
things about the HP unit is that it's able to resolve very small R in
the presence of large X or vice-versa, which is very difficult to do.
But then it costs a couple of orders of magnitude more.
A network analyzer is poorly suited for making measurements of
impedances which are a great deal higher or lower than 50 ohms.
The problem with any of these instruments is that they'll all happily
give you an answer, often to several decimal digits. But as Owen pointed
out for the 259B, the answer can be anywhere from good to total garbage.
The only way to know which is to understand the limitations of your test
equipment and something about the nature of the component you're trying
to measure. There just isn't any instrument which will do the thinking
for you.
Roy Lewallen, W7EL
That is what I thought also Roy but the little L/C meter seems to work
pretty well with low Q inductors. It is not measuring impedance but
measuring a frequency of an inductor and known capacitor in an
oscillator. The Q does change the oscillating frequency but not that
much. As I said before it is super easy to tell the difference between
77/31/43/61 type ferrites. Of course the permeability difference
between those types is a factor of 2 or more so ultra accuracy is not
important. The original question was how to determine what type an
unknown core was and not what impedance it represented at a certain
frequency.

I just grabbed 3 FairRite 59XX003801 torroids (2.4" OD x 1.4" ID x .5")
in 3 materials and measured a single turn with the L/C meter.

Material 61 (u=125) calc. inductance = .173uH, measured = .177uH
Material 43 (u=800) calc. inductance = 1.07uH, measured = .930uH
Material 75 (u=5000) calc. inductance = 6.85uH, measured = 7.39uH

The calculated inductances came from the FairRite catalog. I would say
the "low Q" inductors measured pretty well and the materilas were very
easy to distinguish.

73,
Larry, W0QE
Roy Lewallen
2007-06-04 05:10:46 UTC
Permalink
Post by Larry Benko
That is what I thought also Roy but the little L/C meter seems to work
pretty well with low Q inductors. It is not measuring impedance but
measuring a frequency of an inductor and known capacitor in an
oscillator. The Q does change the oscillating frequency but not that
much. As I said before it is super easy to tell the difference between
77/31/43/61 type ferrites. Of course the permeability difference
between those types is a factor of 2 or more so ultra accuracy is not
important. The original question was how to determine what type an
unknown core was and not what impedance it represented at a certain
frequency.
I just grabbed 3 FairRite 59XX003801 torroids (2.4" OD x 1.4" ID x .5")
in 3 materials and measured a single turn with the L/C meter.
Material 61 (u=125) calc. inductance = .173uH, measured = .177uH
Material 43 (u=800) calc. inductance = 1.07uH, measured = .930uH
Material 75 (u=5000) calc. inductance = 6.85uH, measured = 7.39uH
The calculated inductances came from the FairRite catalog. I would say
the "low Q" inductors measured pretty well and the materilas were very
easy to distinguish.
Yep, that's perfectly adequate to distinguish the types. You must have
made the measurements at a pretty low frequency. Type 75 has a Q of 1 at
about a MHz, and 43 at a few MHz, and they drop at higher frequencies.
Will the circuit oscillate with Q that low?

Roy Lewallen, W7EL
Larry Benko
2007-06-04 05:55:32 UTC
Permalink
Post by Roy Lewallen
Yep, that's perfectly adequate to distinguish the types. You must have
made the measurements at a pretty low frequency. Type 75 has a Q of 1 at
about a MHz, and 43 at a few MHz, and they drop at higher frequencies.
Will the circuit oscillate with Q that low?
Roy Lewallen, W7EL
Referring to http://www.aade.com/lcm2binst/HP.html the measurement freq.
was about 750KHz for the type 61 and 43 materials and about 70KHz for
the 75 material based on the inductances that were displayed.

73, Larry W0QE
Larry Benko
2007-06-04 06:01:50 UTC
Permalink
Post by Larry Benko
Post by Roy Lewallen
Yep, that's perfectly adequate to distinguish the types. You must have
made the measurements at a pretty low frequency. Type 75 has a Q of 1
at about a MHz, and 43 at a few MHz, and they drop at higher
frequencies. Will the circuit oscillate with Q that low?
Roy Lewallen, W7EL
Referring to http://www.aade.com/lcm2binst/HP.html the measurement freq.
was about 750KHz for the type 61 and 43 materials and about 70KHz for
the 75 material based on the inductances that were displayed.
73, Larry W0QE
Darn typo. That should be 750KHz for the type 61 and 43 and 700KHz for
the type 75. Sorry.

73,Larry W0QE
Ian White GM3SEK
2007-06-04 08:11:25 UTC
Permalink
Post by Roy Lewallen
The 259B is, I maintain, a very good instrument for identifying core
materials and for use in the design of inductors, transformers, and
other magnetic components. I've used mine many times for the purpose
and gotten the results I expected. That was, I thought, the subject of
this thread, but it appears to have drifted elsewhere.
It has certainly drifted away from Australia, and towards the USA.

In the USA, it's a good bet that an unknown ferrite core will be made by
Fair-Rite, and probably one of the more common materials; or else it's
probably a dust-iron core from Micrometals. With help from the catalogs,
and a few known cores for reference, even quite limited test equipment
will have a good chance of identifying the specific product.

But that may not be true in the rest of the world. You may have a core
that is marketed in your home country but imported from another, but
having been manufactured in a third country using a process licensed
from... well, who knows any more? There are no world-standard sizes, and
no direct equivalents between magnetic materials from different
manufacturers. The best you can hope for is to identify the material as
being "somewhat like" a known Fair-Rite mix.

With such uncertainties about the material itself, you can afford far
fewer uncertainties about the measurement. If you don't have advanced
test equipment (or an advanced understanding of the limitations of
simpler equipment) then it may be better to forget about characterizing
the magnetic material. If you want to know if it will work in an HF
balun, it may be much easier to *make* a balun.

On the other hand, if you really want to chase down the problem of
identifying and characterizing unknown cores from anywhere around the
world, the following links may help.

http://users.catchnet.com.au/~rjandusimports/
No coincidence that this site is .au - they know about this problem in
Australia.

There are very useful international cross-reference pages at:
http://users.catchnet.com.au/~rjandusimports/xref_mat.html
http://users.catchnet.com.au/~rjandusimports/xref_size_toroid.html
Do remember that these are not exact equivalents, only the closest
available. Also note the huge gaps in the tables, where nothing even
comes close.

Another very useful resource is DL5SWB's Mini Ring Core Calculator:
http://www.dl5swb.de/html/mini_ring_core_calculator.htm
This software contains extensive libraries of cores from international
manufacturers, including dimensions and paint colours as well as
magnetic properties. If you know the identity of the core, it will
calculate the inductance from the number of turns. If you have an
unknown core, and can make some meaningful measurements, there are
separate functions to help identify it.
--
73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek
Cecil Moore
2007-06-03 17:14:09 UTC
Permalink
Post by Owen Duffy
The '259B is no doubt a handy device, but very limited for measuring
components. Have you tried to measure at an inductance that has more than
250 ohms of reactance at some frequency of interest? Have you tried to
explore self resonance of a coil..., invariably it runs into the same
problem of inductive reactance going off scale way below the point at
which self resonance bites in.
Like anything else, there is a limit to the usefulness of an MFJ-259B
but
it is far from useless. Toroids can be characterized by using one or
two
windings to keep the impedance within the 259's range. And self-
resonance
in a coil is super easy. Set the coil up as a base loaded mobile
antenna
without a stinger. Find the first lowest impedance. That's self-
resonance
when the coil is 90 degrees long and the reflected wave is
interferring
with the forward wave at the test point.

Some of the things that limits the usefullness of the MFJ-259B are the
concepts
of the user. If one doesn't believe in (or ignores) the separate
existence of the
forward and reflected waves, then the 259 becomes a lot less useful.
--
73, Cecil, w5dxp.com
Tom Donaly
2007-06-03 19:13:15 UTC
Permalink
Post by Cecil Moore
Post by Owen Duffy
The '259B is no doubt a handy device, but very limited for measuring
components. Have you tried to measure at an inductance that has more than
250 ohms of reactance at some frequency of interest? Have you tried to
explore self resonance of a coil..., invariably it runs into the same
problem of inductive reactance going off scale way below the point at
which self resonance bites in.
Like anything else, there is a limit to the usefulness of an MFJ-259B
but
it is far from useless. Toroids can be characterized by using one or
two
windings to keep the impedance within the 259's range. And self-
resonance
in a coil is super easy. Set the coil up as a base loaded mobile
antenna
without a stinger. Find the first lowest impedance. That's self-
resonance
when the coil is 90 degrees long and the reflected wave is
interferring
with the forward wave at the test point.
Some of the things that limits the usefullness of the MFJ-259B are the
concepts
of the user. If one doesn't believe in (or ignores) the separate
existence of the
forward and reflected waves, then the 259 becomes a lot less useful.
--
73, Cecil, w5dxp.com
Whaddaya mean, "believe in"? If I pray to the waves, will they
bring good luck?
73,
Tom Donaly, KA6RUH
John Smith I
2007-06-03 23:00:29 UTC
Permalink
Post by Tom Donaly
...
Whaddaya mean, "believe in"? If I pray to the waves, will they
bring good luck?
73,
Tom Donaly, KA6RUH
Who knows? Maybe?

At the present time, it is unknown if RF energy is photons, waves or a
combination of the two. It is known that rf exhibits qualities ...

So yes, a belief akin to what one must hold for his creator is in order
here!

But then, you already knew that ...

JS
Cecil Moore
2007-06-04 17:57:29 UTC
Permalink
Post by Tom Donaly
Whaddaya mean, "believe in"? If I pray to the waves, will they
bring good luck?
Many of the posters here believe that reflected EM waves don't
actually exist
in reality. Their belief systems are interferring with their
understanding of physics.
And yes, it might as well be a religion to which one prays. I know a
number of posters
who pray that reflected waves don't exist because their entire house-
of-cards will
come tumblinging down if reflected EM waves actually exist in reality
- while obeying
all the boundary conditions that Mother Nature dictates for EM waves.
Hopefully,
you are not one of those individuals.
--
73, Cecil, w5dxp.com
Tom Donaly
2007-06-04 22:39:32 UTC
Permalink
Post by Cecil Moore
Post by Tom Donaly
Whaddaya mean, "believe in"? If I pray to the waves, will they
bring good luck?
Many of the posters here believe that reflected EM waves don't
actually exist
in reality. Their belief systems are interferring with their
understanding of physics.
And yes, it might as well be a religion to which one prays. I know a
number of posters
who pray that reflected waves don't exist because their entire house-
of-cards will
come tumblinging down if reflected EM waves actually exist in reality
- while obeying
all the boundary conditions that Mother Nature dictates for EM waves.
Hopefully,
you are not one of those individuals.
--
73, Cecil, w5dxp.com
Maybe you'll tell me who you think thinks waves of any sort can't
be reflected. I haven't run into anyone who thinks EM waves can't be
reflected, refracted, etc. Maybe there's a misunderstanding somewhere.
73,
Tom Donaly, KA6RUH
John Smith I
2007-06-04 22:48:50 UTC
Permalink
Post by Tom Donaly
...
Maybe you'll tell me who you think thinks waves of any sort can't
be reflected. I haven't run into anyone who thinks EM waves can't be
reflected, refracted, etc. Maybe there's a misunderstanding somewhere.
73,
Tom Donaly, KA6RUH
Very good, and oh so relevant!

Krist, even the force on a tennis ball is "reflected" back off a wall!

Better question would be, "What can't be reflected?" (well, ok, high
radiation is NOT easy to reflect!)

JS
Cecil Moore
2007-06-05 15:40:31 UTC
Permalink
Post by Tom Donaly
Maybe you'll tell me who you think thinks waves of any sort can't
be reflected. I haven't run into anyone who thinks EM waves can't be
reflected, refracted, etc. Maybe there's a misunderstanding somewhere.
I don't want to get personal but if you have followed the reflected
wave arguments, you know who they are. Some simple true/false
questions will highlight the argument.

1. Do reflected EM waves actually exist in reality?
2. Is the reflected EM wave a traveling wave?
3. Does a reflected EM wave obey the rules for traveling waves?
4. Do reflected EM waves contain ExB joules/second?
5. Do reflected EM waves have any effect on forward waves in a
constant Z0 environment?
6. Do standing EM waves superceed and obsolete the component traveling
waves?
7. Does reflected EM energy violate the laws of physics by standing
still within the standing wave?
8. Does reflected EM energy violate the laws of physics by just
"sloshing" around?
9. Does reflected EM energy travel in the reverse direction at VF(c)
until it encounters an impedance discontinuity?
10. Is it valid to consider the forward EM traveling wave and the
reflected EM traveling wave separately and then superpose the
resulting fields (voltages, currents)?
11. Are the decades-old EM wave intensity equations from the field of
optics valid for an RF EM wave analysis?
12. Can standing wave current be used to determine the delay through a
75m mobile loading coil?
13. Is the current "drop" through that loading coil just an illusion
caused by superposition of forward and reflected currents?
14. Would the delay be different if only a forward traveling wave was
used for measurement purposes?
--
73, Cecil, w5dxp.com
Jim Kelley
2007-06-05 19:04:13 UTC
Permalink
Post by Cecil Moore
Post by Tom Donaly
Maybe you'll tell me who you think thinks waves of any sort can't
be reflected. I haven't run into anyone who thinks EM waves can't be
reflected, refracted, etc. Maybe there's a misunderstanding somewhere.
I don't want to get personal but if you have followed the reflected
wave arguments, you know who they are. Some simple true/false
questions will highlight the argument.
1. Do reflected EM waves actually exist in reality?
2. Is the reflected EM wave a traveling wave?
3. Does a reflected EM wave obey the rules for traveling waves?
4. Do reflected EM waves contain ExB joules/second?
5. Do reflected EM waves have any effect on forward waves in a
constant Z0 environment?
6. Do standing EM waves superceed and obsolete the component traveling
waves?
7. Does reflected EM energy violate the laws of physics by standing
still within the standing wave?
8. Does reflected EM energy violate the laws of physics by just
"sloshing" around?
9. Does reflected EM energy travel in the reverse direction at VF(c)
until it encounters an impedance discontinuity?
10. Is it valid to consider the forward EM traveling wave and the
reflected EM traveling wave separately and then superpose the
resulting fields (voltages, currents)?
11. Are the decades-old EM wave intensity equations from the field of
optics valid for an RF EM wave analysis?
12. Can standing wave current be used to determine the delay through a
75m mobile loading coil?
13. Is the current "drop" through that loading coil just an illusion
caused by superposition of forward and reflected currents?
14. Would the delay be different if only a forward traveling wave was
used for measurement purposes?
It's ridiculous to assert that someone "thinks EM waves can't be
reflected" based on the fact that they might happen to take issue with
one or more of your speculations on the laundry list shown above.

ac6xg
Cecil Moore
2007-06-07 06:09:23 UTC
Permalink
Post by Jim Kelley
It's ridiculous to assert that someone "thinks EM waves can't be
reflected" based on the fact that they might happen to take issue with
one or more of your speculations on the laundry list shown above.
You obviously have not been following the arguments.
--
73, Cecil http://www.w5dxp.com
Tom Donaly
2007-06-07 14:48:32 UTC
Permalink
Post by Cecil Moore
Post by Jim Kelley
It's ridiculous to assert that someone "thinks EM waves can't be
reflected" based on the fact that they might happen to take issue with
one or more of your speculations on the laundry list shown above.
You obviously have not been following the arguments.
Neither have you, Cecil.
73,
Tom Donaly, KA6RUH
Cecil Moore
2007-06-07 16:20:12 UTC
Permalink
Post by Tom Donaly
Post by Cecil Moore
You obviously have not been following the arguments.
Neither have you, Cecil.
Tom, please inquire about reflected energy just "sloshing"
around rather than traveling end to end at a VF(c) speed.
--
73, Cecil, w5dxp.com
Keith Dysart
2007-06-08 14:03:34 UTC
Permalink
Post by Cecil Moore
Post by Tom Donaly
Maybe you'll tell me who you think thinks waves of any sort can't
be reflected. I haven't run into anyone who thinks EM waves can't be
reflected, refracted, etc. Maybe there's a misunderstanding somewhere.
I don't want to get personal but if you have followed the reflected
wave arguments, you know who they are. Some simple true/false
questions will highlight the argument.
1. Do reflected EM waves actually exist in reality?
2. Is the reflected EM wave a traveling wave?
3. Does a reflected EM wave obey the rules for traveling waves?
4. Do reflected EM waves contain ExB joules/second?
5. Do reflected EM waves have any effect on forward waves in a
constant Z0 environment?
6. Do standing EM waves superceed and obsolete the component traveling
waves?
7. Does reflected EM energy violate the laws of physics by standing
still within the standing wave?
8. Does reflected EM energy violate the laws of physics by just
"sloshing" around?
9. Does reflected EM energy travel in the reverse direction at VF(c)
until it encounters an impedance discontinuity?
10. Is it valid to consider the forward EM traveling wave and the
reflected EM traveling wave separately and then superpose the
resulting fields (voltages, currents)?
11. Are the decades-old EM wave intensity equations from the field of
optics valid for an RF EM wave analysis?
12. Can standing wave current be used to determine the delay through a
75m mobile loading coil?
13. Is the current "drop" through that loading coil just an illusion
caused by superposition of forward and reflected currents?
14. Would the delay be different if only a forward traveling wave was
used for measurement purposes?
--
73, Cecil, w5dxp.com
An excellent list of questions, but you left out a few:

15. Can superposition be used in the analysis of linear
time invariant circuits?
16. Does P equal E times I?
17. Can source (or output) impedance be used to compute the
reflection occuring at the generator?
18. Does a directional wattmeter MEASURE power?
19. Do reflections occur at places other than physical
impedance discontinuities?

...Keith
Owen Duffy
2007-06-02 22:18:19 UTC
Permalink
Post by m***@yahoo.com.au
Hello Owen,
I have tracked the product down to Jaycar but they don't know anything
about the material. The person I contacted was very vague and couldn't
steer me towards anybody that would know what material it was. All I
want to know is if the toroids would be any good for HF 1:1 baluns. I
You didn't ask that question initially.

As I said, I think that the material is low loss below about 1MHz. I am
away from home at the moment and don't have access to my records of
testing the things.

I doubt that the material is suitable for a HF voltage balun. Lossy
ferrite is still usefull for suppression purposes, and you could probably
use the cores for a 1:1 choke style balun at HF. One of the issues with
lossy choke baluns is efficiency of the solution, and more importantly
power rating.

Jaycar also sell powdered iron cores in similar sizes (LO1246, HY-2
material, ui 75, Al 165nH). They have much lower ui (need more turns for
a given inductance), lower loss, and are more expensive.
Post by m***@yahoo.com.au
have just made a balun using a FT-140-61 which is very close to the
same dimensions as the 2 toroids in the Duratech packet. If they can
be used they are a fair bit cheaper than sourcing FT-140-61 toroids.
For some reason, US magnetics are overpriced in Oz. It seems everyone
charges FedEx rates to post a couple of dollars worth of cores that
should fit in a padded bag for $5. There is a market there for someone in
the US to sell reasonably priced Fair-rite or similar cores on Ebay with
low postage.

The other option is to try Neosid in Sydney, have a look at their web
site. I know they do a range of ferrites and powdered iron cores of
various shapes and sizes.
Post by m***@yahoo.com.au
In reply to Richard Clark, yes I do have a SWR meter.
If a given balun causes a poor SWR reading on a known dummy load, then
the balun is inadequate, but the converse does not necessarily apply. The
test is an important one, but not comrehensive.

Owen
Owen Duffy
2007-06-18 03:04:32 UTC
Permalink
Post by Owen Duffy
...
Post by Owen Duffy
Search Jaycar's site for a LO1238. If that is what you have, you
could ask them for data.
I should have added that I think it is similar to the L8 material
described in their data sheets.
I have a vague recollection of measuring the inductance of a winding
on the material, and I think the ui was around 1500 which suggests it
is low loss up to a few hundred kHz, perhaps to 1MHz or so.
I am back at home and dug out my measurments for LO1238. I make ui around
1100 at 10kHz (Al ~145nH), so it is a little lower than the L8 material,
probably goes to slighly higher frequency before loss sets in.

Owen

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