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

wrote:
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

On Sat, 02 Jun 2007 09:46:31 -0500, Cecil Moore
wrote:

wrote:
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

Danny Richardson wrote:
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

Cecil Moore wrote in news:9pf8i.10153$4Y.6557
@newssvr19.news.prodigy.net:

wrote:
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

Owen Duffy wrote:

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

Roy Lewallen wrote in
:

Owen Duffy wrote:

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

On Sun, 03 Jun 2007 23:10:10 GMT, Owen Duffy wrote:

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

Danny Richardson wrote in
:

On Sun, 03 Jun 2007 23:10:10 GMT, Owen Duffy wrote:

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.

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

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

Owen Duffy wrote:

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