开云体育

Go to the Micrometals web site. Take a look at their various mix of iron powder cores. You can mix and match size, L and perm
values to see what Q is achieved. Unloaded Q value excess of 400 is quite straight forward. They may still provide their Q curves text. Nice reference.

Use a different core, litz wire is useful up to about 3MHz, higher than that
it provides no benefits.

On Wed, 20 Oct 2021 at 03:36, Andrew Kurtz via groups.io <adkurtz=
[email protected]> wrote:

I am really getting a lesson here! I have a homemade coil of 40 turns on
a Clorox bottle, so length about equals diameter, intended to be best Q
possible. Q is 130 based on X and R reported by nanoVNA at 1 MHz, where I
use this coil. Note that this coil has 60 FEET of wire, and skin effect (I
assume) makes R = 11 ohms or about 100 times DC resistance.

Then I wind 6 turns on my mystery ferrite toroid, using 10 INCHES of wire,
and I get about the same inductance (180 uH versus 200 for the large
air-core coil). And of course I get about the same reactance at the same
frequency…… but R rises to 200 ohms at 600 kHz and over 1000 ohms at 1
MHz!! I guess there is hysteresis, eddy currents, etc., but I expected
that this much smaller coil with much less wire would be the best Q
possible short of having litz wire… but the Q of the toroid is around 1.
Why does anyone use a ferrite toroid for anything??

Anyone know where I can acquire some litz wire?

Andy

On Oct 19, 2021, at 7:23 PM, Jim Lux <jim@...> wrote:

On 10/19/21 3:48 PM, W0LEV wrote:

What could be higher Q (lowest possible losses) than air or vacuum?
Ferrite and powdered iron toroidal cores have a higher ?r which yields
higher inductance per turn than free space, but there are associated
losses. Air core inductors are the highest Q attainable, all other
variables being equal. Anything wound on ferrite or powdered iron cores
will exhibit lower Q than wound in free space.

Dave - W?LEV

Oddly, not necessarily. Yes, the same windings, with a core, will have

higher L and lower Q, because of core losses. However, if you compare equal
inductance and current handling ability, you might wind up with a LOT of
turns (and a very long wire) so the wire losses are higher than the core
losses on a inductor on a core.

It is as simple as the ferrite material you have is very lossy. There
are much better ferrite materials to use at 1Mhz.

With a proper core and litz wire, you can get the R under 1 ohm.

???????????????????????????????????????????????????? Mikek

On 10/19/2021 8:36 PM, Andrew Kurtz via groups.io wrote:

I am really getting a lesson here! I have a homemade coil of 40 turns on a Clorox bottle, so length about equals diameter, intended to be best Q possible. Q is 130 based on X and R reported by nanoVNA at 1 MHz, where I use this coil. Note that this coil has 60 FEET of wire, and skin effect (I assume) makes R = 11 ohms or about 100 times DC resistance.

Then I wind 6 turns on my mystery ferrite toroid, using 10 INCHES of wire, and I get about the same inductance (180 uH versus 200 for the large air-core coil). And of course I get about the same reactance at the same frequency…… but R rises to 200 ohms at 600 kHz and over 1000 ohms at 1 MHz!! I guess there is hysteresis, eddy currents, etc., but I expected that this much smaller coil with much less wire would be the best Q possible short of having litz wire… but the Q of the toroid is around 1. Why does anyone use a ferrite toroid for anything??

Anyone know where I can acquire some litz wire?

Andy

On Oct 19, 2021, at 7:23 PM, Jim Lux <jim@...> wrote:

On 10/19/21 3:48 PM, W0LEV wrote:

What could be higher Q (lowest possible losses) than air or vacuum?
Ferrite and powdered iron toroidal cores have a higher ?r which yields
higher inductance per turn than free space, but there are associated
losses. Air core inductors are the highest Q attainable, all other
variables being equal. Anything wound on ferrite or powdered iron cores
will exhibit lower Q than wound in free space.

Dave - W?LEV

Oddly, not necessarily. Yes, the same windings, with a core, will have higher L and lower Q, because of core losses. However, if you compare equal inductance and current handling ability, you might wind up with a LOT of turns (and a very long wire) so the wire losses are higher than the core losses on a inductor on a core.

--
This email has been checked for viruses by Avast antivirus software.

I am really getting a lesson here! I have a homemade coil of 40 turns on a Clorox bottle, so length about equals diameter, intended to be best Q possible. Q is 130 based on X and R reported by nanoVNA at 1 MHz, where I use this coil. Note that this coil has 60 FEET of wire, and skin effect (I assume) makes R = 11 ohms or about 100 times DC resistance.

Then I wind 6 turns on my mystery ferrite toroid, using 10 INCHES of wire, and I get about the same inductance (180 uH versus 200 for the large air-core coil). And of course I get about the same reactance at the same frequency…… but R rises to 200 ohms at 600 kHz and over 1000 ohms at 1 MHz!! I guess there is hysteresis, eddy currents, etc., but I expected that this much smaller coil with much less wire would be the best Q possible short of having litz wire… but the Q of the toroid is around 1. Why does anyone use a ferrite toroid for anything??

Anyone know where I can acquire some litz wire?

Andy

My experience is in the AMBCB. Some have built air core coils with Qs
reaching 2000. This was with two pieces of 640/46 litz wire in parallel.

?The best toroid Q I have seen is around 1500. These were around 240uh,
the material was R40C1.

Might get better, but two litz wires in parallel won't fit on the toroid.

??????????????????????????????????????????????? Mikek

On 10/19/2021 6:23 PM, Jim Lux wrote:

On 10/19/21 3:48 PM, W0LEV wrote:

What could be higher Q (lowest possible losses) than air or vacuum?
Ferrite and powdered iron toroidal cores have a higher ?r which yields
higher inductance per turn than free space, but there are associated
losses.? Air core inductors are the highest Q attainable, all other
variables being equal.? Anything wound on ferrite or powdered iron cores
will exhibit lower Q than wound in free space.

Dave - W?LEV

Oddly, not necessarily.? Yes, the same windings, with a core, will
have higher L and lower Q, because of core losses. However, if you
compare equal inductance and current handling ability, you might wind
up with a LOT of turns (and a very long wire) so the wire losses are
higher than the core losses on a inductor on a core.

--
This email has been checked for viruses by Avast antivirus software.

You are correct, Jim, only for large inductances requiring lots of wire as
you stated. But for us "average" inductances, still the air core would
yield the highest Q.

Dave - W?LEV

--
*Dave - W?LEV*
*Just Let Darwin Work*

On 10/19/21 3:48 PM, W0LEV wrote:

What could be higher Q (lowest possible losses) than air or vacuum?
Ferrite and powdered iron toroidal cores have a higher ?r which yields
higher inductance per turn than free space, but there are associated
losses. Air core inductors are the highest Q attainable, all other
variables being equal. Anything wound on ferrite or powdered iron cores
will exhibit lower Q than wound in free space.

Dave - W?LEV

Oddly, not necessarily.? Yes, the same windings, with a core, will have higher L and lower Q, because of core losses. However, if you compare equal inductance and current handling ability, you might wind up with a LOT of turns (and a very long wire) so the wire losses are higher than the core losses on a inductor on a core.

What could be higher Q (lowest possible losses) than air or vacuum?
Ferrite and powdered iron toroidal cores have a higher ?r which yields
higher inductance per turn than free space, but there are associated
losses. Air core inductors are the highest Q attainable, all other
variables being equal. Anything wound on ferrite or powdered iron cores
will exhibit lower Q than wound in free space.

Dave - W?LEV

On Mon, Oct 18, 2021 at 9:22 PM Andrew Kurtz via groups.io <adkurtz=
[email protected]> wrote:

Agreed, but isn’t that R, divided into X at 1 MHz, going to give me Q? It
will be terrible. I expected a toroid to offer higher Q than an air core…

On Oct 18, 2021, at 4:58 PM, KENT BRITAIN <WA5VJB@...> wrote:

? That 200 Ohms is not the same as a 200 Ohm resistor at any frequency

other that 1 MHz.

Again Impedance, not resistance. Kent
On Monday, October 18, 2021, 03:53:18 PM CDT, Andrew Kurtz via

groups.io <adkurtz@...> wrote:

Thanks, but I must disagree: the nanoVNA provides a resistance output

as well as a reactance, and that is what I was reading to be 200 ohms at 1
MHz...

On Oct 18, 2021, at 4:45 PM, KENT BRITAIN <WA5VJB@...> wrote:

Not really resistance, but impdeance.
Got a good old DC Volt Ohm Meter?
Try that, but you see only 1 or 2 Ohms.
Most of the Digital VOM;s are using pulses that are much like RF.So

they are reading as much AC impedance as DC resistance.

Kent
On Monday, October 18, 2021, 03:22:44 PM CDT, Andrew Kurtz via

groups.io <adkurtz@...> wrote:

This thread inspires me to ask a question that is not directly about my

nanoVNA: I have a toroid from a flea market that is blue, has OD = 0.875”,
ID = 0.51”, and length = 0.3125”. I wrapped 6 turns on it, and found (on
the VNA) that L is pretty stable around 180 uH. This indicates that Al
must be about 5000 mH/turns^2. ( I know NOTHING about toroids…) but some
reference has very few with Al in the range of thousands. Some of them
claim high Q, but the VNA indicates a (real) resistance of around 200 ohms
at 1 MHz!! This is insanely high; I have air-core inductors for the same
service with 60 FEET of wire showing R = 11 ohms at 1 MHz, and this
“high-Q” toroid, with 11 INCHES of wire, has R = 200 ohms!?! Am I
misunderstanding something? So:

- Is there a way to identify my toroid simply because of its size and

blue color?

- Is such a high Al, suggesting a very high initial permeability,

realistic?

- Why would adding a toroid to less than 1 foot of coil create 200

Ohms resistance?

Thanks!
Andy

On Oct 18, 2021, at 11:37 AM, Tom McKee K4ZAD <tom.m@...>

wrote:

On Sat, 16 Oct 2021 Cliff <mailto:kd4gt.tn@...?subject=Re:%20%22Q%22%2C%20Coils%2C%20toroids%2C%20and%20guesswork%3F>

wrote about an on line toroid calculator available at:

There is a similar Excel spreadsheet based calculator available for

download at:

This link is one of many in my collection of on-line coil calculators

available at:

<>

73,

Tom K4ZAD

--
*Dave - W?LEV*
*Just Let Darwin Work*

On 10/18/21 6:04 PM, Roger Need via groups.io wrote:

On Mon, Oct 18, 2021 at 11:59 AM, Gary O'Neil wrote:

Some may find this does-it-all calculator useful also. It is my go to site for
all things toroid.
…. and even obvious and easy to remember and get to.

Just type the following in the address bar of your browser and hit enter.

Toroids.info

Gary,

There are several calculators online like the one at toroids.info that have a common error. They assume that the initial permeability is the same with frequency. This is not true with ferrite toroids. So if you wanted a ferrite toroid for operation at 3.6 MHz. and you calculated the number of turns required using this calculator you would find the inductance to be lower than expected at 3.6 MHz.

Here is an example. I wound a FT50-43 toroid with 4 turns of 28 AWG wire. Toroids.info gives and inductance of 7.04 uH (see attached graphic). Using a one port VNA (Rig Expert AA-55 Zoom) I measured 4 uh - a considerable difference. A better toroid calculator is needed.

Owen Duffy has covered ferrites extensively on his blog and publishes calculators which take "complex permeability" into account. Here is a link:


The first step using his calculators is to get the manufacturers data sheet and get Al and the initial permeability ?i for the toroid size and mix. For a FT50-43 it is 440 and 800 respectively. The next step is to calculate the complex permeability ?’ and ?” at the frequency of operation. Duffy provides a calculator to determine these values. At 3.6 Mhz. for Mix 43 we get ?’ = 470.2 and ?”. If we enter this into his inductance calculator we get 4.14 uH which is pretty close to the experimental results. Screenshots of the calculated inductance and measured data are attached.

That's the cool thing about Miguel Vaca's program - it takes the data from Fair-rite which gives mu' and mu'' vs frequency and does the calculations.

Those interested in the theory behind the Duffy Calculator should read this link:


Roger

On Mon, Oct 18, 2021 at 11:59 AM, Gary O'Neil wrote:

Some may find this does-it-all calculator useful also. It is my go to site for
all things toroid.
…. and even obvious and easy to remember and get to.

Just type the following in the address bar of your browser and hit enter.

Toroids.info

Gary,

There are several calculators online like the one at toroids.info that have a common error. They assume that the initial permeability is the same with frequency. This is not true with ferrite toroids. So if you wanted a ferrite toroid for operation at 3.6 MHz. and you calculated the number of turns required using this calculator you would find the inductance to be lower than expected at 3.6 MHz.

Here is an example. I wound a FT50-43 toroid with 4 turns of 28 AWG wire. Toroids.info gives and inductance of 7.04 uH (see attached graphic). Using a one port VNA (Rig Expert AA-55 Zoom) I measured 4 uh - a considerable difference. A better toroid calculator is needed.

Owen Duffy has covered ferrites extensively on his blog and publishes calculators which take "complex permeability" into account. Here is a link:


The first step using his calculators is to get the manufacturers data sheet and get Al and the initial permeability ?i for the toroid size and mix. For a FT50-43 it is 440 and 800 respectively. The next step is to calculate the complex permeability ?’ and ?” at the frequency of operation. Duffy provides a calculator to determine these values. At 3.6 Mhz. for Mix 43 we get ?’ = 470.2 and ?”. If we enter this into his inductance calculator we get 4.14 uH which is pretty close to the experimental results. Screenshots of the calculated inductance and measured data are attached.

I just tried to verify pulses on my Bryman BM235, I didn't find any
pulses, no matter what timebase I checked.

I put 610k across the meter with the scope. Just tested again without
the resistor, still no pulses.

??????????????????????????????????????????????? Mikek

On 10/18/2021 4:41 PM, KENT BRITAIN wrote:

Just may have to try that later.Ran into this issue when measuring windings on some transformers and getting impossibly high numbers.? ? Dug out the old Simpson, and saw about what I was expecting.? ? We both know that if you take a bit of wire that measures 1 Ohm, wrap it around a magnetic core, it will still read 1 Ohm.? At DC of course.? ? ?Otherwise you would never see all these switching power supplies.? Kent


On Monday, October 18, 2021, 04:33:56 PM CDT, Mikek <amdx@...> wrote:

That interesting! Maybe I'll be learning something here. What happens if
you measure a 100k resistor with 10uf capacitor across it?

On 10/18/2021 4:27 PM, KENT BRITAIN wrote:

? That's what I see when I hook up my Harbor Freight special to a Tek scope!
And on a Fluke meter as well.
Kent

? ? ? On Monday, October 18, 2021, 04:10:24 PM CDT, Mikek <amdx@...> wrote:

? Type J (75) was my first thought also, but his numbers, 1Mhz, 180uh and
200 ohms R, is a Q of 5 or 6 and I think that is much to low,

unless he used some high resistance wire.

To Kent, I have two disagreements, I don't think DVMs in the resistance
mode work the way you think they do.

And the idea that the OP has a coil that measures 180uh (1131Ω at 1Mhz)
can have 200 ohms of resistance is very possible.

I'm certain the OP know the difference between inductive reactance,
resistance and impedance.

Mikek

--
This email has been checked for viruses by Avast antivirus software.

--
This email has been checked for viruses by Avast antivirus software.

--
This email has been checked for viruses by Avast antivirus software.

Just may have to try that later.Ran into this issue when measuring windings on some transformers and getting impossibly high numbers.? ? Dug out the old Simpson, and saw about what I was expecting.? ? We both know that if you take a bit of wire that measures 1 Ohm, wrap it around a magnetic core, it will still read 1 Ohm.? At DC of course.? ? ?Otherwise you would never see all these switching power supplies.? Kent

That interesting! Maybe I'll be learning something here. What happens if
you measure a 100k resistor with 10uf capacitor across it?

On 10/18/2021 4:27 PM, KENT BRITAIN wrote:

That's what I see when I hook up my Harbor Freight special to a Tek scope!
And on a Fluke meter as well.
Kent

On Monday, October 18, 2021, 04:10:24 PM CDT, Mikek <amdx@...> wrote:

Type J (75) was my first thought also, but his numbers, 1Mhz, 180uh and
200 ohms R, is a Q of 5 or 6 and I think that is much to low,

unless he used some high resistance wire.

To Kent, I have two disagreements, I don't think DVMs in the resistance
mode work the way you think they do.

And the idea that the OP has a coil that measures 180uh (1131Ω at 1Mhz)
can have 200 ohms of resistance is very possible.

I'm certain the OP know the difference between inductive reactance,
resistance and impedance.

Mikek

--
This email has been checked for viruses by Avast antivirus software.

--
This email has been checked for viruses by Avast antivirus software.

Andy,

The high loss R is, I believe, from the toroid ferrite material. This is why they are used for RF suppression, e.g. common mode choke baluns. K9YC has lots of material on this.
See, e.g., , Chapter 2 has graphs showing R, L, X vs. frequency for different ferrite materials. For chokes you want a material that has high R (e.g. several 1000 Ohms) at the frequencies to be suppressed. For inductors you want to operate in a low R region.

73,
Roger

That's what I see when I hook up my Harbor Freight special to a Tek scope!
And on a Fluke meter as well.
Kent

Agreed, but isn’t that R, divided into X at 1 MHz, going to give me Q? It will be terrible. I expected a toroid to offer higher Q than an air core…

Type J (75) was my first thought also, but his numbers, 1Mhz, 180uh and
200 ohms R, is a Q of 5 or 6 and I think that is much to low,

unless he used some high resistance wire.

To Kent, I have two disagreements, I don't think DVMs in the resistance
mode work the way you think they do.

And the idea that the OP has a coil that measures 180uh (1131Ω at 1Mhz)
can have 200 ohms of resistance is very possible.

I'm certain the OP know the difference between inductive reactance,
resistance and impedance.

Mikek

On 10/18/2021 4:00 PM, Zack Widup wrote:

The closest thing I see to that is the Amidon type J ferrite toroids.
Useful frequency range is 1 to 15 MHz for type J. They don't specify a size
exactly the same, but the FT87-J is the closest they have.

73, Zack W9SZ

On Mon, Oct 18, 2021 at 3:22 PM Andrew Kurtz via groups.io <adkurtz=
[email protected]> wrote:

This thread inspires me to ask a question that is not directly about my
nanoVNA: I have a toroid from a flea market that is blue, has OD = 0.875”,
ID = 0.51”, and length = 0.3125”. I wrapped 6 turns on it, and found (on
the VNA) that L is pretty stable around 180 uH. This indicates that Al
must be about 5000 mH/turns^2. ( I know NOTHING about toroids…) but some
reference has very few with Al in the range of thousands. Some of them
claim high Q, but the VNA indicates a (real) resistance of around 200 ohms
at 1 MHz!! This is insanely high; I have air-core inductors for the same
service with 60 FEET of wire showing R = 11 ohms at 1 MHz, and this
“high-Q” toroid, with 11 INCHES of wire, has R = 200 ohms!?! Am I
misunderstanding something? So:
- Is there a way to identify my toroid simply because of its size and
blue color?
- Is such a high Al, suggesting a very high initial permeability,
realistic?
- Why would adding a toroid to less than 1 foot of coil create 200 Ohms
resistance?
Thanks!
Andy

On Oct 18, 2021, at 11:37 AM, Tom McKee K4ZAD <tom.m@...> wrote:

On Sat, 16 Oct 2021 Cliff <mailto:kd4gt.tn@...?subject=Re:%20%22Q%22%2C%20Coils%2C%20toroids%2C%20and%20guesswork%3F>

wrote about an on line toroid calculator available at:

There is a similar Excel spreadsheet based calculator available for

download at:

This link is one of many in my collection of on-line coil calculators

available at:

<>

73,

Tom K4ZAD

--
This email has been checked for viruses by Avast antivirus software.

This cannot be a powdered iron core. I do not know of any powdered iron
cores that have an AL value of 50,000 uH/100T. It has to be a ferrite core.

Zack W9SZ

On 10/18/21 1:16 PM, Andrew Kurtz via groups.io wrote:

This thread inspires me to ask a question that is not directly about my nanoVNA: I have a toroid from a flea market that is blue, has OD = 0.875”, ID = 0.51”, and length = 0.3125”. I wrapped 6 turns on it, and found (on the VNA) that L is pretty stable around 180 uH.

Check the units of your toroid chart - not everyone used the same scale, I've seen? uH/100 turns, mH/100 turns and others as uH/turns^2

L (mH) = AL(mH/turns^2) * 36

0.180 = AL * 36? -> 0.005 mH/turns^2

or 5 uH/turns^2

This indicates that Al must be about 5000 mH/turns^2. ( I know NOTHING about toroids…) but some reference has very few with Al in the range of thousands. Some of them claim high Q, but the VNA indicates a (real) resistance of around 200 ohms at 1 MHz!! This is insanely high; I have air-core inductors for the same service with 60 FEET of wire showing R = 11 ohms at 1 MHz, and this “high-Q” toroid, with 11 INCHES of wire, has R = 200 ohms!?! Am I misunderstanding something? So:
- Is there a way to identify my toroid simply because of its size and blue color?
- Is such a high Al, suggesting a very high initial permeability, realistic?
- Why would adding a toroid to less than 1 foot of coil create 200 Ohms resistance?
Thanks!
Andy

On Oct 18, 2021, at 11:37 AM, Tom McKee K4ZAD <tom.m@...> wrote:

On Sat, 16 Oct 2021 Cliff <mailto:kd4gt.tn@...?subject=Re:%20%22Q%22%2C%20Coils%2C%20toroids%2C%20and%20guesswork%3F> wrote about an on line toroid calculator available at:



There is a similar Excel spreadsheet based calculator available for download at:



This link is one of many in my collection of on-line coil calculators available at:


<>

73,

Tom K4ZAD