开云体育

Dears,

FT240-43 Torroid, Can I use my NanoVNA to meassure my several torroids to be sure that I have the correct ones for HF UNUN?

any info is welcome

73,
Kurt

43 or 31 material are appropriate for HF applications. 43 is better for
20-meters upward and 31 material is best for 160 through 40 meters. If you
are sure you have 43 material, there really is no reason to test the
toroids.

Dave - W0LEV

--
Dave - W?LEV

a useful hint when identifying torrides type 31 has resistance across the
surface . type 43 has none. Different materials.

--
*Gene Ruff*

I should have said that type 43 reads like an open circuit .

--
*Gene Ruff*

reply to Kurt's Toroid Measurement

It's quite easy to get a simple measurement on a toroid inductance and to see the inductor's behavior over a desired frequency band with a nanoVNA. So easy, I think it should be a matter of course for every build.

Getting the most accurate results requires using the proper set up for the expected impedance. Depending on the impedance, the measurement method will change. Using a simple one-port reflection measurement for impedances "somewhere" near 50 ohms is usually sufficient for a quick check. For higher and lower impedances, you'll have to change to a two-port series or shunt method.

To get a reasonable idea of the inductance and resistance of your toroid use a basic fixture and attach it to port 0. Set up the frequency start and stop values, switch to Smith Chart, and calibrate. Then attach your inductor. You will be able to see an estimate of the inductance at the desired frequency of operation. The inductor should create a trace in the upper half of the screen. The trace may be anything from a point to an arc along the entire outer edge of the display.

A good low-loss inductor should create a trace near the outside upper edge of the Smith Chart. If the trace moves inward from the edge, you have losses. If the trace crosses the horizontal axis, you have a self-resonance.

Don't be surprised if the readouts show unexpected results. The outcome really depends on where the toroid came from. Is it really the advertised material? Remember, that the A_L values are usually for 10 kHz (the standard frequency) and your inductance might be quite a bit off what you expected if that is how you decided on the number of turns.

I like to check every component before I use it. I've been surprised by faulty parts. Often it's much harder to fix once you've assembled your circuit. A semiconductor tester, LCR meter, and nanoVNA generally get used on every part.

Garry,
my experiene: when trying the buid a bandpass filter (mesch coupled filter) with ELSIE I noticed that the series L?s are only dependant on the chosen bandwidth. In my case 17.5 uH was the series L. Winding this on a T37-2 toroid. gave full toroid (about 80 cm of wire).?The self resonance using my NANO VNA (channel 0, S11) showed about 12 MHz, Generating an S-parameter file and putting these results into RFSIM99 showed that I cannot use this filter even at 7 MHz!?
? Please explain? why? and wehn a two port measurement is more usefill!
Henning WeddigDK5LV? ??
Dipl. Ing. Henning Christof Weddig

Am Donnerstag, 22. Juni 2023 um 17:36:41 MESZ hat Garry <garry.heard@...> Folgendes geschrieben:

#### reply to Kurt's Toroid Measurement

It's quite easy to get a simple measurement on a toroid inductance and to see the inductor's behavior over a desired frequency band with a nanoVNA. So easy, I think it should be a matter of course for every build.

Getting the most accurate results requires using the proper set up for the expected impedance. Depending on the impedance, the measurement method will change. Using a simple one-port reflection measurement for impedances "somewhere" near 50 ohms is usually sufficient for a quick check. For higher and lower impedances, you'll have to change to a two-port series or shunt method.

To get a reasonable idea of the inductance and resistance of your toroid use a basic fixture and attach it to port 0. Set up the frequency start and stop values, switch to Smith Chart, and calibrate. Then attach your inductor. You will be able to see an estimate of the inductance at the desired frequency of operation. The inductor should create a trace in the upper half of the screen. The trace may be anything from a point to an arc along the entire outer edge of the display.

A good low-loss inductor should create a trace near the outside upper edge of the Smith Chart. If the trace moves inward from the edge, you have losses. If the trace crosses the horizontal axis, you have a self-resonance.

Don't be surprised if the readouts show unexpected results. The outcome really depends on where the toroid came from. Is it really the advertised material? Remember, that the A<SUB>L</SUB> values are usually for 10 kHz (the standard frequency) and your inductance might be quite a bit off what you expected if that is how you decided on the number of turns.

I like to check every component before I use it. I've been surprised by faulty parts. Often it's much harder to fix once you've assembled your circuit. A semiconductor tester, LCR meter, and nanoVNA generally get used on every part.

Hello

I was having an issue with RFI in my shack, I'm in an apartment and my MFJ loop is at the back of the office next to a window and my radio is an Icom IC-7300. I made a CM choke from a 240-31 ferrite toroid core and it solved the problem on 40 and 20 meters. I was still having problems on 17 and 15 meters so I got a 240-43 donut and made a CM choke and it pretty well cleared up my problems aside from a couple of problem areas which were solved by a few more 240-43 ferrite toriod cores. I made up a test jig for my NanoVNA from articles found on the net. I could post a picture if anyone in interested

Steve ve4fx

FT240-43 Torroid, Can I use my NanoVNA to meassure my several torroids
to be sure that I have the correct ones for HF UNUN?
any info is welcome

Hello

Unun means nothing. You should know that the nature of the material of the torus is of great importance if you make a choke (self) with it. If you made a RUTHROFF transformer, it is much less important.

To test the torus, a self must be made. To measure the characteristics, enough turns are needed to cover the *entire* torus. My measurements were failing when I didn't do that. Count the number of coils carefully, you will need this number later. It is the number of wires visible inside the torus that counts; a wire that passes straight is counted as a turn.

You will thus be able to measure, with the NanoVNA, a self (?H) according to the frequency etc. You will be able to calculate the Al and you will be able to calculate the ?r which will allow you to check the nature of the material.

It is not at all an easy thing to do.

73
--
F1AMM
Fran?ois

De la part de Kurt Heernaert
Envoyé : mercredi 21 juin 2023 21:32

Go to

then scroll WAY down to

"The easiest way to identify most ferrite materials is to wind about four turns of wire through the core and then measure the lowest frequency at which the value of reactive impedance equal resistive impedance i.e. X=R. There will be some variation between different batches and sizes of materials. But if you can plot the results graphically you can easily identify the 'signature' of each material.

Here are my references for some common ferrite materials

FT240-77 0.74MHz
FT240-31 3.5MHz
FT100-33 7MHz
FT240-43 17MHz
FT240-K 22MHz
FT240-52 31MHz
FT240-61 58MHz"
-----------
and

--
and this page is long, but might also help ('way down the page)


------------------
And there's
"Name that Core" by Carl Luetzelschwab K9LA"
(a 2-page document for which I have no URL, just a printout of the text, with a graph and a chart.

OR this might work:
}
------------

You can also look back at this group's topic 72777666 for some more tips.
------------------------------------

Doug, K8RFT

The different measurement techniques usually arise due to the propagation of error. In the case of vna's the measurement methods relate to the impedance of the DUT. You will find a number of articles online describing how to mak accurate measurements. One such article is

Basically, a 1-port measurement works best around the 50 ohm port impedance, shunt-through works best for low impedance, and series-through works best for higher impedance.

I'm not sure that changing the measurement technique will help, unless you are experiencing significant errors. You might need to change your core size or even material to make inductors with less parallel capacitance and avoid self-resonance problems. I'm not an expert in filters, I have mostly built other people's designs and not a large number of them. But, it seems your problem may be the inductor construction.

On 6/23/23 6:51 AM, Garry wrote:

The different measurement techniques usually arise due to the propagation of error. In the case of vna's the measurement methods relate to the impedance of the DUT. You will find a number of articles online describing how to mak accurate measurements. One such article is

Basically, a 1-port measurement works best around the 50 ohm port impedance, shunt-through works best for low impedance, and series-through works best for higher impedance.

I believe the original question was more about "how do I figure out which mix this unmarked toroid is" and for that, measurement accuracy may not be super important, especially if you have some known examples to compare to.

The nice thing about a VNA is you can easily sweep a wide frequency range, so you're looking for a "does my curve look more like curve A or curve B", rather than a single spot measurement at a single frequency and trying to figure out if your estimate of mu is correct.

The what do R and X look like vs frequency is a pretty good way to distinguish materials. And if there's a measurement error it might not perturb that much. What you're really looking for is "not lossy at frequency range X but lossy at frequency range Y"

Garry says:

“… Then attach your inductor. …”

The devil is in the details with such a simple-sounding statement. Attach it how? There are 2 ports on the NanoVNA, each with a center conductor and an outside conductor (called, shield, ground, body, etc.) The inductor (DUT) has a single conductor with 2 ends. So, exactly how do you connect those 2 ends to the NanoVNA ports? Considering there is also an option of leaving certain ports, wire ends, or conductors (center/shield) disconnected, there are more than 10 possible options.

Then, once some sort of connection is made between inductor and VNA, which measurement option (menu choice) do you select on the NanoVNA? S11, S21, shunt, thru, etc. This decision adds more complexity.

For those experienced/ trained in using VNA’s and deciding such things for multiple different types of DUT’s, these may be such basic questions as to be assumed inherently obvious. But they are not inherently obvious to the new VNA users attracted to forums such as these.

I have some SMA right-angle connectors. The center pin of coax is supposed
to solder to the inner pin connection in the connector, and the shield is
crimped with a ferrule to the connector. But what I did was solder a wire
about 3 inches long to the inner pin connection and another wire to the
outer (ground) area of the SMA connector. This minimizes the capacitance
between the wires. (This is significant!) I measure 3.5 pF with my leads
and connector.

Make sure your NanoVNA is calibrated for the frequency range you want to
measure. Put the SMA connector on the s11 (top) port of the NanoVNA. Solder
the wires to the two leads of your inductor. You can then measure its
reactance, resistance and inductance with the appropriate measurement
settings of the NanoVNA.

I've done this with dozens, maybe hundreds of inductors,

Zack W9SZ

On Fri, Jun 23, 2023 at 11:42?AM Steve Johnson <cascadianroot@...>
wrote:

Garry says:

“… Then attach your inductor. …”

The devil is in the details with such a simple-sounding statement. Attach
it how? There are 2 ports on the NanoVNA, each with a center conductor and
an outside conductor (called, shield, ground, body, etc.) The inductor
(DUT) has a single conductor with 2 ends. So, exactly how do you connect
those 2 ends to the NanoVNA ports? Considering there is also an option of
leaving certain ports, wire ends, or conductors (center/shield)
disconnected, there are more than 10 possible options.

Then, once some sort of connection is made between inductor and VNA, which
measurement option (menu choice) do you select on the NanoVNA? S11, S21,
shunt, thru, etc. This decision adds more complexity.

For those experienced/ trained in using VNA’s and deciding such things for
multiple different types of DUT’s, these may be such basic questions as to
be assumed inherently obvious. But they are not inherently obvious to the
new VNA users attracted to forums such as these.

I should have also mentioned in detail how you measure things. Choose
"Display," then "Format S11 (Refl)." Looking down the list you will see
"Resistance" and "Reactance." Choose which you want to measure. You can do
further measurements by choosing "More" twice. In the choice of options,
you will see "Parallel R,' "Parallel X", "Parallel C" and "Parallel L."
(These are the best choices for measuring a single capacitor or inductor
connected as I described below. Note, the numbers of the reactance,
resistance and inductance vary with frequency and you would need to choose
an exact frequency by rocking the rocker arm back and forth to display the
values at one frequency.

Zack W9SZ

On 23/06/2023 08:24, Fran?ois wrote:

to be sure that I have the correct ones for HF UNUN?
any info is welcome

Hello

Unun means nothing. You should know that the nature

Hello Francois,
What do you mean "UnUn" means nothing?? It means unbalanced input
to unbalanced output. Many filters, band pass, high pass or low pass
are UnUn and many impedance matching networks are too.
73 Ken g8beq

We discussed it here
/g/nanovna-users/topic/s11_r_x_hz/98279792
--
F1AMM
Fran?ois

On Wed, Jun 21, 2023 at 12:48 PM, Kurt Heernaert wrote:

FT240-43 Torroid, Can I use my NanoVNA to meassure my several torroids to be
sure that I have the correct ones for HF UNUN?

Measuring toroids has been discussed many times in this group over the last few years. There is a wealth of information provided by many knowledgeable group members. If you do a group message search on "toroid" you will find lots on information on how to measure toroids and identify/verify them using the NanoVNA. You can also take a look at this groups wiki for links to relevant posts. How to use the S11 and S21 methods of impedance measurement and NanoVNA limitations with the S21 technique are discussed in depth. There is a wealth of information provided by many knowledgeable group members.

Roger

Fair-Rite has several excellent videos on measuring the yr of unknown
toroids. Search their www site for videos. They are excellent.

Dave - W0LEV

On Fri, Jun 23, 2023 at 3:58?PM Roger Need via groups.io <sailtamarack=
[email protected]> wrote:

On Wed, Jun 21, 2023 at 12:48 PM, Kurt Heernaert wrote:

FT240-43 Torroid, Can I use my NanoVNA to meassure my several torroids

to be

sure that I have the correct ones for HF UNUN?

Measuring toroids has been discussed many times in this group over the
last few years. There is a wealth of information provided by many
knowledgeable group members. If you do a group message search on "toroid"
you will find lots on information on how to measure toroids and
identify/verify them using the NanoVNA. You can also take a look at this
groups wiki for links to relevant posts. How to use the S11 and S21
methods of impedance measurement and NanoVNA limitations with the S21
technique are discussed in depth. There is a wealth of information
provided by many knowledgeable group members.

Roger

--

*Dave - W?LEV*


--
Dave - W?LEV

Excellent points Steve. (you get a Bravo-Zulu for that one)

Mike C. Sand Mtn GA

I think that a few pictures of your fix would be of help to a lot of hams out there looking for cures to their problems.