On Sun, Jun 25, 2023 at 10:25 PM, Jim Lux wrote: ESR is the ohmic resistance *at RF* which will be higher than the DC
resistance (skin effect).
What you should be able to do is measure the Z (both X and R) far away
from self resonance, and get a rough estimate.
Thank you Jim. -- Mike
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Thank you Roger. The coil is 95 turns of 0.9mm enamelled copper wire close wound on a 36mm PVC former.
--
Mike
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On 6/25/23 1:26 PM, Mike wrote: I have wound a 110uH coil for an antenna system and I want to create a model of the inductor that I can use in a simulation program. In other words, I need to know the inductance, parasitic capacitance and ESR.
Using my NanoVNA-H4 I measured the inductance on a Smith chart at a low frequency (around 70kHz) where the reactance is about 50 ohms. I then measured the self resonant frequency (10.5MHz) and calculated the parasitic capacitance as 2pF.
Is that correct so far?
What about ESR? Is that the ohmic resistance of the coil or is it more complicated than that?
Thanks! ESR is the ohmic resistance *at RF* which will be higher than the DC resistance (skin effect). What you should be able to do is measure the Z (both X and R) far away from self resonance, and get a rough estimate.
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On Sun, Jun 25, 2023 at 01:26 PM, Mike wrote:
I have wound a 110uH coil for an antenna system and I want to create a model
of the inductor that I can use in a simulation program. In other words, I need
to know the inductance, parasitic capacitance and ESR.
Using my NanoVNA-H4 I measured the inductance on a Smith chart at a low
frequency (around 70kHz) where the reactance is about 50 ohms. I then measured
the self resonant frequency (10.5MHz) and calculated the parasitic capacitance
as 2pF.
Is that correct so far?
What about ESR? Is that the ohmic resistance of the coil or is it more
complicated than that?
Yes it is more complicated than that. The inductance will vary with frequency and so will the ESR. In the case of an air wound coil the underlying inductance will slightly change as you increase frequency due to the "skin effect" which forces current to the outer perimeter of the conductor. If the coil is wound on a powdered iron or ferrite core there will be considerable change of inductance with frequency due to the permeability decreasing with frequency. The ESR will increase with frequency due to core losses and the skin effect which increases the RF resistance of the coil windings. When you try to measure the inductance of an inductor using a VNA the firmware or PC application will calculate the "apparent inductance" by simpling dividing the measured reactance by 2*pi*frequency. This is not the same as the actual inductance L. The reason is that the parasitic capacitance is in parallel with the inductor and you now have capacitor reactance in parallel with the inductor reactance which results in a higher reactance than that of the inductor alone. This is shown in the attached diagram. So if you tell us what type of inductor you are measuring (air wound, powdered iron or ferrite) more specific information can be provided. Roger
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On rf the resistance is higher as dc resistance
Dg9bfc sigi
Am 25.06.2023 22:26 schrieb Mike <mail@...>:
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Show quoted text
I have wound a 110uH coil for an antenna system and I want to create a
model of the inductor that I can use in a simulation program. In other
words, I need to know the inductance, parasitic capacitance and ESR.
Using my NanoVNA-H4 I measured the inductance on a Smith chart at a low
frequency (around 70kHz) where the reactance is about 50 ohms. I then
measured the self resonant frequency (10.5MHz) and calculated the
parasitic capacitance as 2pF.
Is that correct so far?
What about ESR? Is that the ohmic resistance of the coil or is it more
complicated than that?
Thanks!
--
Mike
|
I have wound a 110uH coil for an antenna system and I want to create a model of the inductor that I can use in a simulation program. In other words, I need to know the inductance, parasitic capacitance and ESR.
Using my NanoVNA-H4 I measured the inductance on a Smith chart at a low frequency (around 70kHz) where the reactance is about 50 ohms. I then measured the self resonant frequency (10.5MHz) and calculated the parasitic capacitance as 2pF.
Is that correct so far?
What about ESR? Is that the ohmic resistance of the coil or is it more complicated than that?
Thanks!
--
Mike
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Name format of the .cal files
Hi. Few questions:
1) I organized the name format of the .cal files stored in the microSD card of my NanoVNA-H4 as per the image in order to easily find them, as only capital letters can be used and dots / commas aren't available. How about you?
2 ) Have you tried to rename them with the PC in order to also use the lower case letters, commas, etc. (e g. 1.8MHz-29.7MHz.cal)? Did you get issues?
Many thanks.
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Thanks for all the help
I do have the smaller original VNA-H model
It does have a rechargeable battery. I charged it up and the unit turns on and there is software in it.
I'll purchase some SMA adapters to able to connect it to antennas.
I was watching videos on the wrong models and got confused.
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i have an extra battery from a smashed screen unit kicking around i could
drop it in an envelope for you if you like
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On Sat, Jun 24, 2023 at 5:49?PM Michael <m005kennedy@...> wrote: I bought one of these. I got the most inexpensive one. It says on the back
it is a VNA-H, it just covers the HF frequencies. I thought it would come
setup and ready to use.
Oops!
I thought it had a rechargeable battery, but doesn't look like it does.
So correct me if I'm wrong.
1 I need a battery pack to run it. 5 volts?
2 I need a SD card of 32 gigs.
3 I have to download the software for it.
4. Then I can figure out how to use it with online documentation.
Are these the correct steps? It is possible to get a card with the firmware
installed on it? I ask because I don¡¯t really have a good computer right
now, but I think I could probably borrow a laptop from the time it would
take to install it.
So will these head me in the correct direction ?
Mike
KB1IUI
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'Way back when the nanovna was new (about 4 years ago, I think), the cheapest ones came without battery - but mainly due to shipping restrictions in the originating country (hazardous material).
Did you look to see if there is a battery inside? The cheapest ones (like I bought then) do not have a case. You can see the circuit boards in it.
Plug yours into a USB connector or charger to give it power, and then see if it works.
--
Doug, K8RFT
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If it's a real -H, it should already have a rechargeable battery inside the
case, and you charge it with a USB cable.
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On Sat, Jun 24, 2023, 3:17 PM Jim Lux <jimlux@...> wrote: On 6/24/23 2:42 PM, Michael wrote:
I bought one of these. I got the most inexpensive one. It says on the back
it is a VNA-H, it just covers the HF frequencies. I thought it would come
setup and ready to use.
Oops!
I thought it had a rechargeable battery, but doesn't look like it does.
So correct me if I'm wrong.
1 I need a battery pack to run it. 5 volts? No, probably a standard 13650 battery - 3.5 volts.
2 I need a SD card of 32 gigs. Nope, not unless you want to save data and move it somewhere else.
3 I have to download the software for it. Only if you want to upgrade the existing firmware or use it with a PC.
Mine's 2-3 years old, and I'm running the original firmware.
4. Then I can figure out how to use it with online documentation.
Yes, and copious questions here.
Are these the correct steps? It is possible to get a card with the
firmware
installed on it? I ask because I don¡¯t really have a good computer right
now, but I think I could probably borrow a laptop from the time it would
take to install it. You don't load software from the SD card - that's just to store
measurements. If you want to upgrade the firmware, you'd do that from a
PC.
So will these head me in the correct direction ?
Mike
KB1IUI
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On 6/24/23 2:42 PM, Michael wrote: I bought one of these. I got the most inexpensive one. It says on the back
it is a VNA-H, it just covers the HF frequencies. I thought it would come
setup and ready to use.
Oops!
I thought it had a rechargeable battery, but doesn't look like it does.
So correct me if I'm wrong.
1 I need a battery pack to run it. 5 volts? No, probably a standard 13650 battery - 3.5 volts. 2 I need a SD card of 32 gigs. Nope, not unless you want to save data and move it somewhere else. 3 I have to download the software for it. Only if you want to upgrade the existing firmware or use it with a PC. Mine's 2-3 years old, and I'm running the original firmware. 4. Then I can figure out how to use it with online documentation. Yes, and copious questions here. Are these the correct steps? It is possible to get a card with the firmware
installed on it? I ask because I don¡¯t really have a good computer right
now, but I think I could probably borrow a laptop from the time it would
take to install it. You don't load software from the SD card - that's just to store measurements. If you want to upgrade the firmware, you'd do that from a PC. So will these head me in the correct direction ?
Mike
KB1IUI
|
I bought one of these. I got the most inexpensive one. It says on the back
it is a VNA-H, it just covers the HF frequencies. I thought it would come
setup and ready to use.
Oops!
I thought it had a rechargeable battery, but doesn't look like it does.
So correct me if I'm wrong.
1 I need a battery pack to run it. 5 volts?
2 I need a SD card of 32 gigs.
3 I have to download the software for it.
4. Then I can figure out how to use it with online documentation.
Are these the correct steps? It is possible to get a card with the firmware
installed on it? I ask because I don¡¯t really have a good computer right
now, but I think I could probably borrow a laptop from the time it would
take to install it.
So will these head me in the correct direction ?
Mike
KB1IUI
|
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.
** It is a French expression to indicate that there are a multitude of unbalanced / unbalanced impedance matching solutions. Already the expected transformation ratio will have major consequences. This transformation ratio only makes sense when considering non-reactive impedances. If a resonant antenna is purely resistive, in its bandwidth it is reactive. In a un/un, incorporating a toroid, the toroid can either be used as a choke or as the core of a transformer (or a bit of both). Don't believe that a un/un using a torus is a one-size-fits-all solution. Even if you use a (theoretical) perfect transformer between your antenna and the transmitter, you will need another device to compensate for impedance variations such as an ATU. That's why I wrote: "Unun means nothing" 73 -- F1AMM Fran?ois De la part de Kenneth Greenough Envoy¨¦ : vendredi 23 juin 2023 19:41
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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.
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On 6/22/2023 8:55 AM, Steve wrote: 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
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Excellent points Steve. (you get a Bravo-Zulu for that one)
Mike C. Sand Mtn GA
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On 6/23/2023 12:42 PM, Steve Johnson 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.
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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
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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
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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
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Roger Need
Andrea I2UEA
john rader
Mike C.