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Author Topic: Litz Coils  (Read 2807 times)

K6STI

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Litz Coils
« on: December 19, 2018, 03:13:21 PM »

I've just added the ability to model coils wound with Litz wire to my coil calculator. Before releasing it, I'd like to check a few Litz coils whose inductance and Q are known. If you have such a coil, please post its dimensions and I'll give it a try.

Brian
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K6STI

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RE: Litz Coils
« Reply #1 on: April 16, 2019, 05:30:54 PM »

I was able to obtain measurements for some Litz coils to validate the coil inductance and Q calculator. For most coils, calculated and measured values were quite close.

As an example of the optimizer function, I designed a 1 mH loading coil for 137 kHz using 420/36 Litz wire with Q > 2000.

The program is here:

http://ham-radio.com/k6sti/coil.zip

Brian
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KM1H

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RE: Litz Coils
« Reply #2 on: July 23, 2019, 05:35:25 PM »

Glad to see your still alive and kicking Brian

Im still using the AO and YO I bought from you ages ago, Id guess there have been no special updates to make it better and I really have no complaints as is.

Carl
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K6STI

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RE: Litz Coils
« Reply #3 on: July 24, 2019, 09:49:21 AM »

Nice to hear from you, Carl. I'll reply via email about AO and YO. Your email here is hidden. If you click on my callsign in COIL, it will display my email address. Send me a note and I'll reply.

I'll take this opportunity to report that I've been regularly updating COIL. It's currently at 3.59 (59th update!). I'm always interested in feedback, both on accuracy and ease of use. I've updated the analysis slightly for both solid and Litz wire, but results have changed little. I realigned my HP 4342A Q meter, remeasured some of the test coils in my small collection and measured some new ones, and updated the accuracy data included with the program. Average accuracy error for the couple dozen coils I measured is 2.4% for inductance and 7% for Q.

The latest version of COIL is here:

http://ham-radio.com/k6sti/coil.zip

Brian
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G0HZU

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RE: Litz Coils
« Reply #4 on: July 31, 2019, 04:55:58 PM »

I just had a go with your coil program and it seems pretty good, thanks! By coincidence I have just been doing some filter design this evening and I have measured a basic solenoid to use in the filter. My own coil design program predicted 300nH and a Qu of 246 at 25MHz. If you look at the image below you can see the coil details in your program screenshot. Also, in the background is measured data for the real coil with a Q plot vs frequency. This seems to agree very closely with your program at several test frequencies. I also have a very good HF/VHF Q measuring setup here and this measured the coil to have a Q of 244 at 25MHz. This Q measuring jig is the one I trust the most. This agrees with the plotted data and your program.

Note that the solenoid is not a toroid, despite what the Genesys workspace name says. It is a 1 port measurement of a solenoid and I was comparing it to a toroid in this simulation. The toroid data is blanked off the screen to avoid any confusion so everything you see is for the 6 turn solenoid :)

Hope this is useful!



« Last Edit: July 31, 2019, 05:04:31 PM by G0HZU »
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Regards
Jeremy

K6STI

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RE: Litz Coils
« Reply #5 on: July 31, 2019, 07:38:06 PM »

Thanks for the feedback. I'm glad the program results are close to your measurements. My HP 4342A has the 001 option that expands low-frequency response but limits the high end to 32 MHz. So I haven't been able to measure any test coils in the VHF range. If you come across any discrepancies, I'd like to hear about them. Click on my callsign in the program to see my email address.

The font you're using shows something else for the omega symbol. If you right-click on the top of the program window, you can select Properties and try another font.

Brian
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K6STI

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Re: Litz Coils
« Reply #6 on: February 21, 2020, 04:10:19 PM »



Version 3.86 of my Windows coil calculator is here:

http://ham-radio.com/k6sti/coil.zip

See README.TXT to install the program.

Some recent changes:

Accuracy
I've refined the inductor model. Average error magnitude is 2.0% for L and 4.8% for Q on a set of test coils measured with an HP 4342A Q meter. See COILS.TXT for details.

Litz Wire
COIL handles Litz wire with 0.02 mm strands, available from Electrisola. Use this wire to make coils with very high Q up to about 10 MHz.

Coil Shape
I've added octagonal, hexagonal, and square shapes. Some long-wave experimenters use polygonal loading coils wound on a cage of PVC pipe.

Form Contact
This is the percentage of the winding in contact with the dielectric. Use it for coils with dielectric ribs (Air Dux), ridges (ceramic and phenolic forms), or wound on a polygonal dielectric cage.

Dielectrics
I've added a number of common plastics as well as cardboard, the latter for your kid's crystal set coil wound on an oatmeal box.
 
Metals
I've added several kinds of copper and aluminum. I include information and references on the effect of tin plating.

Optimizer
The optimizer varies selected coil parameters to maximize Q while keeping inductance constant. Due to code refinement and use of assembly language, it now runs virtually instantaneously even on older computers.

Brian
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