Re: METHOD for MEASURING COMMON MODE CHOKE IMPEDANCE
Assuming that "wires" (transmission line) used to make CMC are much shorter then "lambda" across useful frequencies, how much impact do you expect from "mismatched" characteristic impedance of CMC?
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Miro, N9LR
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#40326
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Re: Smith Charts
When using the rectangular display, you can see that results may be compromised by the limited resolution of the magnitude/angle data, which is 0.001 in magnitude. You can see that the magnitude
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Brian Beezley
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#40325
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Re: Smith Charts
Thanks, Alan. Using dot mode makes it easy. The upper Q = 1 intersection is between two data points. The lower intersection is close to one point, at which I've put the marker. A little calculation,
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Brian Beezley
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#40324
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Re: Smith Charts
Here is a resonator s1p file that you can apply to the Q=1 contour. Capture the Q crossings at upper and lower (XL , XC) positions on the chart along with the zero real crossing. This provides
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alan victor
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#40323
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Re: Smith Charts
Using dots can have a fascinating decorrelation effect. This is group delay for a crystal filter. The response is 80 dB down outside the passband, as shown in the second image. Group delay gets noisy
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Brian Beezley
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#40322
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Re: Smith Charts
I should have added this file listing to my previous post. The lin/log switch occurs in the middle. It's at 720 MHz, not 7.2 GHz. My ability to count zeros is restricted to "one, two, three, many."
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Brian Beezley
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#40321
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Re: Smith Charts
I'm going to add an option to plot data points without a line connecting them. This is useful for assessing the data density, which is not always evident in a normal curve. The sample below reveals
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Brian Beezley
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#40320
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Re: Smith Charts
Excellent.
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alan victor
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#40319
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Re: Smith Charts
No, but clicking the mouse will put a marker at the data point nearest the mouse cursor. Then you can use the mouse wheel to step up and down the curve to the desired point. I'll think about
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Brian Beezley
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#40318
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Re: METHOD for MEASURING COMMON MODE CHOKE IMPEDANCE
Hi Dave Here My message about RG213 coax measurements posted here on Avril 5 2025: for My RG213 cable (25m length) loaded by a 50.3 Ohm resistor , I used the centered impedances circle methode on
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Team-SIM SIM-Mode
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#40317
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Re: Smith Charts
Thank you. Are the data points from the s1p or s2p file highligted on the plot? A cursor that is positioned at or near an input file value is needed. For example, the crossing of a Q contour or SWR
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alan victor
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#40316
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Re: Smith Charts
Thanks, Alan. That's what I figured, but I have no experience with Smith charts so I wasn't sure. I've posted the latest here: https://k6sti.neocities.org/splot.htm Brian
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Brian Beezley
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#40315
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Re: Smith Charts
No. Two different tools applied as needed, others may have different opinion.
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alan victor
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#40314
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Smith constant SWR-circle?
@DiSlord Is it possible to add a function for constant SWR-circles on the Smith-chart of NanoVNA, for example SWR 2 and SWR 3, perhaps in red color? Maybe also in the NanoVNA-App-D as I think it was
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Torbj?rn Toreson
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#40313
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Re: Smith Charts
Alan, currently I do not provide a way to display SWR circles and Q contours at the same time. Should I? Brian
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Brian Beezley
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#40312
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Re: METHOD for MEASURING COMMON MODE CHOKE IMPEDANCE
Hi Dave This method of direct experimental measurement, without any computational artifice and without the risk of modeling errors or theoretical estimations, is simply my own used method, which I
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Team-SIM SIM-Mode
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#40311
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Re: Smith Charts
Excellent, Very nicely done.
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alan victor
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#40310
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Re: Smith Charts
By Royal command . . . After much experimentation, I reverted to the standard grid with optional fill-in. I used the homebrew precision circle maker for the grids and SWR/Q curves. Brian
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Brian Beezley
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#40309
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Re: METHOD for MEASURING COMMON MODE CHOKE IMPEDANCE
Thanks a lot Dave, for the quick response. Here the sun is just rising up! Shall look out for your post by evening (that will be 'tomorrow' for you!). 73 Jon, VU2JO [email protected]> wrote:
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Jon
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#40308
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Re: METHOD for MEASURING COMMON MODE CHOKE IMPEDANCE
Jon, please wait for tomorrow as it's supper time here in N. Colorado. I'll do another procedure using the Smith Chart and the VNA on measuring the C and L. Dave - W?LEV [email protected]> wrote:
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W0LEV
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#40307
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