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cut/lengthen vertical antenna wire
Using formula 234/freq for a 1/4 wave vertical with 4 radials I was building gave me a wire length of 16 feet 6 and 1/8 inches. Nano vna gave swr of 2.3 (too high for my qrp station) so tried to find out whether to shorten or lengthen wire. How can I use the nano vna to help with the direction to go. eventually lengthened by 6 inches which brought swr down to 1.3.
As a newbe to short wave radio tx/rx and to nano vna can anyone help with an easy to follow method to use my nano vna for wire adjustment direction. Thanks but difficult just now after suffering 2 strokes so hence the need for help here. Thanks and 73 to all who read this. Doug MM7DSA |
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Re: nanovna-saver question
#nanovna-saver
On Mon, Jul 25, 2022 at 07:14 PM, Jim Lux wrote:
`That's what I thought. Looked for a file, but no luck so far. |
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Re: nanovna-saver question
#nanovna-saver
On 7/25/22 9:39 AM, Nick wrote:
Using nvna-s 0.3.9.The NanoVNA doesn't have very good visibility into its internal state, i.e. the sweep range and other parameters. The software can send a sweep command to get the current sweep setup sweep ¨C sets the start/stop for the next automatic sweep, but you never know when that will happen or when that will be finished and issuing a pause command stops the automatic sweep (per QRP) - Usage: sweep {start(Hz)} [stop] [points] - If no inputs, then prints current setup eg: 300000000 500000000 101 but there's other things that are more difficult. So the tools tend to have their own sets of defaults (stored in an .ini or setup file or equivalent). NanoVNA-Saver also can do the nice thing of commanding the NanoVNA to make multiple sweeps over a subset of the range, so you can get 1000 points in a sweep, for instance. |
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Re: Common ground and 2-port measuring
If you have to rewind a transformer then you could just buy a core and completely build it...
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Why not just buy a different one that directly fits your needs?!? 73 sigi dg9bfc Am 25.07.2022 12:01 schrieb Ed G8FAX <ed@...>:
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nanovna-saver question
#nanovna-saver
Using nvna-s 0.3.9.
Why does nvna-s default to a sweep range of 1M to 100M when I connect to the device? I have set the cal range to 100k to 50.1M on the device itself. Where is the nvna-s default sweep range stored? |
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Re: Read polar impedance (Ohms and phase) directly?
I see the link is in his message.
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-----Original Message-----
From: [email protected] <[email protected]> On Behalf Of Chuck Bland Sent: Monday, July 25, 2022 6:38 AM To: [email protected] Subject: Re: [nanovna-users] Read polar impedance (Ohms and phase) directly? Ed, Thanks for that link! Do you have a link to the entire work? Chuck Bland On Sun, Jul 24, 2022, 15:58 AG6CX <edwmccann@...> wrote: Re comment: |
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Re: Read polar impedance (Ohms and phase) directly?
Chuck Bland
Ed,
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Thanks for that link! Do you have a link to the entire work? Chuck Bland On Sun, Jul 24, 2022, 15:58 AG6CX <edwmccann@...> wrote:
Re comment: |
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Re: Read polar impedance (Ohms and phase) directly?
Fran?ois,
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Greek letters are everywhere, in Physics, Maths, Medicine &c. &c. In English there is a fairly uniform pronunciation () (apart from UK/US variation, which is minor.) In French, there seem to be two schools of thought as to how to name Greek letters. offers names close to those used in English, whereas offers different names and pronunciation. Zut alors! [English pronunciation is offered, e.g., at , but don't tell l'Acad¨¦mie!] If it's any consolation, discovering how an E is pronounced in French is very confusing for a Brit! ? bient?t, 73, Robin, G8DQX On 25/07/2022 09:57, F1AMM wrote:
I find that the use of Greek letters complicates the pedagogy a lot. Many don't even know how to vocalize the letter, making it difficult to read line online. When to use them on this forum it's a hassle. |
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Re: Read polar impedance (Ohms and phase) directly?
On Mon, Jul 25, 2022 at 01:57 AM, F1AMM wrote:
Hi Francois, It seems you want in EXCEL to separate out the real and imaginary parts of a COMPLEX number. You could use the functions IMREAL and IMAGINARY to do this. and then make use of the other functions for working with complex numbers in Excel There are also other Excel functions useful for working with complex numbers IMABS, IMARGUMENT & IMCONJUGATE Kind regards Ed |
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Re: Common ground and 2-port measuring
I was only able to find on the UK ebay the COILCRAFT TTWB1015
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0,07MHz-225MHz Wideband RF Transformer 1 : 1.5 ( ) Which I bought. I would have liked to buy the 2010 (or -B) versions (to have the 1:1 while the secondary winding has a centre tap).. -Or 3010 (or -C). But so be it, I hope I can rewind the 1015 easily... All the best, Victor Op vr 22 jul. 2022 om 15:14 schreef Miro, N9LR via groups.io <m_kisacanin= [email protected]>: I just ordered COILCRAFT TTWB-1-ALD on ebay (US seller), 20pcs for $25 |
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Re: Read polar impedance (Ohms and phase) directly?
F1AMM
My "formula" are used to perform calculations in Excel; for example, to calculate 'L' adapters. The algebraic form is easier to copy, especially when you have to pay attention to cells with $.
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The "mathematical" calculation is done only once to establish the cooking recipe. I find that the use of Greek letters complicates the pedagogy a lot. Many don't even know how to vocalize the letter, making it difficult to read line online. When to use them on this forum it's a hassle. I was disappointed that Excel did not know how to draw a sequence of complex numbers (a+jb) in the form of a graph. It is necessary to break down the real part into the imaginary part. So I don't use these functions. Good day to all 73 -- F1AMM (Fran?ois) -----Message d'origine-----De la part de Ed G8FAX lundi 25 juillet 2022 09:19 |
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Re: Read polar impedance (Ohms and phase) directly?
Hi Francois,
Your development to conclusion appears correct. To be sure use some test values to check it. You might find an alternative approach less mathematically demanding: Addition and subtraction of complex numbers are very easy to perform in rectangular form, whilst multiplication and division are easy to perform in polar form. So first calculate the top line of the equation in rectangular form, then the bottom line of the equation in the same way. Next, convert both to polar form and perform the division. Finaly, if required convert polar to rectangular. Hope that helps Ed, G8FAX |
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Re: Read polar impedance (Ohms and phase) directly?
F1AMM
And S11 (vector) is indeed identical to Gamma (vector), or S11 and the Reflection CoefficientHello ** I agree gamma=S11 ** In effect If we use Z = Zo * (1+gamma) / (1-gamma) that means: Zo + Zo.gamma = Z - Z.gamma gamma.(Zo+Z) = Z - Zo gamma = (Z-Zo)/(Z+Zo) But the question was how to calculate S11 from the impedances and you didn't explain how you calculated gamma if Z=A+jB Your formulation gamma = (Z-Zo)/(Z+Zo) misled me and stupidly I thought it meant gamma (A-Zo)/(A+Zo) + j (B-Zo)/(B-Zo) To answer the question, if the impedance is Z=A+jB it is necessary to continue the development of gamma = (Z-Zo)/(Z+Zo) and that gives: gamma = (A?+B?-Zo?+2jBZo) / ((A+Zo)?+B?) Is this correct ? It is indeed a pity that nanovna-saver only indicates |S11| on the screen. You have to go to the .S1P file to find S11 = a+jb a and b are then the coordinates of the point representing the impedance in the Smith diagram (xOy mark centered on the chart with the unit corresponding to the large outer circle). x=a and y=b Is this correct ? Sorry to have contradicted you by mistake but, in addition, my language is French and I have to make BIG efforts to write in English (thanks Google). I am not a teacher but an old OM who tries to find his way between what he measures (with his nanoVNA-F + nanovna-saver), what he calculates as an adapter for example, what he realizes practically and the observed results (measurements). -- F1AMM (Fran?ois) -----Message d'origine-----De la part de AG6CX (Edward San Francisco) lundi 25 juillet 2022 00:58 |
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Re: Read polar impedance (Ohms and phase) directly?
Re comment:
¡°But S11 is not the equivalent of gama.¡° Indeed Gamma (a vector) is calculated by the quotient of (Zload-Zo)/(Zload+Zo) with Zload and Zo both complex numbers. The result Gamma of this complex division may be expressed in Cartesian form Gamma= a + jb. Gamma is easily converted to polar form where Gamma = rho angle Theta, where Theta = arctan(b/a) rho is the SQRT of a*a + b*b Magnitude of Gamma or IGammaI = rho And S11 (vector) is indeed identical to Gamma (vector), or S11 and the Reflection Coefficient are one and the same. Refer to RF Formulas One Port Systems by Olivier Pilloud HB9CEM 2005-06-28 At pilloud.net/op_web/one_port.pdf Ed McCann AG6CX |
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Re: Read polar impedance (Ohms and phase) directly?
Two years ago I have built the enclosed spreadsheet in ODS format (Libre Office) for education purpose. Maybe it can helpful, and also be easily modified or adapted. Blue fields are input ones. The main interest is that it follows the label names used for the NanoVNA.
As an example I have fed it on line 5 (cells I5 and J5) with the previous results from Jim Lux. These are reverse calculations, and final results are highlighted in E5 and F5 cells, and it perfectly matches ! F6EGK Jean-Roger |
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Re: Read polar impedance (Ohms and phase) directly?
On Sat, Jul 23, 2022 at 03:57 PM, Jim Lux wrote:
Thanks Jim, I had forgotten about those converter functions. Anyone not familiar with Excel functions, "DEGREES" converts radians to degrees.. Kind regards Ed, G8FAX |
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Re: Read polar impedance (Ohms and phase) directly?
F1AMM
I think I found where the error is.
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You wrote : ? The S1P files contains the real and imaginary parts of the reflection coefficient, Greek letter ¡®gamma¡¯. ? But S11 is not the equivalent of gama. We did everything to complicate this matter of reflection coefficient starting with the identifier: - Either with the Greek letter gamma when it has a complex value like A+jB - Either with the Greek letter rho ¦Ñ when using the module We will use a synonymous identifier: S11 which comes from the S parameters of a quadripole. It should say "S one one" but "S eleven" is common. We will not dwell on the parameters S which find their origin in the matrix calculation. The interest of this synonym is that: ? If we talk about the complex value we write S11 ? If we talk about the module we write |S11| remembering that : ? nanovna-saver displays this parameter |S11| ? nanovna-saver saves S11 It is in fact the reduced coefficient because we will retain as definition If Z = A + jB Then z = Z/Zc = A/Zc + j B/Zc in most cases Zc = 50 S11 = (z-1)/(z+1) To complicate everything, we invented the ROS (which some unfortunately still call the TOS, as in the bottom of many Smith charts) while it is almost impossible to know this relationship between the maximum and minimum voltage generated by a standing wave ROS = (1 + |S11|) / (1-|S11|) And |S11| = (ROS-1)/(ROS+1) In everyday life: VSWR = SWR = ROS so we avoid talking about TOS, it's simpler -- F1AMM Fran?ois -----Message d'origine-----De la part de Jim Lux dimanche 24 juillet 2022 00:58 |
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Re: Read polar impedance (Ohms and phase) directly?
On 7/23/22 8:07 PM, F1AMM wrote:
I get the same answer you do 26.4+j 0.669Please can you explain me where is my mistake; I am like Saint Thomas.The complex impedance Z is given by Zo * (1+gamma) / (1-gamma) using Excel S11 -0.31048 0.011489 complex -0.31048+0.011489i 1+S11 0.68952+0.011489i 1-S11 1.31048-0.011489i divide 0.526041061787863+0.0133788274211592i *50 26.30205309 0.668941371 |
Stephen W9SK
Arie Kleingeld PA3A
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