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Re: S21 balun losses with Z0 renormalisation from 50 Ohm to 78 Ohm
Hi Dave
Thanks I do not use any external artifact to take S21 Losses measurements with equivalent 78.5 Ohm coax Z0 , i just use the DiSlord Z0 renormalisation option on Display menu, this option take on consideration all computing's needed to acte as a real 78.5 Ohm NanoVNA . For measuring characteristic impedance of my Balun i use My owne purely experimental methode , no computing nor modeling just measuring the resistor value that focused the Smith diagram on one dote (resistor trimmer termination) and read the renormalized impedance value that make it exactly on the center of the the shart, it's easy methode, reliable and accurate enougth without any computing errors and estimation, only direct experimental measurement , see screenshoot illustration. 73's Nizar |
Re: S21 balun losses with Z0 renormalisation from 50 Ohm to 78 Ohm
Instead of reading where the plot intersects, read the numbers at the top
of the screen which is where your cursor is placed. You have: -0.774 dB loss at 54.6 + j 35.2 ohms equivalent of 64 ohms for the total impedance -0 440 dB loss at 80.7 + j 24.8 ohms equivalent of 84 ohms for the total impedance The total impedance is derived by calculating the SQRT of the SUM of the SQUARES. Note that using the reflection measurement option as illustrated in the first image, the total loss is 0.5 of the measured value as the RF must pass twice through the network. The ratios above don't change. So the loss at nominally 54 ohms real is 0.167 dB greater at 81 ohms real. Also note that due to the non 50-ohm or non 72-ohm Zo of the transmission line transformer (common mode choke), the Zo of the choke will transform either resistance to something else between 50 and 80-ohms. What you are using for your 50 and 72 ohm non-reactive loads for the load in your common mode choke - the disc in the first picture? How did you measure the impedance of our common mode choke? I usually take two measurements to determine this: 1) Measure the capacitance with the far end of the choke open terminated. This will give you the capacitance of the windings (pretty close). 2) Measure the inductance with the far end of the choke short terminated. this will give you the inductance of the windings (pretty close). Measure both of these using the Smith Chart and the cursor. Then calculate the characteristic impedance of the transmission line choke (common mode choke) using the following: Zo = SQRT [Measured Inductance in Henries / Measured Capacitance in Farads] NOTE: 1 ?H = 1E-6 H and 1 pF = 1E-12 F Dave - W?LEV both the On Sun, May 11, 2025 at 6:03?PM Team-SIM SIM-Mode via groups.io <sim31_team= [email protected]> wrote: Hi All-- *Dave - W?LEV* -- Dave - W?LEV |
Re: S21 balun losses with Z0 renormalisation from 50 Ohm to 78 Ohm
Hi All
i tryed to change the balun designe with the same FT140-43 but with 1X12 turns this time , I measure the charateristic impedance of the balun is around 142 Ohm ( see Smith shart focused on the graph center) , but this time with 78.5 Ohm renormalized coax impedance it gives the half with 50 Ohm normal coax , huge diffrence around 1db at 30Mhz , in add this new balun seems have much more losses -2.5 db compared to the first one -0.2db , why ?? what is not correct with this second balun , see illustration below . 73's Nizar . ![]()
balun 1_1 12 spires.jpg
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nanovna-h4_screen_2025-05-11_18-43-02.png
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nanovna-h4_screen_2025-05-11_18-23-23.png
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nanovna-h4_screen_2025-05-11_18-22-44.png
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Re: S21 balun losses with Z0 renormalisation from 50 Ohm to 78 Ohm
Please compare at the same frequency. Your 50-ohm (actually 52-ohm)
measurement is at 27.7 MHz. Your 72-ohm measurement is at 14.2 MHz. Please repeat at the same frequency and get back with us. Dave - W?LEV On Sun, May 11, 2025 at 4:47?PM Team-SIM SIM-Mode via groups.io <sim31_team= [email protected]> wrote: Hi-- *Dave - W?LEV* -- Dave - W?LEV |
S21 balun losses with Z0 renormalisation from 50 Ohm to 78 Ohm
Hi
I am a little confused, my 1/1 balun done with FT140-43 2x10 turns with 1mm wire as illustrated by photo attached, i want to measure losses by S21 Logmag function after a good thru calibration, with renormalizing the coax Zc impedance from 50 Ohm to 78.5 Ohm it gives me the double of losses with 78.5 Ohm coax compared to 50 Ohm coax Z, i can not explaine this ? why ? see S21 responses attached , knowing that i measured the caracteristic impedance of the balun it is around 62 Ohm as showen by graphic attached here , any help ? H4 + 1.2.40 73's Nizar ![]()
52c35c45-e961-4bca-a16e-8b8097d53401.jpg
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nanovna-h4_screen_2025-05-11_16-45-08.png
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Latest version of nanovna saver...
Is nanovna saver version V0.7.3 the latest?
Is it backward compatible to all (older) nanovna hardware/firmware and all the various forms of the nanovna implementations? Understand that some features will not function on older units without updating their firmware. However, only interested in the most basic of operations including electrical delay which was standard way back in 2019. When Rune was developing the program, it was available as an application executable (exe) and nothing else was required to install. Is that still the case? Thank you, |
Re: H4 + DiSlord 1.2.40 + Nano_App 1.1.218
Hi
It helps me to adjust gaps between 1/1 current balun wires to have a Zc = 48.5 Ohm (initially wires are colled together gives 39 Ohm characteristic impedance of twean lead of balun ) . amazing tools, Now i should adjust another curren balun for my 78 ohm coax . 73's Nizar |
H4 + DiSlord 1.2.40 + Nano_App 1.1.218
Hi
Graphic image option of H4+DiSlord firmware 1.2.40 done by the Nano_App 1.1.218 is a really amasing option, it make bigger the Nano VNA screen with larger PC screen and mouse option running superbely . Thanks to DiSlord . some bugy behaviors still there with windows windowing , Hope it will be debuged soon to make it more reliable , I like it a lot , it make easier almost things graphically. especially less confusing between 0 and 8 characters . 73's Nizar |
Re: Unun Testing - Is a Attenuator really needed?
#calibration
#measurement
#nanovna-h4
I don't plan on putting one up. I do not see it as the best antenna to use.
People say they have worked a lot of stations with it, but others have said they worked people using a gutter or bedspring as an antenna. :-) The best 40m antenna I have built and used was a vertical magnetic loop antenna, 58 feet long for the horizontal run, 12 feet high vertically. I had the bottom wire 5 feet off the ground. It was a two-turn loop with a quarter wavelength of 70 ohm cable at the feedpoint, which made the impedance at the other end of the 70 ohm cable 50 ohms. Low radiation angle made it an outstanding DX antenna on 40m. I ran the design on MININEC and it predicted a gain of 5.5 dB over a dipole off the sides. Of all the 40m antennas I've used, it was second only to a 40 meter beam. Zack W9SZ On Thu, May 8, 2025 at 1:38?PM Mike N2MS via groups.io <mstangelo= [email protected]> wrote: The impedance of an EFHW is dependent on many factors such as<> Virus-free.www.avg.com <> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> |
Re: Unun Testing - Is a Attenuator really needed?
#calibration
#measurement
#nanovna-h4
The impedance of an EFHW is dependent on many factors such as surroundings, groung and wire gauge and changes at the higher harmonic frequencies. Has anyone actually measured the antenna?
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Show quoted text
Mike N2MS
|
Re: Unun Testing - Is a Attenuator really needed?
#calibration
#measurement
#nanovna-h4
Hey Jon,
Yes mate, despite the age, if aren't learning something new every day, then there's something wrong . Always great to step outside of the circle once in a while Jon. Have an awesome day. Pete |
Re: Unun Testing - Is a Attenuator really needed?
#calibration
#measurement
#nanovna-h4
I have also learned a good bit from this discussion Pete.
73 Jon, VU2JO On Thu, May 8, 2025 at 3:41?PM VK4CCV via groups.io <Fritzables= [email protected]> wrote: Jon & Mike, |
Re: Unun Testing - Is a Attenuator really needed?
#calibration
#measurement
#nanovna-h4
On Wed, May 7, 2025 at 11:19 PM, Mike wrote:
Mike, you can use this program to measure your transformer without using a resistor. It lets you vary the effective resistance by typing instead of soldering. Brian |
Re: Unun Testing - Is a Attenuator really needed?
#calibration
#measurement
#nanovna-h4
Jon & Mike,
Thanks very much with this. I have learnt so much over the past 24 Hours and still a long way to. Cheers Pete |
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