Re: Antenna Queries de k3eui Barry prior to Nano VNA talk
My favorite question , not directly related to nanoVNA
Why is having minimal SWR important ?
Optional answer:
SWR is an indicator of IMPEDANCE match between x and y devices -
directly related to "power transfer" between. source - TX - and load - antenna.
Demonstrate by applying Ohm's law.
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Re: Further Confusion about nanoVNA versions
#firmware
Forgive me if I get clumsy, but I am still trying to adjust to this forum.
AT this point I am not concerned whose version I own.
What bothers me - when the silly gizmo powers up I get a flash of info which I am assuming has the
version in it somewhere....
I will dust off my old Polaroid to get a "selfie" of the flash so I can read it ...
I am NOT in favor of taking the hardware apart just to find the birthplace of the thing.
Very bad concept I learned whilst taking apart my parents alarm clock.
( Yes, I got the nanoVNA-saver working, still working - slowly - on DFU...)
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Re: Further Confusion about nanoVNA versions
#firmware
Both companies came from the same people. They are the same. I have ran Deepelec firmware in mine for almost 2 years now with absolutely zero issues. I tried the latest version by sysjoint for $hits and giggles but felt like I took several steps backwards in doing so and flashed 1.0.2 from Deepelec again.
And it may be a very good possibility the same Gerber files were used in production as again both companies came from the same roots. Same packaging and everything, not sure if that was all a matter of convenience or both claiming it was their idea or what.... There's some info on that in the nanovna-f group if you dig back a ways
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Re: Antenna Tuner with NanoVNA incorporated.
Now I am a firm believer in KISS concept.
There is nothing wrong with "show and tell " as you propose it.
To be of practical use I assume you are going to use resonant antenna @ selected frequency.
Further assume that you can vary the frequency not the size of the antenna.
Either way - your nanoVNA will indicate that the antenna is too short or too long
depending on frequency in use.
It will give you corresponding values of parameters of your choice - nice,
but still only show "out of resonance" to the average viewer.
Perhaps you can come up with "gimmick" to involve the audience.
"given current state of antenna - off resonance with such and such parameters as measured by nanoVNA -
calculate the required adjustment in length to "tune it up".
Just a crazy thought ...
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Re: Further Confusion about nanoVNA versions
#firmware
An overall high level block flow diagram being "identical" does not mean they are "identical". In the RF world, since line widths, spacings, routing, vias, etc are all variables, I wouldn't assume they are "identical" unless the same Gerber files were used for both in production.
73 Kees K5BCQ
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Re: Antenna Tuner with NanoVNA incorporated.
ATU with VNA Concept
The signal source power level isn't the main consideration to the experiment. It's whether or not the nVNA would be a useful tuning/adjustment indicate. Or at least at it seems to me.
Also, anything hanging directly off the RF path, e.g., coax from signal source will impact the tuning results.
So I'm putting together a setup as shown. The coax 4-port coupler minimizes the impact of foreign items in the RF path to some extent.
The tinySA output is max 1mW I believe. Or my MFJ259-C has about 3mW. One of my RockMites for a single frequency check is about 250mW. That should be more than enough power to determine proof of concept.
Have fun...
--
Chuck, W5USJ
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Re: Further Confusion about nanoVNA versions
#firmware
Just to be a pain, the statement "absolutely identical..... except for....." Doesn't instill confidence in the content of the message. Get Outlook for Android<> ________________________________ From: [email protected] < [email protected]> on behalf of Cory Ricci K9CDR <coryricci@...> Sent: Tuesday, July 6, 2021 12:31:36 PM To: [email protected] < [email protected]> Subject: Re: [nanovna-users] Further Confusion about nanoVNA versions #firmware I don't know about 2.7 from sysjoint which hardware that actually is but I can confirm, and you'll see with the attached diagrams, that Sysjoint HW ver 2.5 is absolutely identical and completely interchangeable with Deepelec ver 2.2. The only differences are a slight difference in battery capacity with the Sysjoint version having slightly higher, the website printed on the back of the unit will be different along with the marking on the board inside which will say sysoint or deepelec accordingly, then the stylings of the A I think it is for the logo and the presence or absence of a serial number on the case. But the actual circuitry and design is identical, this due to the fact that one of the main members of the one company branched off forming his own.... The almost comical use of the same exact block diagram clearly shows this as the logos a guy could picture being pasted over the other lol.
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Re: Antenna Queries de k3eui Barry prior to Nano VNA talk
Your NANOVNA is a wonderful educational tool. However, it doesn't do
calculus. To answer all your questions, you really need a good graduate
level reference addressing antennas and transmission lines. WARNING: Some
pretty deep calculus.
Dave - W?LEV
toggle quoted message
Show quoted text
On Tue, Jul 6, 2021 at 9:55 AM Barry K3EUI <k3euibarry@...> wrote: Questions to think about concerning antennas and feed lines:
K3EUI's Zoom talk on Nano VNA Part II (Under the Hood)
1) Why do antennas have resistance, reactance, and impedance?
What are typical values for a one-half wavelength dipole mounted
clear of the ground and surrounding conductors?
2) Why does every feed line have a "characteristic impedance"?
What factors affect its value?
3) Why does every feed line have an SWR of some value at some frequency?
Is my measured SWR in the shack the same value as (or pretty close to)
the SWR at the antenna terminals?
If so, why? If not, why not?
What exactly is the SWR telling us about the "quality" of the match of
feed line and antenna?
Let's take a specific example now:
4) Say I have 100 ft of 50 ohm coax connected to a one-half wave 80m
center-fed dipole about 120 ft long and 50 ft above ground. It is tuned to
the center of the band.
Why is the SWR high (above 3:1) at the 80m band edges?
What kind of loss (in dB) is acceptable on this antenna on 80m?
Can I use this antenna on 40m? Why or why not?
Can I do anything (in my shack) to improve its performance on 80m?
5) What do the following impedance values all share in common:
25 + j0 40 + j30 40 - j30 100 + j0
How can my Nano VNA tool help me to get the answers to ALL of these
questions?
Send your responses to
Barry K3EUI K3euibarry@...
--
*Dave - W?LEV*
*Just Let Darwin Work*
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Re: impedance test of a TV antenna, How do I adjust 50 ohm to 75 ohm
Based on your measurement, it doesn't look 'that bad' to me. Return loss
is generally < 15 dB (SWR of 1.4:1). Loss less than 1 dB. For the mass TV
market, not too bad by my estimation.
Dave - W?LEV
toggle quoted message
Show quoted text
On Tue, Jul 6, 2021 at 5:26 AM <roncraig1@...> wrote: I use a Mini-Circuits FT-1.5-232+. They are a bit expensive.
Most TV antennas don't have that great a VSWR. Also common for TV
antennas to uses a 75 to 300 ohm balun which makes things worse.
Attached is data on balun.
--
*Dave - W?LEV*
*Just Let Darwin Work*
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Re: Further Confusion about nanoVNA versions
#firmware
On 7/6/21 9:31 AM, Cory Ricci K9CDR wrote: I don't know about 2.7 from sysjoint which hardware that actually is but I can confirm, and you'll see with the attached diagrams, that Sysjoint HW ver 2.5 is absolutely identical and completely interchangeable with Deepelec ver 2.2. The only differences are a slight difference in battery capacity with the Sysjoint version having slightly higher, the website printed on the back of the unit will be different along with the marking on the board inside which will say sysoint or deepelec accordingly, then the stylings of the A I think it is for the logo and the presence or absence of a serial number on the case. But the actual circuitry and design is identical, this due to the fact that one of the main members of the one company branched off forming his own.... The almost comical use of the same exact block diagram clearly shows this as the logos a guy could picture being pasted over the other lol. Imitation is the sincerest form of flattery, after all.
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Re: Further Confusion about nanoVNA versions
#firmware
I don't know about 2.7 from sysjoint which hardware that actually is but I can confirm, and you'll see with the attached diagrams, that Sysjoint HW ver 2.5 is absolutely identical and completely interchangeable with Deepelec ver 2.2. The only differences are a slight difference in battery capacity with the Sysjoint version having slightly higher, the website printed on the back of the unit will be different along with the marking on the board inside which will say sysoint or deepelec accordingly, then the stylings of the A I think it is for the logo and the presence or absence of a serial number on the case. But the actual circuitry and design is identical, this due to the fact that one of the main members of the one company branched off forming his own.... The almost comical use of the same exact block diagram clearly shows this as the logos a guy could picture being pasted over the other lol.
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Re: Antenna Queries de k3eui Barry prior to Nano VNA talk
On 7/6/21 8:55 AM, Barry K3EUI wrote: Questions to think about concerning antennas and feed lines:
K3EUI's Zoom talk on Nano VNA Part II (Under the Hood)
1) Why do antennas have resistance, reactance, and impedance?
What are typical values for a one-half wavelength dipole mounted
clear of the ground and surrounding conductors? This could get into an interesting discussion of electromagnetics and physics. Ultimately, antennas have a combination of radiated and non radiated fields with energy moving back and forth between the stored and radiated fields. The ratio is the Q of the antenna (where Q is defined as "energy stored"/"energy lost per cycle" - it happens to be *similar* to a RLC resonant circuit, but the mechanism is different.
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Antenna Queries de k3eui Barry prior to Nano VNA talk
Questions to think about concerning antennas and feed lines:
K3EUI's Zoom talk on Nano VNA Part II (Under the Hood)
1) Why do antennas have resistance, reactance, and impedance?
What are typical values for a one-half wavelength dipole mounted
clear of the ground and surrounding conductors?
2) Why does every feed line have a "characteristic impedance"?
What factors affect its value?
3) Why does every feed line have an SWR of some value at some frequency?
Is my measured SWR in the shack the same value as (or pretty close to) the SWR at the antenna terminals?
If so, why? If not, why not?
What exactly is the SWR telling us about the "quality" of the match of feed line and antenna?
Let's take a specific example now:
4) Say I have 100 ft of 50 ohm coax connected to a one-half wave 80m center-fed dipole about 120 ft long and 50 ft above ground. It is tuned to the center of the band.
Why is the SWR high (above 3:1) at the 80m band edges?
What kind of loss (in dB) is acceptable on this antenna on 80m?
Can I use this antenna on 40m? Why or why not?
Can I do anything (in my shack) to improve its performance on 80m?
5) What do the following impedance values all share in common:
25 + j0 40 + j30 40 - j30 100 + j0
How can my Nano VNA tool help me to get the answers to ALL of these questions?
Send your responses to
Barry K3EUI K3euibarry@...
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deembedding fixtures for SMDs
This might be interesting
SMD CHARACTERIZATION USING PROGRESSIVE DE-EMBEDDING METHODS
(AUTOMATIC FIXTURE REMOVAL) WITH A VNA
Copper Mountain Technologies (CMT) will present modern methods to measure SMD type components mounted on 1-port and 2-port fixtures. The proposed methods uses advanced algorithms to de-embed fixture effects. The session will compare traditional and modern ways of de-embedding fixture effects.
I don't think you have to be an IEEE member to sign up, they're just the sponsor - the member number is an optional field in the registration
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Re: impedance test of a TV antenna, How do I adjust 50 ohm to 75 ohm
On 7/6/21 4:49 AM, Lawrance A. Schneider wrote: I would think that using a transformer to match impedence would introduce even more error: nano - transformer - antenna. That is a question and not a declaration.
Thanks, larry Depends on what you call error.? If the transformer is part of the VNA (i.e. you do the cal at the DUT end of the transformer) any effects of the transformer are rolled into the calibration. If the transformer is part of the DUT, well, it is what it is - you're measuring the combination of antenna and transformer as a system. In either case the "error" (interpreted as deviations of calibrated result from those that could be made by a perfect instrument) will be related to the SNR for the measurements - and that won't be significantly different in either configuration.
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Re: [softrock40] homemade chebyshev 7th order BB band stop to begin soon
Something that might be of interest is that the Surrey Amateur Radio Club, VE7SAR, < <>ve7sar.net > has a wonderful newsletter that comes out bi-monthly. The newsletter is usually around 110 pages. The last several issues have had articles titled, Measurements with the NanoVNA". The Nov - Dec 2020 article deals specifically with "Establishing the Characteristics of Unknown Toroids".
73,
Gary - W6GVS
Dowagiac, MI
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Re: impedance test of a TV antenna, How do I adjust 50 ohm to 75 ohm
I would think that using a transformer to match impedence would introduce even more error: nano - transformer - antenna. That is a question and not a declaration.
Thanks, larry
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Re: impedance test of a TV antenna, How do I adjust 50 ohm to 75 ohm
I use a Mini-Circuits FT-1.5-232+. They are a bit expensive.
Most TV antennas don't have that great a VSWR. Also common for TV antennas to uses a 75 to 300 ohm balun which makes things worse.
Attached is data on balun.
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Re: impedance test of a TV antenna, How do I adjust 50 ohm to 75 ohm
Here's the display from 10KHz to 610Mhz (I think) of a 75 ohm resistor after my DIY 50 ohm to 75 ohm matching pad.
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Re: impedance test of a TV antenna, How do I adjust 50 ohm to 75 ohm
Hi guys, The OP here. After watching the video on use of the 50 to 75 ohm adapters I decided I'd try to build one.
I think I did good... almost! As you may recall I'm working with TV antennas my channels are between 180MHz and 610MHz.
So I ran a scan,180MHz and 610MHz, of a 75 ohm resistor through my DIY 50 ohm to 75 ohm pad.The resistance varied from 50.1 ohm to 49.6 ohms.
and the reactance was as high as 168pH. I thought this was great. Then I decided to run the scan all the way to 900MHz. At about
675MHz the resistance goes down until at 900MHz it is 0.2 ohms.
Just posting for your feedback, to see what I did right or wrong.
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Cory Ricci K9CDR
Chuck Carpenter
Barry K3EUI
