Re: Coax length and defect identification
Yes 100ft Mookeef RG-8X from Amazon.
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On Jun 19, 2023, at 2:01 PM, Jim Lux <jimlux@...> wrote:
?On 6/19/23 8:23 AM, RJOLLIS via groups.io wrote:
I have experienced a sudden and unexplained increase in the SWR of my HF antenna, I suspect the cheap coax or one of its pre-installed connectors. Before I chop the PL259s and install new ones, I tried to check for defects with the nanovna-h. There is no physical signs of damage. But I get an unexpected outcome.
Procedure. I have set up the VNA on Trace 0 in the Linear mode. VF is set to a nominal 80% for the 100 ft (30.5m) RG-8X coil of coax. The Transform function is selected and Low Pass mode is on. I sweep from 500Khz to 125Mhz. I get a spike at 14.79m. When I swap the inputs, the number doesn¡¯t change. I would expect that if there was a short in the coax, I would observe 15.21m when I flip the ends. That's pretty close to 50 ft. Sure it's a 100 ft coil?
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Re: S21 Function does not work with NanoVNA-saver
Sri? error? 73 qr0Envoy¨¦ depuis mon appareil Galaxy
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-------- Message d'origine --------De : Joel Gui <joelguiheneuf@...> Date : 19/06/2023 22:18 (GMT+01:00) ? : [email protected] Objet : Re: [nanovna-users] S21 Function does not work with NanoVNA-saver Hello Robert et les amis?Je ne vous oublie pas mais impossible actuellement op¨¦ration ?il gauche reprise peut ¨ºtre fin du mois73qro et 88 ¨¤? tous les qrasF8EZZ? joelEnvoy¨¦ depuis mon appareil Galaxy-------- Message d'origine --------De : "WY6K Mike Watts via groups.io" <wy6k@...> Date : 19/06/2023? 20:37? (GMT+01:00) ? : [email protected] Objet : [nanovna-users] S21 Function does not work with NanoVNA-saver It works with the NanoVNA-app software and the screen is correct.? But the -saver S21 is just a scatter pattern.? Help!? Any idea what is wrong?
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Re: S21 Function does not work with NanoVNA-saver
Hello Robert et les amis?Je ne vous oublie pas mais impossible actuellement op¨¦ration ?il gauche reprise peut ¨ºtre fin du mois73qro et 88 ¨¤? tous les qrasF8EZZ? joelEnvoy¨¦ depuis mon appareil Galaxy
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-------- Message d'origine --------De : "WY6K Mike Watts via groups.io" <wy6k@...> Date : 19/06/2023 20:37 (GMT+01:00) ? : [email protected] Objet : [nanovna-users] S21 Function does not work with NanoVNA-saver It works with the NanoVNA-app software and the screen is correct.? But the -saver S21 is just a scatter pattern.? Help!? Any idea what is wrong?
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Re: Wish list of future features for nanovna
On Mon, Jun 19, 2023 at 10:47 AM, n7wy wrote:
a vector network analyzer should not be further burdened with the functions of
a spectrum analyzer.
Yahbut you've already got the sweeping receivers and log amp/detectors, adding rudimentary SA functions is just code. That is why so many instruments, including from the big manufacturers, combine functions; the extra features have no incremental cost beyond the software development. 73, Don N2VGU
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S21 Function does not work with NanoVNA-saver
It works with the NanoVNA-app software and the screen is correct. But the -saver S21 is just a scatter pattern.
Help! Any idea what is wrong?
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Re: Coax length and defect identification
On 6/19/23 8:23 AM, RJOLLIS via groups.io wrote: I have experienced a sudden and unexplained increase in the SWR of my HF antenna, I suspect the cheap coax or one of its pre-installed connectors. Before I chop the PL259s and install new ones, I tried to check for defects with the nanovna-h. There is no physical signs of damage. But I get an unexpected outcome.
Procedure. I have set up the VNA on Trace 0 in the Linear mode. VF is set to a nominal 80% for the 100 ft (30.5m) RG-8X coil of coax. The Transform function is selected and Low Pass mode is on. I sweep from 500Khz to 125Mhz. I get a spike at 14.79m. When I swap the inputs, the number doesn¡¯t change. I would expect that if there was a short in the coax, I would observe 15.21m when I flip the ends. That's pretty close to 50 ft. Sure it's a 100 ft coil?
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Re: Coax length and defect identification
Also, for a cable that long using the 101pt scan, you need to set your stop frequency to about 70MHz to see the reflection from the whole length of the cable. So what you are seeing now may be due to aliasing or something. (I just experimented with the Transform settings with a 100ft length of good cable on my -H4. When I had it at 400pt scan, 125MHz let me see much longer than 100ft, but at 100pts I needed to set the frequency down to see the reflection from the end of the cable. This is due to the "bin size" used in the FFT.) On Mon, Jun 19, 2023, 10:13 AM Roger Need via groups.io <sailtamarack= [email protected]> wrote: On Mon, Jun 19, 2023 at 08:23 AM, RJOLLIS wrote:
Procedure. I have set up the VNA on Trace 0 in the Linear mode. VF is set to
a nominal 80% for the 100 ft (30.5m) RG-8X coil of coax. The Transform
function is selected and Low Pass mode is on. I sweep from 500Khz to 125Mhz. I
get a spike at 14.79m. When I swap the inputs, the number doesn¡¯t change. I
would expect that if there was a short in the coax, I would observe 15.21m
when I flip the ends.
Question. Am I doing something wrong here or do I have a defective nano? I
haven¡¯t yet characterized impedance or line loss. Those come next.
Looking at your photo your yellow trace shows S21 linear instead of S11
Linear.
I don't know what revision of firmware you have but recent firmware has a
Cable Measure function built in. Have you tried that?
Roger
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Re: Coax length and defect identification
On Mon, Jun 19, 2023 at 08:23 AM, RJOLLIS wrote: Procedure. I have set up the VNA on Trace 0 in the Linear mode. VF is set to
a nominal 80% for the 100 ft (30.5m) RG-8X coil of coax. The Transform
function is selected and Low Pass mode is on. I sweep from 500Khz to 125Mhz. I
get a spike at 14.79m. When I swap the inputs, the number doesn¡¯t change. I
would expect that if there was a short in the coax, I would observe 15.21m
when I flip the ends.
Question. Am I doing something wrong here or do I have a defective nano? I
haven¡¯t yet characterized impedance or line loss. Those come next.
Looking at your photo your yellow trace shows S21 linear instead of S11 Linear. I don't know what revision of firmware you have but recent firmware has a Cable Measure function built in. Have you tried that? Roger
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Re: Coax length and defect identification
John. Thanks for your reply. Yes I have examined 2 meters each side of center. No issues are visible. That doesn¡¯t mean that there is no damage. I will look at return loss and characteristic impedance later this afternoon. I would expect return loss would be impacted by a cable defect.
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On Jun 19, 2023, at 12:14 PM, John <ve3kkqve3kkq@...> wrote:
?You didn't mention this but to me what you have determined is that there is
something causing an indication close to the centre of your coax, have you
visually inspected where the VNA is indicating where there is a problem?
Look very closely for signs of a pinch, puncture or other sign of damage.
What your VNA is telling you is that there is an issue somewhere close to
the centre of the coax, by turning the cable end for end and retesting, the
issue is within half a metre of centre.
That's what I get out of this anyway.
GL
John
VE7KKQ
On Mon, Jun 19, 2023 at 8:23?AM RJOLLIS via groups.io <rjollis=
[email protected]> wrote:
I have experienced a sudden and unexplained increase in the SWR of my HF
antenna, I suspect the cheap coax or one of its pre-installed connectors.
Before I chop the PL259s and install new ones, I tried to check for defects
with the nanovna-h. There is no physical signs of damage. But I get an
unexpected outcome.
Procedure. I have set up the VNA on Trace 0 in the Linear mode. VF is set
to a nominal 80% for the 100 ft (30.5m) RG-8X coil of coax. The Transform
function is selected and Low Pass mode is on. I sweep from 500Khz to
125Mhz. I get a spike at 14.79m. When I swap the inputs, the number doesn¡¯t
change. I would expect that if there was a short in the coax, I would
observe 15.21m when I flip the ends.
Question. Am I doing something wrong here or do I have a defective nano? I
haven¡¯t yet characterized impedance or line loss. Those come next.
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Re: Coax length and defect identification
You didn't mention this but to me what you have determined is that there is something causing an indication close to the centre of your coax, have you visually inspected where the VNA is indicating where there is a problem? Look very closely for signs of a pinch, puncture or other sign of damage. What your VNA is telling you is that there is an issue somewhere close to the centre of the coax, by turning the cable end for end and retesting, the issue is within half a metre of centre. That's what I get out of this anyway. GL John VE7KKQ On Mon, Jun 19, 2023 at 8:23?AM RJOLLIS via groups.io <rjollis= [email protected]> wrote: I have experienced a sudden and unexplained increase in the SWR of my HF
antenna, I suspect the cheap coax or one of its pre-installed connectors.
Before I chop the PL259s and install new ones, I tried to check for defects
with the nanovna-h. There is no physical signs of damage. But I get an
unexpected outcome.
Procedure. I have set up the VNA on Trace 0 in the Linear mode. VF is set
to a nominal 80% for the 100 ft (30.5m) RG-8X coil of coax. The Transform
function is selected and Low Pass mode is on. I sweep from 500Khz to
125Mhz. I get a spike at 14.79m. When I swap the inputs, the number doesn¡¯t
change. I would expect that if there was a short in the coax, I would
observe 15.21m when I flip the ends.
Question. Am I doing something wrong here or do I have a defective nano? I
haven¡¯t yet characterized impedance or line loss. Those come next.
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Re: Coax length and defect identification
Postscript: I note that I the pictures that I had attached show a sweep from 500Khz to 200Mhz. This was a photo setup error. When resetting the stop frequency to 125Mhz, the peak moves ever so slightly to 14.65m but the max length moves to 37m.
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On Jun 19, 2023, at 11:23 AM, RJOLLIS via groups.io <rjollis@...> wrote:
?I have experienced a sudden and unexplained increase in the SWR of my HF antenna, I suspect the cheap coax or one of its pre-installed connectors. Before I chop the PL259s and install new ones, I tried to check for defects with the nanovna-h. There is no physical signs of damage. But I get an unexpected outcome.
Procedure. I have set up the VNA on Trace 0 in the Linear mode. VF is set to a nominal 80% for the 100 ft (30.5m) RG-8X coil of coax. The Transform function is selected and Low Pass mode is on. I sweep from 500Khz to 125Mhz. I get a spike at 14.79m. When I swap the inputs, the number doesn¡¯t change. I would expect that if there was a short in the coax, I would observe 15.21m when I flip the ends.
Question. Am I doing something wrong here or do I have a defective nano? I haven¡¯t yet characterized impedance or line loss. Those come next.
<IMG_9423.jpeg>
<IMG_9422.jpeg>
<IMG_9421.jpeg>
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Coax length and defect identification
I have experienced a sudden and unexplained increase in the SWR of my HF antenna, I suspect the cheap coax or one of its pre-installed connectors. Before I chop the PL259s and install new ones, I tried to check for defects with the nanovna-h. There is no physical signs of damage. But I get an unexpected outcome.
Procedure. I have set up the VNA on Trace 0 in the Linear mode. VF is set to a nominal 80% for the 100 ft (30.5m) RG-8X coil of coax. The Transform function is selected and Low Pass mode is on. I sweep from 500Khz to 125Mhz. I get a spike at 14.79m. When I swap the inputs, the number doesn¡¯t change. I would expect that if there was a short in the coax, I would observe 15.21m when I flip the ends.
Question. Am I doing something wrong here or do I have a defective nano? I haven¡¯t yet characterized impedance or line loss. Those come next.
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Re: Wish list of future features for nanovna
Jim is right, a vector network analyzer should not be further burdened with the functions of a spectrum analyzer. Bob - N7WY
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Re: Whats the best way to test your NanoVNA H4
#nanovna-h4
female female?? or sma to reverse sma??
a friend grilled his 13cm amp with using a sma to reverse sma (accidently)
no contact ... swr sky high .. final amp went in semiconductor heaven
dg9bfc sigi
Am 19.06.2023 um 15:50 schrieb Muggs KC3UDZ:
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Stan,
OK, I have found the problem... And it is ME!
First of all let me thank you for for explaining how to calibrate the NanoVNA; although I am well aware of how to do a calibration, it forced me to look at things more carefully.
In my attempt to extend the SMA connections and protect them I ordered some SMA Male-to-SMA Female connectors; OR SO I THOUGHT!
After taking everything down to bare-bones I noticed that the connectors are actually female-to-female! DUH!! I'm embarrassed and I feel like a complete IDIOT, but I put this "out there" as a reminder to others to check everything, even things you "know" are OK.
Anyway, thank you again and thanks for the "Absolute Beginners Guide" PDF; great resource.
Muggs KC3UDZ
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Re: Whats the best way to test your NanoVNA H4
#nanovna-h4
Stan,
OK, I have found the problem... And it is ME!
First of all let me thank you for for explaining how to calibrate the NanoVNA; although I am well aware of how to do a calibration, it forced me to look at things more carefully.
In my attempt to extend the SMA connections and protect them I ordered some SMA Male-to-SMA Female connectors; OR SO I THOUGHT!
After taking everything down to bare-bones I noticed that the connectors are actually female-to-female! DUH!! I'm embarrassed and I feel like a complete IDIOT, but I put this "out there" as a reminder to others to check everything, even things you "know" are OK.
Anyway, thank you again and thanks for the "Absolute Beginners Guide" PDF; great resource.
Muggs KC3UDZ
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Re: Wish list of future features for nanovna
The tiny SA ultra.....with it's 4" screen, will also measure 2 tone IMD of a linear amplifier, like imd 3-5-7....and also harmonic suppression of a linear amplifier.
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Re: Wish list of future features for nanovna
Hi David,
The TinySA looks perfect for my needs - wow.
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Re: Wish list of future features for nanovna
On 18/06/2023 11:14, erica edens wrote: My issue is the output of the signal generator is unnknown and it would
be a useful feature at some future stage if 'namovna calibrated' signal
outputs were incorporated into its general design. I do not have much
tuning equipment, none of it is calibrated and I am simply looking for a
cheap and easy means to tune my antennas and rigs without turning my
shack into an RF lab! Erica, Yes, these devices are indeed remarkable! Many thanks for those who design and produce the devices and their extensive software. For a calibrated signal generator (and highly functional spectrum analyser) you might like to look at the TinySA Ultra which is in stock in the UK: Details: The signal generator part of the spec is here: I think you'll find the spectrum analyser function very useful in any case. I have no relation to the firm other than as a very satisfied customer. 73, David GM8ARV -- SatSignal Software - Quality software for you Web: Email: david-taylor@... Twitter: @gm8arv
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Re: Wish list of future features for nanovna
NanoVNA can`t change output (only 4 steps), also output depend from frequency
PS yes possible use external attenuator controlled by NanVNA over Serial, calibrate it. For this need software update (this also depend from Attenuator use)
PSS you can use TinySA for this
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Re: Measuring swr on fan dipole or windom antenna
On Fri, Jun 9, 2023 at 12:29 AM, Steve Johnson wrote:
When using a NanoVNA to measure SWR on a multi-element antenna, with different
length elements but all fed from the same feedpoint, which element¡¯s swr is
the Nanvna displaying data for?
What are your START and STOP frequency settings? On which bands is the antenna supposed to work? When I sweep a multiband antenna, the nanovna shows me the SWRs of all the resonances within the range of the sweep. I have preset scan choices for 1.5 to 30 MHz and for 3.0 to 30 MHz sweeps, and it works very well. I see all the resonances on that one sweep setting. The Nano will only show you what you actually tell it that you want to see. -- Doug, K8RFT
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Donald S Brant Jr
WY6K Mike Watts
Roger Need
n7wy
Muggs KC3UDZ
David J Taylor