Always perform a reset before setup and SOL.
I have a piece of that DX400max 50ft long I do not see that oddity.
That cable would have to be really poor to get that result.
Several possible things, adaptors, connectors, or cable was kinked.
also the load at the other end? If using a intermediate cable check
it and all adaptors.
Generally if called with a 51 ohm load and its used at the far end of the
cable its should not be as pronounced as you show.
Remotely possible is the cable is really off spec or someone substituted
75 ohm material.
Allison
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No direct email, it goes to bit bucket due address harvesting in groups.IO
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As the TCXO frequency is out of tolerances, it's certainly a defect component.
As i wrote, i ordered the Nanovna-H at "Wish". I've read, but too late, that this was not the best solution...
The solution, for me, is to ask to a known friend, well equipped and trained for small SMD components replacement
to do the work. Now, i must find an equivalent or compatible component.
Rudi
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Le 21.05.2020 ¨¤ 17:41, hugen@... a ¨¦crit?: The NanoVNA-H we produced should not have such a large deviation. Can we provide PCB pictures and test pictures? If it is the version we made, we can provide a new one for free.
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DR Kirkby,
That would be a corner case and a very very long cable.
Typical cables used ran maybe as long as 100M, so we
haven't reached a radar mile yet. Usually we have no
reason to make sudden frequency range changes but
have in the past. Most of the expensive VNA/PNAs
the dwell times, numbers of points are programmable
and that also dictates the sweep rates. However,
as HP/Agilent/Keysight has noted you can tell the machine
to do ill advised things and get the deserved nebulous results.
More typical would be a piece of RG400 10M long. We
used a lot of specially made cables that were ferrite loaded.
Bench cable are typical 1M commercial made like minicircuits
ULC-1M-NMNN (1 meter cables). or ULC-6FT-NMNN (6ft).
Costly but quality when using 6ghz PNA in the 5700mhz range.
The payback is quality commercial cables have good useful
lifetimes. Often they can be found used or surplus in good
condition.
Allison
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No direct email, it goes to bit bucket due address harvesting in groups.IO
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The NanoVNA-H we produced should not have such a large deviation. Can we provide PCB pictures and test pictures? If it is the version we made, we can provide a new one for free.
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With a loop, i was able to measure the TCXO frequency and found
25.997748 MHz instead of 26MHz ! This error correspond to ~ -86ppm,
not too far of the output error of -85.5 ppm at 100MHz CW !
As i'm not able to replace the TCXO (+/- 2.5 ppm Max according the data-sheet...),
i must look for an other solution. Unit return to the vendor "Wish" seems impossible.
A 1st and last experience, not with NanoVNA-H but Wish !
Rudi
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Re: [Measuring] Is there an easy way to measure balun loss?
Thanks for sharing will look into it !
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On Thu, May 21, 2020 at 02:35 PM, <gaionim@...> wrote:
try to see
and
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Please read the forum WIKI and notes in the forum FILES sections.
You need to install the latest version of firmware for the model of Nano you purchased.
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On Thursday, May 21, 2020, 11:03:31 a.m. GMT-4, marxtech@... <marxtech@...> wrote:
I just got my Nanovna-Hv3.4 from amazon seesii.? I was ready to return it because the back states frequency:50k-300MHz.? I am looking for the 10KHz starting frequency.
Now I see your expert review.? Thanks so much!
How do I access the lowered starting frequency?
Rolf
KC6HTR
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I just got my Nanovna-Hv3.4 from amazon seesii. I was ready to return it because the back states frequency:50k-300MHz. I am looking for the 10KHz starting frequency.
Now I see your expert review. Thanks so much!
How do I access the lowered starting frequency?
Rolf
KC6HTR
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Just by curiosity, i entered a CW value of 100.0086 Mhz and i measured 100.00002 MHz.
It should be a solution with Si5351 programmation but, after reading a lot of related information,
i don't find a solution.
Rudi
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REF: /g/nanovna-users/message/13681Hello, again. Well, after the Special Interest shown here, we would like to inform you that, in direct contrast with what Gary O'Neil, N3GO believed on 2009-09-30 - in the "Errors of error models. Who is following this and who is confused" thread, at his message: /g/nanovna-users/message/3492- that is that: "They appear to have done limited testing of their math model", there are plenty Measured Results by a VNA under these Most Interesting Extreme Conditions created by many Open- and Short- circuited loads, which were produced by purposely constructed for that reason Special Antennas, and we plan to present some of these results, as soon as possible, within the frame of discussion: "errors of "error" models". Sincerely, gin&pez@arg
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I'm a little bit disappointed; i measured a CW 100MHz output from my NanoVNA-H received one week ago.
The reference of my frequency meter is a 5MHz G3RUH GPSDO and i get a 99.99144 MHz (~ -85.5 ppm error);
same result with a calibrated SDR receiver. I'm not able to measure the TCXO output frequency.
At my non professional point of vue, 2 possibilities:
-1- The TCXO is totally out of specifications.
-2- Something is wrong with the Si5351A-B-GT frequency programming command.
Can somebody explain what is wrong with my NanoVNA ?
Thank you in advance for your help.
Rudi
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Re: [Measuring] Is there an easy way to measure balun loss?
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The 50 ohms cables as far as I remember were rated by different
manufacturers as 50 to 52 ohms years ago, so my guess is that 51 ohms
is on the ballpark. It is also a standard resistor value.
Try to find out the cable impedance, it seems to me to be the culprit.
Find the frequency where the cable is lambda/4 as a RF short circuit
with the end of the cable physically open. Set half the frequency
found before on the VNA and read the reactance, that is the cable?s
impedance.
I am writing by heart, a mistake might have slipped...
Jos¨¦, CO2JA
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On 5/21/20, ed@... <ed@...> wrote: After calibrating, I connected my nanovna to my VHF antenna via a brand new
75 foot length of 50ohm DX400MAX coax. The SWR measurement oscillates up and
down every 4MHz or so (see attached). These correspond exactly to the
half-wavelength harmonics of the cable. Looking at the smith chart, it is
clear that the impedance is tracing a circle around about 45 ohms rather
than the constant-SWR circle centered at 50 ohms, resulting in a
frequency-dependent SWR.
Is there is a good way to determine whether this is a problem with my
nanovna, with the calibration standard, or with the cable?
One note: the calibration standard load measures 51 ohms DC resistance,
which seems like a problem to me. Should my standard be exactly 50 ohms dc
resistance?
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After calibrating, I connected my nanovna to my VHF antenna via a brand new 75 foot length of 50ohm DX400MAX coax. The SWR measurement oscillates up and down every 4MHz or so (see attached). These correspond exactly to the half-wavelength harmonics of the cable. Looking at the smith chart, it is clear that the impedance is tracing a circle around about 45 ohms rather than the constant-SWR circle centered at 50 ohms, resulting in a frequency-dependent SWR.
Is there is a good way to determine whether this is a problem with my nanovna, with the calibration standard, or with the cable?
One note: the calibration standard load measures 51 ohms DC resistance, which seems like a problem to me. Should my standard be exactly 50 ohms dc resistance?
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Re: UI Suggestion: Big Numeric Display Format for CW Stimulus Mode
Hi,
Is it posible for add the big CH0 screen info in version 0.7.1-20200321 by edy555 ?
Tnx
Andy - ON7BA
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Bob- thanks will give that a try.
Dan KC2STA
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On Wed, May 20, 2020 at 3:32 PM Bob Solimeno <kc2jav@...> wrote: I've been able to install the NanoVNA-Saver on Ubuntu 20.04 using the
attached helper document. I regret to say that I forgot where I found it
... memory loss is the first sign of senility!
The nice thing about this approach is that it can be set up with a script,
saved as a desktop icon and run easily. One caveat is that your username
must be part of the"dialout" group on your Linux system so that access to
the usb port will be allowed to connect the NanoVNA to your computer. As
always, your mileage may vary if running other versions of Ubuntu or other
distros.
73 Bob KC2JAV
--
Dan Ziolkowski KC2STA
SKCC #4290T
Ubuntu LINUX
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Hello,
Can somebody give me the 26MHz oscillator reference for my NanoVNA-H ?
Many TNX in advance.
73 QRO, Rudi, HB9ARI
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CT2FZI
gin&pez@arg
Jose Amador
