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Using the SMA-M/SMA-F adapters as connector savers like I think you show, Stan, is a very good idea. Even very high quality SMA connectors (>$50 each) degrade in match very quickly. Cheap ones with only 2 jaws on the center conductor are pretty much worthless for repetitive use. I was once told by the ME at Omni-Spectra their SMAs were rated to meet spec for the initial connection only! I am getting a bunch and will swap them out as soon as any gold flaking or wear is apparent under magnification. Most of the cheaper SMA connectors from China look to me to have plain brass center contacts which will not apply any contact pressure after the first mating. A capacitive gap results. The only inexpensive SMA-M/SMA-F adapter I can find with a Beryllium center conductor is the Cal Test CT3673. The only reason to use BeCu which costs more and is poisonous to machine is if they heat treat it, to make the jaws springy. I don't know whether there are more than 2 jaws to the F pin. Better ones have more, but at < 1GHz it probably won't make any difference untll the jaw loses its spring. I have a question into the tech support to ask about it. Data sheet kere: . They are dirt cheap at Amazon:.
Jason NJ7K

Dr. Kirkby is right, as I can confirm from my own experience. Last year I wanted to do a RL measurement o find the losses of several lengths (up to 25 m) of leftover coaxial cables on all amateur bands from 2 m up to 13 cms IN ONE GO. So I set my HP8753C to a span of something like 100 to 2500 MHz and measured the RL of each cable on one end while leaving the other end open (or shorting it), with default settings of the 8753. Or maybe I used 401 iso 201 points. Anyway, I then noticed unexplainable steps along the way in the measured RL curves. This turned out to be simply a matter of the default sweep time being too short. I haven't tried a similar thing with my NanoVNA-F up to 1.5 GHz, and maybe I will just for curiosity. But you can't change the sweep time of a NanoVNA anyway, to my early knowledge of the device.

73's Hans PA3AZA

Sounds like a perfect excuse to buy a 3D printer!

73 Ed N5KZW

Thanks for all the suggestions!

No it look like hardware problem (or measure frequency problem)

It possible fix by software need redefine

// XTAL frequency on si5351
#define XTALFREQ 26000000U

To current XTAL frequency and rebuild

Or replace XTAL

On Thu, May 21, 2020 at 09:06 AM, Rudolf Schaffer wrote:

As the TCXO frequency is out of tolerances, it's certainly a defect
component.

DiSlord suggested the error could be due to the firmware. What version are you running?

Roger

On Thu, May 21, 2020 at 06:35 AM, <gaionim@...> wrote:

try to see
and

Interesting way to measure balun loss with a single balun and a VNA. Thank you for posting this information.

Roger

Hi,

Is it posible for add the big CH0 screen info in version 0.7.1-20200321 by edy555 ?

Tnx

Andy - ON7BA

I just joined the nanoVNA group a couple of days ago and followed your thread on the balun measurement. If possible, why don’t you measure the scattering params, save the data, build a 3x3 scattering parameter matrix with the data and convert it to mixed signal to get the diff output? See for example . You would need one of the math software tools out there and I understand that practice and theory... have some issues to get along! but eventually they should go hand in hand. Just a suggestion.

Luciano

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
-----------------
No direct email, it goes to bit bucket due address harvesting in groups.IO

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

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
-----------------
No direct email, it goes to bit bucket due address harvesting in groups.IO

Try update firmware to my last version and check
/g/nanovna-users/files/Dislord%27s%20Nanovna%20-H%20Firmware

As i remember old Hugen (and edy555 < 0.6) firmware not fully correct select settings for SI5351

But for freq > 300 MHz error bigger * harmonic range

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.

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

Thanks for sharing will look into it !

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.

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

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

REF: /g/nanovna-users/message/13681

Hello, 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