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YES IT IS HF,73

The firmware can be configured for up to 201 points, but there are still a few minor UI glitches we need to fix before this can be advertised. Sweep rate is by default 100 points/s, and this is what the plots shown above are taken at, but this can be adjusted in code to trade off noise vs speed. However V2 always shows new data in realtime as the sweep progresses (I'll maybe post a video if my internet speed allows) rather than a screen update every full sweep, so in practice it feels faster. There is a caveat though which is that the first sweep after changing frequency limits is always slower, because it has to do various internal corrections (see firmware code for details). In USB mode this means it's not advisable to do "segmented sweep", but there isn't a need because up to 1024 frequency points are supported in USB mode. This is all mainly capped by device RAM. Firmware is at:

#86": Two Notes On #86': UPGRADE : On the Results of Measuring Two-Ports
Using Only [NanoVNA] Channel [CH0] or a [LeastVNA]
16 December 2019 - /g/nanovna-users/message/8278

Note 1
At the paragraph (1) of the above, the "the usual form of { -1, 0, +1 }" must be
corrected and/or understood as follows:

"the usual form of { (-1, 0) , (0, 0) , (+1, 0) } ordered pairs of values in Cartesian
form"

in accordance with the remarks made at:

#73': On the sine qua non Core Uncertainty of AnyVNA - incl. NanoVNA - System
6 November 2019 - /g/nanovna-users/message/6529

Note 2
At paragraph (3) of the above -as well as in general- "The Common User" may
have a control on these matters, but only in the extent and depth that is permitted
by the manufacturer, who makes available any related information to him.

gin&pez@arg

:86"#

@Gary O'Neil, N3GO - 18 December 2019
/g/nanovna-users/message/8386

Dear Gary, Thank you for the interesting suggestions. We will prepare and
send you two copies - the one with colored underlined highlights. Best regards,
gin&pez@arg

How many sweep points? and how fast full-range single sweep?

It does appear that the cable is somehow involved.? Be all that as it may, my problems are not stopping me from getting good use out of the units.? I am repeatedly amazed at the accuracy and versatility it offers.? If careful I can make measurements to better than 1%.
The main lack for me is its inability to measure at audio frequencies.? No big deal; I have fancy gear for that.
I am tempted to buy a couple more just so I have redundancy big time.
Bob

Update.? I recalibrated and now the Smith display is okay.? Maybe I goofed and mixed up the calibration fixtures.
Both units have a problem where they turn themselves off without provocation.? Sometimes in the middle of a measurement.? One unit already has had the power control IC replaced.? Batteries are fine.
The one still won't go above 900 MHz.
Bob

I had your second problem when viewing the NANO on its screen while
connected to the PCwith the USB cable. Once I removed the USB cable, all
was as expected.

The first: I've never been able to get mine to go above 900 MHz, free
standing or connected to the PC with the USB cable.

Dave - W?LEV

On Thu, Dec 19, 2019 at 2:16 AM Bob Albert via Groups.Io <bob91343=
[email protected]> wrote:

I have two nanoVNAs each with a different problem.

One refuses to accept any frequency above 900 MHz. I think I have had
that aspect working before but now am not so sure.

The other gives me a bad display on Smith chart, with the open circuit
near the middle rather than at the left. This one for sure worked fine
before.

Is there some kind of basic reset that can restore operation on the second
one, at least? The usual menu option RESET doesn't do it.

--

*Dave - W?LEV*
*Just Let Darwin Work*
*Just Think*

I have two nanoVNAs each with a different problem.

One refuses to accept any frequency above 900 MHz. I think I have had that aspect working before but now am not so sure.

The other gives me a bad display on Smith chart, with the open circuit near the middle rather than at the left. This one for sure worked fine before.

Is there some kind of basic reset that can restore operation on the second one, at least? The usual menu option RESET doesn't do it.

well the antenna is my tv mast,total lenth about 45ft,its shunt fed thru a loading coil made from brake pipe tubing,the ground/counterpoise is all my copper plumbing,i live in a flat in a conservation area so imposible to do much antenna wise,its funny as with the current lash up my atu in the rig (kenwood ts-850 seems to match it on all the bands from 1.9mhZ thru to 10m.,would just be nice to measure it with the vna tho,i find it good for contacts 2000+miles but rubbish into g,i guess the take off angle is to low for the uk,dont know if i can alter it for nvis?,73.

Hi all,ive got strange readings on my modded vna,the mods are sma to bnc adapters on it,ive calibrated it with homebrew load and shorted termination and used a lenth of rg-58u cable with bnc fittings for the thru callibration,its fine from 130-450 mhz,its from 1-30mhz i get the strange readings,see pics,i assume its due to the capacitance of the sma to bnc adapters?,if so is there any way to compensate for this?,cheers in advance.

I presume this is for HF. A vertical antenna is not a differential
source/load and should not be fed with a balanced line - your 600-ohm
ladder line. A vertical of 1/4-wavelength long should be roughly 37 ohms
real. Even if you match it with a base loading coil, it is still
single-ended source/load and is appropriate for coaxial feed, NOT balanced
(differential) line. Eliminate the ladder line and the 9:1 transformer and
feed with coaxial cable.

Dave - W?LEV

--

*Dave - W?LEV*
*Just Let Darwin Work*
*Just Think*

well i was looking at the losses using coax,the ladder line is homebrew as i had a lot of enameled copper wire,thats why the 9-1 unun is by my tx,as then the atu matches it ok,whats the best way to conect to it then,just some crock clips on a short piece of coax from the vna connectors?,cheers in advance.

Bigger question is why a balanced 600 ohm line to an unbalanced vertical which
typically is low impedance?

Short form is the 19" of wide at most will skew the data as your moving the VNA 18 inches
above your ground reference ( the counterpoise for the antenna) and will likely see variations
between holding it and laying it on the ground.

IF you use a balun the only one is a 1:1 isolation as you have no idea what the antenna
impedance is but its likely lo. If you use a lot to high your likely going to see greater mismatch.


Suggested hookup is short as possible leads from connector to the antenna connection
points as then you get the actual antenna feed impedance (R,jX).

Allison
-----------------
I do not accept private email due to forum scraping groups.io

Hi all,ive a nanovna with bnc conectors,i want to connect it to my homebrew vertical to play with the base loading coil,currently i have 600 ohm ladderline with one leg going to the loading coil and the other to ground,if i conect the center of my bnc coax to the coil and screen to ground,will it work,the coax with the bnc on the end to go on the nano is about 18 inches long,will that work or do i need a balun?,at the moment the ladderline goes to a 9-1 balun in the shack.73

GIN&PEZ;

Indeed an interesting experiment, and one of which my contribution may be quite small and insignificant. :-)

I am certain I can (with some effort) locate the reference Hackborn article, but with limited effort on the web, I also have not met with success.

I have however found references to his work, and also the works of others pursuing goals quite similar to yours. Acknowledging that your work, as well as there’s spans decades, and that Hackborn’s paper serves as a reference standard for comparison, it is unlikely I will be the investigator most capable of finding noteworthy feature differences, flaws, or revelations. At best I would expect to gain understanding and confidence in the results I am able to achieve.

Having said that; I would remiss to make assumptions that you are (in deference to my judgement), intimately aware of “all” similar efforts past and present. To that end I will alert you to information that you may wish to review and comment on for relevance before I confuse myself with Information overload.

The following by example:



Also a possible item of interest is a Patented scheme (US6,300,775B1) with similar stated goals, by far exceeding my current math skills.

--
73

Gary, N3GO

any plans on selling the boards without the screen?

Looks ok but as I do not use Octave on Linux I suggest you use google to find the documentation for the instrumentation-control package

--
NanoVNA Wiki: /g/nanovna-users/wiki/home
NanoVNA Files: /g/nanovna-users/files
Erik, PD0EK

On Wed, Dec 18, 2019 at 09:54 AM, Gabriel Tenma White wrote:

On this particular unit the nastiness starts at 3.4GHz.

Exceptional performance, especially taking the target price point into account. You all did a very good job.
I wish my home build 3GHz VNA would be that good

--
NanoVNA Wiki: /g/nanovna-users/wiki/home
NanoVNA Files: /g/nanovna-users/files
Erik, PD0EK

Rune,

Yes something is not quite right.

I used the TDR function on the NanoVNA in stand-alone mode and got impedance measurements that made sense to me. I cascaded some 50 ohm (RG58), 75 ohm (RG59) and 93 ohm (RG62) coax and could see the impedance steps.