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On Sun, Jan 26, 2020 at 11:46 AM, hwalker wrote:

2. I set <marker 1> to half-way around the smith chart (1/8 wave length) and
- Herb

Herb, it seems to me that a half-way around the smith chart is 1/4 wave length. Isn't it? )))

Herb,

This is an eye opener for me, it appears that at start NanoVNA-Saver is using the C0? calibration of NanoVNA, untill now I thought these calibrations were independant.

I just made a new 100 Segs calibration. Please see the attached results.

NanoVNA-H4 is a great device, just the CH1 impedance could be a bit better and the enclosed 50 Ohms standard I measure (4? point measurement @ 10kHz) 50.940 Ohms, also could be a bit? better, I use one that I previously received wich I measure 49.850 OHms and correct it in NanoVna-Saver's? "Calibration"? window. Yes I can do that for the portsavers also.

Best regards,

Jos

Op 26-1-2020 om 01:24 schreef hwalker:

On 1/25/2020 3:37 PM, Jos Stevens wrote:

Hi Oristo and Herb,

Thinks for the pictures Oristo, i think they are from the 2.8" NanoVNA-H, my 2.8 -H version works well, this problem is? with my VNA new version H4.

Herb,? yes I did use the calibration wizard and I have done it so often that I can do it blindfolded..

The only thing different is that For the H4 I used portsavers and used one of the cables that were in the box of the -H4, the firmware is still from the first of Januari 2020, I did not upgrade yet because I learned that there are problems with the new firmware.

Anyhow you say that you have no problems,? I'm using NanoVNA-Saver 0.2.2.1, the latest version as far as I know. I hardly can believe that the problem is in the hardware, because the hardware stand alone shows "Ch1 Logmag 10 dB/-1.42 dB @ 50 kHz" , -0.07 dB @ 810Mhz and -1.55 dB @ 1500 MHz after a 101 point calibration. A minute ago I ran the calibration again on NanoVNA-Saver and attached the pictures before and after pressing "Apply".

What can I do more ?

Jos

The RG174 jumpers that came with my Nano were very noisy.? I bought a kit of 5 teflon cables, now cal works good and no more noise.

Eric WA3UYI

Oristo, thanks a lot! I will try and let you know, best,
颁é蝉补谤.

If the NanoVNA had a WiFi transceiver on board in addition to the USB port, so
it could be controlled remotely by NanoVNA Sharp, NanoVNA Saver, or similar
applications.

If nanoVNAs had BlueTooth, then they could also be controlled by iOS apps.
There are fairly cheap BlueTooth modules with programmable microcontrollers
and also fairly cheap USB host shields.
Firmware integrating those for a dongle could work for all nanoVNAs, not just H4s..

the 1/8 wave method

added to /g/nanovna-users/wiki/Application-Notes#Collected-wisdom

Hi Hans -

and advise is clear "config"

see /g/nanovna-users/message/10215

Is calibration also required ?

It will be, after clearconfig

Before all that, check for SMA connector integrity.

Hi Cesar -

I suppose that your issues are related,
and I suggest that the problem is/was corrupted calibration data area
which has been my experience with first calibrations with some new firmwares.

The workaround:
----------------------
Using a serial terminal program to communicated with nanoVNA's USB virtual COM port
(e.g. PuTTY )
invoke the console shell command `clearconfig 1234`
/g/nanovna-users/files/NanoVNA_Console_Commands_Dec%209-19.pdf
then power off and back on
then recalibrate the touch panel using touchcal and touchtest
/g/nanovna-users/message/7759
perhaps check vbat and tweak by vbat_offset
/g/nanovna-users/message/6549
/g/nanovna-users/message/9868
then saveconfig

then, by touchscreen menu CAL->RESET

then CAL->CALIBRATION
/g/nanovna-users/message/7759
/g/nanovna-users/message/7810

Thanks Herb for confirming my suspicion.

I've looked at the specs once again: VSWR: 1.05 + 0.008 f (GHz) max @ DC - 18.0 GHz, 1.30 max @ 18 - 26.5 GHz
so I would expect 1.30 at frequencies above 18GHz, which is not my case.

PS: I did compare with Radiall SMA terminators rated up to 4GHz and I don't see such behaviour at low frequencies.

Hello Rudi,
hello Oristo,
thank you very much for your reply!
If I use i.e. RG58 with a length of abt. 1m I don't see the problem as well due to the high loss of this cable (RG58 1m.jpg). But if you take a low loss coax cable like RG402 ( RG402 semi rigid.jpg) you will see the quality of your calibration standard settings. The expert Kurt Poulsen, is working the issue, and I am confident that he will solve it.

Best regards
Norbert, DG1KPN

Hi all,

I just got my NanoVNA-H 3.4 (official version via alibaba/Maggie). Generally it works quite well, but I find two issues:
1) SWR reading shows always 1 across the entire sweep range, from 50kHz up to 900MHz, regardless of what DUT is at the port, even for open, short, always I get a flat SWR=1. Any idea how to solve this? shall I try firmware update? and if so which version do you recommend?
2) another less important issue is with the calibration. It seems quite difficult with my unit to calibrate the open port. After the full SOL calibration, I always check again each S, O and L, typically Short and Load are OK, but Open is quite off, generally in the capacitive region.
Apologize if these topics have been discussed already in any other thread, if so I was unable to find them in this group.
Any hint will be wellcome! thanks,

César, EA5IOQ

Hello all,
Just flashed firmware 0.60 by Edy555 in my NanoVNA ( ) and advise is clear "config" NanoVNA.
I searched in the menu and manual of the NanoVNA but i can't find it.

Is calibration also required ?

Thanks in advance !

Hans

On Sat, Jan 25, 2020 at 10:01 PM, Bob Albert wrote:

"... When I measure 50 Ohm coaxial impedance with the 1/8 wave method, I always get 50 Ohms. I tried some 75 Ohm cable and still get 50 Ohms!.."
=====================================================================
Bob,
I haven't tried the 1/8 wave method with my NanoVNA-H4 yet so your question gave me a reason to do so. See the attachment for details.

1. I connected a 2 mtr length of RG-59 (75 ohm) cable to CH0. My calibrated range was 50k-1G and I reduced the stop frequency until I had one full revolution of the smith chart.

2. I set <marker 1> to half-way around the smith chart (1/8 wave length) and read the frequency (24 MHz)

3. I set <marker 2> to half that frequency (~12 MHz) and read the impedance (~75 ohms).

I could not set my second marker to exactly 12 MHz because my original calibration points landed me on either side of that frequency. One side was 76.4 ohms and the other side was 73.2 ohms. If I had done a 101 point cal from 50k-50M I could have landed on 12 MHz (~75 ohms).

I've used this method since it was introduced to the group and its always worked for me.

- Herb

Bob,
On a 50 ohm Smith chart, the bottom (6 o'clock) location will always be -j50 ohms.

The trick to measuring the cable impedance is to adjust the CW test frequency so that an open cable measures as a short: The cable is 1/4 wave long at that frequency. The CW frequency is then cut in half: The cable is now 1/8 wave long. A 50 ohm cable will measure as -j50 ohms, right at the 6 o'clock point. A 75 ohm cable will measure -j75 ohms, about 5 o'clock.
This all assumes proper calibration at the reference plane where the cables are attached, of course.

If you want, you can just do the frequency adjustments by changing the Stop frequency. The display will then be an arc instead of a point, but the high frequency end of the arc is the relevant place to read the value with the marker.

--John Gord

On Sat, 25 Jan 2020 at 23:12, John via Groups.Io <n0ure@...>
wrote:

Was my First purchase from China a mistake? This is a no battery clone I
assume. First session I used Saver 0.2.2-1 to do a calibrate.
My device is now non responsive. I do see the 'Disconnect' on Saver but no
movement in any process.

Did you fit a battery before trying to use it, or just use it on a USB
power adapter?

Dave.

--

Dr. David Kirkby,
Kirkby Microwave Ltd,
drkirkby@...

Telephone 01621-680100./ +44 1621 680100

Registered in England & Wales, company number 08914892.
Registered office:
Stokes Hall Lodge, Burnham Rd, Althorne, Chelmsford, Essex, CM3 6DT, United
Kingdom

On Sat, Jan 25, 2020 at 09:51 PM, <tonyg1hmo@...> wrote:

I saw the 'save'menu item but as it was under 'cal' I wongfully assumed that it would save just the calibration.
I have just saved a cal and settings for 1.6 - 30MHz. which I use mostly as the default into location 0.
When I switch it on, that is now recalled automatically, so perfect, i'll now save the calibration for various bands that I use in the remaining memories and then manually recall them as and when I require them.
==========================================================

Glad to help Tony. That's pretty much how those save locations were intended to be used and how a lot of other members, including myself, use them. I wish there was a way to re-name the save locations to something more meaningful than 0-4. Maybe I'll just add a sticky note to the front or rear of the -H4 to remind me what I have stored in each.

- Herb

On Sun, 26 Jan 2020 at 00:08, hwalker <herbwalker2476@...> wrote:

Larry,
I've made a few like that myself and they all perform well up to 1
GHz. My main reason for the post was to show that if you measure a
termination with a dc meter and have it read 50.01 ohms that it isn't
necessarily good for use at VHF or UHF frequencies.

My company makes VNA calibration kits. I don't measure the DC resistance
at all - I just ensure that the return loss meets its specifications.

I see so many people on here believing that they are measuring the SWR of
their own loads, I give up replying, as I would never have time to do any
real work.

Dave
--
Dr. David Kirkby,
Kirkby Microwave Ltd,
drkirkby@...

Telephone 01621-680100./ +44 1621 680100

Registered in England & Wales, company number 08914892.
Registered office:
Stokes Hall Lodge, Burnham Rd, Althorne, Chelmsford, Essex, CM3 6DT, United
Kingdom

On Sat, Jan 25, 2020 at 07:55 PM, Larry Rothman wrote:

Hugen's H4 unit with the 4 inch display already has a serial port available in addition to the USB for use with additional peripherals like wifi and Bluetooth dongles.
The only problem at this time is none of the devs have enabled them just yet but its just a matter of time now.
===========================================================

hugen also made the uart port available on the 2.8" NanoVNA-H v3.4 for users who want to add Bluetooth or wifi capability. Interested DIY'ers might look at the wifi and Bluetooth adapter designs used on the minVNA for inspiration, .

With the generous amount of flash memory available and faster processor, I think as Larry commented that, the -H4 would be the better candidate for such a project.

- Herb

When I measure 50 Ohm coaxial impedance with the 1/8 wave method, I always get 50 Ohms. I tried some 75 Ohm cable and still get 50 Ohms!

When I use my old method of adjusting the termination it works fine and I get the expected 75 Ohms.

I think I got a reading at 1/8 wave of roughly 200 pF and 15 MHz, if memory serves. So either the method is flawed or I am doing something wrong. What I do is sweep the frequency to the point where the Smith chart trace is at the bottom of the chart, or one-eighth wave out (open end), and read the figures on the screen. Then I compute the capacitive reactance.