开云体育

#84: On the Virtuality of the "Measurement Port"

Hello,

Allow us, please, to inform you that since in our sow we see the
"Measurement Port" facupov as the Virtual Port of the irreversible,
non-reciprocal, two-port V2P [1], at least in the case of the basic
HP 8502A Transmission/Reflection Test Set [2], we just uploaded
a rather big (2,752 pixels width X 2,060 pixels height), and rather
clean, figure of its equivalent circuit of some version of it [3], at:



After that, we hope it would be crystal clear the objective fact that
facupov this device is * N O T * a TWO-PORT at all, but it is the
FOUR-PORT Network : w

[RF INPUT] - [TEST] - [INCIDENT] - [REFLECTED].

Therefore, also allow us, please, to inform you that, about 25 twenty-
-five years ago, we started our research on this very [anyVNA] subject,
by expressing -at least in the "Low Frequencies"- the shown Four-Port
as an effective "Error" Two-Port - after a long sequence of assumptions
and approximations, of course.

Sincerely,

gin&pez@arg

REFERENCES

[1] #77: On the current explanation of full one-port "error" model
in our sow - facupov, as always - with an Application to the
Measurements of Two-Port Devices :
11 November 2019 - /g/nanovna-users/message/6798

[2] archive.org,HP: 8502A :

[3] archive.org, HP: 8502A, p. 5/6 :

:84#

On Fri, 13 Dec 2019 at 22:58, <roncraig1@...> wrote:

You are not going to be able to improved reading of high impedance very
much as the primary limitation is the 50 ohm impedance bridge and signal
level differences get very small at the higher load impedance.(refer to
right hand, high Z side point of Smith chart. The difference in reflection
coeff. is very small at higher Z).

The best solution is to make a transmission measurement. That allows high
impedances to be measured better than a reflection measurement

Probably the best thing to improve unit's overall accuracy is the
replacement of the cheap thick film 49.9 ohm chip resistors (EIA96 marking
'68X') in the input bridge with 50.0 ohm 0.1% tolerance high frequency thin
film resistors. They are about $1.50 each at Mouser Elect. for Vishay
FC0603E50R0BTBST1 part number.

I don’t know the tolerance of the 49.9 ohm resistors, but 49.90000000 ohms
is plenty good enough

Here are a couple of equations for VSWR that I personally find convenient

VSWR=R/50 for R>=50
VSWR=50/R for R <= 50.

So for 49.9 ohms

VSWR=50/49.9=1.002

You will find it is a 60 dB return loss if you use an online calculator
such as;



The guaranteed return loss of the loads in my $13,000 Agilent 85052B 3.5 mm
calibration kit is 48 dB at low frequencies.

IMHO, unless the 49.9 ohm resistors have a poor tolerance, *the difference
between 49.9 and 50 ohms is not worth worrying about. *

I measured the source match at port 1 using an HP 8720D VNA with 85052B
calibration kit. The match is *excellent* - it far exceeds the uncorrected
performance of the 8720D. On port 2, the match is poorer, but still quite
good.

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

Just for fun I have ordered one of these 1:9 baluns for a test.
Won't be here until next year though.

It's a cheaper version, so I'm not sure if it's gonna be much good, but what the heck, it's only $4 !



I've noticed that on all the versions I have seen, the appear to have a varistor across the input.

I guess that'll have to be removed.

73 de Andy

Hi Kurt,

Thanks for the very detailed manuals. It will be help for me a lot. It requires more time to understand everything.

73,Lajos

I always read the forum online, not as emails, so it's easy to scroll up and refer to the original post of a thread...

The stated use-case is measuring the feed-point impedance of end-fed half-wave (EFHW) antennas. Being fed at a voltage antinode, feed-point impedance (at resonance) is quite high (typically 2500-4500 Ohms), and varies depending on the antenna's installed environment. Measuring it is useful for designing the correct feed-point impedance transformer. The design currently going around in EFHW circles is the 1:49 (impedance) toroidal transformer. However, that's just a ballpark, which should be be adjusted to optimize the ratio for each particular installation. I can think of several other cases where measuring high impedance is useful, including sweeping non-resonant broadband doublets, characterizing ladder-line, building stubs and transmission line transformers, sweeping high CMRR chokes, etc.

Early in the thread, someone correctly replied, "use an impedance transformer," and so I obtained such a device and proved it's a useful and simple solution to the original question, without need of re-engineering the nano's bridge.
--KV5R

Gin&pez
Thanks for the reply.no need for any action from you side.
Garry already help me to understand better

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

Kurt,

Thanks for supporting BNC connectors. I do lots of portable operation on HF and 6 meters and an constantly rearranging equipment so I have standardized on BNC connectors and purchased your calibration kit. I have front ended my VNWA2 and nanoVNA analyzers with BNC connectors on a bulkhead panels.

73,
Mike N2MS

Neal Pollack wrote:

1. ...it appears to be a NanoVNA-H hardware version but without the plastic case. It is black, USB-C, with RF shields and LiPo battery containing charge/protection circuits on the battery ...

The NanoVNA-H is hugen's newest release of the NanoVNA with plastic case, battery monitoring circuit, and USB-C to USB-C resistors. The "-H" suffix was added to distinguish it from other NanoVNA's.

2. Is there a command, either in the PC software via USB cable, or else via the USB serial console,
that will show what version firmware I have?

More recent firmware can display the version number through the menu by selecting <CONFIG-VERSION>. I believe on earlier firmware you could connect the NanoVNA to a PC and then using a terminal program type "version" to get the version number.

3. How can I tell if I can use the newer firmware, perhaps the H version, so that I can get the added features such as TDR

The various firmware available is useable with all NanoVNA and NanoVNA-H models. They cannot be used with the NanoVNA-F which is the 4.3" screen model.

- Herb

From: Neal Pollack: Which versions of firmware can be used on these?

Yours sounds like the one I have and I use edy555 firmware.

NanoVNA-Saver has no limitation on the number of saved calibrations. They
are saved as files.

--
Rune / 5Q5R

George Kokolakis, SV3QUP: Would it be possilbe to have more store positions for settings? 9 would be great for HF bands.

Is there any limit to the number of possible calibration settings in NanoVNA-SAVER?

Hello:

I am a new user, and just received one of the recent, but not "-H" versions of the NanoVNA.
It seems to have a build date of second half 2019. No case, but shielded, and the sides are open,
with removeable backplate to see the battery and RF shields.

Is there a command, either in the PC software via USB cable, or else via the USB serial console,
that will show what version firmware I have?

Second, how can I tell if I can use the newer firmware, perhaps the H version, so that I can
get the added features such as TDR?

Sincere Thanks for helping/teaching.

Neal, N6YFM
================================

Neal,

Welcome to the group!

I suggest installing the NanoVNA-saver software.



IIRC it can show the firmware level. It /may/ also be displayed when you boot the device (mine doesn't).

73,
David GM8ARV
--
SatSignal Software - Quality software for you
Web:
Email: david-taylor@...
Twitter: @gm8arv

I should correct my post above, since upon reading more on the wiki,
it appears to be a NanoVNA-H hardware version but without the plastic case.
It is black, USB-C, with RF shields and LiPo battery containing charge/protection
circuits on the battery.

Which versions of firmware can be used on these?

Thanks!

@ Erik, PD0EK
10 December 2019 - /g/nanovna-users/message/8105

Dear Erik,

Thank you very much indeed for your continuing interest in our work !

However, since we are not sure at all what would you expect from us
regarding your Work contained in your three links you gave to us,
we don't want to jeopardize any related comment, which will be
considered as inappropriate by a possibly biassed member of this
group, and thus to give him the chance to start a nonsensical dispute
on matters definitely belonging in the subjective sphere of personal
habits and/or tastes.

With our kind regards,

gin&pez@arg

Hi All

I have been asked about how to convert calibration kit files for the VNWA
calibration kit to the format used by NanoVNA-Saver so I have made a couple
of documents

Where the first one is how the settings shall be for the NanoVNA-saver for
the SDR-Kits 3 or 4 parts universal BNC calibration kit



How to convert, which also can be used for any unknown calibration kit
provided it is measured on an correct calibrated VNA with saved s1p files
for short open and load, is described in the document


Kind regards

Kurt

Hello:

I am a new user, and just received one of the recent, but not "-H" versions of the NanoVNA.
It seems to have a build date of second half 2019. No case, but shielded, and the sides are open,
with removeable backplate to see the battery and RF shields.

Is there a command, either in the PC software via USB cable, or else via the USB serial console,
that will show what version firmware I have?

Second, how can I tell if I can use the newer firmware, perhaps the H version, so that I can
get the added features such as TDR?

Sincere Thanks for helping/teaching.

Neal, N6YFM

Unfortunately, there is no more room in the firmware for more storage locations.?

Sent from Rogers Yahoo Mail on Android

On Sat, 14 Dec 2019 at 1:48 am, George Kokolakis, SV3QUP<kokolakis@...> wrote: Would it be possilbe to have more store positions for settings? 9 would be great for HF bands. Does anyone now if the limitation is on the hardware or just on the firmwares available?

George, SV3QUP

Hugen removed c4 so he could fit in the larger fonts.?

Sent from Rogers Yahoo Mail on Android

On Sat, 14 Dec 2019 at 1:33 am, Luigi Mantuano<l49mantuano@...> wrote: Hello again,
earlier today I finally loaded hugen's? v0.4.0-3, AA-4 traces ( NanoVNA-H_20191125_AA.dfu) FW on my nV... all looked good but when I went to set up and store the 5th calibrated range in C4, there is no C4!? there is no SAVE 4 nor RECALL 4 tabs, only 0, 1, 2 and 3....
Honestly I can't remember (not paid nuff attention perhaps) whether my earlier FW version/s had 5 memory locations for cal data, as per documentation.
Please forgive my clumsiness if this turns out to be a triviality or if I missed the relevant bit of info.
TIA
Luigi M

The Octave serial interface library is different. Rest should work.

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

On Mon, Oct 28, 2019 at 06:52 AM, W1RS wrote:

Has anybody tried this with Octave? (Matlab open source "clone")
=================================================================

Paul Fredette, K1YBE, has uploaded a sample Octave script for interfacing with the NanoVNA. The script can be found at: . Of course it also is applicable to MATLAB users.

-Herb