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I think you need to explain "doesn't seem to be working." Does that mean that when you turn it on, absolutely nothing happens? Likewise, explain "don't get any results." Nothing appears on the screen? Also, "I would have thought that I should see something" needs further explanation. That implies that you see NOTHING. So, why don't you tell us what you are seeing? Which traces do you have turned on? Do any traces appear on the screen? Does the Smith chart appear on the screen? Are there any traces overlaying the Smith chart? If you are looking at return loss, or VSWR, for example, is there a line across the screen? If so, where is it? Top of the screen? Bottom of the screen? You say you have calibrated it a number of times, that implies that you are seeing something on the screen. What are you seeing? You really haven't given us anything to go on here.

Luis,
Yes, it should also work with an UNUN. A caveat: It should give a low VSWR (high return loss) when properly terminated.
--John

... saving me the cost...

By the way. This case was an especially a good deal for me because it was just a short 20 min drive from the store for me to go pick it up,swing m the cost of shipping. I also picked up some cheap BNC connectors the make some calibration plugs to match my SOTA antenna/cable connections. Ordering a few mute needed items would make the $4.50 charge less of a burden.

Craig, N1HI

The Nanovna-saver program has an issue where you can try and calibrate it
and it doesn't work. Make sure you use the "calibration wizard" in the
nanovna-saver program under the. You will soon learn to save the
configuration file of commonly used setups.

Robert M

P.S. The tubing was placed back over the stylus and the the assembly was held in place while running the beads of hot glue. This provides for proper alignment and acts as a heatsink for the pieces of tubing as they are being installed.

Craig, N1HI

The attachment for the stylus is two pieces of 3/8" heatshrink tubing I shank down around the stylus. The tubing can then be loosened for a good fit by rolling the stylus between two hard surfaces. The tubing can also be stretched by slipping it over a pair of needle nosed pliers and firmly but carefully opening the pliers` handles/jaws. When the tubing was the right size to slide on and off the stylus with little friction, I ran a small bead of hot glue between each side of the tubing pieces, attaching them to the enclosure. I used a small, low temperature hot glue gun to minimize the chance of the shrinking the tubing too tightly around the stylus. I thought it turned out nicely.

Scan for 10MHz to 500MHz. Your antenna is probably too long and will not show on the 140-150 MHz scan.

WO4ROB
________________________________
From: [email protected] <[email protected]> on behalf of aleks07111971@... <aleks07111971@...>
Sent: Wednesday, May 20, 2020 1:38:05 PM
To: [email protected] <[email protected]>
Subject: Re: [nanovna-users] Reseting or proving that the new nanoVNA actually works

Check the calibration load of 50 ohms.

Hello.

Let us ask, please, two "rhetorical" questions, which are addressed to all
readers of this thread:

- Is there anyone, ever, wondered, in any similar to this, under discussion,
case - that is both "near by"- and "far away" from- a VNA:

= (1) What is the behavior of the three "Traditional" measurement "errors"
(ED, EM, ER) or (D, M, R) ?

- We had; and found the following results [1][*]:
-

= (2) How much "the measurement errors are taking over" ?

- We had; and found the following results [2][*]:
-

for two substantially different loads under the two, most typical,
telecommunication situations, respectively, that is of:

- a load "near by" a VNA - in fact, a DC-50-Ohm Resistor - and

- an Antenna "far away" from that VNA - in fact, a Ground-Plane one.

Well, from the last figure, any reader can easily see how much the
Error of Measurement is, as:

(a) A "Traditional", Absolute, Real Non-Negative, Error: Delta-S11,
as it is calculated by using the technique introduced by HP and thus
resulted as a couple of circles on the Complex Plane of this figure,
as well as,

(b) An Estimation of the Complex Core Uncertainty of the Measurement
Error Delta-Rho, computed and drawn by using two methods [3]:

a differential and a numerical one, and thus resulted as a continuous line
and a cluster of points, respectively, on the Complex Plane of this figure.

CONCLUSION

Although, in comparison, these two Estimations of the Measurement Error
have quite different appearance, because the Traditional Error is arbitrarily
less or more than the Core Uncertainty Error, "near by"- and "far away" from- that
VNA, respectively, the final judgement of which one of these two estimations
represents more accurately the Measurement Error is left to the reader.

Sincerely,

gin&pez@arg

REFERENCES

[1][*] : Fig. 2 & Fig. 4
[2][*] : Fig. 13
[*] : [researchgate] :

[3] : gin&pez@arg : [errors of "error" models"] : a thread, beginning with
#2,770 : 2019-09-21: /g/nanovna-users/message/2770

I ran a test case with a 4:1 xmfr after adding resistive loss to the xmfr.
A plot of return loss (from s11) and then transmission loss (from s21) is provided.

Looks like 1/(1-|s11|) where S11 is obtained from the return loss value matches up with the calculated transmission loss.

Hi John,

Do you agree this will also work with an UNUN, shorted to ground?

Yes. If we are trying to measure the so called TRUE INSERTION loss... |S21|. And the vna has a reasonable dynamic range, then we could build an appropriate MINIMUM LOSS PAD. It would provide a match between 50 ohms and the UNUN transform ratio. Example, say it was a 9:1. Then I would need a 450 ohm to 50 ohm minimum loss pad. That pad has a minimum loss of ~ 16 dB. Higher loss will result in "nicer R values"... So now measure the pad, then measure the pad + UNUN and find the delta. Yes, something so simple has the devil in the details. And it can be more difficult than first realized!

Alan

Hello again Alan,

Thanks for the detailed answer.

I had to google for the design, I have found this website:

I have made a small screen shot of the T design. If one terminates this circuit with a 50 ohms resistor it will work, correct? Assuming the R T values will convert the input impedance to 50 ohms...

The loss relationship should be written as 1/(1-|s11|^2)...

Need to check, is this a valid form for a passive transformer network?

Here is some info on the MFJ cal loads suggested by W7ZQ. Says rated to 1 GHz. - really?

Roger

Check the calibration load of 50 ohms.

Seems like I got errors very much like that when I installed on Mint 19.3 Cinnamon. However, I am still able to start and run it by navigating in terminal to the nanovna-saver folder and entering "python3.7 nanovna-saver.py". I think with earlier versions I had to use "python3.7 ./nanovna-saver.py" but I could be remembering wrong. I am using nanovna-saver 0.2.2.

Hi Luis. Your query stated BALUN. However, if an UNUN, then a simple R pad, either PI or T with a Z value that matches the UNUN transform ratio is required.

The method in either case requires a measure of only s11 or the return as this is directly tagged back to the insertion loss as loss= 1/(1-s11).

If it is a large transformer ratio, the prior post of measurement of short and open s11 is a method to try.

My VNA doesn't seem to be working but occasionally, I can get a reading on it. Thinking that it might be me, is there a way to reset the nanoVNA back to it's delivered format, in case I have done something that is causing the problem or is there a test that I can do to prove to myself, that the device is actually working?
Any suggestions or help would be appreciated. I have calibrated it a number of times but that didn't seem to make much difference. I have connected to nanoVNA-Saver and can set frequencies etc but still don't get any results if I connect it to an antenna for 2m and set the device to scan from 140mhz to 150mhz. I would have thought that I should see something.
Bill

Very nice. The stylus holder is a great idea. Thanks for sharing.
---?
Ciao baby, catch you on the flip side??
73 de W3AB/GEO ???



You can say "over", you can say "out", you just can't say "over and out".