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Date
Re: Oscillator 26MHz

 

Thank you for your quick reply and data-sheet's link.

Rudi

Le 21.05.2020 ¨¤ 12:23, hugen@... a ¨¦crit?:
Re: [Measuring] Is there an easy way to measure balun loss?

 

try to see
and
Re: Calibration issue causing ripples in SWR? #calibration

 

The 50 ohms cables as far as I remember were rated by different
manufacturers as 50 to 52 ohms years ago, so my guess is that 51 ohms
is on the ballpark. It is also a standard resistor value.

Try to find out the cable impedance, it seems to me to be the culprit.
Find the frequency where the cable is lambda/4 as a RF short circuit
with the end of the cable physically open. Set half the frequency
found before on the VNA and read the reactance, that is the cable?s
impedance.

I am writing by heart, a mistake might have slipped...

Jos¨¦, CO2JA

On 5/21/20, ed@... <ed@...> wrote:
After calibrating, I connected my nanovna to my VHF antenna via a brand new
75 foot length of 50ohm DX400MAX coax. The SWR measurement oscillates up and
down every 4MHz or so (see attached). These correspond exactly to the
half-wavelength harmonics of the cable. Looking at the smith chart, it is
clear that the impedance is tracing a circle around about 45 ohms rather
than the constant-SWR circle centered at 50 ohms, resulting in a
frequency-dependent SWR.

Is there is a good way to determine whether this is a problem with my
nanovna, with the calibration standard, or with the cable?

One note: the calibration standard load measures 51 ohms DC resistance,
which seems like a problem to me. Should my standard be exactly 50 ohms dc
resistance?
Calibration issue causing ripples in SWR? #calibration

 

After calibrating, I connected my nanovna to my VHF antenna via a brand new 75 foot length of 50ohm DX400MAX coax. The SWR measurement oscillates up and down every 4MHz or so (see attached). These correspond exactly to the half-wavelength harmonics of the cable. Looking at the smith chart, it is clear that the impedance is tracing a circle around about 45 ohms rather than the constant-SWR circle centered at 50 ohms, resulting in a frequency-dependent SWR.

Is there is a good way to determine whether this is a problem with my nanovna, with the calibration standard, or with the cable?

One note: the calibration standard load measures 51 ohms DC resistance, which seems like a problem to me. Should my standard be exactly 50 ohms dc resistance?

IMG_20200518_133238866_2.jpg

Re: UI Suggestion: Big Numeric Display Format for CW Stimulus Mode

 

Hi,

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

Tnx

Andy - ON7BA
Re: Oscillator 26MHz

 

Re: saver software linux

 

Bob- thanks will give that a try.
Dan KC2STA

On Wed, May 20, 2020 at 3:32 PM Bob Solimeno <kc2jav@...> wrote:

I've been able to install the NanoVNA-Saver on Ubuntu 20.04 using the
attached helper document. I regret to say that I forgot where I found it
... memory loss is the first sign of senility!

The nice thing about this approach is that it can be set up with a script,
saved as a desktop icon and run easily. One caveat is that your username
must be part of the"dialout" group on your Linux system so that access to
the usb port will be allowed to connect the NanoVNA to your computer. As
always, your mileage may vary if running other versions of Ubuntu or other
distros.

73 Bob KC2JAV



--
Dan Ziolkowski KC2STA
SKCC #4290T
Ubuntu LINUX
Oscillator 26MHz

 

Hello,

Can somebody give me the 26MHz oscillator reference for my NanoVNA-H ?

Many TNX in advance.

73 QRO, Rudi, HB9ARI
Re: Reseting or proving that the new nanoVNA actually works

 

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.
Re: [Measuring] Is there an easy way to measure balun loss?

 

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

On Wed, May 20, 2020 at 03:38 PM, CT2FZI wrote:


Hi John,

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

On Wed, May 20, 2020 at 09:17 PM, John Gord wrote:


Luis,

One method: Measure the return loss of the balun with the balun shorted.
The
return loss should be about twice the balun loss. This is similar to
measuring the loss of a shorted or open piece of cable.

--John Gord
Re: nanovna cases #enclosure

 

... saving me the cost...
Re: nanovna cases #enclosure

 

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
Re: Reseting or proving that the new nanoVNA actually works

 

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

On Wed, May 20, 2020 at 1:29 PM billcoombes <bill@...> wrote:

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
Re: nanovna cases #enclosure

 

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
Re: nanovna cases #enclosure

 

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.
Re: Reseting or proving that the new nanoVNA actually works

 

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.
Re: Calibrating to a long coax? #applications #calibration #measurement

 

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
Re: [Measuring] Is there an easy way to measure balun loss?

 

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.
Re: [Measuring] Is there an easy way to measure balun loss?

 

Hi John,

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

On Wed, May 20, 2020 at 09:17 PM, John Gord wrote:


Luis,

One method: Measure the return loss of the balun with the balun shorted. The
return loss should be about twice the balun loss. This is similar to
measuring the loss of a shorted or open piece of cable.

--John Gord

On Wed, May 20, 2020 at 10:01 AM, CT2FZI wrote:


Hello team,

Is there an easy way to measure balun loss, without another one in tandem
S11-S21 ?

I only have one and I would like to have its characteristics, including
loss.

Cheers and thanks in advance.

Lu¨ªs CT2FZI
Re: [Measuring] Is there an easy way to measure balun loss?

 

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
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