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Re: Crystal measurements & QEX review

Joe Rocci
 

Nick

Keep in mind that the loaded Q of the crystal + measuring circuit will be affected by the source and load impedances the crystal is embedded in. The crystal itself will probably have an equivalent series resistance of 10 ohms or less, so connecting it directly to a 50 ohm signal generator and a 50 ohm measurement device will dramatically affect the Q, and thus the bandwidth, of the measurement. You can make some simple resistive terminations to do this if you can tolerate the loss (shouldn't be a problem considering that the NanoVNA has around 70 dB of range at HF), or you can make some transformers, or a combination of both.

If you're characterizing crystals for use in a crystal filter, keep in mind that frequency matching is far and away the most important consideration and, for best filter shape, you should try to match all the crystals within 5% or less of the intended filter bandwidth.

Joe
W3JDR


Re: Updating the firmware

 

Ciao Alberto,
nessun rischio seguendo questa procedura;
/g/nanovna-users/files/Firmware/Windows%20guide%20on%20how%20to%20write%20firmware.pdf

--
*73, Lucio I0LYL Rome, Italy*


Re: Updating the firmware

 

You cannot brick the unit.Please refer to the user guide in the files area.It has all the info you'll need.

On Friday, January 3, 2020, 10:51:59 a.m. GMT-5, Alberto I2PHD <i2phd@...> wrote:

Could please some kind soul point me to the detailed instructions on how to update the firmware on my nanoVNA, the 2.8" , 50 kHz to 900 MHz model ?
I have just downloaded the 0.5.4 version, but before risking to make my unit totally inoperative I would like to be sure about the steps to be done, thanks.

Alberto


My "armored" design for the N type.

 

This is my design for N type.
No claim to originality.
And a calibration kit for N type lines.


Updating the firmware

 

Could please some kind soul point me to the detailed instructions on how to update the firmware on my nanoVNA, the 2.8" , 50 kHz to 900 MHz model ?
I have just downloaded the 0.5.4 version, but before risking to make my unit totally inoperative I would like to be sure about the steps to be done, thanks.

Alberto


Re: New book on the NanoVNA

 

David,

as far as the NanoVNA-F is concerned, I'm sorry but I have to disappoint you. We do not own an F-model and have no intentions to buy one, so chances are very low that we will extend our book there. However, as a member of this forum you will be aware of the talk concerning the NanoVNA-H V2. Depending on the final outcome of this model (features and pricing) we might extend the book accordingly.

I haven't been aware of Lulu up to now, but will check into that.

Vy 73,
Chris, OE1CGS
=================================

Noted, Chris.

I would hope that if you asked the makers on the NanoVNA-F, they would provide you with one on loan, perhaps to keep, as your book has obviously proved popular based on the feedback here. Of course, having the NanoVNA-F in your book would help to increase their sales.

Yes, I'm aware of the possibility of a newer model, and I would likely get one if:

- the coverage is significantly greater (3.5 GHz minimum, 6 GHz highly desirable for 5 cm etc.).
- it works with present software (e.g. NanoVNA-saver).
- the screen size is at least "4 inches".
- the size is similar to the present NanoVNA-F.
- the price is similar to the present NanoVNA-F.

Whether it comes from the NanoVNA or the NanoVNA-F suppliers wouldn't bother me providing support and service are good, and it's legitimate.

I would check with both Amazon and Lulu, but from both I've seen "updated versions" at a low cost, or free of charge to the original purchasers. I don't know how that works, though.

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


What is the best method to measure a stripline impedance with the nanoVNA????

 

Is the nanoVNA able to measure the characteristic impedance of a short stripline?

For dead-bug builds it is sometimes required to have a 50ohm stripline to connect two adjacent parts of the circuit.
One approach is to use a small coax but according to the stripline calculator that can be found here
using a small isolated wire and some copper foil should also give about 50 ohm.
So I made a test PCB and added a rather high-tech stripline consisting of a thin insulated wire and some copper foil covering the wire and keeping it close to metal layer of the PCB.
One end of the wire is connected to the center pin of a SMA connector and the other end is connected to ground
Then I connected the nanoVNA to the SMA connector using a male-male and tried to use the TDR function of the nanoVNA to measure the characteristic impedance of the stripline.
It is possible to see the effect of adding the copper foil as the maximum impedance nicely reduces from above 150ohm to 67 ohm but the resolution of the TDR is on the edge of being able to see something.
The measurement point selected was the point with the highest impedance when no foil was added.
Replacing the test PCB with a 50ohm load gives 50ohm at the same measurement point and using a 1k5 resistor to ground on another test PCB showed the measurement point to be the highest resistance.
Replacing the test PCB with a short give -4ohm

Is there a better way to measure sripline impedance with the nanoVNA, or is this the maximum possible?


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


Re: Calibration standards

Ed Jones
 

On Thu, Jan 2, 2020 at 10:12 AM, Kurt Poulsen wrote:

Hello Ed SDR-Kits has both SMA and BNC calibration kits which is documented. Soon there will also be 5 parts N calibration kit The 4 parts BNC and N kit is universal as being both male and female. Individual data for each kit will be provided on a paper slip for BNC and N and also as downloaded calibration kit file suited for the VNWA, which is a file to read with a text editor for copy paste purpose.
For the SMA find the documentation in attached file or from my homepage link below As the NanoVNA does not have facilities for settings of calibration kit data (assumes ideal kit) the application NanoVNA-saver by Rune Broberg has facilities for entering such individual calibration kit data. to May 2017 calibration kit.pdf If you chose this way to get good quality calibration kit do not hesitate to contact me for how to utilize the NanoVNA-saver facilities as there are some details to consider with the NanoVNA-saver. Kind regards Kurt

Thanks for the information, Kurt. Those seem like a practical, less expensive way to get some decent calibration standards. As I have poked around the Wiki and the links you posted, I now realize you have spent a lot of time documenting these standards. Thank you for that! Do you know when the N-calibration kit will be available from SDR-Kits?

Ed Jones - K8MEJ - Lewis Center, Ohio U.S.A


SimSMith

GmailK4KV
 

Hello,

Talking about Smith charts, you guys download the SimSmith program?

Lets you do "what if" things by pulling in just about any kind of element (inductor,

capacitor, coaxial stub, etc) into the analysis.

73

Glen K4KV


Re: New book on the NanoVNA

 

Hello,
I'm waiting for the mine non-model H that I bought a couple of weeks ago,
and I want to use it as Antenna Analizer up 900 or 400.

What is the most appropriate firmware? Can I use the firmware for H models?

73
Enrique LU8EFF




El vie., 3 de ene. de 2020 a la(s) 04:10, Sverre Holm (svholm54@...)
±ð²õ³¦°ù¾±²ú¾±¨®:

Thanks for this book. I bought the NanoVNA some months ago, but never had
the time to dig through all the forum information about it. The authors of
the book have now done it for me. Based on their book, and in an hour or
so, I have been able to add the battery diode, update the firmware to the
large letter AA-version, and started to use it.


Sverre
LA3ZA





Re: First PCB pictures of the V2

 

Hi,
I agree with Jean and Larry - keep going with this discussion - as for me it already helped much in my pcb design ;)
Mel: THANK YOU for the tips and explanation, this is going to be very neat analyzer!

--
Slawek/SP9BSL


Re: First PCB pictures of the V2

 

Wow, Fantastic discussion. I, and I'm sure may others, enjoy reading these "RF" design topics. A lot of first hand experience and know how from practical designs feed back.
Thanks a lot for sharing this.
Jean


Re: New book on the NanoVNA

 

David,

as far as the NanoVNA-F is concerned, I'm sorry but I have to disappoint you. We do not own an F-model and have no intentions to buy one, so chances are very low that we will extend our book there. However, as a member of this forum you will be aware of the talk concerning the NanoVNA-H V2. Depending on the final outcome of this model (features and pricing) we might extend the book accordingly.

I haven't been aware of Lulu up to now, but will check into that.

Vy 73,
Chris, OE1CGS


Re: New book on the NanoVNA

 

Thanks for this book. I bought the NanoVNA some months ago, but never had the time to dig through all the forum information about it. The authors of the book have now done it for me. Based on their book, and in an hour or so, I have been able to add the battery diode, update the firmware to the large letter AA-version, and started to use it.


Sverre
LA3ZA


Re: errors of "error" models

 

Happy New Year GIN&PEZ et al who follow this thread.

Post #9070

#101 : A Mechanical Proof of the Invariability of the Cross-Ratio
Under the Moebius Transformation of G to g of a Two-Port

Is this simply a missed observation until now?

The Smith Chart itself is a graphical mapping of a bilateral Moebius transform of G to Z.



I¡¯m learning that there¡¯s a lot I did not completely understand about this tool (the Smith Chart) to benefit from its utility during my career.

A nicely done animated graphical presentation:



I also discovered that there remains ample material to cover on this topic to span my retirement. :-)






--
73

Gary, N3GO


SMITH CHART TUTORIAL

 



--

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


Re: Impedance , C and L measurements with PC software

 

Hi Chuck. Yes I understand. Then you are correct, forget about navigating around the little vna screen. Although you will have to do an initial calibration and setup on the hardware first. There after you can use the SAVER PC software to achieve any desired data format you want as well as calibration from the pc software.

Alan


Re: Copy results to clipboard from NanoVnaSaver? #nanovna-saver #improvement

 

Snipping shortcut in Win 10 is Windows-Symbol + Caps-Key + S

-----Urspr¨¹ngliche Nachricht-----
Von: [email protected] <[email protected]> Im Auftrag von Clyde Spencer
Gesendet: Mittwoch, 1. Januar 2020 15:20
An: [email protected]
Betreff: Re: [nanovna-users] Copy results to clipboard from NanoVnaSaver? #nanovna-saver #improvement

Also, If you are using Windows 7/8/10 there is a built in program called "Snipping Tool". Search for this in windows. It not only captures the screen but also allows cropping in the process.
*Clyde K. Spencer*

On Wed, Jan 1, 2020 at 8:56 AM David J Taylor via Groups.Io <david-taylor= [email protected]> wrote:

If you are doing a sequence of screen-shots, the well-known, free
IrfanView software allows screen-capture with the Ctrl-F11 keystroke.
It can save in PNG (and many other) formats to keep the captured file
size to a minimum, and names the files using date and time in a format
you specify. Include the cursor or not.



Having said that, a right-click, copy to clipboard over the graphs
would be a helpful addition to NanoVNA-saver.

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





Re: First PCB pictures of the V2

 

Hey Pablo and Hey Larry,

It¡¯s really cool that you two have an eye on our conversation ?
And thanks for your opinions! I wish you both a Happy New Year~

Hey Gabriel,

Thanks for giving me your development data! It¡¯s always exciting to see someone else¡¯s design style. ?

As a common advice (to everyone ?): If you want to filter your power supply, I highly recommend to not use those standard 100nF Caps! Yes, it looks like everyone is using them (and unfortunately those still get recommended in the datasheets). But at a RF-view they far from optimum.
The purpose of those Caps is to filter noise thus acting like a pass through at low frequency (DC) and shorting higher frequencies to GND as much as possible. At most frequencies these Caps are above their self-resonance frequency (SRF). That¡¯s why you should use a SMD ceramic capacitor with as many internal layers as possible at your desired size to lower parasitics like ESR and ESL, for example, a 4u7 at 0402 or 10u at 0603. In plain theory they are not recommended at high frequencies due to their SRF. But if you measure them with a precise VNA you¡¯ll find out that due to the internal layer stacking the parasitic inductance (ESL) is very low as many layers connected in parallel. Therefore, the capacitors impedance (even as it acts as an inductor) stays quite low at higher frequencies (several GHz) and obtain a very neat noise filter characteristic!
Oh, and please put those bypass caps as near as possible to the desired IC supply pin. In fact, not all ICs need to have the bypass cap directly next to their power supply pin, but for some especially RF-ICs this is essential!

1) Absolutely! This SMA connector style you are using has a really bad performance at higher frequencies. It¡¯s not just the stub giving you a parasitic inductivity also the discontinuity inside the bended connector affects the port match (at least if you don¡¯t want to pay some extra to have a perfectly matched bending)¡­ But unfortunately, it¡¯s the only connector type you can use as you need to maintain a really (really!) good mechanical resilience and a long bulkhead. (But just between the two of us: most of the high end VNAs do not even reach a 20dB return loss at their ports either¡­)

Concerning the RF input cap: Your DGS seems to be fine (just by looking at it). Am I right assuming the Cap can endure 6.3V (max 10V?)

2) Yeah, I already thought this might be the reason why. As JLC is not able to put those IC on the PCB you need to do it on your own. But even so you should put critical passive components at the same side as the ICs. (e.g. some bypass caps or this 50Ohm E-Cal match!) ? It nearly adds no extra time to the population process

RF-switches: That¡¯s why those Infineon switches produce a negative voltage level internally~ Please check them out as you can also use them easily up to several GHz, which might come handy in further versions/designs ;D

3) Don¡¯t you think the cut out might be a bit too much? :¡¯D
And I had a look again at JLC¡¯s part library. The 68Ohm 0402 is available now:

So maybe you can change the size and get rid of the DGS.

As you want to use only ¡®standard¡¯ components those 50Ohms resistors have typically a bad impedance behaviour at higher frequencies due to their high parasitic inductance¡­ At least for the E-cal and reference 50Ohm match you should think about replacing those single resistors with 2x100 Ohm resistors parallel +DGS. (At high end application they even try to force their 50Ohm reference to be a good match by adding attenuators in front of it, as those internal used SMD resistors are most of the time not as good as the external calibration match is ?)
And once more: I highly recommend to put at least the E-cal match resistor directly next to the switch pad, as this would improve your internal calibration and add a bit more stability to your system!
4) Oh yeah, the reference match¡­! I truly remember the same experience meanwhile I developed my directional module ?.
To obtain a good performance at (very) high frequency it is necessary to mirror the signal pathway. Not only due to the not ideal match but also due to the uncertainties within the trace (and if you want to refer the internal match to the external calibration load /DUT also due to the mismatch given by the DC-Block).
But I do admit that inside your frequency range the given mismatches/discontinuities shouldn¡¯t be to high and may just appear at higher frequencies (>2 GHz), thus the gain and phase shift might be not affecting the system so much.

5) If you catch the wrong balun type, the yield can be awful! ?
That¡¯s the reason why so many devices out there need to be tuned before they get delivered to the costumer¡­ As you can not afford this in this application a stable balun with a good yield is the rise and fall of your whole application.
Give those TC1-1-13M+ a try. As far as I know from my and others designs they should obtain a fairly good performance!
I also did a simulation with your resistor values. But instead of a 50Ohm and 0.3pF I used 2 times 50Ohm to balance the baluns and adjusted the tuning R&C! Look how good it turned out ?
6) If you use ferrites for debugging please be careful at 1GHz and above, as ferrites permeability is decreased significantly, and they start to act dielectric.
7) Having U301 switched to port 2 there is also a signal at the trace to U2 reduced by U301s isolation value. The datasheet gives an isolation between 15 to 20dB at 3GHz (with perfect termination!). The signal then gets reflected at U2 and propagates trough U301 back to your mixer with a total attenuation of roughly 25 to 30dB, whereas signals which got coupled into the trace between U301 and U2 are only attenuated by 15dB!

If you want to, I would suggest to change U2 into an low noise amplifier. For example BGA2800, as this LNA just needs 3 caps to be up and running. It is also pretty cheap and concerning your application you can surely run this amplifier up to 4GHz! ?
The amplifier can be used exactly the same way as the switch by turning it on and off. The isolation between U301 and U1 is better than 20dB when turned off. In addition, it would amplify your couplers output signal, hence improving your SNR. This comes in handy as your LO signal from mixer is just 27dB damped (Isolation between RF-IN and LO Port) and interferes with your S11-signal. Furthermore, thanks to LNA¡¯s output match with better 20dB, the mixers does not see any bad impedance match coming from the baluns!
8) To add some stability to your system it would be good, if you would add some DC-Block Caps between mixer and BB-Amplifier (like those 10u 0603) depending on your lowest IF frequency.

Hopefully this helps you to solve your problems soon~
I wish you all the best! ?

-Melanie


Cancelling out coax feeder length?

 

Hi,

Very new to the nanoVNA, still on the steepest part of the learning curve!

I believe it should be possible to set the reference plane option in such a way as to effectively cancel out the effect of a short length of coax? I have a 1GHz groundplane antenna to test, but due to it being constructed before I received my nanoVNA, the 25cm coax feeder to it cannot be removed to calibrate, and I dont have an identical patch lead spare to calibrate with.

It is my understanding in this situation that I need to enter a value into the Reference Plane setting, but I cant seem to find out what the units for this are? Is it mm, degrees, or what? Knowing what the units are will allow me to either measure or calculate what value to enter,

Cheers
Martin