NanoVNA Custom Software

[radiolistener]

After some period of time I found that cable influence disappears.  May be it happens when battery is charging. And when battery is full this effect disappears.

Here is 500 Ohm terminator measurement with 247 ps correction for wave propagation delay in SMA-SMA adapter:



Now it looks great 


By the way, my NanoVNA has 3.7V 450 mAh battery and can work from battery up to 130 minutes.

[rhb]

You probably should probe the output of U3 with a scope and DMM and see what Vdd looks like with and without external power.

The +5 V connection on terminal 3 of U3 looks as if it would power the whole board any time the USB had 5 V unless it's an unconnected power input.  But it looks to me as if it is coming from the USB.  So I'm a bit puzzled by the schematic.

[radiolistener]

Confirmed. Measurement is affected when battery is charging.
When charge LED stops flashing, measurement error disappears.

I tried to measure voltage between GND and VDD on ST-LINK connector.

When powered from the battery: 3.3350 V
When external power connected: 3.3306 V
After some time with ext. power: 3.3325 V (measurement error is still present)
When charge LED stops flashing: 3.3339 V (measurement error disappears)

[joeqsmith]

Someone had posted this comment about torque wrenches.  This is my super expensive torque wrench calibration station.   The bolt that holds the scale and hex standoff is mounted on two ball bearings that were clamped in the Panavice.   The steal is very close to 1lb.      Lower right, you can see the screwdriver style and my modified deep wall socket.  Also my ultra thin spanner that is used to hold some of the SMA parts, when using the torque wrench.   

After reading their comment, I would be very interested in knowing how much other SMA torque wrenches vary as they describe.  As I note, mine is about 1" and you need to choke up on the rubber to get to 8".   I could see more error in the technique used if you didn't follow the instructions.   

[hendorog]

Confirmed. Measurement is affected when battery is charging.
When charge LED stops flashing, measurement error disappears.

I tried to measure voltage between GND and VDD on ST-LINK connector.

When powered from the battery: 3.3350 V
When external power connected: 3.3306 V
After some time with ext. power: 3.3325 V (measurement error is still present)
When charge LED stops flashing: 3.3339 V (measurement error disappears)

Very interesting discovery. I had not heard of that and it might explain a few issues people are having comparing similar devices.

I'll try and replicate as all of my testing has been done with the devices plugged in.

[KE5FX]

Choking up on the wrench should make no difference to the breakover torque.  That's the whole idea behind a torque wrench. 

That said, it does make a subtle difference regarding how the force is applied.  There is one right way and (numerous) wrong ways to use a torque wrench (actually two wrenches) on high-grade connectors.  A great operator training guide was created for UC Berkeley students at one point but I couldn't find a straightforward .PDF edition, just a bunch of skeevy links to "slide sharing" sites and (with some effort) the original PowerPoint file.  I went ahead and printed it to a .PDF, linked here (61 pages, 6 MB).

Highly recommended reading even if (like me) you blow off 80% of these guidelines in day-to-day use.  At least you will know what you're doing wrong. 

[joeqsmith]

Choking up on the wrench should make no difference to the breakover torque.  That's the whole idea behind a torque wrench. 

That said, it does make a subtle difference regarding how the force is applied.  There is one right way and (numerous) wrong ways to use a torque wrench (actually two wrenches) on high-grade connectors.  A great operator training guide was created for UC Berkeley students at one point but I couldn't find a straightforward .PDF edition, just a bunch of skeevy links to "slide sharing" sites and (with some effort) the original PowerPoint file.  I went ahead and printed it to a .PDF, linked here (61 pages, 6 MB).

Highly recommended reading even if (like me) you blow off 80% of these guidelines in day-to-day use.  At least you will know what you're doing wrong. 

[joeqsmith]

I had mentioned in the last video I made about the limited resolution (distance) when making TDR measurements.    I talked a bit about how you may be able improve it but with it being a $50 unit, I don't see much of a point.   Well except for the pure fun of it.....

So I talked it over with a friend of mine and we had a good laugh about the whole project.  He offered one idea that should help improve the setup but it's all a guess if the Nano can actually be used this way and get any useful information from it.   Of course, cost will need to be ignored which is part of the humor.... 
 
First baby step,  modify my software to support the range extender.   It may not look like anything is going on in the attached plot, but what you see the Nano using Channel 1 for S11.  That's not a misprint.   Granted, it's only 100MHz.       Like I said, baby step.   

***
Should mention, yes, it is indeed a 100 ohm resistor. 

[joeqsmith]

If you read the document you linked, on page 14, they show the hand placement.  That is the marking that the person commenting on my video mentions.   He is absolutely correct that it will have an effect which is why this training manual talks about it.  Page 15, they show the damaged connector after the person chokes up on the wrench.   

What I would like to know is how much of an effect various wrenches have.  I only have the one click type. 

[KE5FX]

If you read the document you linked, on page 14, they show the hand placement. 

Yes, together with the completely bogus reasoning that it has anything to do with the grasping point along the moment arm. 

It's still a good document, IMO, despite that.

That is the marking that the person commenting on my video mentions.   He is absolutely correct that it will have an effect which is why this training manual talks about it.  Page 15, they show the damaged connector after the person chokes up on the wrench.   What I would like to know is how much of an effect various wrenches have.  I only have the one click type.

I've always found that I can apply pretty much whatever torque I want by holding it in a certain (incorrect) way, whether dealing with a ratchet or an open-ended torque wrench.  The angle at which you apply the force is important, but the distance along the handle considered by itself is not.

[joeqsmith]

Again, you can lead the horse to water....  But I can't help you. 

[hendorog]

If you read the document you linked, on page 14, they show the hand placement. 

Yes, together with the completely bogus reasoning that it has anything to do with the grasping point along the moment arm. 

It's still a good document, IMO, despite that.

That is the marking that the person commenting on my video mentions.   He is absolutely correct that it will have an effect which is why this training manual talks about it.  Page 15, they show the damaged connector after the person chokes up on the wrench.   What I would like to know is how much of an effect various wrenches have.  I only have the one click type.

I've always found that I can apply pretty much whatever torque I want by holding it in a certain (incorrect) way, whether dealing with a ratchet or an open-ended torque wrench.  The angle at which you apply the force is important, but the distance along the handle considered by itself is not.

Hmm, I am not so sure. I think that the position of the force you apply to the handle will matter - because of the construction of the wrench. The breaking 'knuckle' is offset from the centre of rotation of the nut.

So there are two levers involved- one from your hand to the nut, and a shorter one from your hand to the knuckle.

If you were to use the wrench and measure the exact force to the end of the handle to break the knuckle, then:
Reduce the hand-knuckle lever length to 10% of what it was, then obviously you will need to apply 10 times more force to break the knuckle. Force x distance.
Now 10 times more force is being applied to the end of the hand-nut lever. The lever is shorter than it was, but it is not 90% shorter because of the nut-knuckle distance hasn't changed.

That is also the case - but with a smaller nut to knuckle distance - in the posted video.

[KE5FX]

That is also the case - but with a smaller nut to knuckle distance - in the posted video.

But that's a different moment arm than the one shown in the document.

As long as you hold the torque wrench somewhere along the actual handle (i.e., the red part shown here, using the model of torque wrench I have here as an example) you will be able to deliver the specified torque or something very close to it.  It (should) go without saying that if you grab the wrench just behind the knuckle, you can apply pretty much whatever force you want in whatever direction you want. 

[joeqsmith]

I like this website for practical information:

https://www.microwaves101.com/encyclopedias/torque-wrench
https://www.microwaves101.com/encyclopedias/connector-care

[radiolistener]

It seems that CH1 on my NanoVNA has not so good VSWR, is it ok?

[hendorog]

That is also the case - but with a smaller nut to knuckle distance - in the posted video.

But that's a different moment arm than the one shown in the document.

Same principle applies, just different dimensions.

As long as you hold the torque wrench somewhere along the actual handle (i.e., the red part shown here, using the model of torque wrench I have here as an example) you will be able to deliver the specified torque or something very close to it.  It (should) go without saying that if you grab the wrench just behind the knuckle, you can apply pretty much whatever force you want in whatever direction you want. 

Makes sense to me - as long as it's designed for that usage, so that it stays it in the torque range its spec'd for - or at least not far enough out of range to break stuff if you aren't doing critical stuff.

[edigi]

Confirmed. Measurement is affected when battery is charging.
When charge LED stops flashing, measurement error disappears.

I tried to measure voltage between GND and VDD on ST-LINK connector.

When powered from the battery: 3.3350 V
When external power connected: 3.3306 V
After some time with ext. power: 3.3325 V (measurement error is still present)
When charge LED stops flashing: 3.3339 V (measurement error disappears)

My NanoVNA creates zig-zags on the display between 295 and 300 MHz when the battery is low or charging. Not a surprise that it's sensitive to supply voltage in that frequency range, as per datasheet the clock chip supposed to operate till 200 MHz...
I heavily suspect that the random lines occasionally appearing is also not just a drawing error but a consequence of this.

As for the torque wrench I don't think that the low frequency range and precision of NanoVNA justifies it (it's more like a waste of money and time for this level), the SMA connector can be tightened without it quite well but NanoVNA is just the perfect tool to check this.

Replacing the MCU is an interesting idea. What would be even more interesting if clock chip could be replaced with something that allows operation up till 2-3 GHz range (means mixer replacement as well...). Probably the resistor bridge would not cut it till 6 GHz but still if clocking (test signal generation) could be improved it would be a significant improvement (sure, not in this price range as significantly more expensive chips would need to be used...).
Note: When there is integer relationship between the clock source of the clock chip and its output signal is quite OK, but when I set 800MHz it's not so clean anymore (it uses 3rd harmonic, so in reality chip is set to 266.6...MHz or so)..

[radiolistener]

My NanoVNA creates zig-zags on the display between 295 and 300 MHz when the battery is low or charging.

Is your NanoVNA has these zig-zag spikes at 300 MHz with low battery only? 
My one always have these 300 MHz spikes... Sometimes it higher, sometimes lower, but it always here...

Here is CH0 and CH1 both terminated with 50 Ohm:


What is your CH1 SWR at 900 MHz?  (just connect CH0 to CH1 with good cable to measure it)

My CH1 SWR is 1.31. Measured with 15 cm RG405:


Cable delay is 1550 ps. I entered it into ELECTRICAL DELAY, and it shows Rs = 41 Ohm at 900 Mhz...

[Flynt]

joeqsmith,i Sent You a PVT Message....

TANKYOU VERY MUCH

[joeqsmith]

As long as you hold the torque wrench somewhere along the actual handle (i.e., the red part shown here, using the model of torque wrench I have here as an example) you will be able to deliver the specified torque or something very close to it.  It (should) go without saying that if you grab the wrench just behind the knuckle, you can apply pretty much whatever force you want in whatever direction you want. 

Makes sense to me - as long as it's designed for that usage, so that it stays it in the torque range its spec'd for - or at least not far enough out of range to break stuff if you aren't doing critical stuff.

Which if you read my response, it pretty much what I had stated. 

Looking at the error of the torque wrench shown, using a knife blade and going from one end of the handle to the other, the variance is about 1" lb. Still well within spec no matter where you hold it.

  Obviously the torque is dependent on the position but my question is how much do different wrenches vary.  I assume many of you have them and would know or at least be able to measure them within some degree of accuracy.   

[joeqsmith]

joeqsmith,i Sent You a PVT Message....

TANKYOU VERY MUCH

I appreciate your enthusiasm for the Nano and your wanting to try other software.  As you were told by _Wim_ and I have stated a few times in this thread, mentioned in my videos and answered numerous time in the comments, the answer is the same. 

Your persisting to SPAM my inbox after clearlying being told no, is part of the reason I won't release it.  I just don't have the time to support it.   

***
As _Wim_ mentioned, you should look at some of the other software being offered here.    It seems that they are off to a very good start and could use some encouragement. 

[Flynt]

 

joeqsmith, I apologize, for what you call "SPAM", but I didn't get any of your Rejection messages, and as I wrote you, I don't read English well and I can't program ... I just needed your software, to work and I was even willing to give you a donation.

I can't use a Translator to convert 10 pages of trhead ...

Okay it does nothing, I will use the original software.

Thanks anyway, even if it didn't cost you anything send it to me ...

[_Wim_]

It seems that CH1 on my NanoVNA has not so good VSWR, is it ok?
(Attachment Link) (Attachment Link)

I think this is caused by the input impedance of channel 2 in your method, not by channel 1. If you connect your calibration load to ch1 (and preferably calibrate the NanoVNA with a smaller bandtwidt, for example 800M to 900M) you can achieve a VSWR or 1.02 (S11 of -40dB) for 800M<->900M, and even better for lower frequencies.

[edigi]

My CH1 SWR is 1.31. Measured with 15 cm RG405:

It's roughly the same (1.33) here.
For the price though there is still nothing to complain.

_Wim_
NanoVNA has CH0 and CH1 and what is meant is what you describe (just naming is different).

[_Wim_]

_Wim_
NanoVNA has CH0 and CH1 and what is meant is what you describe (just naming is different).

 

Mine is indeed also simular than. When calibrated with a 100Mhz span it drops a little to 1.28.