NanoVNA V2 aka S-A-A-2

[rf-loop]

What happens when you terminate S21?

I often make temporary cases for my hardware out of cardboard because its easy to make and gets them out of harms way. In order to have shielding I then usually use either copper tape or sometimes I will use what you describe, a copper "O" a flat strip joined with solder with holes cut to give SMAs good ground points.

I will then often solder a wire to the copper tape to ground it to the chassis and also ground the power at the same point the DC power is attached.


USB noise is oten hard - very hard to get rid of.

My previous answer was from memory.
Now after full teardown it is again back working and I can answer with real data if can think image as data.

Sweep 1 - 3000 MHz.
As  previously also used, segments 10.
S11 Calibration.

First image
S11 50 ohm  load, same as in Cal.
S21 just SMA fully Open (nothing in SMA) .

Second image
S11 50 ohm  load, same as used in Cal.
S21 just Short, same as used in Cal.

I do not explain result, images talk.





S11 50 ohm Load, S21 Open






S11 50 ohm Load, S21 SHORT

[OwO]

Looks good; if you want to fix the enclosure reflection issue there are RF absorbing ferrite sheets like these:


The 3.2 inch clone is just one of the many clone manufacturers that played it fair, and I don't mind recommending it if you want a NanoV2 with a metal enclosure.

[rf-loop]

Looks good; if you want to fix the enclosure reflection issue there are RF absorbing ferrite sheets like these:
(Attachment Link)

The 3.2 inch clone is just one of the many clone manufacturers that played it fair, and I don't mind recommending it if you want a NanoV2 with a metal enclosure.

  OMG this was good ! Not only for Nano but... I have totally forget to try find some this kind of things even more importantly to my some other things... I have direct places for these products after I return my homeland.  (not only just in image but they have also other things..)

But for NanoVNA it need experience what exact product and how is best to try -- of course without experience it can find using  long iteration... but it is not nice to teardown for several iteration if there is allready some experience..
Even some advisory so that do not start from empty board. What material exactly, they have many, and where exactly add in Nano. There is several thickness and different materials.

[OwO]

From experience the thicker the better (up to 0.5mm at least). The best positions for the absorbing material are hard to predict, but you can always just put it on all walls of the enclosure.

[rf-loop]

From experience the thicker the better (up to 0.5mm at least). The best positions for the absorbing material are hard to predict, but you can always just put it on all walls of the enclosure.

If I understand right there is different permeabilities,  types "50", "80" and  "TE" but difficult to understand (language) all what they tell.

[OwO]

The higher permeability versions have more ferrite "dust" mixed in; there is a small improvement in isolation last time I tried.

[cdev]

You can use layers of anti-static foam. The lowest resistance/most conductive should be the closest to the conductive surface beneath it and them as you go out from there each layer should be less conductive more resistant. You can use anti-static foam. How well does it work? Ive tried it but have never been able to test it beyond just subjectively. But it does seem to help. 

The following is just for fun/as an experiment.. I'm not suggesting you do this for any commercial product.

You might also be able to make RF absorbent material using a two part foam, activated charcoal (and possibly iron or ferrite powder, but I would suggest not using that, even if it improves its RF qualities- see below) .

But if you do try to do this, plan out the workflow really well and to the second because its hard to mix quickly and hardens to a very tough consistently almost immediately. Whatever clothes you are wearing if it gets on them it will be in these forever. It will be very very hard to get off of anything it splashes on.

Also,I suspect iron powder is likely dangerous inhaling it is likely very bad for you.  So i would just use activated charcoal (which I got from used up water filters (Brita) which have a lot of it in them).  You need a lot to get a resistance low enough to measure. Which makes the  pinkish black "foam" I ended up with as hard as a rock. Its very hard to mix it before it hardens. It hardened so quickly I think for me because the activated charcoal I used was wet. (Dry used up activated charcoal might harden much more slowly)

Anyway, for what its worth, thats how I tried to do it.

Looks good; if you want to fix the enclosure reflection issue there are RF absorbing ferrite sheets like these:
(Attachment Link)

The 3.2 inch clone is just one of the many clone manufacturers that played it fair, and I don't mind recommending it if you want a NanoV2 with a metal enclosure.

  OMG this was good ! Not only for Nano but... I have totally forget to try find some this kind of things even more importantly to my some other things... I have direct places for these products after I return my homeland.  (not only just in image but they have also other things..)

But for NanoVNA it need experience what exact product and how is best to try -- of course without experience it can find using  long iteration... but it is not nice to teardown for several iteration if there is allready some experience..
Even some advisory so that do not start from empty board. What material exactly, they have many, and where exactly add in Nano. There is several thickness and different materials.

[asmi]

I would really like that device with larger and higher-resolution screen, because normally I look at them from some distance (to have enough space for DUT directly in front of me). I wonder if it's possible to re-design the display part to utilize something like 7" RGB24 screen (perhaps via something like EVE controller - FT813 or BT815). Or use beefier main MCU which supports parallel RGB LCD panels directly.

[AlfBaz]

My 4" displays finally arrived.

I've created a rough model of both the nanovna and lcd boards to begin design of a 3d print enclosure for the whole lot.

Due to the large overhang created by the LCD display the case would have to be a weird small bottom large top enclosure so as to have the sma ports, jog buttons, on/off switch and USB port protrude from the walls of the enclosure

I can accommodate for the jog buttons, SMA ports and and on/off switch by placing the nanovna board in the bottom left corner of the enclosure and then using a ribbon to connect the LCD display but we're still left with a problem accessing the USB port

Maybe a design similar to bicycleguy's with the nanovna board flat and the LCD display tilted will do the trick

[Gandalf_Sr]

I've done a design for a case (the bottom half anyway) that deals with the issues you describe but I have been unsuccessful in making an array of holes for cooling purposes.  I may print a prototype just to prove the dimensions - give me a few more days.

[aargee]

I have just printed ch_scr's enclosure from the beginning of this thread using https://www.proto-pasta.com/pages/magnetic-iron-pla, not sure how/if it will improve performance - I was just interested to print one in this material. I bought the reel off EBay that was surplus to someone's requirements a while back.

Interestingly... https://3dprintingindustry.com/news/3d-printing-proto-pasta-create-magnetic-donut-transformers-117936/

Here is the result. The last photo is the enclosure being picked up be a HDD magnet.

[AlfBaz]

... I have been unsuccessful in making an array of holes for cooling purposes.

I wasn't aware the unit got hot enough to warrant ventilation. I'll have to make some measurements

[AlfBaz]

I've done a design for a case (the bottom half anyway) that deals with the issues you describe ... give me a few more days.

Looking forward to it

aargee, is that enclosure for 2 batteries?

[cdev]

The magnetic PLA may not have desired RF properties and may not even be that compatible with electronics, if they were I would expect their web page would be crowing its benefits for use in cases of RF devices.

Powdered iron may in fact be at best a major irritant and at worst dangerous.

Note that I really know next to nothing about this stuff and could easily be wrong, this is just my gut feeling from spending around two minutes reading the web page at https://www.proto-pasta.com/pages/magnetic-iron-pla

-----

[bicycleguy]

.....
Maybe a design similar to bicycleguy's with the nanovna board flat and the LCD display tilted will do the trick

I was going to go that route but got caught up with a neat drawer.  As you noted, the USB connector is too deep even with the 3.2 inch display and the display and RF boards have a mismatch at the SMA connector.  In my design the angle of display (50°) and its height are dictated by the bend of the RF cables.  Straight cables and a 60° angle would have been nicer.

Separating the boards would have required wiring some headers.  As long as they are separated why not a flip up display since the wiring would have allowed it.  I stopped when realizing this was becoming a time-nut like obsession

You can't see it in the pictures but I have a ton of air circulating holes.  I had noticed the board got very hot sitting horizontal on my desk but it never caused any issues.  The angle of the board does help the cooling.

[aargee]

The magnetic PLA may not have desired RF properties and may not even be that compatible with electronics, if they were I would expect their web page would be crowing its benefits for use in cases of RF devices.

Powdered iron may in fact be at best a major irritant and at worst dangerous.

Note that I really know next to nothing about this stuff and could easily be wrong, this is just my gut feeling from spending around two minutes reading the web page at https://www.proto-pasta.com/pages/magnetic-iron-pla

-----

Probably the same risk as having a case of ferrite material. The iron is bonded up in the PLA filament, there is no powder floating about at all. There is no conduction across the case using probes and a multimeter. I'm not sure what you mean about 'compatible with electronics' - it seems to me the suggestions in this thread so far about using conductive foam might be more of a risk?
Then again, it would also be possible to line the case with adhesive copper tape if external noise was a concern, I too am not sure how well ferromagnetic material acts as an RF shield, I'm sure a search would bring up some reading material when I get aroiund to it :-)

I don't think the people who make this stuff ever thought of the electrical uses up front, most of the suggested applications are for 'rusted look' 3D prints, any electrical specs seem to be an after thought.

AlfBaz - that enclosure fits one 18650 battery in it.

[bicycleguy]

@aargee
Can you try a test like this: https://www.eevblog.com/forum/testgear/nanovna-v2-aka-s-a-a-2/msg3182046/#msg3182046 in and out of your case and see if you get the rise at high frequency?

[AlfBaz]

Had a busy weekend so was unable to do a test print to check sizes. That's why no stl attachment
Instead a small jerky video of the assembly for a unit with the 4" display.
I'm thinking I might add a draw or some pockets on the opposite side of the battery for the SOLT cal pieces

I had to go a little bigger to allow for an 16850 battery holder since locally its hard to source these batteries with wires already attached and I dont want to mess around soldering stuff when ever I have to change the battery

PS
the file is zipped so that the forum software lets it upload

[AlfBaz]

pps
forgot to mention the lcd is meant to be attached with ribbon

[Gandalf_Sr]

Looks good Alf, better than my half-assed one.

[AlfBaz]

Thanks

[cdev]

How could we visualize the interaction's causes better? Make fixing it more of a realtime interaction (faster)

@aargee
Can you try a test like this: https://www.eevblog.com/forum/testgear/nanovna-v2-aka-s-a-a-2/msg3182046/#msg3182046 in and out of your case and see if you get the rise at high frequency?

[cdev]

Having a pop up screen that would remain at an approximately 45 degree angle while being used
would be extremely helpful for my use case which is usually on my desk behind my computer keyboard.


 

pps
forgot to mention the lcd is meant to be attached with ribbon

[Gandalf_Sr]

I haven't done a test print but I did figure out how to do the vent holes.  My battery is between the 2 PCBs so it doesn't need extra space.

[AlfBaz]

I haven't done a test print but I did figure out how to do the vent holes.  My battery is between the 2 PCBs so it doesn't need extra space.

I looked back through this thread to see what battery you used, it didn't occur to me that perhaps cordless phone batteries might be usable as they come wired with connectors.

I like your approach to the case design, there's no need to modify the nvna board. The on/off switch has to be removed on mine