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Homebrew sheilding

 

Hi just spent a UK windy afternoon confined to my radio 'shack' , so decided to upgrade the screening on my 'basic' clone nanoVNA to see if the INPUT 'noise' could be reduced.
I made the screens out of some 'shim' brass foil and formed them round some srbp (Tufnol) formers THAT I made first.
I am pleased with the improvement that just a couple of hours 'metal bashing' has produced.
Hopefully this will inspire others to have a go?
Dave

Homebrew screens.jpg
P1030673.JPG
P1030722.JPG

 

Hello Dave,
Your screen shots does *not* tell the whole story.
72, Rudi DL5FA
 

Hi Rudi what did you wish to know?
My nanoVNA was the 'BAD' clone without screening cans over the input stages
and exhibited unwanted vectors due to noise pickup when is Smith Chart mode.
Since adding the cans the noise is cured :-)
Dave

On Sat, 23 May 2020 at 17:05, <reuterr@...> wrote:

Hello Dave,
Your screen shots does *not* tell the whole story.
72, Rudi DL5FA
 

Hello Dave,
The screen shots you appended show just a quarter of thr screen.
I think you wanted to append the whole screen size of the nanoVNA.
I thought you have already seen that.
73, Rudi DL5FA
G7TAO
 

On Sat, May 23, 2020 at 02:04 PM, Dave B wrote:


round some srbp (Tufnol) formers THAT I made first.

Hello,

Have you got any images of the formers you made and any more close ups of your finished work? I've got a clone, non-shielded and wondered about adding something to it. Given the plethora of units on eBay I don't think I could have been sure to get one with shielding
 

Dave,

I am curious how you soldered (braized?) the brass shim. I've been thinking about making my own shields (not for my nano) but am a bit intimidated by my lack of experience with brass.

Thanks,
Dave L

On Sat, May 23, 2020 at 07:04 AM, Dave B wrote:


Hi just spent a UK windy afternoon confined to my radio 'shack' , so decided
to upgrade the screening on my 'basic' clone nanoVNA to see if the INPUT
'noise' could be reduced.
I made the screens out of some 'shim' brass foil and formed them round some
srbp (Tufnol) formers THAT I made first.
I am pleased with the improvement that just a couple of hours 'metal bashing'
has produced.
Hopefully this will inspire others to have a go?
Dave
 

Thin brass solders easily with regular electronic solder (at least it did before they took the lead out). You might want to tin it along the edges you are soldering together. Also cuts fairly easily with ordinary scissors.
 

Yes I just made a former out of 1/4" thick 'Tufnol' that measured 34mm x
13mm which is good for the two outer shields.
Then using 0.005" thick brass foil I marked out the shapes of the shields
34mm x 13mm and added 4mm tall sides to fold down. (see pics)
I carefully folded the foil over the former and bent the little tabs round
over the ends and soldered the flaps down.
Easy with ordinary soldering iron as the brass is so thin.
Once the shields were fabricated I rubbed them back and forth on a smooth
flat file to make sure all the sides were flush with the pcb.
ie filed off any high spots.
I then kept offering the shields to the pcb and marked out where I needed
to file away the side to avoid the SMD components going to the audio codec.
I then 'tinned' the edges with solder and tinned the 'fixing pads' on the
board.
Carefully lined up the shield and tinned one corner in place.
Final adjustments and then soldered the other pads.
Phew!
Dave

On Sun, 24 May 2020 at 19:22, Dave VE3LHO <dave@...> wrote:

Dave,

I am curious how you soldered (braized?) the brass shim. I've been
thinking about making my own shields (not for my nano) but am a bit
intimidated by my lack of experience with brass.

Thanks,
Dave L

On Sat, May 23, 2020 at 07:04 AM, Dave B wrote:


Hi just spent a UK windy afternoon confined to my radio 'shack' , so
decided
to upgrade the screening on my 'basic' clone nanoVNA to see if the INPUT
'noise' could be reduced.
I made the screens out of some 'shim' brass foil and formed them round
some
srbp (Tufnol) formers THAT I made first.
I am pleased with the improvement that just a couple of hours 'metal
bashing'
has produced.
Hopefully this will inspire others to have a go?
Dave


P1030737.JPG
P1030736.JPG
P1030738.JPG
P1030735.JPG
P1030739.JPG

 

Speaking of the shielding, I have a "bad" clone but it does have shielding.

However it seems to have one big shield that covers all three mixers. It has a considerable amount of noise coming back that I get points outside of the Smith chart, suspecting channel cross-contamination though unsure exactly where the noise is coming from.

I wonder if it's worth the effort to remove the one large shield and splitting off the mixer sections or some other way to get each section its own shield? Seems like it would be tough to remove the shield, would even say that those who didn't get a shield are the lucky ones - adding them is easier than modifying in this case *sigh*

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