N Connectors for the NanoVNA

The NanoVNA is a cute little handheld VNA at an incredibly low price (given its performance).  One small issue, though, is that it uses SMA connectors, which can be a bit fragile.

Thinking that this might become an issue, I thought I would change the connector type to N by using N-to-SMA adapters.

But I wanted to ensure that the weightier N-connectors (and whatever might be attached to them) were not physically supported only by the NanoVNA’s SMA connectors themselves.  That could increase the chances of future SMA connector failure.

So I purchased two N-to-SMA bulkhead adapters, and, after they arrived, I made a simple chassis from PCB stock onto which to mount both my NanoVNA and the two adapters: 

I used two pieces of copper-clad PCB stock.  One piece (double-sided) serves as the bottom plate onto which the NanoVNA attaches (using 4 screws -- these screws are longer than the stock ones used to attach the NanoVNA’s back cover).  

The original back cover is still attached (so that I wouldn’t lose it) – you just cannot see it.

The second piece of copper-clad is single-sided, and upon it the two N-to-SMA bulkhead adapters mount.  I chose single-sided stock because, on the NanoVNA PCB itself, the grounds for the two SMA connectors split apart, and I wanted to continue this “separate-ground” approach out to the N adapters and their mounting hardware.

Thus, if you look at the next two pictures, you will see how each N-connector has its body and mounting hardware isolated from the other N-connector as well as from the ground-plate holding the NanoVNA.

No conductive copper on the front side:

And mounting hardware isolated on the backside. (I used a Dremel tool with an engraving bit to create the copper "islands", but you could use an Xacto knife, too.  It’s just a bit more work.)  Note that only two screws hold each adapter to the front plate.

If you look closely at the photo, above, you’ll see the solder-seam connecting the two boards.  There is an identical seam on the other side of the bottom plate, as you can see in the photo, below:

Solder on both sides makes this joint mechanically rigid, relieving any mechanical stress on the NanoVNA's SMA connectors.

By the way, the only change I made to the NanoVNA, itself, was to use slightly longer screws (I believe the thread size is M2.5, but don’t quote me!).

That's it!  Hopefully this will spur your own ideas!



Standard Caveat:

As always, I might have made a mistake in my equations, assumptions, drawings, or interpretations.  If you see anything you believe to be in error or if anything is confusing, please feel free to contact me or comment below.

And so I should add -- this information is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.