NanoVNA and a curious kit

I spent much of yesterday Christmas shopping, which I hate (can't stand being in large crowds), but in the evening started to get to grips with the NanoVNA. But before that, I put together the perspex case kit that had arrived for the DSO138 oscilloscope.

Some instructions would have been nice!

This kit contained three more panels than I had expected, and absolutely NO instructions! So it took quite a bit of experimenting to discover the correct way to put it all together. From the photo above, the top right piece is the base - add to that the four long bolts and two nuts (to lock the bolts in position), the bottom left panel then goes over the main PCB but BEFORE the display! So, the display had to be removed for that stage. There were also four tiny nuts and bolt to secure the display to this panel. Once that is done, the two pieces with the large cut-out go on, these stack up and form the channels into which the button and switch levers fit. I found that these could move in use and make the switches stiff, so Ive added more nuts to secure them in position 8mm above the main board. Then the side panels go on, ensuring that the cut-outs align. This is easy for the BNC and power connector as the holes are different sizes, but the USB port cut-out is slightly off-set and needs some playing to find the right way around for the panel. The buttons and switch levers are now added, making sure the switch levers fit correctly over the switches. Finally, the top panel (top left in photo) goes on. A bit of jiggling is required here to align the eight studs in the side panels, and also the five button tops. The whole is then secured  with four dome nuts.

Actually looks quite good

 The completed case and kit actually looks quite good! I did find that the test point was now rather hard to access using the croc-clip probe, so used needle-nosed pliers to adjust this to make it easier. Other builders might want to take that into account during soldering and make a bigger loop!

An agreement was also found with the seller, concerning the faulty display, resulting an an acceptable partial refund.

So onto the NanoVNA. For such a tiny and low cost device, this thing is incredibly capable! However, when you first turn it on - it is rather daunting! It boots up in a full display mode - all four measurement channels, 50kHz to 900MHz range, making for a very busy and confusing display. Once you master the basics of driving the menu, which can be done via the touch-screen or the rocker control switch (which I actually found less reliable) and have turned off the traces you don't need, it becomes more manageable and easier to understand.

VSWR and Smith chart plot of a 2m rubber ducky antenna

So far the most I have done with it is to look at a 2m band rubber ducky antenna, but this is enough for finding your way around the menus, learning the modes and features etc. One thing I didnt expect, its charger port is a USB-C rather than the more usual micro-USB. Luckily it comes with a cable - as this is the only USB-C device I have!

I paid a little under £30 for this, shipped from the Far East of course. Compare that with the cost of an MFJ-259B, which doesnt display graphs, has to be manually adjusted for each frequency, is massively bigger, only goes to about 200MHz if that - and costs around 5x as much even second hand!