Nano Vector Network Analyzer

VNAs used to be expensive devices used by engineers to analyze antenna systems, among other things. I have had an antenna analyzer (similar to the 259D) for decades, keep in mind though that some antenna analyzers are VNAs, but not all. It cost a pretty penny when I got it. I end up using it a few times a year.

This new nano VNA cost about $65 (including tax) and came in a nice box with quite a bit of useful connectors… That is a heck of a deal and since I have a Buddypole a useful investment. The Buddypole antenna needs to be tuned every time it is set up, so having a graphic tool to facilitate the process is going to be great.

The device purchased is the NanoVNA-H Vector Network Analyzer. It should be capable of measuring S Parameters, Voltage Standing Wave Ratio, Smith Chart, TDR

The storage box included:

NanoVNA-H (with battery)

USB Type-C data cable

15cm SMA male to male RG316 RF cable

Calibration connectors:

  • SMA male calibration kit – OPEN
  • SMA male calibration kit – SHORT
  • SMA male calibration kit – LOAD

Since this machine is equipped with a small touch screen, you can operate the device by the touch screen or using the multi-functional dial/switch on the top of the case.

Using the PC software NanoVNASaver (a github open-source project), a PC can connect to the NanoVNA via a USB port and display the data, as well as save the information to files. The SNP files can be exported for use with other software.

There appears to be a fairly active users group on Groupsio for this device (something I always look for when buying just about anything), averaging well over 500 posts a month.

To connect the device, I plugged the cable into the USB port on my PC and turned on the VNA device. My computer found it quickly. Next, I loaded up the software on my PC, made sure the right port was selected and then clicked the connect button.

I tried it out on an old 2M antenna I had sitting around, and the results made sense. The first thing you need to do is calibrate the device (I calibrated the software on the PC as well). Be sure to celebrate using port 0 on the device. I started out using port 1 and that just didn’t work. This is a straightforward process that probably should be done periodically. I did figure out that I needed to turn the device off and on again after calibration before the readings made sense.

Here is a picture of the SWR screen on the device:

The yellow line shows the SWR graph. Not the SMA connector in the Channel 0 port. That should give you some scale for the size of this thing.

Here are the same measurements shown on the PC:

I think we can all agree that the PC is easier to read.

So far, I am pleased with out it works. I’ll need to take it in the field to evaluate it in action though.

Anyone else noticed a frenzied feel to tourism?

This past week there has been a significant uptick in tourism around Hilton Head. I guess peoples perspective about Covid has shifted and they have a ‘can do’ attitude about getting out of the house.

There have been significant traffic jams trying to get anywhere. Each time I go out to Hilton Head, Beaufort or Savannah I run into a jam caused by some accident. Every time one of the cars involved has out-of-state plates. Sometimes both cars are from somewhere else. People — let’s pay attention out there.

Just because you made it down here from the great white north, doesn’t mean you can take your eyes off the road. These cars just don’t drive themselves, yet.

New phone – a Motorola 4G One

There comes an time when an event takes place that causes you to shift from thinking about a new phone to buying one. That happened to me last week when the case that protects my phone cracked in two. Granted that is better than the phone cracking but still…

The reasons were mounting for me to replace the phone:

  1. I live in the hinterlands where my cell phone service is poor. The microcell installed from AT&T to address the problem will no longer be supported after December 2021. Any new phone would need to support Wi-Fi calling.
  2. There is good 5G coverage in the area, so having a 5G phone would be nice.
  3. The old phone has been getting slower lately, so I was going to have to rebuild (factory reset) it anyway. Granted a rebuild takes me about 4 hours, but I’d have to do that work on a new phone anyway.
  4. I had just put on my last tempered glass protective screen, so I’d need to buy more of those if I am going to keep the phone.
  5. I had not received an update for my phone in over a year. I’ve had it for about 4 years and now even Motorola had given up on support. They supported me through 3 major Android operating system versions — what more could I hope for. Based on what I’ve heard about some phones from other manufacturers, having Motorola support that long was a gift. As hopefully everyone is aware, updates are a critical element of having a secure phone.

The case breaking apart was just the straw that broke the camel’s back.

Motorola is having their spring sale, which means that they are probably coming out with new models. The 5g One was over $150 off its list price. The 5g One appeared to have high real-world satisfaction ratings, nice camera options, high performance, good battery performance and supported Wi-fi calling.

The one downside is that all the phones I’ve purchased for at least a decade have been unlocked phones. This one is tied to AT&T.

Time will tell if it can last as long and be as effective as my last phone, but for under $300 – I just felt I could risk it.

The last tessellation

Since I purchased by CNC machine, I’ve been creating various wooden tessellations. Now I’ve finished my fourth one and I hope my last.

It is not that these are that hard to design and create, it is just tedious.

I cut these out four at a time

I am thinking about taking all four designs:

Seahorse

Lizard

Turtle

as well as a topographical map of Hilton Head and the surrounding area.

I definitely know much more about the use of epoxy resins than I did when I started. It is hard to believe the lizard started back in 2019.

Vaccinated

Well, I finally got my 2nd Moderna vaccine on Monday. Other than feeling a bit tired on Tuesday and taking a two-hour nap, it all seems to be working out OK.

I can’t wait to get back to doing some ‘normal’ things with my vaccinated neighbors. It is also good I have it done now, since I am going to play the trombone for our church on Palm Sunday and Easter and getting sick before those activities could have been a disaster.

I had to laugh a bit about the controversy over the Moderna Vaccine effectiveness and its approval this week. There is documented evidence, based on a large-scale phase 3 vaccine trial involving more than 30,000 participants, that the Moderna vaccine is effective at preventing illness from COVID-19. This evidence is recognized by the CDC and the FDA.

Sure some could say I drank the Kool-Aid, but I am just grateful to have this stage behind me.

Pi Day 2021

Pi Day is celebrated on March 14th (3/14) around the world. Pi (Greek letter “π”) is the symbol used in mathematics to represent a constant — the ratio of the circumference of a circle to its diameter — which is approximately 3.14159.

Pi is the most recognized mathematical constant in the world. Many Scholars consider Pi the most important and intriguing number in all of mathematics.

The most important element for me on Pi day is to eat pie — pizza, cherry…, it doesn’t matter.

Pi has been calculated to over one trillion digits beyond its decimal point. As an irrational and transcendental number, it will continue infinitely without repetition or pattern. Yet only a handful of digits are needed for typical calculations.

Not only that, but the fourteenth of March is also Albert Einstein’s birthday, so all together it’s nothing short of a mathematician’s delight. Here is a link to some of the most usual facts about Pi.

A trial at moving away from Universal G-code Sender for my CNC

It has been a while since I’ve written a blog post so I thought this topic was worthy. I was having trouble with the latest updates to GCS. The commands were just not flowing at a consistent rate. I rebuilt by old Pi2 and it still wasn’t working well. In the process, I had to recall all the things I’d forgotten about rebuilding the code and using VNC to access it.

Finally, I just thought to myself “What else is out there that may work more reliably?” I first built a version of Grbl Controller. This worked, but it was a pretty low end tool. I got the instructions to build it at:

Installing GRBL Controller on the Raspberry PI (alldonemyself.blogspot.com)

I then thought I’d try another open source approach. This one is primarily written in python. bCNC is a fully cross-platform solution. It was easy to install on the Raspberry Pi and runs within the GUI. This project is nearly full-featured with a g-code visualizer, code editor, virtual pendant, jogging, and easy coordinate system setup. I have it running over VNC still, though it wants a larger screen than my old 7” Android tablet I have mounted over my CNC machine.

Once you have python installed on the Pi, installing bCNC consists of:

sudo pip install --upgrade bCNC

You can also do an install from git:

sudo pip install --upgrade git+https://github.com/vlachoudis/bCNC  # if you want git version

To run it just:

python -m bCNC

The one problem I have had so far with bCNC is the visualization of the model isn’t quite right. It stops at line 9999, though the instructions to the CNC go all the way until the end. I am going to install from Github and see if that is more up-to-date. Here is what it looks like:

As you may notice (at the bottom of the screen) this G-code file has 456978 lines, so 9999 is just not going to cut it.

Who knew that you could have secondary cataracts

I had cataract surgery years ago now. Slowly over the last few months, I have started to have blurred, double and even triple vision in my right eye.

I went to the doctor and it appears the issue is something that is easily addressed. There is a membrane behind the lens that they don’t usually remove during cataract surgery. It is kept, since it helps hold the artificial lens in place.

Months or even years later this membrane can become clouded, much like a cataract. It doesn’t happen to everyone, but it appears to be happening to me.

So tomorrow, I have the joy of having laser capsulotomy, where a small opening in the clouded area is made, so that light can shine through to the retina unobstructed.

Laser Capsulotomy illustration

This is supposed to be a quick procedure where the eye is numbed, and a ‘special’ laser is pointed at the back of your lens and an X is cut into the membrane.

Hoping for the best. I’ve been doing quite a bit with lasers lately, but now the table has turned.

3D printing a board game

Over the past few weeks, a neighbor, my wife, and I have been playing a board game for 4-6 people. Since covid-19 is raging elsewhere, board game usage is probably up. I’ve been thinking about the board design and its limitations and thought I could make some improvements.

First the board is huge – about the size of a small card table. Secondly, it was fairly difficult to make. The six-sided side looks like this:

Secondly, the board design is relatively inflexible in that you have to have either 4 or 6 people to play.

Vendors charge a small fortune for these on Etzy. Once I finished my design, I noticed there were some designs on Etzy of a similar nature, though I am not sure they can go to a 3 person configuration – I guess form follows function. In case you are wondering, I used Fusion 360 to create this and ensure that it could be placed in this configuration without collision.

Although the rules and the flow stay about the same, I decided to restructure it so it can be played with 3-9 people, in teams or individually. Here is a picture of the 3-person configuration.

I made it small enough that it would print on a 220×220 3D printer. If you would like to 3D print your own version, I uploaded this flexible 3-9 person game board to Thingiverse, including the rules that we’re using. I made the design small enough that it can be taken on a cruise or other travel, without being too hard to pack. You’ll also need a deck of cards (with the jokers).

This game has many variations and goes by many names (Dog, marble wars, pegs and jokers…) and I only made minor modifications to the rules to fit the more flexible design.

Have fun and Happy New Year,