The holidays are over and I am back home from visiting family. So it is about time to get back to some of my projects. I am going to start the year with a update to my SNA Jr. I had started it previously, and ran into problems with my original design. After looking around the net I found two different designs that have some of the options I want to include in my design. One is the Antenna Analyzer by IW2NDH and other the SI5351 Network Analyzer by UR5FFR. With a lot of help from Google Translate I was able to get all the information I wanted from their documents.
My new design will include much of the circuitry from their projects, along with some of the things I developed while working on the 'Test Gadget'. My earlier design used an Arduino Nano as the processor, but I found I needed more program and storage memory. This design will use a ESP32 development module, along with a 320 x 240 TFT display. I will also use a small Joystick instead of a rotary encoder for the user input. Before the holidays I designed a PCB board and sent it off to one of the Chinese board houses that I have been using recently. The board arrived shortly after I returned home, and I started building up one so I can test it in sections.
One of the things I want is that the instrument will run off of an internal battery. In the earlier version of the SNA, I used a pair of 18650 lipo batteries with a separate charge controller board. This gave me around 7-8 volts that I could feed to a 5 volt regulator on the main SNA board. I recently found a lipo module that has a built in holder for a 18650 battery, a charge controller, boost converter and regulators that gives 5 and 3 volts regulated out. One of these should power the new SNA board with the ESP32 without having to include a regulator on board. But, just in case it does not work out I did include a 5V regulator on the circuit board.
After I got all the major parts in, I could design a case for everything to fit in. What I really like about having the 3D printer is the ability to design a case to exactly fit the project. Along with the proper holes for controls and displays, I can also design in all the mounting posts and standoffs for all the major components. It might take a couple tries to get everything to fir the way I want them. But it usually costs less than a dollar in plastic to print a part in draft quality. When everything is the way you want it, print in higher resolution.
It took a couple tries to get everything exactly the way I wanted, but finally printed the top and have all the parts mounted. Just need to finish wiring everything up. Using one of the early attempts as a mounting platform to use while working on the software. The case I have now is in regular PLA, but I have some Carbon Fiber filled filament that I might try. It should add some RF shielding, but don't know if it will help in the HF range or just at VHF and UHF frequencies. The way I designed the clam-shell case, the top and bottom are symmetrical. When I get around to designing the bottom half, all I have to do is remove the existing cutouts and mounting posts and replace them with the posts needed for the SNA circuit board itself.
Which version of ur5ffr You plan to build?
ReplyDelete(if You have any problems with translation from russian, I can help)
Thanks for the offer, but I was able to get everything I need using the online translator. Only using part of the ur5ffr design, mainly the mixer and 455 KHz. IF stage. Since I have a bunch of AD8307 chips on hand I am using a separate one for the direct power meter input instead of using another analog switch. Also adding forward and reverse readings from a directional coupler I added to the SI5351 output stage.
ReplyDeleteso I'm waiting for next interesting realisation ;-) 73
ReplyDeleteBTW - did you see Andreas'es mod for battery module? https://youtu.be/joAkJ9QA2bw
good project,..
ReplyDeletei wait for continue this job