AmateurLogic 178: USB Relays, Nano VNA, WFD Rearview Easily and cheaply control relays over a USB port. Nano VNA explorations. Brutal Southern Winter Field Day rearview mirror edition. https://amateurlogic.tv
I'm doing something similar with an ESP32 and a generic quad relay driver board to drive coaxial relays. Allows for physical toggle switches or remote switching over wifi at the same time with tasmota firmware. I have a lot of ESP2866 and ESP32 devices and they are all quiet.
I've been using a nano vna with my multiband doublet. If you bring up both the vswr and Smith chart traces it allows you to tune much easier than with trying to do it with the vswr alone. Tuning I never could get with an antenna analyzer was relatively easy with the vna. Watch the impedance curve as you tune and you'll soon get the feel. When close watch both impedance and vswr and you can get it practically right on. I find a little touch up is necessary on the lower bands because the frequency of the vna isn't as accurate as the rig. Higher bands the tuning is more broad and the error of the vna doesn't matter. True, it's not a $50k analyzer but for our purposes it's plenty good enough
ESP32 can be a general tool, can be used through USB, but its strength is rather in its ability to serve TCP/IP clients through wi-fi (or even Ethernet with some extension) in a safe way using hardware supported TLS cryptography and communication with relatively small, bearable response times. I'm also developing a fairly advanced switch box (using relay modules) but it is web-based. It mostly works already but as usual, I just could not continue with it in the last couple of months. The tricky part is the real-time communication (without polling) on a HTML page vivewed in a browser, secure websockets had to be written for it. Not from scratch, of course, the ESP-IDF has done the most, but this is still not a fully beaten path, a lot of things had to be tweaked, fixed, modified, and everything. Certainly, if there are no many users with different priviledges, you can hide the whole shebang behind a VPN, and there's no more problem with the security, but this project is to create a remote station manager, a series of main switches for several equipments on the remote location for a group. Despite of being decent ham folks, having individual users and logging are a wise decision to do, not only for troubleshooting but to share up the electricity bills of remote operations... The base of every friendship is the clear financial matters, hi. We have such an ESP32 with static HTML pages and basic password security but it got old now.
I wrote code to do this on an ESP8266 2 years ago. I migrated it to ESP32, and now Raspberry Pi Pico W. There seems to be always one more thing to fix or add. It's still a work in progress, but getting closer to complete.
