so ive been messing around with this idea for a while now and finally starting to actually put it together. basically i have a hexbeam and a vertical and i'm constantly having to manually flip the coax switch depending on what band im on or what direction i want to point. its not a huge deal but it gets annoying especially during contests when youre trying to move fast.

my plan is to use an arduino uno with a relay board to handle the antenna switching and maybe tie it into some kind of rotator control at some point. i already have a raspberry pi 4 sitting around that i use for wsjtx and js8call, so i figured i could have the pi send serial commands to the arduino to trigger the relays based on whatever band the radio is on. my radio is a ts-590sg so i can poll it via cat for the current frequency and just write a little python script to handle the logic on the pi side.

has anyone actually done something like this or something similar? im not a great programmer but i can fumble through python and arduino sketches well enough. main thing im worried about is rf getting into the arduino and messing things up, ive heard that can be a real problem especially if the relay board is anywhere near the feedlines. any advice on shielding or grounding for that kind of thing would be appreciated. also not sure if i should use opto-isolated relays or just regular ones for this application.

yeah rf into the arduino is absolutely a real thing and it will drive you crazy if you dont deal with it upfront. i fried two nano clones before i figured out what was happening — kept getting random resets during transmit on 40m. what finally fixed it for me was putting the whole arduino board in a grounded metal enclosure, adding ferrite beads on every wire going in and out of the box, and using shielded cable between the pi and arduino. also bypass caps on the power supply lines help a lot.

on the opto-isolated relay question — yes use them, dont even think twice about it. the isolation between your control side and the switching side is worth it especially if youre switching coax that has any chance of picking up rf. sainsmart makes decent 8-channel opto relay boards, cheap enough that its not worth skipping. your cat polling idea with the ts-590 should work great btw, kenwood's cat implementation is pretty solid and python-serial makes it easy enough to talk to it.

done almost exactly this with a pi zero w and an uno clone for my shack. works most of the time lol. the one thing i'd add is think about what happens when the pi crashes or the script dies — make sure the relays fail in some sane state so you're not transmitting into an open or into the wrong antenna. i added a watchdog timer on the arduino side that defaults back to the vertical if it stops getting commands from the pi after a few seconds. took me a while to think of that but glad i did because the pi has locked up on me twice and it just falls back cleanly now instead of leaving things in a weird state.