so ive been messing around with an arduino uno for a few weeks now trying to get it to control my 6-port coax switch automatically based on what band i select on the radio. the idea is pretty simple — read the band data output from my IC-7300 (it puts out band voltage on the ACC port) and then drive some relays accordingly. in theory its straightforward but ive been fighting with the relay timing and the arduino is occasionally glitching when i key up, probably RF getting into the thing somehow.

i wrapped the whole arduino in foil as a quick test and it helped a little but didnt fully solve it. im running about 100w into a dipole, nothing crazy. has anyone actually built something like this and got it stable? im wondering if i need to add ferrites to the USB cable or if theres something more fundamentally wrong with how im powering it. right now its just running off a cheap wall wart through the USB.

also curious if a raspberry pi would be better for something like this or if thats total overkill for just switching relays based on a voltage level

yeah RF into the arduino is a classic problem, been there. the foil helps a little but what really fixed it for me was bypassing the power leads going into the relay board with some 0.1uF caps right at the board, and putting a ferrite on the USB cable close to the arduino end. also make sure you have flyback diodes across each relay coil if your relay board doesnt already have them, the voltage spike when the relay opens can reset the thing.

separate power supplies for the arduino and the relay coils helped too. i was powering both from the same 5v line and that was causing all kinds of weirdness. once i split them and added a small cap on the arduino Vcc it got much more stable. for just reading a voltage and switching relays the arduino is totally the right tool, pi is overkill unless you want logging or a web interface or something like that

i did almost exactly this with a nano a while back for my hexbeam controller, different application but same RF noise problems. what band data voltage levels does the 7300 actually put out on that port? i seem to recall some radios put out like 0-8v across different bands and you just do a voltage divider into an analog pin, but i wasnt sure if icom does it the same way. curious what your mapping looks like in the code