so ive been messing around with an arduino mega for a few weeks now trying to get it to handle antenna switching based on what band i dial in on the rig. the idea is pretty straightforward — read the band data output from the radio (im running a kenwood ts-590sg which outputs band voltage on the ACC2 port), decode that with the arduino, then fire relays to switch between my verticals and my dipole depending on band.

the relay board i got off amazon is one of those 8-channel 5v jobs and it works fine when i just manually trigger it through serial but im having weird issues where it glitches when i transmit. like the relays chatter or sometimes switch to the wrong position mid-over. my shack ground isnt the greatest and i suspect RF is getting into the arduino somehow even though i have it a good 4 feet from the radio. tried adding a ferrite on the USB cable going to the laptop but still happening. the sketch itself is pretty simple, polling the analog pin every 200ms and comparing against voltage thresholds for each band.

wondering if anyone else has dealt with RF getting into microcontrollers in the shack and how you actually fixed it. also curious if a raspberry pi would be better for something like this or if thats overkill for relay switching

yeah RF and arduinos in the shack is a classic headache. the relay board is probably the culprit more than the arduino itself — those cheap chinese boards have no isolation to speak of and the relay coil switching can couple noise back into the logic side too. what i did on mine was add a 100ohm resistor in series on every input line plus a small cap to ground right at the arduino pin, like 100pf or so. made a huge difference. also make sure your relay board has its own power supply and shares ground with the arduino but not through the USB — i was powering mine off the arduino 5v rail and that was causing all kinds of weirdness.

the other thing worth checking is whether your band voltage lines are shielded. even a few inches of unshielded wire near the coax can pick up enough to confuse the analog read. i ended up running mine through a small RC lowpass filter before the ADC pin and the chatter went away completely. as for pi vs arduino for this kind of thing — arduino is honestly fine, the pi is way overkill for relay switching and you have to deal with linux boot times and SD card corruption if power goes out mid-contest which is no fun

the rf immunity thing bites everyone eventually. one trick i havent seen mentioned much is wrapping the whole arduino in a grounded metal enclosure — even just an old altoids tin works surprisingly well for a lot of shack builds. bond it to your station ground and a lot of the gremlins go away. also maybe consider opto-isolating the relay triggers if you havent, those cheap relay boards sometimes have them built in but not always wired correctly from the factory.