so ive been messing around with an arduino uno for a few weeks now trying to get it to handle my antenna switching automatically based on what band the radio is on. right now i have a yaesu ft-991a and it puts out band data on the accessory port so thats at least something to work with. the idea is to read that band data and then fire the appropriate relay to switch between my wire antennas out back.

ive got the relay board wired up and the arduino reads the band voltage fine, i tested it with a multimeter and it all checks out. but the switching itself is kind of glitchy — like sometimes it switches twice real fast or hesitates before it does anything. i think its a debounce issue or maybe im not filtering the input properly but honestly im not 100% sure. the code is pretty basic right now, just a bunch of if statements checking the analog voltage.

anyone tackled something like this before? wondering if i should ditch the uno and move to a pi or if thats overkill for something this simple. also not sure if the relay board im using is rated for the coax switching side of things, its one of those cheap 8 channel ones off amazon.

yeah the glitchy switching sounds like a debounce thing for sure. what i did on a similar project was add a small delay after detecting the band change — like dont act on it until the voltage has been stable for maybe 50-100ms. just poll it in a loop and reset a counter every time it changes, only trigger the relay when the counter hits your threshold. cleaned up all the spurious switching on mine.

also those cheap 8 channel relay boards are fine for the control side but if youre actually switching RF through them forget it, the contacts arent really rated for that and youll get all kinds of problems, insertion loss, arcing if youre running any power at all. you want proper coax relays for the RF path, denkovi or maybe look at what hy-gain sells. the arduino just fires the coil on those, keeps the RF completely separate.

and honestly stick with the uno for this, a pi is massive overkill and it boots slow, you dont want your antenna switcher sitting there for 30 seconds while linux comes up every time you flip the radio on.

the band data voltage thing on the 991a is a little finicky i remember dealing with that. what resistor are you using on the input to the arduino? if youre reading it direct you might be loading it down enough to mess with the readings. i put a 10k in series and that sorted it out for me.