so ive been mulling this over for a while and finally decided to just start messing with it. basically i want to use an arduino mega to handle my antenna switching between like 4 different antennas based on what band i qsy to. right now im doing it all manually with a coax switch and its getting old especially during contests when im jumping around a lot.

my rough idea is to read the band data output from my ic-7300 (it has that on the acc port i think?) and then use relays to switch between the antennas automatically. i already have a relay module i pulled off an old project, 8 channel one from amazon that i never really used for anything serious.

has anyone done something like this or something similar? im not super experienced with arduino stuff but i can read code okay and modify things. not starting from zero but not super confident either. also wondering if a raspberry pi would be better for this or if the arduino is overkill or underkill or whatever. pi seems like more than i need honestly but maybe im wrong

yeah done almost exactly this with a uno actually, though the mega would give you more i/o headroom which is probably fine. the ic-7300 does output band data on the acc connector, its a set of logic lines that go high or low depending on the band — theres a table in the manual, page like 19 or something. you can read those directly into the arduino digital pins, just watch your voltage levels, the 7300 runs at 3.3v on those pins so dont go connecting straight to 5v arduino inputs without a level shifter or you might have a bad day eventually.

the relay module approach works fine, i used one of those sainsmart 8ch boards. only thing i'd say is put some snubber diodes on the relay coils if they arent already there, the back-EMF can mess with the arduino in weird ways especially if your wiring is sloppy like mine was at first. took me like two weeks to figure out why my arduino kept resetting randomly during transmit.

pi is overkill for pure switching logic imo. arduino is perfect for this, boots instantly, no OS to worry about, just does its thing. save the pi for something where you actually need linux or networking.

I did something kind of like this a while back but I used a Raspberry Pi and kind of regret it honestly. Booting up takes forever and if the power blips the thing doesn't always come back clean. For just relay switching an Arduino or even a bare ATmega chip is way more reliable in my experience. The Pi is great if you want to run fldigi or log software or something that actually needs real compute power but for I/O stuff the Arduino wins on simplicity.

One thing to watch out for with that relay module — make sure it's optoisolated between the control side and the relay side or RF can get into the Arduino and cause all kinds of weirdness. Most of the cheap ones are optoisolated but not all of them, worth checking the board markings.