so ive been messing around with this for a few weeks now and i think im overcomplicating it but here goes. i have a 6-position antenna switch (the manual kind, big rotary knob) and i keep forgetting to switch antennas when i move between bands. like ill be on 40m and then jump to 2m for a net and wonder why my signal sounds terrible and yeah its because im still on the HF vertical.

so i started building this thing with an Arduino Uno and a relay board — the idea being that when i change bands on the radio the arduino reads the band data output from my IC-7300 (it puts out band voltage on the ACC port) and then fires the right relay to switch the antenna. seemed simple enough but now im deep in interrupt handling and debounce timers and honestly questioning whether i should just buy one of those commercial band decoders instead.

anybody done something like this? is there a library or sketch floating around that already handles the 7300 band voltage stuff because i feel like ive seen something on github but cant track it down again. also wondering if a raspberry pi would be made more sense here since i want to eventually log things and maybe display current antenna on a little screen.

yeah ive done almost exactly this, well close enough. i used a Nano instead of the Uno just for the smaller footprint and powered it off the USB port on the back of the 7300. the band voltage decoding is actually pretty straightforward once you figure out the voltage table — Icom publishes it in the manual but the values are a little weird in practice, like theyre not always exactly what the spec says, probably just ADC tolerance on the arduino side. i ended up adding about a 50ms debounce delay and that cleaned up most of the false triggers when scanning through bands quickly.

as for github i think W6JL or somebody had a band decoder sketch floating around a while back but i honestly just wrote mine from scratch, wasnt that many lines of code. the relay board thing works fine but make sure your relays are actually rated for whatever youre switching — i fried a cheap 5v SRD relay board the first time because i was running more coax switching current through it than it liked. swapped to a proper DIN rail relay and no issues since.

the pi idea is cool if you want the logging piece but its way more setup for something that a tiny microcontroller handles perfectly fine. that said if youre already comfortable with python and dont mind the boot time, go for it.

not going to lie the commercial band decoders are pretty decent and not that expensive if you shop around. microHAM makes a nice one and theres some eastern european stuff on ebay that people seem to like. but building it yourself is half the fun right so dont let me talk you out of it.

one thing i will say — if you go the Pi route, look at a Pi Zero 2W instead of a full Pi 4 or whatever, way less overkill for something that just needs to read a voltage and flip some relays. and you can run a little flask app on it and have a webpage showing your current antenna state which is kinda neat for shack monitoring. i did something like that for my rotor controller and it works surprisingly well.