so ive been messing around with a raspberry pi zero w for the past few weeks trying to get it to handle some basic automation stuff at my shack. right now its running a python script that listens to my rig via CAT control (IC-7300 over USB) and logs contacts automatically to ADIF, which then syncs to LoTW every night via cron job. works pretty well honestly.

the part im stuck on is the antenna switching. i want to use the GPIO pins to drive some relay modules i picked up off amazon - like the 4-channel 5v ones everyone uses. problem is im not sure if i should be handling the switching logic on the pi itself or if i should offload that to a small arduino nano sitting between the pi and the relays. the relays are switching coax so its not a huge current thing but i want to make sure im not doing something dumb with RF getting back into the GPIO lines or whatever. anyone dealt with this? the shack isnt super clean RF-wise, im running 100w on HF and the antenna feedpoint is maybe 15 feet from the pi.

also curious if anyone has done band-based automatic antenna selection tied to the rig's current frequency - that would be the dream honestly

yeah the RF into GPIO thing is a real concern, especially at 100w that close to the feedpoint. i had the exact same issue with a pi 3 i was using for WSPR beacon stuff and random resets drove me crazy for about a month before i figured out what was happening. what ended up working for me was putting ferrite chokes on every cable going in and out of the pi - power, USB, whatever - and also grounding the pi case to the station ground. made a huge difference.

on the arduino question, honestly for something like relay switching i do like having a nano in between just because it keeps the logic simple and if the pi crashes or does a software hiccup the arduino can hold its last state or go to a safe default. you can have the pi send simple serial commands like 'ANT1' or 'ANT2' and the nano handles the actual relay timing and debounce. gives you a layer of protection too since the arduino isnt running linux and wont randomly decide to do updates at the wrong moment. the band-based switching is totally doable, the 7300 spits out its VFO frequency over CI-V so you can parse that and just do a big if/elif block based on frequency ranges. i have something similar running for my amp's band switch, took like an afternoon to get working.

the relay modules you got from amazon are probably fine but check if they're active-low or active-high trigger - the cheap blue ones usually need the input pulled LOW to activate which trips people up when they first wire them to GPIO. burned an afternoon on that myself lol

also yeah 15 feet from the feedpoint at 100w you're gonna want some shielding or at least good ferrites, a pi zero isnt exactly known for being robust against RF