so ive been messing around with this for a few weeks now and im pretty close to getting it working but wanted to see if anyone else has gone down this road before i go too far in the wrong direction

basically i have four antennas — a 40m dipole, an end fed half wave that i use on 20 and 15, a vertical for 10 and 6, and a 2m/70cm colinear — and right now im manually swapping the coax at the back of my radio which is obviously annoying especially during contests. i figured a pi zero w with a relay board would be the cheapest way to automate the whole thing and control it from a little webpage i could hit from my phone or laptop in the shack

ive got the relays switching on and off fine, gpio stuff is straightforward enough, and im running a tiny flask app to serve up the control page. the issue im running into is latency with the relays i got off amazon — theyre the 4 channel 5v jobbers and they click but there's a noticeable delay between hitting the button on the webpage and the actual switch happening. not a huge deal for normal operating but it bugs me. also not 100% sure if these relays are actually rated for the RF current/voltage or if im going to blow something up eventually

anyone dealt with this? is there a better relay module i should be looking at or should i just use a proper antenna switch and just automate the motor/actuator on it or something

yeah those cheap amazon relay boards are fine for low current DC stuff but honestly i wouldnt trust them on the RF side at all, the contacts arent rated for anything meaningful and youll get all kinds of intermod garbage especially if youre running more than like 50 watts through them. the latency thing is probably just flask being flask, you could try using something lighter or just do the gpio writes more directly without the web layer involved but thats a rabbit hole

what most people do is exactly what you mentioned at the end — use a real coax relay like the ones from tohtsu or even the DX Engineering ones and then just use the pi to trigger the control voltage on those. the tohtsu CX-2N or similar can handle a kilowatt and you just need 12v to actuate them, so your relay board is only switching the control line not the RF. that way your pi can be garbage and it doesnt matter because the RF path is handled by something actually designed for it

the web latency thing — honestly for antenna switching i dont think itll ever bother you in practice, how fast are you really switching between antennas mid-qso

i did almost the exact same project about two years ago except i used an Arduino Mega instead of a pi because i already had one sitting around and didnt need the whole linux overhead just for switching relays. ended up being way simpler honestly, just serial commands from a python script on my main shack PC and the arduino handles the actual relay timing. no latency issues because theres no network stack in the way

but if you want to keep the pi approach the flask thing is probably your bottleneck, try FastAPI or even just a raw socket server, made a noticeable difference for me when i was prototyping something similar for my rotor controller. also seconding what the other guy said about the RF relays — i fried one of those cheap boards pretty quickly at 100w on 15m, wasnt pretty