so ive been messing around with this for a few weeks now and i think im overcomplicating it but wanted to see if anyone else has gone down this rabbit hole. basically i have a hexbeam and a vertical and i keep forgetting to switch when i move between HF bands, ended up transmitting into the wrong antenna twice last month which was not fun.

my plan was to use an arduino mega with a relay board to handle the switching automatically based on what frequency the rig is outputting. ive got a kenwood TS-590SG which has the CAT interface so i figured i could just poll it over serial and check the VFO frequency then trigger the relays accordingly. wrote a rough sketch that does the polling part and it works fine on the bench, reads the frequency no problem.

the issue is the relay timing. i dont know if im just being paranoid but im worried about the relay switching while theres still RF present if the timing is off even slightly. thinking about adding a PTT sense line to hold the switch until the radio goes back to receive but not sure if thats overengineering it. also wondering if a raspberry pi would actually be better for this since i could run a proper python script with better error handling but then i feel like thats overkill for what is basically just reading a serial port and flipping some gpio pins

anyone built something like this or have thoughts on the arduino vs pi question for something this simple?

yeah the PTT sense line is absolutely the right call, not overengineering at all. you do NOT want to switch relays under load even for a fraction of a second, the contacts will arc and youll be replacing the relay board way sooner than expected. i learned that the hard way on a similar project a few years back.

i ran almost the exact same setup on a TS-590S actually, using an arduino uno and a 4 channel relay board from amazon. the way i handled it was just monitor CTS or RTS on the CAT connection, most kenwoods pull one of those lines when in transmit but you might have to check the manual or experiment. alternatively just wire a simple optocoupler off the PTT line directly, that gives you clean isolation and the arduino just reads it as a digital input. whole thing cost me maybe 12 bucks in parts.

as for pi vs arduino for this specific task, honestly the arduino is fine. the pi boots slower, needs a proper shutdown procedure, and is overkill unless you want to run a web interface to control stuff remotely or log to a database or something like that. if you just want reliable switching, stick with the arduino, less to go wrong.

i did something similar but went the raspberry pi route mostly because i already had one sitting in a drawer doing nothing. ended up being a bigger project than i planned, added a web dashboard so i can see antenna status from my phone which is kinda neat but definitely not necessary lol. python makes the serial stuff really easy with pyserial but like the other guy said the boot time is annoying if you ever lose power, arduino just comes back up instantly.

one thing worth mentioning — make sure whatever relay board you use is rated for the voltage you're switching, some of the cheap ones are fine for 12v control circuits but check the coil voltage matches your supply. also if you're in a high RF environment near your antennas you might get weird behavior from induced RF on the arduino gpio lines, had that problem and had to add some ferrites on the control cables which cleared it right up.