I use a hefty open frame relay to turn on the majority of the AC to my station at the antenna farm. This controls the power supply for the transceiver, automatic antenna switch, rotor, etc. And another open frame relay is used to turn on AC for the ACOM. I was experiencing hum in the audio at the control location, particularly when I turned on the ACOM power relay. It was not a killer, just an aggrivation. I found the hum was eliminated when I used a quality power source to supply the 12v used for the relay coils.
I had been using a 1 amp power brick. I switched to a small Astron supply which I keep on all the time to supply wakeup voltages as well as coil voltages. Use a quality filtered source for your coil supply voltages.
