What could be a symptom caused by a ground loop in your station's audio connections?
Why A ground loop happens when equipment is grounded at more than one point, so the shields and ground leads form a closed loop that picks up stray AC power-line currents. Those currents appear as a small 60 Hz (and harmonics) voltage in series with your audio, which gets amplified and modulated onto the signal. The classic symptom is other stations telling you there is hum on your transmitted audio. The cure is bonding all equipment to a single common point so there is only one ground path.
Watch out High SWR points to an antenna or feedline fault, and harmonic interference comes from overdriving or inadequate transmitter filtering; neither is caused by audio wiring ground paths.
Ground loop = loop of wire near AC power = 60 Hz hum in the audio. Hum on audio, think loop.