There are many times in amateur radio where you want to “isolate” two pieces of equipment or avoid “ground loops.” For example, when connecting a computer to a rig to do digital modes, you should isolate the signals so that there’s no direct connection between the rig and the radio.
What does it really mean to be isolated, though? And, for that matter, what is “ground”?
You can learn what these terms actually mean and when and why you need isolation if you view the webinar Fundamentals of Signal and Power Isolation. Here’s how they describe the webinar:
This Fundamentals course will briefly look at power isolation (often required in conjunction with signal isolation) and then focus on signal isolation techniques. It will look why it is needed, where it is needed, the relative attributes of techniques for implementing it, and other considerations.
I will certainly read that, thanks for the link. However, recently I was trying to connect an Elecraft KX3 to a MacBook Air. I assumed I would need isolation so I used a Signalink for the audio USB. But I still got considerable electrical noise in the audio which turned out to be coming over the second USB used for rig control. To get to the punch line, turns out what I needed to do in my case was not try for isolation but just the opposite, to establish an excellent common ground. I used coax braid to connect the rig and the computer cases and plugged both power supplies into the same electrical outlet. Once that was in place, all was quiet and I didn’t even need the Signalink at all.