Quote Originally Posted by mwmkravchenko View Post
Toroidally wound transformers have benefits. Mostly the elctromagnetic noise from them is very controlled and even in it's radiation around the transformer. They are a pain to wind by hand that I know first hand. Try winding little iron core inductors! Even more fun. EI core is the easiest. FOr audio work EI has the benefit of filtering out all the AM radio and Ham radio interference. A toroidal is a wide bandwidth transformer. Not so good at the filtering. Needs external filtering.
If you are experiencing interference from a Ham then they are a hack not a real operator. Hams pride themselves on clean frequency usage However if you are in direct alignment with someone's ground plane that could be some of what you are experiencing, in noise. call the operator up and explain that you are having some noise issues possibly caused by their equipment. I can almost assure you they will be more than receptive to trying to correct the issue. Noise is their enemy as well because it drains power from their transmissions. Hams love to be able to talk all the way around the world in any direction using the lowest possible power output.