Ok, always learning, seems older Maules have non shielded P-leads to the mag switch. Or at least that seems to be the case on my M4. As such, they are provided with a noise filter between the mag and the switch. Now, I just had a new radio installed due to my King 170 being old and just not the most ideal flying experience. The old king worked for the most part but I had some minor noise issues here and there and its function was suspect. Now, I have a new PS Engineering PAR200B that I love at least in my ramp flying. But today I tried to get in its first flight and I god serious engine noise through two headsets and even the overhead speaker when increasing RPM to 1500 or higher. It was an alternating static buzz in time with the engine and RPMs. I could still hear transmissions from others just fine. I found that the noise largely went away if not completely when I was on the left mag only. This is where the filter comes into play I think. I believe I only have a filter on the right mag. It’s certainly old and crunchy. Aside from obvious grounding issues etc, what are the odds this filter from god knows when has failed. And what would I replace it with. Or, is it better the have my P-lead wires swapped for shielded wires.

Anyways, all suggestions welcome, I will have the radio installer try to sort out any other possibilities in the mean time.

Finding a possible part number 5087B Magneto Filter Installation but nothing comes up in Google.

Scratch that, I have a filter on the left mag as well. But it was loose and dangling. Apparently it was missed when they put my engine in. One end was in contact with a bare steel sleeve. I’m wondering if my mag wires were crossed at the switch at some point. Maybe my left is my right and right is left. Never the less I will secure it tomorrow and see if that fixes the issue.

Good luck!

I removed the filters, and installed shielded P leads. No noise. Don't overlook the alternator filter if you have a buzzing sound that varies with RPM. I have the same radio. Works great.