Van's Air Force
Western Canada Wing |
“So what about the capacitor. Will it help reduce any noise in the intercom, radio, etc, system if we install one. A friend of mine recommended that I install a capacitor in the system along with shielded wire from the alternator.”
A builder called me about ten years ago
and spent several minutes outlining all the shielding, filtering, pre-positioning
of hardware in the airplane all in the name of eliminating electrical noise.
All in all, several dozens of hours, pounds of hardware and no small sum
of cash.
I was a bit astonished and asked what
kind of noise problem he was having. “Oh,” says he, “I don’t have a noise
problem, the airplane is not yet ready to fly.” My advice is generally
this: put shielded wire on magneto p-leads, spark plug wires and
on any appliances where the manufacturer recommends it and describes how
it is to be hooked up.
Then, if a noise problem presents itself, you need to identify the source, propagation mode, and victim and plan the best way to handle that particular problem by filtering at source, breaking the propagation mode, or filtering at the victim. Given that there are dozens of possible combinations, you can easily spend the time and dollars represented by our hero’s precautions and still not assure yourself of a noise-free airplane.
Begin with good basic installation practice and whip each problem as it presents itself. It’s generally not hard to do.