I've read the old threads, and think I have a diagnosis but want to confirm my expected cure.
I have alternator noise (varies with engine speed and only occurs when alternator is switched on) which is annoying on some radio freqs (some freqs will break squelch just from the noise; on others I hear it "overlayed" on other's transmissions). Intercom alone does not have the noise, only perceivable when receiving on radio (may be in outbound, too, but I can't hear that).
Alternator = Van's 60 amp internally regulated, purchased last year.
Battery located a long way from the alternator, on the other side of Avionics bus
Suspected solution: Install a honkin' big capacitor between alternator B-lead and Ground, as close to the alternator as possible.
Questions:
- How much difference does it make moving the capacitor closer to the alternator (e.g. is mounted on the firewall behind the engine just as good as glued to the alternator)?
- Is there such a thing as "too big" for the capacitor (e.g. someone suggested a couple of hundred thousand microfarads, but for $25 I can get a 1 farad (1,000,000 microfarad) capacitor meant for huge stereos and already having really nice attachment terminals and mounting bracket)?
- If this DOESN'T fix the problem and I have already spent an excruciating amount of time tracing ground runs, what to try next (e.g. is the Van's alternator a particularly bad generator of noise, and would upgrading to an externally regulated alternator have any effect on this)?
Thanks,
Bill
I have alternator noise (varies with engine speed and only occurs when alternator is switched on) which is annoying on some radio freqs (some freqs will break squelch just from the noise; on others I hear it "overlayed" on other's transmissions). Intercom alone does not have the noise, only perceivable when receiving on radio (may be in outbound, too, but I can't hear that).
Alternator = Van's 60 amp internally regulated, purchased last year.
Battery located a long way from the alternator, on the other side of Avionics bus
Suspected solution: Install a honkin' big capacitor between alternator B-lead and Ground, as close to the alternator as possible.
Questions:
- How much difference does it make moving the capacitor closer to the alternator (e.g. is mounted on the firewall behind the engine just as good as glued to the alternator)?
- Is there such a thing as "too big" for the capacitor (e.g. someone suggested a couple of hundred thousand microfarads, but for $25 I can get a 1 farad (1,000,000 microfarad) capacitor meant for huge stereos and already having really nice attachment terminals and mounting bracket)?
- If this DOESN'T fix the problem and I have already spent an excruciating amount of time tracing ground runs, what to try next (e.g. is the Van's alternator a particularly bad generator of noise, and would upgrading to an externally regulated alternator have any effect on this)?
Thanks,
Bill