Yet Another Magneto Noise Thread

[BC12D-4-85]

Interesting problem. The USB 12>5VDC convertor can be noisy, especially if a non-suppressed cheap unit. Switching power supplies from offshore may lack FCC Part 15 noise limit certification (a no or low interference output requirement). Edit: And must meet FAA TSO-C71 for air carrier aircraft. Private....it may help ensure low noise.

As far as the hand held radio, usually removing the antenna to search results in low signal gain and localized source. How far from the plane will the hand held with antenna pick up the noise? Or is it limited to engine/panel? Removing power to one electrical circuit at a time can often get to the offending source.

Gary

 

[Steve Pierce]

USB ports are a huge source of noise. Cheap 12 volt to 5 volt circuits are usually the gremlin.

 

[FatCub300]

This persistent problem is reminding me of an old Stinson I had that as I mentioned before...only after essentially unhooking everything...did I finally realize that my right magneto itself was arcing internally and was in fact the source of a huge mess of noise. The problem was that it only did it as it heated up, so when cold for 10 to 20 minutes it was fine...every time I thought I'd found the problem 30 minutes in it was back.

Very frustrating, but on a side note, that Stinson ended up with a really nice electrical system upgrade compliments of beer and anger!!!

A trip to Cliff Orcutt for a mag overhaul solved the problem in the end.

Steve.

 

[Farmboy]

Could be an internal mag issue and could be the ignition harness that was replaced with engine change.

 

[FabricGATOR]

Switched to an electronic tach. Unhooked it with no help.

The E-tach is a pulse generator so it may need to be physically disconnected from rotation?
Not just unwired?

 

[Skywagon185]

Unhooked the USB charger, no help. Meanwhile the old oil temp gauge gave up so I installed the EI replacement (pressure/temp). Still chasing the noise but really feel like an internal mag issue makes the most sense. No easy way to troubleshoot that though.

 

[Steve Pierce]

Need a spare set of mags. Slick or Bendix?

 

[Skywagon185]

Need a spare set of mags. Slick or Bendix?

That certainly would be better than sending newly overhauled mags out. Bendix.

 

[Steve Pierce]

I have a spare set of Slicks but let me see if I have some Bendix.

 

[FabricGATOR]

Hey Skywagon, I am subscribed, I am invested, I hope to help you find this solution

I am not sure if I asked yet but please be sure and return and tell us what and how you eventually correct this e-noise in your headset/radio.

I participate and utilize many forums in many different genre's and I have noted a trend that is less than ideal.
Someone has a fault, the community pitches in to help with their experience, exposure, and background knowledge...

Then, many times, the thread just goes cold
No answer, no solution, and sadly no "thank's guys"

I suppose that Gerry get's his soccer mom's van running again, he is the hero, and then gets online to learn why their dishwasher is not opening the soap dispenser... No solution, no answers
It is like borrowing a novel from the library and reading the whole of it, only to find out the last few pages are missing. Oh how frustrating!

ALSO, it is the feedback and answer that makes these forums complete.
How many times are you trying to search for the solution to a problem and find a forum thread that has your same exact fault
Alas, thread goes cold once the OP finds a fix (or hires a repair shop) regardless, tell us what the mechanic found!

 

[Farmboy]

Have you reinstalled the original mag harness and tested yet?

 

[BC12D-4-85]

Another question might be: Are any similarly equipped aircraft completely static free?

Gary

 

[Skywagon185]

Hey Skywagon, I am subscribed, I am invested, I hope to help you find this solution

I am not sure if I asked yet but please be sure and return and tell us what and how you eventually correct this e-noise in your headset/radio.

I participate and utilize many forums in many different genre's and I have noted a trend that is less than ideal.
Someone has a fault, the community pitches in to help with their experience, exposure, and background knowledge...

Then, many times, the thread just goes cold
No answer, no solution, and sadly no "thank's guys"

I suppose that Gerry get's his soccer mom's van running again, he is the hero, and then gets online to learn why their dishwasher is not opening the soap dispenser... No solution, no answers
It is like borrowing a novel from the library and reading the whole of it, only to find out the last few pages are missing. Oh how frustrating!

ALSO, it is the feedback and answer that makes these forums complete.
How many times are you trying to search for the solution to a problem and find a forum thread that has your same exact fault
Alas, thread goes cold once the OP finds a fix (or hires a repair shop) regardless, tell us what the mechanic found!

Yes, I will for sure keep this thread updated. Thanks for your help.

 

[Skywagon185]

Have you reinstalled the original mag harness and tested yet?

Yes, no joy.

 

[Skywagon185]

Another question might be: Are any similarly equipped aircraft completely static free?

Gary

I'd be fine with static. This is much more annoying.

 

[FatCub300]

I'd be fine with static. This is much more annoying.

you could always just pull one mag at a time out entirely, throw a cover plate over the hole and run it on one and test if that makes a difference...quick and easy to find out if one is bad...

Steve.

 

[Skywagon185]

Had an avionics guy come out hook up a Standing Wave Ratio (SWR) analyzer to measure the energy reflected back from the antenna system. All systems normal. Based on everything that has been done I'm going to talk with the engine shop that arranged the overhaul of the mags and see if those can go back to the shop for analysis.

 

[BC12D-4-85]

I dislike repeat, but did you try removing the coax at the antenna and listen for the same static? Just trying to see if the source is mainly the antenna input, or is it coming in through the power/audio components?

Gary

 

[MartyC]

Just wondering if there is anything new to report. Hopefully it's problem solved.

 

[Skywagon185]

Just wondering if there is anything new to report. Hopefully it's problem solved.

No progress. Haven't been flying now due to weather.

 

[MartyC]

Thanks!!!

 

[Skywagon185]

I just received a pair of these noise filters (last resort before pulling the mags) and could use some advice. What should I do with the shield on the wire for the lead to the mag? My plan is to use a ring terminal to the mag but not sure what exactly to do with the shield.

 

[FatCub300]

I just received a pair of these noise filters (last resort before pulling the mags) and could use some advice. What should I do with the shield on the wire for the lead to the mag? My plan is to use a ring terminal to the mag but not sure what exactly to do with the shield.

View attachment 109565

My old Stinson / Franklin went P-lead wire to ring terminal to filter screw. then shielded wire out of filter...(conductor) spliced to "cigarette" into mag.

Shield was connected to ground, via case screw on mag with a ring terminal

Steve.

 

[AZinAK]

This should help.

 

[Skywagon185]

This should help.

Thanks for posting this. I am trying to avoid using the caps as I have integrated caps with a terminal end. I'm guessing essentially the shield would then just connect to the mag cap screw acting as a ground?

 

[AZinAK]

Thanks for posting this. I am trying to avoid using the caps as I have integrated caps with a terminal end. I'm guessing essentially the shield would then just connect to the mag cap screw acting as a ground?

That makes sense based on the loose description of your P-leads.