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ron228rj(at)gmail.com
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 Posted: Mon Sep 14, 2020 3:58 pm Post subject: B&C SD-8 Alternator/Regulator |
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To close this one out ...
The source of the noise was the magneto itself. Disconnect the p-lead to the engine monitor, and all of the data was stable. However, the magneto was still radiating RF that was causing other problems. It would stop data recording to the USB stick on my EFIS. It created some radio noise. It possibly took my GPS antenna offline (or it might have just been the location, which I also changed).
So, why was the brand new magneto creating noise ... because when I bought the plane it was set up to use auto spark plugs, specifically Autolite 386. Other than some radio noise, the previous owner didn't have any issues because he had few electronics in the plane, mostly steam gauges. My theory is that the magneto reacts poorly to high resistance downstream of it. You are supposed to throw out an aircraft plug when it hits 5000 ohms, but most Autolite 386 plugs are around 10000 ohms out of the box. The manufacturer provides a large range from 3k to 12k ohms. I tested six new ones and measured between 7k and 12k ohms. There is probably an auto plug solution that would work fine on my magento, but I am done experimenting for now. I flew with the aircraft plugs and it fixed all my problems at once.
Ron
On Wed, Aug 26, 2020 at 8:19 PM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
| Quote: | At 06:28 PM 8/26/2020, you wrote:
| Quote: | | Just did a test flight and shot some video of the EIS to compare to the EFIS. I haven’t even looked at it yet because I did something else for the first time. I shut off the magneto and everything got perfectly quiet on the EFIS, along with the noise that seems to be getting louder in my headset on each flight! |
Aha! One more flight test:
Leave the mag wire totally unhooked at
the engine end. Of course this leaves
you an always-hot mag but the p-lead
effects are now out of the diagnostic
loop.
If the effect goes away, you're looking
at p-lead; if it stays you're looking
at plug wires.
Bob . . .
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ceengland7(at)gmail.com
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| Posted: Mon Sep 14, 2020 5:49 pm Post subject: B&C SD-8 Alternator/Regulator |
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Yeah...That would have been a useful data point to supply for troubleshooting. 
Some have gotten away with using specific plug wires & automotive plugs with mags, but the whole reason mags have shielded wire and shielded plugs is to suppress the intense RF ignition noise from the mag.
Here's one way to do it successfully:
http://www.g3ignition.com/magmod.html
Note that the 386s are being used by some of us with electronic ignition, but internet lore says they have a higher heat range than typical a/c plugs, or the metric plugs that require an adapter.
Charlie
On 9/14/2020 6:54 PM, Ron Springer wrote:
| Quote: | To close this one out ...
The source of the noise was the magneto itself. Disconnect the p-lead to the engine monitor, and all of the data was stable. However, the magneto was still radiating RF that was causing other problems. It would stop data recording to the USB stick on my EFIS. It created some radio noise. It possibly took my GPS antenna offline (or it might have just been the location, which I also changed).
So, why was the brand new magneto creating noise ... because when I bought the plane it was set up to use auto spark plugs, specifically Autolite 386. Other than some radio noise, the previous owner didn't have any issues because he had few electronics in the plane, mostly steam gauges. My theory is that the magneto reacts poorly to high resistance downstream of it. You are supposed to throw out an aircraft plug when it hits 5000 ohms, but most Autolite 386 plugs are around 10000 ohms out of the box. The manufacturer provides a large range from 3k to 12k ohms. I tested six new ones and measured between 7k and 12k ohms. There is probably an auto plug solution that would work fine on my magento, but I am done experimenting for now. I flew with the aircraft plugs and it fixed all my problems at once.
Ron
On Wed, Aug 26, 2020 at 8:19 PM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
| Quote: | At 06:28 PM 8/26/2020, you wrote:
| Quote: | | Just did a test flight and shot some video of the EIS to compare to the EFIS. I haven’t even looked at it yet because I did something else for the first time. I shut off the magneto and everything got perfectly quiet on the EFIS, along with the noise that seems to be getting louder in my headset on each flight! |
Aha! One more flight test:
Leave the mag wire totally unhooked at
the engine end. Of course this leaves
you an always-hot mag but the p-lead
effects are now out of the diagnostic
loop.
If the effect goes away, you're looking
at p-lead; if it stays you're looking
at plug wires.
Bob . . .
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ron228rj(at)gmail.com
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| Posted: Mon Sep 14, 2020 8:00 pm Post subject: B&C SD-8 Alternator/Regulator |
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Remember, I only discovered that this had something to do with the ignition system in the very last post. This whole thread has been focused on the electrical system, not the ignition, because the problem could only be produced in flight shortly after the charging system kicked in at takeoff. It did not occur on the ground at any power setting from idle to full throttle.
I didn’t omit any information about the spark plugs because we haven’t been talking about the ignition system in this thread. I dealt with that on my own.
Ignition noise is usually suppressed by adding resistance to the plug, wires, or both to reduce current at the expense of performance. In this case, it appears that there may be too much resistance causing the mag to behave badly. The Autolite plugs on my electronic ignition work just fine. It was just a problem with the mag.
I had two sets of auto harnesses to choose from. One was a modified aircraft harness with auto plug terminals. That is low resistance wire with a metal shield. I also had a harness utilizing 8.8 mm Accel wires with a resistance of about 700 ohms, advertised to be RFI suppression wires. Neither set of wires made a difference. It was all due to the plugs. That website you mentioned advertises low resistance MSD wires on their auto plug harness but they don’t mention the plugs that they recommend for a magneto.
Ron
Sent from my iPhone
| Quote: | On Sep 14, 2020, at 9:58 PM, Charlie England <ceengland7(at)gmail.com> wrote:
Yeah...That would have been a useful data point to supply for troubleshooting.
Some have gotten away with using specific plug wires & automotive plugs with mags, but the whole reason mags have shielded wire and shielded plugs is to suppress the intense RF ignition noise from the mag.
Here's one way to do it successfully:
http://www.g3ignition.com/magmod.html
Note that the 386s are being used by some of us with electronic ignition, but internet lore says they have a higher heat range than typical a/c plugs, or the metric plugs that require an adapter.
Charlie
On 9/14/2020 6:54 PM, Ron Springer wrote:
| Quote: | To close this one out ...
The source of the noise was the magneto itself. Disconnect the p-lead to the engine monitor, and all of the data was stable. However, the magneto was still radiating RF that was causing other problems. It would stop data recording to the USB stick on my EFIS. It created some radio noise. It possibly took my GPS antenna offline (or it might have just been the location, which I also changed).
So, why was the brand new magneto creating noise ... because when I bought the plane it was set up to use auto spark plugs, specifically Autolite 386. Other than some radio noise, the previous owner didn't have any issues because he had few electronics in the plane, mostly steam gauges. My theory is that the magneto reacts poorly to high resistance downstream of it. You are supposed to throw out an aircraft plug when it hits 5000 ohms, but most Autolite 386 plugs are around 10000 ohms out of the box. The manufacturer provides a large range from 3k to 12k ohms. I tested six new ones and measured between 7k and 12k ohms. There is probably an auto plug solution that would work fine on my magento, but I am done experimenting for now. I flew with the aircraft plugs and it fixed all my problems at once.
Ron
On Wed, Aug 26, 2020 at 8:19 PM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:
| Quote: | At 06:28 PM 8/26/2020, you wrote:
| Quote: | | Just did a test flight and shot some video of the EIS to compare to the EFIS. I haven’t even looked at it yet because I did something else for the first time. I shut off the magneto and everything got perfectly quiet on the EFIS, along with the noise that seems to be getting louder in my headset on each flight! |
Aha! One more flight test:
Leave the mag wire totally unhooked at
the engine end. Of course this leaves
you an always-hot mag but the p-lead
effects are now out of the diagnostic
loop.
If the effect goes away, you're looking
at p-lead; if it stays you're looking
at plug wires.
Bob . . .
|
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Virus-free. www.avast.com [url=#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2] [/url]
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ceengland7(at)gmail.com
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| Posted: Tue Sep 15, 2020 9:02 am Post subject: B&C SD-8 Alternator/Regulator |
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Understand. Apologies if that was offensive; it was intended to be light
hearted. I would have bet that it didn't show up at low throttle because
the ignition isn't working hard until MAP goes up at higher power settings,
but that doesn't square with your symptoms.
One thing that plug wire mfgers say in their docs is that it's important to
use compatible wire & plugs. IIRC, solid conductors with resistor plugs or
resistor wire with non-resistor plugs. That site I linked will probably
tell you which plugs to use when you pay them their $30. 
Just out of curiosity, did you try a new set of 386s? Any chance the
original setup had a different plug; perhaps a 14mm plug with thread
adapter? My plane had 14mm plugs on the Lightspeed ignition when I bought
it, but I changed to 386s out of paranoia when I found one of the adapters
backed out about half way about a month after purchasing the plane.
Charlie
On Mon, Sep 14, 2020 at 11:06 PM Ron Springer <ron228rj(at)gmail.com> wrote:
[quote] Remember, I only discovered that this had something to do with the
ignition system in the very last post. This whole thread has been focused
on the electrical system, not the ignition, because the problem could only
be produced in flight shortly after the charging system kicked in at
takeoff. It did not occur on the ground at any power setting from idle to
full throttle.
I didn’t omit any information about the spark plugs because we haven’t
been talking about the ignition system in this thread. I dealt with that on
my own.
Ignition noise is usually suppressed by adding resistance to the plug,
wires, or both to reduce current at the expense of performance. In this
case, it appears that there may be too much resistance causing the mag to
behave badly. The Autolite plugs on my electronic ignition work just fine
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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ron228rj(at)gmail.com
Guest
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| Posted: Tue Sep 15, 2020 10:08 am Post subject: B&C SD-8 Alternator/Regulator |
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Well, when I first tore out all the wiring and installed an EFIS in my plane, I refreshed all my Autolite 386 plugs with new ones. I did not have any problem with noise in the data like I had recently, but on my third flight my EFIS did not record data to the USB stick. I suspected a problem with the EFIS when that happened. I certainly wasn't thinking it was caused by the spark plugs at the time. In some of the following flights it would periodically not record portions of the flight. However, as soon as I installed a brand new mag, I got extreme noise on the engine data plus failure to record data on every single flight starting shortly after takeoff.
So, I have not tried a set of new plugs recently. Maybe it was not due to the high resistance but one of the plugs was defective instead? Blaming the problem on high resistance is only a theory at this point. However, I have done nine test flights in the pattern sorting this out over the last couple months, and now it is time to go places instead of experimenting any further. Summer is almost over. I will gladly pay for expensive aircraft plugs to put these problems behind me.
Ron
On Tue, Sep 15, 2020 at 1:11 PM Charlie England <ceengland7(at)gmail.com (ceengland7(at)gmail.com)> wrote:
| Quote: |
Just out of curiosity, did you try a new set of 386s? Any chance the original setup had a different plug; perhaps a 14mm plug with thread adapter? My plane had 14mm plugs on the Lightspeed ignition when I bought it, but I changed to 386s out of paranoia when I found one of the adapters backed out about half way about a month after purchasing the plane.
Charlie
|
| | - The Matronics AeroElectric-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
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