Magneto Shielding

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eschrom

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Jan 18, 2006
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Manchester, PA
Hi Gang,

Can someone tell me the right way to shield magneto wires? I'm trying to eliminate radio static and I know the mag is the problem because the static disappears when I shut it off.

Thx,
Ed
 

Soneraifred

N99FK and me at OSH
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Hi Ed:
I did that a couple years ago. Use 20AWG shielded wire. Connect the center wire to the mag p-lead connection and one terminal of the mag switch. Connect the shield wire to the other terminal of the mag switch and the ground terminal on the mag. I found some good shielded wire fabrication instructions online.
 

eschrom

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Messages
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Location
Manchester, PA
Thanks, Fred. Just to be clear...

Right now the cockpit switch is connected to the p-lead on one terminal and airframe ground on the other, and the shield at that end is also connected to ground. You're saying connect the shield directly to the switch terminal and use no other ground connection in the cockpit? I believe my wire is 18AWG - is that close enough?

Thx,
Ed
 

Soneraifred

N99FK and me at OSH
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Correct. There is no need for the airframe ground. When connected as I described, the p-lead is connected directly to the magneto ground when the mag switch is closed. 18 gauge wire is OK.
 

ChuckerF14

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Nov 1, 2013
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Location
Prescott Valley, AZ
Old thread....but I am new to Slick Magnetos.

I have a Slick 4216. There is a round cover (size of a quarter) on the top of magneto held on by a short screw. Is this the proper ground contact location? There is also a distributor block mounting screw right next to the P-lead. Is that a better place for the ground wire?

Since I mentioned the small cover, is that simply a breather port so that the magneto can vent air while climbing and descending?

ATB,
Chucker
 
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Soneraifred

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The little aluminum cover is a breather cover. The ground connection is the threaded hole next to the p-lead connection.
 

ChuckerF14

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Prescott Valley, AZ
Hi Fred,

I do not have an unused threaded hole anywhere near my P-Lead. I do, however, have a screw that holds the distributor block housing to the main housing. That is likely the hole of which you speak. I removed the screw and it looks as though it will be a fine location for shield grounding....and p-lead grounding via the mag switch and back through the shield wire.

Thanks!
Chucker
 

ChuckerF14

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Location
Prescott Valley, AZ
Okay! It's confirmed. I do not have that feature on my magneto. My serial number is 3010005. Yours must have been a later version.

Thanks for the photo, John. I'll just use the case screw for a ground.

ATB,
Chucker
 

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