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  #1  
Old 02-12-2021, 06:12 PM
smithflys23 smithflys23 is offline
 
Join Date: Feb 2017
Location: Jupiter
Posts: 202
Default RV8 Tail Strobe Shield Ground

I am in the process of correcting my Aeroled strobe wiring. Originally, it was grounded to the airframe causing headset noise. After corresponding with Aeroled, they recommend grounding each strobe at the main ground block. They also recommend grounding the wire shielding to the frame of each light, and then grounding the shields at the main ground block. The wing tip lights were fairly straight forward. The tail strobe is causing me problems. I ran the strobe ground to the main ground block, but I can not figure out a good way to ground the shield to the strobe frame. The mounting location in the fiberglass fairing doesn't present an easy solution. I thought I could put a ring terminal behind the top screw, but that wont allow the tail of the light to fit in the mounting hole. I bought a longer mounting screw thinking I could put a nut on the back. The fairing is too narrow at the top to allow the nut.
Does anyone have a suggestion on how I might ground the wire shield to the strobe frame? Your help is appreciated.

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  #2  
Old 02-12-2021, 09:30 PM
mfleming's Avatar
mfleming mfleming is offline
 
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Location: Joseph, Oregon
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It's my understanding and the way I wired all my AeroLEDS lights is that the shield ground is different than the case ground.

The black wire from the light attaches to the shielding around the 3-20 wire, which runs the entire length to the instrument panel, then gets converted back to a black wire that then grounds to your IP ground bus (or whatever your using for IP grounds)

The ground to the light case is to a local airframe ground just to drain off any built up charge and should not be connected to the shield ground.

That's how it was explained to me anyway. I also asked about ground loops and the factory told me the case does not have enough energy to produce a ground loop.
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RV-7 Slider #74572
Started 11/2016
Empennage completed 11/2016 (sans fiberglass)
Ailerons and flaps completed 3/2017.
Wings completed 12/2017
Started on QB fuselage 01/2018
Sliding canopy mostly completed 10/2020
Wiring in progress
Donated for 2021 and so should you
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  #3  
Old 02-13-2021, 05:29 AM
smithflys23 smithflys23 is offline
 
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Quote:
Originally Posted by mfleming View Post
It's my understanding and the way I wired all my AeroLEDS lights is that the shield ground is different than the case ground.

The black wire from the light attaches to the shielding around the 3-20 wire, which runs the entire length to the instrument panel, then gets converted back to a black wire that then grounds to your IP ground bus (or whatever your using for IP grounds)

The ground to the light case is to a local airframe ground just to drain off any built up charge and should not be connected to the shield ground.

That's how it was explained to me anyway. I also asked about ground loops and the factory told me the case does not have enough energy to produce a ground loop.
When I contacted Aeroled, they recommended grounding the shield on the light frame, and then the main ground block. The head engineer said this may be a bit overkill, but would ensure no ground loops, and that the shield would act as an actual shield.

Even if I did ground the light frame locally, Id still have the same problem. I cant figure a good way to get the wire attached to the light frame, and then through the mounting hole. The mounting hole is too small, and Im not sure how much material I have in the event I tried to make the hole larger.
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  #4  
Old 02-13-2021, 08:34 AM
sf3543 sf3543 is offline
 
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Location: San Antonio, TX
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Strip a piece of wire back about 1/2 , fray out the strands to flatten the wire, and stick it in the screw mounting hole of the fairing from the back.
Insert the screw as normal and it should screw into the wire as the screw tightens down inside the fairing. You can install a connector on that wire which is now connected to the screw and light casing.
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  #5  
Old 02-13-2021, 08:46 AM
smithflys23 smithflys23 is offline
 
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Quote:
Originally Posted by sf3543 View Post
Strip a piece of wire back about 1/2 , fray out the strands to flatten the wire, and stick it in the screw mounting hole of the fairing from the back.
Insert the screw as normal and it should screw into the wire as the screw tightens down inside the fairing. You can install a connector on that wire which is now connected to the screw and light casing.
So basically, the wire strands would wedge themselves between the fiberglass screw hole, and the screw?
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  #6  
Old 02-13-2021, 09:10 AM
Carl Froehlich's Avatar
Carl Froehlich Carl Froehlich is online now
 
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Overkill.

Here is how I wired the AeroLeds on two RVs:
- Each nav/strobe is fed via a 3 conductor, #20 shielded wire. The three conductors are for nav power, strobe power and sync wire. The shield provides the ground.
- The early AeroLeds (2011 time frame) had a bad RFI issue with the wingtip units (that has since been fixed). At that time however I solved the RFI issue with adding a small aluminum backplate to the inside of the wingtip. The nav/strobe ground wire was cut short and anchored under the nav/strobe mount screw inside the wingtip - so that it connected to this backing plate. The shield from the feed line also connected to this same anchor. The effect was the ground lead was very short, and connected to the nav/stobe case via this anchor.
- For the tail nav/strobe no such backing plate was used - as it was not needed. Just the three wires plus shield to connect.
- The feed line shield ending at the panel (at the associated switch breaker) with a pigtail going to the firewall ground.

End result - zero RFI.

Carl
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  #7  
Old 02-13-2021, 01:49 PM
sf3543 sf3543 is offline
 
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Quote:
Originally Posted by smithflys23 View Post
So basically, the wire strands would wedge themselves between the fiberglass screw hole, and the screw?
That's correct
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  #8  
Old 02-13-2021, 05:39 PM
smithflys23 smithflys23 is offline
 
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Quote:
Originally Posted by Carl Froehlich View Post
-Overkill.

Perhaps, but this was the recommendation from Aeorled

- The early AeroLeds (2011 time frame) had a bad RFI issue with the wingtip units (that has since been fixed).

I believe these are the multi voltage lights, which is what I have. I think this is why they recommended the "overkill"
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Last edited by smithflys23 : 02-13-2021 at 05:52 PM.
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  #9  
Old 02-13-2021, 05:43 PM
smithflys23 smithflys23 is offline
 
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Here is what I ended up with.

I appreciate all of the replies!

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