A

apatti

Well Known Member
All,

Is anyone out there experiencing interference from their HID lights with magnetometers mounted in the wingtips? I researched this and only saw where one person building a -10 had asked this question in an existing thread. However, no one answered him. Also, I do know there are alternative magnetometer mounting locations in the aft section of the fuse. But, I'd really rather use the wingtip if possible.

Thanks,
 
My Magnetometer is in the fuse, but I can tell you that with a Comm antenna in one tip, and Nav in the other - and HID's on both sides, the Comm gets trashed completely when the HID is on, and the NAV works fine. I would be nervous (as you seem to be) about the HID and Mag in the same tip.
 
Thanks for the reply, Paul. I have found that I get "nervous" about a lot things regarding this build that turn out to be non problems. So much so that I feel I can't trust that nervous feeling when it comes up. I think your intuition becomes stronger and more reliable after you have gone through the whole process and been flying for a year or two.

Lately, I have been working on mounting the empennage and playing with the ailerons and such. These are parts I haven't touched in five years. It is funny to look at certain parts and remember how much I agonized over some issues that came up. Like on the HS... I over-torqued an AN3 bolt (I was learning to use my new torque wrench) and the head broke off. I was sure the HS was trashed. Van's told me to drill out the AN3 and put in an AN4 bolt in its place. Problem solved. No big deal. "Build on!" I wonder how much time I have spent fixing non problems?

I guess the best thing for me to do is get a compass and see if the HID light interferes with it. I'll report back here what I find.
 
I have Duckworks HID lights in the wing, and also in the wing tips. Yes I look like a UFO at night...about as fast as one too :D. These lights had trashed an Archer tip mounted nav antenna, and I wound up installing a Comant cat whisker nav antenna on the fuselage belly at the tail wheel. It works great, providing nav input to both an SL30 and a G430W.

So when I upgraded my panel to AFS equipment, I made the decision early on to locate the magnetometers in the aft fuselage, just forward of the 'static port' bulkhead. The biggest problem with locating the magnetometers in this location is alignment....it's not a lot of fun working in this area, especially in an -8; the AFS spec is within 0.2 degrees in all 3 axes. But while it was a difficult installation, they have performed very well in this location. The tips would have been a much less difficult installation, but I wanted to do the installation only once, and I figured the fuselage location was a safe bet. YMMV
 
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I got rid of noise from my HID lights (RV-7a, one in each wing) by putting braid over the cable from the ballast to the lamp, and using a noise filter on the power leads to the ballast. Before I did this, the hash from the lights would break the squelch on a handheld radio 5 feet away. Afterward, I had to hold the radio next to the light to hear any noise. The right wingtip has an Archer Nav antenna in it and I have no problems with interference.


Mark Olson N407V RV-7A, flying
N16XV F1-EVO, almost flying
 
Mark, what type of noise filter did you use?

When I upgraded my panel to the AFS magic boxes, I completely rewired the aircraft, as I thought that would be easier than trying to fish wires along with existing wire bundles in the wings and other difficult areas. Because I had a little HID noise with the old installation, this time I decided to run shielded wire to the HID lights (2 conductor shielded - mil spec CHEAP on eBay :)) and run grounds back to a common ground point. Previously I used unshielded and a local airframe ground. In the old installation I would get a little noise in my headset. Now, I get a very minor amount of noise while the lights heat up, but after about 10 seconds they are noise free.
 
Well, tonight was the experiment with the compass. I used my left wing (since the right wing where the magnetometer will be doesn't have the HID light installed yet). I powered up the HID and LED Nav lights. I moved the compass all around the area. I even held it right up against the wires feeding the LED Nav lights. Also, I moved the compass into the bay where the HID lamp and the ballast are. I never saw any movement of the compass needle. I made sure to watch carefully during the HID warmup period. Still, no movement whatsoever.

So, I am going to go ahead and put the magnetometers in the wingtip. I will try to remember to report back here when I power up everything for real.

As always, YMMV.
 
My HID's in Wingtip w/Magnetometer

My Magnetometer is located with my HID in the Wingtip and I have not had any interference. You can see in the pic that I kept everything as far forward away from the Magnetometer as possible.

DSC01076.JPG
 
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