Discovery Lite...What am I doing wrong?

[Rynoth]

David, how are your efis and radio grounded?

By that I mean, do they share a wire, do they ground separately to a common ground block, through the airframe, etc?

[Stogie6]

David, how are your efis and radio grounded?

By that I mean, do they share a wire, do they ground separately to a common ground block, through the airframe, etc?

Ryan,

I will have to go thru my photos and ask my dad. The plane is in his hangar in Lockhart, TX. I am over here in the Memphis area. If I had to guess, I would say we have wired to a common ground. That may be an issue. I will go back and read MGLs recommendation as to how to "not wire" the product. Sometimes it is hard to get old school builders to do something they are not accustom to doing...
Thanks for the reply. How goes your build?

[gammaxy]

I agree that you should probably check the grounds, but I noticed a similar problem with my MGL Stratomaster and just think it's electrically noisy and there's only so much you can do about it. This is purely my opinion and might be contested by MGL, but I suspect some of the more expensive EFIS units aren't as noisy. When I was having the problem you describe, I could hear the effect of my hand passing by the screen of the EFIS, and every button I pressed and every mode the EFIS was in would give off a different characteristic sound. You might try adding ferrite beads to the power wires feeding the EFIS. Nothing I tried fixed it, BUT I don't think it was as big a problem as I initially thought.

I noticed the problem when I was working on the airplane at my house. Since I could not pick up any radio stations, I had the squelch set really low. I believe the automatic gain control in the radio was amplifying the noise from the EFIS making it sound like a big issue. Once I got to the airport and could tune to the AWOS and got the squelch set to ~10 I've never noticed the problem again. Basically, when I am picking up an actual signal, it's amplitude is so great that the noise from the EFIS is completely blocked, but if there's no real signal on the radio, the amplifier is so good that it will take even a tiny amount of noise and make it sound pretty bad.

[jjbardell]

Also make sure the florescent lights are not causing interference. They can with the radio and EFIS. It depends on the ballast type in the lights. Mine trigger both the EFIS and v6.