There probably isn't anything wrong with your display. EMI can be a bit hard to predict, but here's the full story (the below is a repost from a couple other threads)..Unfortunately, all of the engineers who could possibly weight in with a bit more helpful advice are at Aero Friedrichsafen at the moment. I'll ping them to see if they can offer anything else, but, it will be at least a few days before we'll have an update.
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We performed tests at a fully certified lab that Boeing (we're in the Seattle area) also uses. SkyView meets/exceeds RTCA DO-160F, category H, for aviation COMM, NAV, and GPS bands. Cat H is the hardest to pass, for devices that are in direct view of an antenna. We did our tests with a full SkyView network with long cables, modules, servos, GPS antenna, battery, etc. As some of you have found, the display by itself is "quieter" than a whole network, but the whole network does pass including all accessories and wiring.
Certification requirements do allow some noise output. No electronics are silent, and the standards do have noise limits. This is why you will see squelch level differences when you have a SkyView on vs. off. We're by no means claiming it does not output RF noise at all.
We have also tested a D100, and it also passes by a substantial margin. We have never heard of EMI issues with a D100, so it appears that some customer installations are more sensitive than the FAA requires.
RF interference can be a hard issue to track, and wiring configuration, antenna location, antenna ground-plane, and general dimensions and construction materials of the airplane can make a big difference. Even manufacturers of certified planes struggle with these problems. So we're thinking that some installations are more sensitive than others, which is why not every customer is experiencing issues.
We do a lot of work on EMI, and as proved recently, we do pass the certification requirements for avionics. Even though that is true, we're committed to making SkyView work well for everyone, so we'll continue to work on improvements, including hopefully some hints on wiring practices that may help a lot.
Just the same, the good news is that we lab-tested and field-tested filters that are simple plug-in devices on the D37 and D9 connections (for use on early SkyView displays only) that offer a large amount of noise reduction. It performed in the field as well as it worked in the lab, solving any noise issue, and we should be able to offer it shortly. Newer SkyView displays have this filtering built into them already.