RFI from EFIS/EMS systems?

[AntiGravity]

I received a phone call tonight from a local guy that is helping me with my panel. He was concerned about possible RFI from the AFS Advanced Deck that I plan to use (or any other EFIS/EMS for that matter) causing interference with radio. He relates how another builder has such bad interference that he has to shut off his EMS to use his radio! I've never heard of this being an issue in well designed electrical systems here on the VAF forums but told him I'd ask around. So, for those of you flying, especially RV-8s, and will EFIS/EMS systems in their panels; anything to report? Any issues with radio clarity? I have no concerns myself about these units, but wan;t to be able to put this guy's mind at rest.
Cheers,

[rleffler]

Of all the installations that I'm aware of, I've never heard of anyone having such a noise problem that they had to turn off their EFIS to use their Com.

Without any details, I would suspect that other aircraft has some major issues with wiring. Ground loops, improper grounding, and non-optimial wiring routing are usually the culprits and can be fixed.

Keep noisy wiring away from audio and nav/com wires. Just take your time wiring your aircraft and ensure that you appropriately ground everything and avoid ground loops and you should be fine.

[AntiGravity]

Originally Posted by rleffler

Without any details, I would suspect that other aircraft has some major issues with wiring. Ground loops, improper grounding, and non-optimial wiring routing are usually the culprits and can be fixed.

My thoughts exactly Bob, so I intend to tread carefully here, and hence my question. Of the nearly three years in construction and hanging around these forums I've not heard anything untoward along these lines.

[PaigeHoffart]

I think any EFIS is probably going to raise the noise floor on your comm a little. Depending on how well its designed and how well its installed, you may or may not notice. Jerry Thorne talked about it in his kitlog (or maybe it was the kitlog of Wendell Folks, also on Jerry's site) I know the original Dynon D10 had issues that required an external filter in some installations, and I've heard the older Blue Mountain systems could sometimes be very noisy.

I think all manufacturers are aware of the issues now, but you'll still probably lose a little bit of reception range. I know on the SL-30 there is a capability to display the noise level; when I turn my Dynon on it goes up, but not above the squelch threshold.

Paige

[N395V]

The early BMA G4 units had a severe problem with interference, I believe due to the fact that the capacitors installed were of the wrong value. The problem was so bad you had to turn off the efis to use the unit. This has since been corrected.

On other installations with this problem the keep alive wire or AP disconnect wires were run but not connected providing a great antenna for ther RF interference.

If you end up with interference a fix that works well is a conec filter that is a DB 25 or DB26 connector with capacitors built in.

The DB25s can be ordered from Digikey, BMA has a stock of the DB26s


or

http://www.conec.com/section1/c/new....art=1-12&dia=1

http://www.conec.com/section1/c/new....art=1-14&dia=1


I have not heard of any problems with your particular unit and indeed most problems of this nature stem from installation errors.