Ferrite Ring Placement

[Derek]

Although the weather here is still quite cold and I'm not prepared for cold flying, I thought I'd get back to finishing up my FPV plane. There seems to be some controversy whether braiding the servo wires it better or using ferrite rings is better for eliminating RF noise. Last season, I did fly my FPV plane (with all the leads braided) and for the first few laps, the plane was doing just fine. I flew over an area of the field that I've not flown over before and the plane got ridiculously unstable and then it happened....no control and down the plane goes. Destruction!!!

I've built a new one and I'm using all the same electronics as before. I still have all the wires braided and I ordered a bunch of ferrite rings. 50 to be exact...they are inexpensive, lol. I'm planning on adding a ferrite ring to each of the braided wires but let me ask you this...does it matter where the ferrite ring is placed? Should I put them near the servos and near the esc or should I put the ferrite rings near the plug that connects to the rx? Or, does it even matter?

I sure hope that 2015 brings me much more than 6 FPV flights.

[Tony]

Hey Derek, ferrite cores are useless unless you are having known RFI or EMI interference. They only suppress high frequencies. As for placement, they should be put at the ends of the cable. Question is, are you having known RF or EM interference. I've had an oscilloscope on all the data lines from the gyro to servos and RX and never seen any HF interference at all. This was on my 450.

[Derek]

In all honesty, I'm not sure what caused the crash. The first few minutes were going along flawlessly. Then I ventured out to a different section of the field, still very much in line of sight, and the plane just dove to the ground. Upon recovery, the control surfaces still worked and the motor would run. I was just thinking that there was something in that area of the field that "shot me down". I was hoping (guessing) that the ferrite rings may help.

[Tony]

Unless you flew under a HV power line or some other high energy transmitter I can't see how RFI or EMI could have caused that crash.. Take another aircraft to the same field and see if it does the same thing, could be an idea... I have an emi detector I designed myself which would have done the trick to detect magnetic fields. You can buy them quite cheap... Might be a bit extreme though...lol

[Derek]

I suppose to could take one of my lesser valuable planes to that area and see if anything happens....when the weather warms up a bit, of course, lol

[Tony]

I presume you didn't fly under power lines then....lol

[Derek]

No. There weren't any power lines within a mile or so.

When I first started flying, my original flying field had a "death spot". This one area in the field shot down two of my planes. I stopped flying there.

[Tony]

Funny you should say that Derek, on the field I fly at it has the same death spot, when I flew heli over it it lost altitude very quickly, there's a couple of my vids show this effect... Weird eh...

[pvolcko]

Bermuda Triangle of Indiana!

That is odd. No metal light poles or anything else in proximity to your line of site with this spot? I suppose mounds of dirt and other stuff on the ground may be able to cause some odd reflections that create a null spot.

[Tony]

I've got an idea for uA Derek, get hold of a metal detector and see if there's anything underground... Brilliant....lol, you never know...

[pvolcko]

Probably a top secret ELF site underground there. We'll notify your wife if you go missing for a few days.

[Derek]

That's funny!!!

[Tony]

haha, nice one Paul, i like the "Few days"....