Edwin:
I wondered about those. I surfed the web a bit on the subject.
It seemed like these needed to be selected for the type or? frequency of the EMI, is that the case? How does a guy know when he has the right ferrite choke?
Where would you put these? On the beacon circuit wires? On the lines from the receiver to the servos and/or to the power board? On the lines from the power board to servos?
I have found some possible shielding: I could replace the 38 inches of two wire twisted from the nose to center of the fuselage with something like this:
http://www.ebay.com/itm/priced-per-f...item51a00c57be
I could probably snake this around the run from center fuselage to tail:
http://www.ebay.com/itm/Coaxial-Cabl...item3359a06dc6
But, it would be very difficult to do anything with the length of wire within the fin, so I worry about whether or not these would solve the problem.
I found a 9v flashing system listed at Radical RC and I have sent Dave Thacker an email in hope that unit might solve the problem:
http://www.radicalrc.com/category/Lighting-System-267 (last item on the page, High Sky strobe).
In 22 years in rc I have never had this problem before.