European manufactured Electronic ignitions are required to be designed to a very stringent safety and RF interference standard. That's why they have BOTH a shielded cap/lead and a resistor spark plug. The ignitions that come with ZDZ, RCS and ROTO gas engines all have this "CE" Mark (Conformité Européene) certifying that they have passed all the required tests. It is kind of like a combination UL (safety) and FCC type B certification (interference), expect that the European standards are more stringent.

The purpose of the resistor, in the plug or in the lead, is to slow down the rise time of the high voltage pulse. This has the effect of reducing the amplitude of high frequency noise that interfere with the operation of receivers. For a simple (and not entirely correct, but you will get the idea) explanation see: http://educate-yourself.org/be/upper...d22may02.shtml


David Garrison

RC Showcase

ZDZ, RCS and ROTO gas engines