I am having fits trying to solve my ignition noise problem. Whenever the engine ( NIB Fuji 64 EI ) is running , the range I get is no more than 25 ft with TX antenna collapsed. I am using a FM receiver to reduce noise as much as possible before switching to PCM or the MPX IPD type rcvr. All the rcvr components and servos are at least 14 inches away from the ignition unit and its associated components. THe spark plug is resistor plug .

With the gasser engine running on a test bench, I placed the plane in question ( GP Christen Eagle ) as well as a second plane 2 to 3 ft ft away and checked both their ranges. Its still only about 25 ft for both planes . Now this indicates to me the problem is with the engine and the ignition unit because the two planes are electrically isolated from the running engine . I even bypassed the engine kill switch in this experiment .

Not sure what to do next. Maybe I should add RF chokes on all the servo leads ? Will opto isolators help? Plse advise where I can buy RF toroids and what frequencies to use to supress the ignition noise? Thanks