Stephen,
with all due respect to the others, I'd like to add some thoughts and experiences on the subject.
The worst offenders for
actual RF are magneto equipped engines. The older versions being the worst by far. The reason for the italics will come later. Next in line for actual RF are ignition equipped engines that use 1/4" and 14mm plugs. Those are non-resistor type plgs, and breaks in the wire shielding can wreak havoc in a plane, regardless of component locations.
Best of the bunch are ignition equipped engines that use a resistor plug and Bosch shielded wire caps. If all the parts are in good working order, you can darn near stack the throttle servo, ignition battery, and the receiver on top of the ignition module and have no problems. I don't for a second suggest that, though.
Back to the italics. Far too many times I have seen someone pop up with an "ignition' problem that wasn't ignition at all. It later turned out to be a mechanical vibration problem. It has been a wire connector, a loose nut on a metal control rod (not to mention the one on the tx
), a loose wire in a switch assembly, a bad solder joint on a battery, and many other things. The use of quality components that are carefully checked PRIOR to installation eliminates more "RF" problems that you can imagine. The re-use of
older and previously crashed components have been a
prime cause of "RF" noise. Gassers present vibration issues quite different from glow engines, and care has to be taken to prevent that vibration from having an impact on the components used.
There is no problem at all with using metal or carbon fiber rods for throttle linkage as long as you maintain some form of separation of the throttle rod to the carb lever. Usually the use of a simple ball link with a plastic housing or a nylon clevis is more than enough at both ends of the rod. Being certain that everything is tightly connected and the use of some form of thread locker on nuts and bolts to prevent things from coming loose helps a bunch.
With todays ignition systems, the condition, installation method, and quality of the components used have far more impact on "RF" than their location in relation to the engine.