Hi,

I'm getting RF interference using my 42cc petrol engine. The radio works fine when the engine isn't running (even if ignition power is turned on) but as soon as I start it up and get about 40 feet away with Tx the servos start jumping. I am not using any metal connectors and receiver is positioned well away from engine/ignition. I have tried moving Rx and antenna all over the place but it's not making any difference. I am using a PPM Futaba setup with a Resistor spark plug.

Anyone have a solution to this frustrating problem?

Liam,
I don't like to have any metal rods, servos, RX batteries or RX switches between the reciever and the engine. You may want to get a new resister plug and maybe reduce the gap to 0.020"( .5 mm).

Regards, Dave

liamkirkham,

I just went through this myself and it took a couple months to find the problem. One of the most important areas to look at is the ground wire from the rubber boot unless your using a Bosch cap. Make sure it is grounded well to the block, a good place for the ground wire is to wrap it around the spark plug where you would put your wrench to tighten it and secure it with a hose clamp. If this is your first gasser you may think you have no metal to metal contact but you might want to take a second look or have someone else take a look at it. A second pair of eyes can sometimes see things in a different way. I know, that was one of my problems. Another thing you can do is to have the engine running and let someone walk away with the TX and once it starts going crazy disconnect one servo from your receiver. If your control sufaces are still glitching then plug it back in and try another. If you diconnect a servo and the gitching stops then you have found a bad servo. The thing to do is try everything you can that doesn't cost you any money first and hopefully you'll find it. My plane did the same thing as yours, range checked fine with the engine off but as soon as I started it up and got about 50' away it went crazy. That tells you that it's ether RF or vibration. My EI was bad.

Thanks very much.

Will give it all a try tommorrow and let you know the outcome.

Liam,

I just solved my similar problem, but had to change the engine to do it. It is a long tale and I will not hijack your thread by going through it. The suggestion to check ignition ground is only good if you have an electronic ignition. A mag coil ignition does not have such ground. At least my Quadras don't.

I had run the check suggested above and determined that the interference was coming in through the aileron leads. I already had noise traps on them, but I guess the rf was just too much. I replaced the wing extensions with shielded leads to no benefit. In the end the engine change was the solution. Though the problem entry was the ailerons. The problem was coming from elsewhere.

Good luck,

Bedford