I fired up my new ZDZ-80 engine in my newly built Lanier Laser 200 today for sytem checkout and range checks. Radio system is brand new also (Futaba 9CAF with R148DF receiver). Range check with engine not running 50 paces ( approx 150 feet), with engine running 10 paces (30 feet)! Arghhhh! Pulled antenna out of fuselage and noted no difference. Receiver and servos are way back from engine. Ignition and battery for ignition are behind firewall. Spark plug cap is on tight. Ignition shields well grounded. What next? Thanks

Make sure you have a resistor plug in it...

Process of elimination is best in this scenario. First and easiest is to try the transmitter with another plane, do the same same test, and see where you get. Then start eliminating things on the plane itself...servo by servo if you have to.
You dont really state the symptoms though, such as severe glitching, outright loss of signal, intermittent loss of signal, etc.. Maybe a bit of info in that area might help someone here to diagnose.
I can tell you, Futaba is $15 to inspect a reciever, and well.....if it's new.......your probably under warranty too. You might well even think about putting it in a less expensive plane before flying it in your new "pride and joy".
Don't take any chances though, sounds like you've got a beautiful plane there.

WHat I would recommend is that you pull the receiver out of the plane, with servos connected and test it again. I had this happen once and it was WHERE I placed the receiver. I never did know why that particular position made any difference.

Don't forget to check your switches. Vibration can cause them to arc. Move batteries around, try a different receiver. Are you using nyrod for your throttle (and choke) linkage?

I had a similar problem recently, I was using a servo reverser & when I throttled up the elevators would move to the up position as the engine increased rpm's, I removed the reverser & cured the problem.

Gil

Look for any metal to metal connections on the plane. Like 4-40 pushrods with a metal clevis. The vibration will cause interference.

Most devices can be vibration sensitive. It could be the receiver, battery, switch, servo , or the wireing. It does not have to be an RF problem. Replace each component one at a time. I expect you will find it.

Richard, what have you done and has your situation improved.

Should the range check be done with the transmitter antenna removed or just collapsed. I fly Airtronics and the antenna wil unscre to store in the transmitter case.
Brian

For all of you that provided suggestions, thank you. I found the problem and really feel stupid . I should have known better! The metal choke rod that I ran straight down and out the bottom of the cowling was resting against the Pitts style muffler. As soon as I removed the rod the problem went away and now both range checks (engine running/engine stopped) are the same . I fabricated a new choke linkage using nyrod and running it back into my canopy hatch area and out the side. It works perfect. Also, while running ground tests I found several other vibration induced problems (box holding throttle servo came loose from side of fuselage, one aileron with Robart hinges worked loose). Even though I balanced all rotating components there is still a lot of vibration with this big single. The engine runs beautifully and I know this baby is going to fly really well. Sure glad none of this has happened in the air.

cool

Your explanation is right on. Metal to metal contact like that is a radio killer.

Ken

Glad you found the problem and it was so simple. Don't feel embarrassed. It happens to all of us. I have my share. This one sounds like it was a simple fix and I'm sure your glad it was nothing more.