buzzard bait

I have a 1/5 scale Thomas Morse Scout that has never flown due to radio problems. With the engine running the servos make erratic movements. Everything is rock steady till the motor starts. The builder tried substituting nylon connectors for metal on all the control wires and put epoxy on the connections between the bracing wires and other parts, but it hasn't helped. The rx antenna is running out one wing perpendicular to most of the wires and control cables.

The rx is an old Airtronics. One club member thought that a modern rx like the Berg micro or FMA M5 that "remembers" the particular signal of the tx might do better. Who can tell me if this is true or if there is some other rx that will help? I'm really not hopeful about finding the source of the problem and would like to just use a better rx.

Thanks,
Jim

solo_one

My Feedback: (13)

I seem to remember someone in my club having a similar problem, and someone reccomended that he zig zag the antenna wire rather than having it perpendicular to any other wires. His interference came from the antenna running too close to his pull-pull wires for the rudder.

dirtybird

My Feedback: (5)

Try this:
Remove the engine and install it on a test stand. Sit the airplane near the test stand and run the engine. If you still have the problem its caused by an RF leak from the ignition. If you don't have a problem its the wires in the rigging.

buzzard bait

I have substituted two rxs and gotten improvement. The JR 700 was the best, but there is still a very strange problem. I'm starting a new thread for it. Jim

Rodney

Make sure that EVERY metal to metal contact is very tight. Any metal to metal vibration (movement) can cause this problem. You do have a non metalic push rod on the throttle, correct?

buzzard bait

Yes, it is a nylon clevis on the metal throttle arm. Every place a flying wire is attached is epoxied and every clevis is nylon.

Jim