Recently I have been experiencing problems with radio interference and I can’t figure out if it is internal or external… What I am looking for is some suggestions for eliminating the internal stuff or narrowing down to what the real cause is.

Here is a description of my setup:

Futaba 6 EXA TX on Ch. 60 (Saving for a 9CAP)
Futaba 127DF RX
5 Hitec 5625MG Digital Servos for the control surfaces
1 HS-81 for the throttle
2000Mah Nimh 6 volt battery
RAM Onboard glow starter connected to a standard Y harness on channel 3
MPI Miracle Y for elevators
24 inch servo extensions for rudder and Ailerons
12 inch extension for throttle
2 - 6 inch extensions to plug the ailerons into
MPI Voltage regulator (Removed at the suggestion of someone at the field)
Standard Hitec switch
Saito 180 for power

Okay here is what happened, Yesterday while flying I experienced two glitches so I landed and removed the voltage regulator. I range tested well beyond the 100 feet for a normal range test and all was solid… After sorting out an engine problem I was running it on the ground and after about 5 minutes or so of running the controls started glitching… Rudder, flaperons, ailerons and throttle all moving without my input. I was standing approximately 2 feet from the plane with the antenna about halfway up. The glitches lasted about 5 to 15 seconds and stopped and never happened again. Only one other person was there and they were on Ch. 23. This movement was enough that it could have easily caused a crash. Others have reported getting radio hits at this field but I have flown there dozens of times without a problem. I suspect these problems are external, but I was looking for any suggestions anyone might have to offer to isolate the problem.

I suspect that the extensions might be a problem due to their length… This is my first plane of this size so I am still in the process of learning my way around.

Since I have $1200+ invested in this plane I really want to know what is going on before I lose it…

I hope someone has some suggestions

Thanks,

I too have had this on several occations with digital servos. Fortunately, it only happens on the ground. Some say ashalt, etc. I zip tied all of my servo wires apart, so that none are touching others. Not saying this is the solution, but so far it has worked for me! Also, where is your antenna routed? I ran mine out the bottom away from the switch harness ( which will definately cause twitching!) and through a clear pushrod tube on the bottom of the fuse-or inside the fuse and out the tail. Good luck

I believe your problem is using a 6 volt battery pack. Futaba radios do not seem to like the higher voltage. A friend of mine was experiencing tail surface glitching on his F-104 which always occurred when the plane was turned on for the first time after a fresh charge. He uses 4.8 volt packs but after a fresh charge, these batteries will produce well over 5 volts for a period of time. His glitching always went away after the receiver was on for a few minutes and the voltage dropped down some. He was using a Futaba 8UAP PCM radio. PCM radios won't show the glitching from interference (i.e. from loss of signal), they just go into failsafe mode. So, I can conclude that his glitching was not from any external source since his radio never went into failsafe.

I think your problem will go away if you convert to a 4.8 volt battery pack. If you are concerned about current drain from the digital servos, I suggest a higher mah rating on your onboard pack like the 3000mah packs I use in my jets.

If you don't think this is right, I suggest you post your question in the Futaba Radio Support subforum and see what they have to say about it.

I agree, the problem is likely external. Especially since it range checks OK and the glitches only happened once. Everybody uses extensions and puts the antenna inside the fuselage. I would experiment again with the engine running to determine if the glitches are induced by the engine.

Tom

I'm not sure why, but this sometimes happens when the Tx and Rx are too close to each other.