buudy22

Ok fellas,

I could really use some help on this one.

The setup is in a Gee Bee with a gasser on it. The setup is a simple 4 channel FM. We have the elevator on 2 servos with a "y harness" and the aelerons as well. The gas engine has a magneto.

The receiver is located away from the battery and servo...and the antenna is ran down the inside of the fuse in a tube.

Here is what is happening.
We turned it on...and the servos went to full throws...they continue to bind, and don't really respond to the radio.
We figured out that if we unplugged Channel 4 and plugged it back in, the receiver would start responding normally. It even passed a range check, but 5 minutes later all the servos when to max throw and started straining again.

Anyone have an idea what the problem is? We can't figure it out.

Thanks all for the help!

A.T.

What motor? DIY conversion of home tool?
Check sparkplug is an "R" resistor type and the lead is fully shielded.
Wrap RXbattery in alloy foil and separate well from both motor and RX.
What is fuse made of? shielding antenna?
As RX aerial is inside tube & fuse, a material that could be shielding such as C/F?
Any steel push rods/wires close by that could be eitherparallel to antenna or rubbing metal to metal?
No metal pushrodto carburettor.
Much more info under sections:
"Petrol engines, carburettors and ignition systems"
"Giant Scale, Large RC models, Twins & Multi Engines"
"Receiver - FAQ, guides and aids to best reception"
"Glitches & Jitter in Receiver, Servo & ESC - causes and cure"
at
Alan's Hobby, Model & RC FAQ Web Links

Regards
Alan T.

aghost

My Feedback: (13)

When you write " We turn it on", what exactly do you mean. Tx and Rx, or just RX, or Tx, Rx, and engine?

What size, type of Rx battery are you using.

Are the Tx and Rx new?

buudy22

Here is the procedure we have gone through.
1. Turn the radio on
2. Turn the plane on (receiver)
3. Watch it malfunction
4. Unplug servo on channel 4 and plug it back in (stops malfunctioning)
5. within 5 minutes it is doing it again.

Wether the engine is running or not...it does not matter. The problem will persist without the engine running. The engine is a zenoah g26 with a magneto. It has the correct spark plug in. The receiver is well separated from the battery. I do not believe this is interference...I think it is a short somewhere. I was hoping someone else had experienced this and could give me a heads up.

Just to offer some background. This is in my brother-in-laws plane. We have both been flying for 15 years. I'm not saying it isn't something stupid that we are doing...but we do know kind of what we are doing. What do you guys think. Thanks for the input so far.

A.T.

"Y", switch harnessand Extension leads are common causes of problems, even if new.
Try plugging servos & battery direct to RX on bench and see if problem is replicated, if not try RX back in model with replacement leads.
Also how is RX aerial placed in relation to rudder pushrod or cables? change angle/direction
What model RX :FP-R127DF
Alan

jaka

Hi!
First you must check how the radio functions without the ignition system !
You should have 100m range with the transmitter antenna fully collapsed ! If not it's either the receiver that needs triming or the receiver batteries that needs replacing.
Some advise!
Use a 4,8V or 6V /2000-2800 mAh NiMH battery and charge it with the wall charger that you got when buying the radio!

pilotpete2

It sounds like the servo on channel 4 (rudder?) is trying to tell you something, do you have another servo to swap it with?
It sounds as though the problem exists with or without the engine running, so since it's a magneto engine and you get the condition when it's not running, that pretty much takes ignition interference off the table.
Pete

buudy22

Great feedback guys. I'm thinking about the 4th channel thing. I agree. Not to mention the servos are on a "y" connector. We'll swap out both servos...if that doesn't work, I'll replace the "y".

The radio equipment should be fine. This is a brand new set up. We've even swapped recievers and had the same problem. Must be servo related.

Thanks guys. I'll post an update when I have something.