goose_wrench

I have always flown 72 mhz radios without any issues over the years, But I came across a weird problem today at the field. My son and I built a Senior Kadet kit and made it a bolt on wing and added built up barn door ailerons. We have flown it several times with no issues but today I noticed something weird. We just fueled up and did our control check and was getting ready to start the engine. I set the radio down under the right wing on the stand. Normally I have the antenna collapsed when starting the engine so as not to catch it on anything and extend it when getting ready to move the plane from the bench. Well today the antenna was fully extended and after I set the radio down the right aileron went crazy doing what ever it wanted. If I moved the antenna over the left wing the right aileron would still act up. None of the other servos moved or acted up when I would place the antenna close to them. i have long servo extension leads on the aileron servos Could that be my problem. The system passes a range check when I walk out about a hundred feet with the antenna collapsed. We didn't fly because I wasn't sure what the issue was. Any advise or comments are welcome. The radio is a Futaba 6EX if that helps any. I have thought about switching to 2.4 but I have not had any issues to do so yet. Thanks in advance.

GREG DOE

The transmitter was swamping the receiver. The combination of a fully charged transmitter battery, and the extended antenna were too much for the receiver. Keep in mind that our radio systems depend on the sensitivity of the receiver, and not the power output of the transmitter to achieve their range, so when they are close together, the radio single can overwhelm the receiver. It's possible that the long servo extension is picking up the signal too, and contributing to the problem. Try rerouting the antenna, and get it as far away from the aileron extension as possible. You might also try turning your transmitter on for about 30 minutes, to see if the problem goes away. When leaving your transmitter on for extended periods of time, pull the antenna out. They used to say that that's better for the electronics. Good luck, Greg

AA5BY

And... sometimes it can be the RF swamping a single servo. And... the long lead could be the reason as it acts like an antenna carrying the RF into the servo or back into the receiver.

2.4 systems also experience it. Sometimes binding is frustrated until the TX is placed a few feet away from the RX. Sometimes servos jerk when the TX is too close.

On 72 mhz, something that i do when noting any control concerns is turn the RX on without the TX and monitor the frequency for any jittering of the servos.

skylark-flier

I also fly only 72MHz units and I've noticed for many years that when I hook up the glow plug from my power panel I get dancey servos. Once the engine is started and the wire's disconnected it always goes away.

Rodney

It is not swamping, if so all the servos would be acting up, not just one. Very highly the problem is that the servo extension on that servo has poor conductivity at one or more of the plugs. Try just un mating all the connection on that servo from the reciever all the way to the servo and remating them a couple of times to scrub any oxides or corrosion off the connections. Chances are that will cure the problem. Let us know what you find out please. It is always nice to know what the real problem turns out to be. I've had many of the popular brands of transmitters/receivers and in 50 years of use have never had a swamping problem.

Gray Beard

My Feedback: (-1)

When I read this early this morning this was my thinking too. I have run into some bad leads right out of the package once to often and gave up using them. I cut and splice the servo wires to avoid the plugs.

goose_wrench

Thanks everyone for the advise. It will have to be next weekend before I can pull the leads and try it. I promise I will post the results. I have always had great advise and lots of help from everyone on this forum and I am very appreciative for all the help. I wanted to try it today but ended up making wooden gears for my daughter's simple machines project for school that turned out not to be so simple on my part. Thanks again.

flyinwalenda

My Feedback: (5)

If there is slack in the servo extension try tying a few knots in it.

GREG DOE

Goose_wrench. Is your daughter doing Science Olympiad? That program has a B Division "Simple Machine" event this year.
Rodney makes some good points that I didn't consider, but I have to disagree on the Possibility of "swamping". I've been in RC Airplanes for a long time too. I never flew Single Channel Carrier, but I started with Single Channel Tone in the late '50's. I followed that with Reeds, and AM, and FM Proportional. Today I fly mostly 2.4 Spread Spectrum. I have personally seen, and experienced swamping. There is a good possibility that the extension is the problem, and it could be from poor connections, but it also could be acting as an antenna too. There was a time when all the big gas airplane guys used extensions with "chokes" or "filters" in them. I don't know if they are still popular or not? If all else fails, you might try one of them.
Skylark-flier, Your experience is probably do to RF Noise from the electronics of your power panel. Or simply sparking in the connection to your plug. We used to isolate all metal to metal contact to reduce it, especially when we flew AM radios. I've also seen a lot of "jittery" radios, that got better when the glo plug battery was disconnected. Greg

Luft-Gangster

Something also to consider. About 15 years ago a new member at our field had a interfearance problem on 72 MHz on channel 42 or 44. His plane would just lock up and spin in. Controls would all fully deflect on way and stay there. He was a electrical engineer and was determined not to let this beat him. After it happened about 5 times in one season it was noted that he was the only one in our club flying on that channel and the only one having the problem. It was found that a commercial user was on that channel once a week transmitting between Detroit and Grand Rapids and we were between. Solution was not to fly on that channel in the 72 MHz band at our field. No one else has had that problem at our field. The electrical engineer quit the hobby still trying to use the same channel.

goose_wrench

Greg, No this project is not for science olympiad. This thank goodness is just a plane ole science project. My third grade daughter is doing the don't bug me part of the science olympiad and the amount of material she has to study is a little overwhelming. Thank goodness the competition is this weekend. Did I also mention she is as head strong as her mother and when those two disagree on some information watch out.

goose_wrench

Luft-Gangster, I don't think that is the problem, but I will try a different channel just in case. I got it to act up at home as well. Even though that is only three miles from the field which I will admit is really nice.

GREG DOE

Goose_wrench, I'm trying to coach 6 different teams, in 5 different events, at 3 different schools, in Science Olympiad. I only help with build events; bridges, airplanes, compound machines, and air trajectory. That's why I asked about your daughter's "Simple Machine" project. It's a lot of work, but it's very rewarding when kids learn a new subject, and better still when the win. Last rear I coached my granddaughter in the B Division Helicopter event, and she and her partner took first at State. Lest anyone might question it, they built both of their helicopters. I was sick for the state event, so I didn't even get to see them win. I've high-jacked this thread, so I need to stop bragging. Greg

goose_wrench

I swapped out the regular extension leads with twisted wire leads and it made a pretty good difference. I still get a little interference but nothing like it was doing.

goose_wrench

Here's a couple of pics of the plane. This is a great flying model. It will do a low inverted pass and go right into a outside loop with the Saito .82 on the nose. I love this thing.

flyinwalenda

My Feedback: (5)

Now try tying a simple overhand knot or two in the lead close to the receiver or get a ferrite ring and wrap the lead through/around it 3-4 times, again close to the receiver.

flyinwalenda

My Feedback: (5)

Now try tying a simple overhand knot or two in the lead close to the receiver or get a ferrite ring and wrap the lead through/around it 3-4 times, again close to the receiver.

goose_wrench

Sorry for the delay in responding I work out of town during the week and have very little time at home. I will try that this weekend and post my findings.

goose_wrench

I'm a little late posting but here is the good and the bad news. First the good news. I tied knots in the leads near the receiver and the problem went away. Now for the bad news. I got home late Thursday and tried the knots and it worked so i took the kadet to the field early Friday with my wife. It was a little foggy but not too bad. I took off and did a few touch and goes and went to change the pattern at the end of the field when a bug flew in my eye. I blinked and the plane was gone. I tried to circle back but my wife and i could not see it. So i cut the throttle and added a little left aileron and waited for the crunch. The plane has some damage but nothing terminal. It will be repaired after i finish building the herr cloud ranger. I will post pics of both planes this weekend. I had to build one after seeing the budlight youtube video with the cloud ranger.

goose_wrench

Alright I finally have a minute to post between work and honey do lists. The damage is not bad but i am getting off topic so i will post and get back on target.