flyboyrc

I have a 1/4 patty wagstaff extra and all of a sudden the other day the rudder started twitching and we couldn't figure out why. I have all my switches mounted near the receiver but this has never happened before. I havent been able to fly the planeyet because every time it is ready a new problem arises. yesterday with the plane not running so I knew it wasn't the engine kill-switch causing inteference it just started. A little whileafter this started the elevators stared to act strange also, but that hasn't happened again and I have been working on it all mornig. It also seems that the closer I get to the airplane the worse it seems to get but in walking across the street with the transmitter antenna down it showed no sign of interference or any twitch. Any information or Ideas you may have would be great

Thanks
Mike

Stick Jammer

I seen a guy at our field last season with a 1/4 scale gasser doing the same thing. For some odd reason the rudder would twitch badly when the transmitter was too close. It didn't seem to bother him as he was apparently used to it. The plane flew fine but that condition would make me a little nervous. Wished I could tell you the reason for the twitching but he didn't know either.

Tired Old Man

My Feedback: (1)

Couple of things, any one or combination of will cause problems.

1) Is the antenna exposed, or completely inside the fuselage? Expose it.

2) Is the antenna taped down using any kind of mylar (plastic) tape? If yes, get rid of the tape.

3) Is the antenna run in such a way that there is nothing obstructing "it's" view of the outside world? Run the antenna in such a manner that at least part of it is hanging free of any support, and outside of any tube or fuselage.

4) Are you using servo extension leads from the flight servos to the receiver? If yes, are they new or used? If they have been used before, change out to new, heavy duty leads, such as the ones from JR and Cermark.

5) How old is your receiver battery? How good are the connections?

6) How old is the on/off switch? How good are the connections?

7) In what condition is the receiver crystal? How well is it placed in the receiver? Is it taped in place to prevent movement caused by vibration?

8) What is the condition of the antenna wire connection at the receiver?

9) Is the antenna wire stretched tight to reach it's final destination?

10) Do you have electronic ignition on a gas engine? If so, where is the ignition battery located in relation to the rest of the radio gear? Hopefully it' not real close to the primary radio system and flight battery.

11) Are you using an extension lead on an ignition battery? This is a VERY common problem area.

Stick Jammer

How many giant scale planes have you seen with the antenna exposed? What problem could plastic tape possibly cause? No offense, but I don't think any of this is the problem. He has good radio contact at longer range with the Tx antenna collapsed.

Don't think this is it either, he said the engine wasn't running.

wd4rtg

Sounds a little like receiver swamping to me from close proximity of the transmitter to the receiver. Try collapsing your tx antenna and if it gets better just back off about ten feet and it should stop. The power from the transmitter that close just overwhelms the front end of the rx. If on the other hand you see any twitching when you are further away that wouldn't be "swamping" You might help by twisting your servo leads which helps to cancel a lot of interference. Don't forget to pull that antenna out before taking off though-they won't twitch at all then.
Best of luck
Wayne

flyboyrc

Thanks guys I think I found the problem though. One of my local club members suggested that I take a look at each of the two servos and test them to see if one is bad. It just so happens that one of them was. The EMP put off by the bad one was causing the elevators to hum as well. I replaced the bad servo with just a regular one to see if it had any twitches an it was perfecly still. Thanks for all of your help though I'm sure I'll need it again.