I have an AW 31% 300L with long servo leads to the elevators and ailerons. Second flight had a very quick "glitch" with my ailerons. Landed the plane, took it home a checked over everything. Nothing loose, no metal to metal contacts. Fourth flight today and same type of quick "glitch" but with my elevator servos. All of my radio equipment is mounted atleast 18" from my ignition. some one suggested that I use servo amplifiers/buffers on these long wires. Trying to find info if anyone has used these and have they helped? Any info appreciated.

I seriously doubt that amplifiers or buffers would help you.
Try stringing the antenna out the wing or changing the receiver.

THANKS DIRTYBIRD
THINK I AM GOING TO TRY A NEW RECIEVER (PCM)

Beside the crystal there is a ceramic filter in a rx. And the thin plates of such a filter are pretty vibration sensitive. Every time I experienced glitches with my JR rx the service engineer had to change that ceramic filter. That filter is a rather cheap part.
Joe

You mentioned that your leads were 18" from your ignition which is fine. Is your throttle pushrod non-metallic? I'm guessing it is.
The ailerons shouldn't be a long enough run to cause problems. They are usually the shortest. The antenna is a good start. What are your engine on and engine off range test differences?
Twisted leads often help to keeep the noise down, and your leads are all one piece and at least 22awg correct?

make sure your servo leads aren't balled up. keep them straight and short as you can. twisting is also good {if they are to long shorten them}

The PCM receiver will probably make the glitch go away but it won't fix the problem if it is not in the receiver. It will just cover it up. Change to a PPM rx and if the problem goes away you will know that it was in the receiver and you need to send it in for repair.

I have a TF Cessna that had some problems with the wing servos. It was straight radio noise - not engine related. THe buffers worked very well - but are expensive when you need to do multiple channels.

I'm going to try out using ferrite beads on my first gasser this week. It was getting hit, just at certain times/locations during the flight. turned out to only happen at certain orientations wrt the transmitter and only with the engine running. We'll see how that goes.

I would get rid of the amplified or buffered leads. I tried some JR amplified extensions in 2 different planes and had problems that were eliminated when I went back to normal extensions. One plane used a Futaba 129 pcm receiver and the other used a Futaba 148 pcm receiver. One plane had JR 4721 servos that flat wouldn't work at all with the amplified Y-harness. The other plane used Hitec 5945 digital servos that glitched terribly on a freshly charged 4-cell pack. Perhaps the problem was related to mixed equipment, but the planes have been flying fine on normal extensions - never a glitch. The planes are both 33% gas aerobats.

As Diablo discovered, buffers and amplifiers are just a needless expense that very well may make the problem worse. Until you start flying airplanes with 100 ft wings forget them. You don't need an amplifier on a 10 ft wire. The input resistance of the servo is in the order of 1K. The resistance of the wire is less than 1 ohm. This means the line loss is 1/1000. About 0.01 %.
RF reflections? Buffers and amplifiers won't help that. Their purpose is to restore line loss.

Thanks for all of the info. I have been doing some testing with another reciever and I think this might be the problem. I started by ranging testing the plane. Everything was fine at about 50' as I walked further away then things started to act up. It was not constant interferance, but definately noticable. I still had control but when I left the sticks at neutral, this is where I could see the surfaces start to "glitch". I walked out to about 100' and put the radio standing up on a table and walked back to the plane. The control surfaces would start bouncing around aggressively and then stop. I put another FM reciever and did the same test without any problems. I also discovered that the Y-harness from my elevator servos called a "Miracle-Y" has a built in choke/amplifier which is very close to my reciever. I will do more testing to see if this "Miracle-Y" has any affect on either reciever. I will definately change recievers, but I also would like to see if this Y connector has any affect while range testing. Will let you know what I find. Also I would appreciate any suggestions on what distance is acceptable when range checking your plane. Thanks for all of the help guys! :idea:

I didn't want to but wound up using a JR "Y" harness with a built in amp in my 33% 540T. I had a JR tech on the phone and asked why the amp. He couldn't really answer that question. I asked if JR supplies one without the amp and he said no. My plane seems to work OK with all JR radio equipment so far. We'll see_Bob

I've had the glitch problem on an open class glider (120" span) with a 4 servo wing. I found from other glider guiders that it was pretty common to have this with long extensions. Twisting helps but mostly they depend on ferite terroidal coils or "lifesavers" (shaped like the candy). Just wrap your wire in and around it about 3 turns near the rcx and your are good to go. Multiplex sells them and they might be more effective than buffered amps. Some have claimed 6 volts systems are less prone too. I'm right with you and was asking what to do on my 27% the other day. Gassers said "PCM". I think I'll do both PCM and coils.
Jack

I also had that very same problem with long leads, tried the ferrite beads, worked to a degree, tried glitch busters, worked to a degree, and when I got fed up with so-so results, I went about developing an extension that is bullet proof, a bit more expensive then what we are used to, but then it works.
The Fiber Optic servo extensions.
http://www.geocities.com/roger_forgues/Aerografixs.html
http://www.geocities.com/roger_forgues/batteries.html

Roger


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