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Throttle servo jittering??

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Old 10-06-2003, 12:42 AM
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Lonestarxp
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Default Throttle servo jittering??

Alrighgt.. on my zdz 40... i use a JR standard servo for the throttle and a plastic pushrod type asembly...

WHat happens is when i give the plane some gas the throttle moves in and out and you can hear the power change. I was wondering if this is due to the servo being a cheap one.. or the pushrod type being a "loose" type of config. maybe i should use steel? Also note that the throttle has a spring in it that wants to stay closed.
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Old 10-06-2003, 11:04 AM
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Rodney
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Default RE: Throttle servo jittering??

On all my gas burners, I disconnect the spring which tends to hold the throttle closed; why have your servo fighting a spring (with increased battery drain) when the servo will hold the commanded position? That may be your problem but it could also be high friction in the pushrod, vibration problems, sloppy linkage, soft linkage (pushrod tends to buckle when pushed) plus many others. Does the servo jitter if the linkage is disconnected at the servo end, if not, then the problem is linkage; if it does either vibration or a poor servo. Do not use a metal pushrod as you will increase the possablility of RF interference from the ignition system if you do. Make sure there is no metal to metal connections that can vibrate or move relative to one another under vibration. Ball joint connections are advisable.
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Old 10-07-2003, 03:25 PM
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Default RE: Throttle servo jittering??

Could be Interference, that is where I would put my money. Any other servos jitter?
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Old 10-07-2003, 03:50 PM
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Lee Belew
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Default RE: Throttle servo jittering??

Just had this problem with a gasser. Had to put a higher quality servo on throttle. I think the problem is the quality of the pot in the servo. The higher quality servo has a better pot. I removed a JR 517 that was erratic and installed a JR 4131 and I have had no more problems. A JR 531 might have worked however I did not have one available.

Hope this helps

Lee
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