servo judder help !!

[mick a]

hi gents wonder if you could help solve this :
i have two hitec 125 mg wing servos in model
both work great when plugged straight in receiver direct
however when i use extension lead one of them judders all the time
ive tried extension lead on both and its not lead , battery fully charged
took back to shop and it works in rec but not with extension
any ideas , driving me nuts !!!!

[Happy Days]

Hmmm, I'm thinking it might be a little bit of rf getting into the servo amplifier. Are you using 35Mhz or 2.5Ghz Mick?

Keith

[Fred]

Hi Mick,
Twisted wires? Or straight (flat)?

[billscottni]

Stick a ferrite ring in the line near the rx end of the extension, should reduce any interference

[Happy Days]

Are you sure Bill?

I'd have thought it would be better to put the ring near the devise that appears to be picking up the stray RF. (If the problem is stray rf) That way the ring will be acting like an rf choke. ('Choking off' the rf before it gets into the servo.)

I'm thinking that if Mick puts the ring near the rx then the extension lead will still be acting like an antenna and feeding radio energy into the servo.

That's my understanding of it anyway

Keith

[Fred]

Yep, Ferrites near the RX.
Saying that, I never used any, and God, some of my gliders have meters of cables!
But rule number one, use twisted cables. Always!
I believe the twisted cable "shield" itself, but anyway, whatever the sorcery behind it, no ferrites in my case, never had a glitch (in 41 or 35Mhz).

This might not be the case with 2.4Ghz, as of not needed anymore, but in this case, I would maybe suspect a low voltage on the RX output (loss of volts because of the long cable maybe?)

Have you tried different servos on the leads?