Are you inside and do you have any Fluoro lights switched on in the room?

I bet that sounds like a weird question to some but let me explain

The OP is in australia - 36 MHz radios.
The power there is 50 Hz this seems to bring the frequency from the fluoro lights (maybe the ballasts or the starters - I don't know much about it) close enough to cause servos to chatter.
I have quite a few planes that chatter inside when the lights are on - especially Fluoro lights. - turn off the lights, or take them outside and the problem goes away.


Otherwise - tell them to behave themselves and be quiet or you won't buy them an ice cream when Mr Whippy comes down the street next.