I have read on several thread that the Jr 811 with the 770 rx have that problem also a unregulated 6.0 pack wll jitter with a hot rx pack I read somewhere its because a freash packs voltage is higer than 6 volts I use to let mine set for a few min. on and working the surfaces and it would stop as the voltage came down and never a jit after the first flight or two made me nervous tho heh