The title explains it all: for months we had a Stanford SR560 preamplifier (set on Gain = 10) located in EE_room, whose differential input was connected with two very long coaxial cables to the electrical ground of the WI electronic crate and to the electrical ground of the WI vacuum chamber.
Yesterday during maintenance we moved the preamplifier closer to the base of the WI tower, south side (see attached photo); now it's the preamplfier output that has a long coaxial cable connected to the ADC located in the EE_room.
The shape of the signal ENV_CEB_ELECTRIC has not changed (see attached plot).