Here's a shot showing the upper level of the central support structure (CSS) containing the bubble lifter mechanism, also shows the collar (without the ribs), the radar and the bubble. The cam in the CSS rotates up into the collar area pushing the neck shaft up as it goes. This gives about 3" of travel and testing shows it can lift the bubble to the extended position in less than 1/4 second or a rate of about 12"/sec, much faster than most linear actuators.
Here's some more pics:
