Ramping takes days (maybe even over a week). The RF is obviously off most the time though, and the gradient magnets are off too - these tend to be the evil bastards. The slew rate messes with your balance and after a few you come to dislike certain sequences - gradient echoes, diffusion and a few other - loud with high slew rates. You feel like your spinning and this causes slight nausea (in me) and 10 minutes or so of vertigo. Edit for spelling