I've tried doing this with a 1 KHz 3vpp signal (AC coupling), a 1.5v
alkaline battery (DC coupling), and an open circuit (AC and DC
couplines). The behavior is the same in all three cases. I will try
short-circuiting the probe to see if the behavior changes.

Thanks, Michael


In article ,
says...


Not connecting anything to channel 1, doesn't mean voltage = 0V, it is
"in the air" so, any voltage may be there. Try shortcircuiting the
channel, and see if the same problem appears...