"Eric R Snow" wrote in message
...
Thanks all for the info so far. Now another one. The probe is set at
1X. The volts/div is set at 50 m. the time/div is set at .1 ms. So
this tells me that each vertical division is 50 millivolts and each
horizontal division is .1 milliseconds. The probe is clipped to the
calibration bar. This bar is labeled as 300 mV 30mA ~1KHz. The display
shows the square wave with 6 divisions vertical and just over 10
divisions horizontal. Using the VAR knob in the center of the time/div
knob I can adjust the display to show exactly 10 divisions. When this
is done is the display correct? Or is it the calibration bar that is
wrong?

I've no clue about the correct answer but you might want to download the PDF
file found here and look it over:

http://www.tek.com/Measurement/cgi-b...=oscilloscopes

which is a primer on scopes by Tektronix. Here's another on probes:

http://ece-www.colorado.edu/~mcclurel/tabcprobes.pdf

Mike