On Fri, 10 Feb 2006 11:58:14 -0800, Eric R Snow
wrote:

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?
Thanks,
Eric

Your vertical sounds right. Either your reference calibrator, your
sweep timebase or your horizontal gain is off a tad. If you set
the variable timebase to show exactly 10 divisions, then the
horizontal scale really is 0.1 ms/div if the calibator is accurate.
You could check it with a counter if you can borrow one.

The timebase on the calibrator says ~1KHz, so it's probably not
crystal controlled. My counter says mine is running at 986.37 Hz.

Household power is a pretty good reference at 60 Hz. Use a
transformer.

If you have an old digital watch, it'll contain a 32768 Hz
crystal-controlled timebase that is accurate to 50 parts per million
or better, usually considerably better.