Tektronix 11A72 Manual page 71

Part 8 AV DC Accuracy
[-] Step 5: Set the reference point for measuring the AV DC accuracy.
@ Touch Compare and References in the MEASURE major menu and then
A. Press the FINE resolution button above the left control knob, and then
position the Vert Ref cursor on the trace.
[-] Step 6: Set the voltage on the power supply so that the waveform is on the
first graticule line below the top of the screen. Read the DMM and add the
absolute value (again, disregard the polarity) to V,. Record this value as V2.
("] Step 7: Read and record the voltage difference between the previous
waveforms as follows:
@ Read and record the AMean value in the MEASURE major menu as V3.
A Press the FINE resolution button above the right control knob, and the
position the AVert cursor on the trace.
A Read the AVert readout and record this value as V, for later use.
([] Step 8: Divide V, by the AMean readout [that is, 1 -t (.008 + .03 div/6 div)]
V3. Then, divide this result by the characterization factor of the oscilloscopes
calibration voltage reference (obtained in Part 3, Oscilloscope Characteriza-
[-].Step 9: Check that the result is within specification as follows:.
¢@ Check that the result obtained in Step 7 is >0.993 but <1.007 [that is,
7: (006 + .01 div/8 div).
A. Check that the result obtained in Step 7 is >0.987 but <1.013 [that is,
DO NOT perform Step 10 if only performing a functional test.
Proceed to Step 11.
[_] Step 10: Repeat Steps 3 through 8 for the vertical size settings listed below.
1 Vidiv
When testing with small voitages, it may help to install attenuators in series
between the BNC-to-alligator clip adapter and the coaxial cable, so that you
can set the voltages with better resolution. You.can also use a DC voltage
calibrator to achieve better resolution (when testing with small voltages).
11A72 Service Reference
REV AUG 1989 237