Ac Square Wave Voltage Calibration - Fluke 5520A Service Manual

4. Ensure the HP 3458A reading is 0.0 V DC
5. Press the GO ON blue softkey.
6. Calibration voltages 33 V and greater will automatically put the Calibrator
Mainframe output in standby. When this occurs, press
Mainframe to activate the output. Allow the HP 3458A DC voltage reading to
stabilize. Enter the reading via the Calibrator Mainframe front panel keypad, then
press ENTER.
The Calibrator Mainframe will warn when the entered value is out of
bounds. If this warning occurs recheck the setup and carefully re-enter the
reading insuring proper multiplier (i.e., m, , n, p). If the warning still
occurs, repair may be necessary.
7. Repeat steps 6 until the Calibrator Mainframe display indicates that the next steps
calibrate ac voltage. Press the OPTIONS, then STORE CONSTS blue softkeys to
store the new calibration constants.
AC voltage must now be calibrated. Continue with the next section.

6-105. AC Square Wave Voltage Calibration

This procedure uses the same equipment and setup as DC Voltage calibration but
requires different settings on the HP 3458A. See "Calibration and Verification of Square
Wave Functions" earlier in this section for technical details on the procedure. DC
voltages are measured and entered in the Calibrator Mainframe to calibrate the AC
Voltage function.
Set up the Calibrator Mainframe to Cal ACV. Press OPTIONS and NEXT SECTION
blue softkeys until the display reads "The next steps calibrate -SC300 ACV". Then
follow these steps to calibrate ac voltage:
1. Press the GO ON blue softkey.
2. Connect the Calibrator Mainframe's SCOPE connector to the HP 3458A input, using
the BNC cable and the BNC(f) to Double Banana adapter.
3. Set the HP 3458A to DCV, NPLC = .01, LEVEL 1, TRIG LEVEL, and the DELAY
to .0002 for measuring the upper part of the wave form (i.e. topline), and the
DELAY to .0007 for measuring the lower part of the wave form (i.e. baseline).
Manually range lock the HP 3458A to the range that gives the most resolution for
the topline measurements. Use this same range for the corresponding baseline
measurements at each step.
4. For each calibration step, take samples for at least two seconds, using the HP 3458A
MATH functions to retrieve the average or mean value. See "Setup for Square Wave
Measurements" earlier in this chapter for more details.
The "true amplitude" of the wave form is the difference between the topline and
baseline measurements, correcting for the load resistance error. To make this
correction, multiply the readings by (0.5 * (50 + Rload)/Rload), where Rload =
actual feedthrough termination resistance if used.
Calibration and Verification of Square Wave Functions
100 V.
on the Calibrator
Note
SC300 Option 6
6-79