Fluke 5500A, Service Manual

Page: 149 / 296

SC600 Option
Calibration and Verification of Square Wave Voltage Functions
6
6-23
measurements at each step. Note that in the EDGE function, the topline is very near
0 V, and the baseline is a negative voltage.
3. For each calibration step, take samples for at least two seconds, using the HP 3458A
MATH functions to enter the average or mean value. See “Setup for SC600 Edge
and Wave Generator Measurements” 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.
6-37. Leveled Sine Wave Amplitude Calibration
This procedure uses the following equipment:
•
5790A AC Measurement Standard
•
BNC(f) to Double Banana Plug Adapter
•
50
Ω
feedthrough termination
•
BNC cable supplied with the SC600
Press the OPTIONS and NEXT SECTION blue softkeys until the display reads “Set up
to measure leveled sine amplitude”. Then follow these steps to calibrate Leveled Sine
Wave amplitude.
1. Connect the BNC cable to the Calibrator Mainframe’s SCOPE connector. Connect
the other end of the BNC cable to the 50
Ω
feedthrough termination then to the
5790A INPUT 2 using the BNC(f) to Double Banana adapter.
2. Set the 5790A to AUTORANGE, digital filter mode to FAST, restart fine, and Hi
Res on.
3. Press the GO ON blue softkey.
4. Press
O
to activate operating mode on the Calibrator Mainframe.
5. Allow the 5790A rms reading to stabilize. Multiply the 5790A reading by (0.5 * (50
+ Rload) / Rload), where Rload = the actual feedthrough termination resistance, to
correct for the resistance error. Enter the corrected rms reading via the Calibrator
Mainframe front panel keypad, then press ENTER.
Note
The Calibrator Mainframe will warn when the entered value is out of
bounds. If this warning occurs recheck the setup and calculation and
carefully re-enter the corrected rms reading insuring proper multiplier
(i.e., m, u, n, p). If the warning still occurs, repair may be necessary.
6. Repeat step 5 until the Calibrator Mainframe display indicates that the next steps
calibrate Leveled Sine flatness. Press the OPTIONS, then STORE CONSTS blue
softkeys to store the new calibration constants.