Characterizing The Dc Source; Self-Calibrate A Fluke 752A Divider With A Fluke 8508A As The Null Detector - Fluke 5790B Service Manual

Characterizing the DC Source

To meet the test uncertainty requirements for the main input dc calibration, first
characterize (calibrate to a higher uncertainty than the published specifications)
the dc function of the 5730A at the required points. Table 3-1 lists the equipment
required for dc source characterization. Table 3-2 shows the test record in which
you will record the results of the following procedure. Make a photocopy of this
table before you proceed.
Table 3-1. Equipment Required for DC Characterization
Equipment
Multifunction Calibrator to
Characterize for dc calibration
Reference Divider
Null Detector
10 V dc Reference Standard
To prevent possible electrical shock, fire, or personal injury, do
not touch any exposed conductors. Some steps in the
subsequent procedure involve calibrator outputs at lethal
voltages.

Self-Calibrate a Fluke 752A Divider with a Fluke 8508A as the Null Detector

1. Connect the 5730A, 752A, and 8508A as shown in Figure 3-3.
2. Set the 8508A to the 200 mV dc voltage range at 7 digits. The filter is "ON"
and "FAST" and internal guard is selected (external guard not selected).
FAST mode updates the reading every 1.5 seconds. This lets the reading
track the adjustments but the reading changes frequently and is somewhat
noisy. FAST can be turned off so that the readings are updated every 5.3
seconds.
3. Set the 752A MODE switch to CAL and the CALIBRATE switch to 10:1 +.
4. Wait for the reading to settle (this can take several minutes); zero the meter
with the Zero Rng button.
5. Connect the 5730A, 752A, and 8508A as shown in Figure 3-2.
6. Set the 5730A to output 20 V.
7. Wait for the reading to settle (this can take several minutes); note the
reading. Set the CALIBRATE switch to 10:1 – and note the reading.
8. If the readings in step 7 are not the same, adjust the BALANCE control until
they are the same. (see note 4 below).
9. Set the CALIBRATE switch to 10:1+. Adjust the 10:1 CALIBRATE adjustment
until the reading is 0 ±0.5 μV.
10. Set the 752A CALIBRATE switch to 100:1 +.
11. Wait for the reading to settle (this can take several minutes); note the
reading. Set the CALIBRATE switch to 100:1- and note the reading.
Manufacturer and Model
Fluke Calibration 5730A
Fluke 752A
Fluke 8508A
Fluke Calibration 732A or B
 Warning
Calibration Adjustment and Verification
Minimum Use Specifications
0 - 1000 V dc, short term stability
better than 1 ppm
Uncertainty ±0.5 ppm @ 100:1,
±0.2 ppm @ 10:1
0.1 μV resolution
10 V Uncertainty ±1 ppm
3
Calibration
3-5