Fluke 8508A, Service Manual

Page: 59 / 120

Calibration and Verification
Routine Calibration
3
3-19
Initial Setup and Connections
1. Press the
Ω
key and select the
200
Ω
range.
2. Press the
CONFIG
key and select
Filt
and
4w
Ω
.
3. In calibration mode the resolution defaults to
RESL7
in the resistance function. It is
recommended that this resolution is used for calibration of all resistance ranges.
4. Reselect
Ω
.
5. Confirm that the Multimeter is configured for internal guard (External Guard is
deselected) by checking that the
Ext Grd
legend does not appear on the left-hand
display.
6. Ensure that the calibrator output is set to
STANDBY
and configured for Internal
Guard (
EXT GRD
is deselected). On the calibrator select
EX SNS
(4-wire).
7. Connect the Calibrator to the Multimeter as shown earlier in this chapter.
8. If using standard resistors in place of the calibrator refer to "Measuring Resistance"
in Chapter 3 of the Users Manual for information regarding 4-wire resistance
connections.
Normal
Ω
Mode Calibration
1. Press the
Ω
key and select the
2
Ω
range.
2. Press the
CONFIG
key and select
Filt
and
4w
Ω
. Ensure LoI is deselected.
Range Zero and Gain Calibration Procedure
After the initial setup and connecting up, use the following procedure to calibrate range
zero and range gain for the ranges and points detailed in Table 3-5 for the Normal
Ω
mode. For the 2 G
Ω
range use the 1 G
Ω
standard resistor in place of the calibrator. Just
one range can be calibrated if required, but for a full-calibration start with the 2
Ω
range
and work up to the 2 G
Ω
range.
Note that EX SNS (4-wire) is not available on the 5720A 100 M
Ω
range, and the 8508-
7000K 1 G
Ω
standard resistor is used as a 2-wire device with the calibrator 2-wire
resistance zero used for the corresponding zero points.
4W
Ω is deselected on the
Multimeter when calibrating the 200 M
Ω
and 2 G
Ω
range, range zero, and range gain
points.
On each range, the Multimeter automatically recognizes the appropriate value as range
zero or range gain from the applied resistance value.
Note
It is unlikely that the resistance standard will be at exactly the nominal
value required. The Set feature allows a user to enter the true output value
of the calibration standard where it differs from nominal range gain point.
If the resistance value is exactly the nominal value required, omit steps 2-4
for the Range Gain Point.
Zero Point
1. On the Multimeter, select the required range.
2. On the Calibrator, select zero and Operate. Alternatively if using a standard resistor
connect the standard resistor for a 4-wire resistance zero. (For the 200 M
Ω
and 2 G
Ω
ranges, de-select EX SNS on the calibrator and de-select
4W
Ω
ο
n the Multimeter.)
3. On the Multimeter, press
CAL
to enter the
CALIBRATION
menu.
4. Press
SAMPLE
to initiate the calibration operation.