Routine Calibration - Fluke 8508A Service Manual

Non-volatile input-offset compensation adjustment is available only when the rear panel
calibration keyswitch is in the
main display.
Adjustment is performed by initiating an input zero operation with the Multimeter in this
condition, using the INPUT menu as described in Chapter 3 or using the IEEE 488 input
zeroing commands described in Chapter 4. Appy a high-integrity low-thermal emf 4-wire
short to the input terminals for this operation. Following adjustment for a particular
combination of function, range, and input a compensation is also stored for the
corresponding volatile input zero, and the Zero legend is shown on the main display. The
Zero legend may be removed from the display without affecting the stored non-volatile
compensation by using one of the following operations:
1. Power the Multimeter down.
2. Press the
CLEAR
3. Press the
CAL
4. Use the corresponding IEEE 488 commands.

Routine Calibration

The 8508A Digital Reference Multimeter offers state-of-the-art performance. This
procedure is intended as a guide for qualified metrology personnel who have access to a
standards laboratory with equipment available to support an Multimeter of this level of
accuracy. It reflects the calibration process used by Fluke to perform Multimeter
calibration implemented in an automated system, but as a manual procedure for users to
follow. The procedure is based on the following assumptions:
1. Users are familiar with relevant best measurement practice.
2. Users will take precautions to avoid introducing errors from sources such as thermal
emfs, leakages, electromagnetic interference, etc.
3. Users will make adequate allowance for equipment stabilization and measurement
settling times.
This routine calibration procedure describes the calibration points and sequence of
operations required to calibrate the Multimeter and assumes calibration references of
adequate traceable uncertainty are available – in this case a Fluke 5720A calibrator and
5725A amplifier used with an 8508A-7000 Calibration Kit. The procedure assumes the
user is able to calibrate and characterize the calibration standards, without describing the
process required to do so.
Characterization of the 5720A/5725A combination allows the 8508A to be calibrated
with uncertainties lower than otherwise available from that equipment. The
characterization process determines the 5720A/5725A errors from nominal at the values
required for 8508A calibration, and may be performed using Fluke's recommended
verification procedures appearing in the 5700A/5720A Service Manual as a guide. If a
characterized 5720A/5725A combination is available where the error from nominal at the
various points required is known, those errors may be taken into account during
calibration to reduce the uncertainties. The errors may be determined by measurement
against suitable standards or may be taken from an applicable certificate of calibration.
The uncertainty of the characterized calibrator should be combined with the Multimeter
Relative to Standards specifications to determine Multimeter performance after
calibration. (RSS summation is recommended).
If the calibrator is not characterized to determine its errors from nominal, its output
should be assumed to be nominal at all points. Its performance specifications should be
position and the
ENABLE
key and make any of the selections from the CLEAR menu.
key and entering mode.
CAL
Calibration and Verification

Routine Calibration

legend is not shown on the
CAL
3
3-9