Advanced Features And Special Considerations; Storing Variable Inputs; High-Frequency Ac Calibration Steps - Fluke 8842A Instruction Manual

8842A
Instruction Manual
5. The calibration procedure is now completed. Exit the calibration mode by pressing

6-15. Advanced Features and Special Considerations

1.
2.
The 8842A has several advanced calibration features which are not necessary for the
basic calibration procedure, but which can make calibration easier. The following
paragraphs describe these features and also discuss special considerations for optimizing
the performance of the 8842A in special situations.

6-16. STORING VARIABLE INPUTS

As a convenience, the VAR IN (variable input) feature lets you calibrate the 8842A using
reference source values which differ from the values prompted by the 8842A. For
example, you may want to calibrate the 200 range using a reference resistor with a
precisely known value of 99.875 , rather than 100 as prompted. This feature is not
available during A/D Calibration.
To use the variable input feature, proceed as follows:
1. When the 8842A prompts you for an input, press the VAR IN button. The blank
2. Change the displayed prompt to correspond to the desired reference source by
3. Connect the desired reference source to the appropriate input terminals of the 8842A.
4. Press the STORE button.
To meet the specifications over all ranges, the reference source for the high prompts must
be between half and full scale. (The high prompts are those prompts that are between
50% and 100% of full scale.) The reference source for the low prompts must be equal to
or greater than the prompted value, but not more than that value plus 4000 counts. (The
low prompts are those prompts that are zero or 5% of full scale.)
For special applications, the 8842A can be calibrated at values outside the recommended
range. This can enhance the performance at the calibration value. However, performance
at other values may be degraded.
6-16
the CAL ENABLE switch, and attach a calibration certification sticker over the CAL
ENABLE switch.
Table 6-11. High-Frequency AC Calibration Steps
STEP
A
B
C
D
E
The display also indicates "U" to show that HF AC cal is selected.
Inputs should be between 90 kHz and 100 kHz. (nominal) is recommended.
digits will be replaced with zeroes. You can then increment each digit of the display
by pressing the range buttons. The 20 /mV button toggles the displayed sign.
pressing the appropriate range buttons.
1 2
DISPLAYED PROMPT ,
100.0 mV AC
1.000 V AC
10.00 V AC
100.0 V AC
200.0 V AC