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7.4.13 Ohms calibration
Perform the following procedure to calibrate the ohms func-
tion of the Model 6512:
1. Connect the Model 263 to the Model 6512 as shown in
Figure 7-3. Note that Model 263 COMMON must be
connected to Model 6512 COM.
2. Enable GUARD on the Model 263, and set the Model
6512 guard switch to the "ON" position.
3. Place the Model 6512 in the ohms function, and select
the 20G Ω range.
4. Zero correct the Model 6512 by enabling zero check and
zero correct in that order.
5. Program the Model 263 to output the 10G Ω resistance.
The actual value of that resistance will be displayed by
the Model 263.
6. Release zero check on the Model 6512, and allow the re-
sistor reading to settle.
7. Adjust the display, using the ADJUST buttons of the Mod-
el 6512, to correspond to the reading on the Model 263.
8. Disable guard on the Model 263, and set the Model 6512
GUARD switch to the "OFF" position.
9. Using Table 7-5 as a guide, repeat steps 4 through 7 for
the 200M Ω , 2M Ω , and 200k Ω ranges.
Table 7-5
Model 6512 ohms calibration
6512
6512
range
guard
20G Ω
ON
200M Ω
OFF
2M Ω
OFF
200k Ω
OFF
20k Ω
OFF
* Set Model 6512 reading to exact resistance displayed on Model 263 using
Model 6512 ADJUST keys.
10. Set the Model 6512 to the 20k Ω range.
11. Zero correct the Model 6512 by enabling zero check and
zero correct in that order.
12. Set the Model 263 to the 10k Ω range, and press ZERO
to source ohms to the Model 6512.
13. Release zero check on the Model 6512. The reading on
its display is test lead resistance and zero offset.
263 calibration
resistance *
263 guard
(Nominal)
10G Ω
Enabled
100M Ω
Disabled
1M Ω
Disabled
100k Ω
Disabled
10k Ω
Disabled
14. Enable suppress on the Model 6512 to zero the display.
15. Press ZERO on the Model 263 to source 10k Ω to the
Model 263. The actual value of that resistor will be dis-
played by the Model 263.
16. Adjust the displayed reading on the Model 6512 to cor-
respond to the reading on the Model 263.
7.4.14 Permanent storage of calibration constants
The procedures given in the preceding paragraphs will tem-
porarily store calibration constants in internal RAM memory
and will be lost when the instrument is turned off. For cali-
bration to be permanent, you must perform NVRAM stor-
age. Once all points have been calibrated, press PROGRAM
SELECT to exit the calibration program. Assuming that the
calibration jumper is in the enable position, calibration con-
stants will be stored in NVRAM, and the following message
will be displayed briefly:
Also, constants for uncalibrated ranges are derived at this
point.
If the calibration jumper is in the disable position, NVRAM
storage will not take place, and the following message will
be displayed briefly:
Only changed constants are affected with uncalibrated rang-
es unaffected. The new calibration constants will be used by
the instrument until power is turned off. Temporary calibra-
tion is denoted by the flashing exponent decimal points.
7.4.15 IEEE-488 bus digital calibration
Digitally calibrating the Model 6512 over the IEEE-488 bus
requires the use of a calibration program, which is listed in
Appendix D (paragraph D.9).
The manual calibration adjustments cov-
ered in paragraphs 7.4.7 and 7.4.8 must be
performed before performing digital cali-
bration.
Maintenance
Stor
Out
NOTE
7-7
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