Model 6487 Reference Manual
Measurements and Sourcing Voltage
3-5
Zero correct
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The Model 6487 saves a single Zero Correct value (not one for each range). For
best results, acquire a new Zero Correct value after changing to the desired
range.
The Model 6487 has a zero correct feature to algebraically subtract the voltage offset term
from the measurement (to actually reduce the voltage at the input terminals, see
). Perform the following steps to algebraically zero correct the
measurement:
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The REL key toggles zero correct on and off if zero check is enabled
(“ZEROCCHK” message displayed). The MON annunciator turns on when zero
correct is enabled.
1.
Enable zero check (“
ZEROCHK
” message displayed).
2.
Select the range that will be used for the measurement or select the lowest range.
3.
Press REL to enable zero correct (“ZCORRECT ON” message displayed briefly).
4.
Press ZCHK to disable zero check.
5.
Readings can now be taken from the display. The MON annunciator indicates that
the displayed reading is zero corrected.
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With regard to the zero correct feature:
•
The Model 6487 will remain zero corrected even if it is upranged. If
downranged, re-zero the instrument.
•
The Model 6487 does not have to be re-zero corrected as long as the
ambient temperature remains stable.
•
Zero correction cancels the voltage offset term of the amplifier. With both
zero check and zero correct enabled, the instrument may not display a
perfectly zeroed reading.
•
If the Model 6487 is operating at or near T
CAL
, zero correction will have
very little effect. T
CAL
is the internal temperature of the Model 6487 when it
was last calibrated.
