2-2
2.2
Environmental conditions
Voltage and 20µA-20mA current calibration procedures
should be performed at an ambient temperature of 23° ±5°C,
and at a relative humidity of less than 70% unless otherwise
noted. 20pA-2µA current and coulombs calibration should
be performed at 23°±3°C because of Model 5156 tempera-
ture restrictions.
NOTE
If the instrument is normally used over a
different ambient temperature range, cali-
brate the instrument at the center of that
temperature range.
2.3
Warm-up period
The Model 6517A must be allowed to warm up for at least
one hour before calibration. If the instrument has been sub-
jected to temperature extremes (outside the range stated in
paragraph 2.2), allow additional time for internal tempera-
tures to stabilize. Typically, it takes one additional hour to
stabilize a unit that is 10°C (18°F) outside the specified tem-
perature range.
The calibration equipment should also be allowed to warm
up for the minimum period specified by the manufacturer.
2.4
Line power
The Model 6517A should be calibrated while operating from
a line voltage within the range specified by the LINE VOLT-
AGE switch on the rear panel, at a line frequency of 50 or
60Hz.
2.5
Recommended calibration equipment
Table 2-1 summarizes test equipment recommended for cal-
ibrating the various Model 6517A functions. Alternate
equipment may be used as long as that equipment has speci-
fications equal to or better than those listed in the table.
NOTE
The Model 5156 Electrometer Calibration
Standard is recommended for calibrating the
20pA-2µA amps ranges and all coulombs
ranges. Alternate resistance and capacitance
standards may be used as long as those
standards are characterized to an uncertainty
that is at least four times better than
equivalent Model 6517A specifications.
NOTE
Make all input low connections directly to
the triax INPUT connector instead of
COMMON to avoid calibration errors
caused by internal voltage drops. Use the
connecting methods shown in this section
to avoid this problem.