Multifunction Calibrator
Full Verification
59
15. If the readings in step 14 are not the same then adjust the BALANCE control
until they are the same (see note 4 below).
16. Set the CALIBRATE switch to 100:1+. Adjust the 100:1 CALIBRATE
adjustment until the reading is 0±0.5 μV.
17. Push on the Product.
18. Set the CALIBRATE switch to OPERATE and the MODE switch to the
necessary position.
19. This completes the self-calibration of the 752A.
Notes
1. The 10:1 adjustment must be done before the 100:1
adjustment can be done.
2. Following the “Self-Calibrate a Fluke 752A Divider with a
Fluke 8508A as the Null Detector” procedure above adjusts
the 752A to within 0.09 ppm or less of the nominal ratio for
10:1 and 0.18 ppm or less for 100:1.
3. Be sure the 752A is well stabilized in a constant temperature
environment before calibration starts. The instrument stays
calibrated as long as the temperature remains constant.
4. It can be difficult to adjust the BALANCE control for a
difference of exactly 0
μ
V but it is not necessary to get it to
exactly zero to get good results. Instead, adjust the
BALANCE for as close to zero as is practical but a difference
as large as 1
μ
V is still acceptable. Then adjust the 10:1 or
100:1 CALIBRATION adjustment for a reading that is the
same for the switch in the 10:1+ position as the 10:1- position
but opposite sign. For example, if the BALANCE difference is
1
μ
V, then adjust the appropriate CALIBRATION adjustment
until one switch position is say +0.5
μ
v and the other position
is -0.5
μ
V. These two readings do not have to be the same to
meet the
±
0.5
μ
V requirement given in the procedure. To
determine if the adjustment is close enough, use the
following equation: Take the reading in the 10:1+ position
and add it to the reading in the 10:1- position and then divide
the result by two. For example, if the reading in the 10:1+
position is +0.75
μ
V and in the 10:1- position is -0.25
μ
V
then: (+0.75
μ
V+(-0.25
μ
V))/2 = +0.25
μ
V. This meets the
requirement for an adjustment to within ±0.5
μ
V.
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