Bird Technologies 4412A - Manual (Page 32)

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Calibration Environment
In order to assure the best results obtainable, the following environmental con-
ditions must be provided to the utmost degree practical.
1.
The work space must be free from electrical noise and radiated signals. The area
in which the calibration is to be performed may be checked for spurious radiation
with a Bird Model 43 Thruline Wattmeter equipped with a Model 4030 relative
field strength element. Be sure the gain on the Model 4030 is set at maximum.
Calibration should not be performed in areas where spurious radiation is present
as indicated by any meter deflection on the Model 43/4030 combination.
2. The work space and equipment must be at a uniform and stabilized ambient
temperature between 20°C and 25°C (68°F to 77°F).
3. The relative humidity of the work space must be no greater that 50 percent
and must be noncondensing.
Calibration Procedure
Allow all the equipment and the instrument to be calibrated to completely stabi-
lize with respect to the environment of the work area (specified above). The
Series 4410 Wattmeter to be calibrated and the Bird Model 4410-070 calibration
element may require up to 24 hours for complete environmental stabilization if
brought from an extreme storage environment. Remove the dust plug or any
element from the line section during this environmental stabilization period.
With the wattmeter’s range switch in the OFF position, carefully turn the zero
adjust screw on the face of the meter for a zero setting. Using the BATT and OFF
positions on the switch, repeat this process until a repeatable zero setting is
obtained.
The access hole for the calibration potentiometer is sealed with a protective
label. This label, which is signed and dated showing the original calibration date,
must not be disturbed until recalibration becomes necessary and certainly not
within the warranty period. Disturbing this label voids the warranty. If the unit is
to be field calibrated, after the warranty period, access to the calibration poten-
tiometer is provided by piercing the protective label at the point shown by a cir-
cle with an “X” in it, see figure 10, Calibration Potentiometer for reference.
Follow the steps below to calibrate: