Calibration Procedures
Introduction
Calibration of the Model Z9216 is composed of several parts: open and short circuit calibrations,
standard resistor calibration, and amplitude calibration.
The open and short circuit calibrations (described in Volume 1 of this manual) are offset corrections to
correct for any stray impedances of the test fixture. These Calibrations may be performed at any time
and should be done whenever the fixture is changed.
The standard resistor calibration sets the accuracy of the Model Z9216, since it allows the LCR meter
to determine the values of its internal standard resistors. The Standard Resistor Calibration need only
be performed periodically to account for component aging and drift.
Amplitude calibration sets the amplitude of the AC test signal, and only needs to be done periodically.
The amplitude calibration does not affect the Model Z9216’s accuracy.
Calibration Enable
The Model Z9216 is shipped with amplitude calibration disabled. When calibration is disabled only
the open and short circuit calibrations are allowed. The internal calibration enable jumper must be set
to enable amplitude and resistor calibration. To set the jumper, remove the Model Z9216 top cover by
removing its four retaining screws (this will break the calibration seal). In the rear center of the circuit
board is a three-pin jumper labeled JP1001. Use the jumper to connect the center pin and the "cal"
pin to enable calibration. Connecting the center pin and the "normal" pin will disable calibration.
Calbytes
The Model Z9216 calibration is controlled by calibration constants ("calbytes") that the firmware uses
to adjust the impedance calculations. These calbytes are stored in the Model Z9216 RAM.
Recalibration of the Model Z9216 involves determining new values of the calbytes and storing them in
the RAM. The calbyte values that are determined at the time of the Model Z9216 manufacture are
also stored in ROM and may be recalled at any time. The standard resistor calbytes are automatically
determined by the standard resistor calibration subroutines. The amplitude calbytes must be
manually determined.
The 95 amplitude calbytes, which are one-byte integers in the range of 0 to 255, are directly
adjustable from the front panel and are organized as shown in Table 2-10. The 120 floating point
frequency correction, reference resistor values, and open and short circuit calbyte values, whose
organization is given in Table 2-11, are automatically determined by the Model Z9216's calibration
subroutine. These calbytes cannot be directly changed from the front panel, but they may be
changed via the computer interfaces.
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