HP 8530A, Руководство по эксплуатации и программированию, Страница: 122 / 439

Modifying Network Analyzer Cal Kit Denitions
C
total
= C
0
+ C
1
*F + C
2
*F
2
+ C
3
*F
3
Where C
0
is the DC capacitance , C
1
*F is the capacitance times frequency , C
2
*F
2
is the
capacitance times frequency squared, and C
3
*F
3
is the capacitance times frequency cubed. The
shielded open circuits in the 3.5 mm calibration kit use a center pin extender , so the models for
these devices also include a linear phase shift component to account for the oset from the
reference plane .
Specications , Modifying a Cal Kit
The specications contained on the calibration kit data le are nominal values based on typical
expected responses of the standards . If you wish to substitute your own standards , or change
the models for the standards supplied in the calibration kit, you may use the
NNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNNN
MODIFY CAL KIT
sequence .
Common Problems
Common calibration problems which can be traced to standards are:
Non-repeatable contact due to wear , dirt, grease , or other contaminants on the contacting
surfaces or other accessible parts of the standard. Assure that the standard is properly
cleaned. Make sure the connector is dry .
Connector damage due to connecting the standard to a connector with mechanical defects or
out-of-spec tolerances . Use the connector gage on both the test port and the standard prior
to measurement calibration.
P oor contact due to improper alignment or torquing practice . Use the correct connection
technique and the proper torque wrench for each connection.
Using cal standards whose response does not match the constants in HP 8530 Cal Kit
memory . Load the proper cal kit data le for the cal kit you are using.
V erifying Calibration Data
Immediately following calibration, and at intervals during the measurement process , it is
recommended that you measure a standard device with known responses . This is to verify
that the system characteristics have not changed thus making the current calibration error
coecients invalid. Measuring a device from the calibration kit used for measurement
calibration will allow you to determine that the system is making repeatable measurements .
The measured response of a calibration standard will be exactly the modeled response if the
connection is repeatable .
T o determine measurement accuracy , however , it is necessary to measure an independent
standard with known responses , such as the attenuators or air lines in the HP 8510 verication
kit, or a standard you produce that is representative of the devices you are testing. If
standards-quality data for the device is available , it can be compared with your measurement
results to determine accuracy . If the data is outside acceptable limits and good technique was
used during the calibration, then the system characteristics have changed, thus making the
current calibration error coecients invalid. Standards-quality measurement data is supplied
with the HP verication devices .
Menus Block 5-39