Keysight Technologies 16197A, Operation And Service Manual

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48 Keysight16197A Operation and Service Manual
User Maintenance
Deterioration Check
4-
Therefore, . Accordingly, if R fluctuates by 20% (120 m
Ω
), Q
will change by about 20%; and if L fluctuates by 20% (2 nH), both L and Q will
change by about 20%. In other words, to measure L and Q at an accuracy of
20% or less error, errors in L and R must be 2 nH and 120 m
Ω
at the most,
respectively. Considering that both L and R may fluctuate, and allowing for
possible causes of error other than a deteriorated fixture, the errors must be set
smaller than the above-mentioned values. For the present example, with the
error set at 25% for both L and R, the user limit values for L and R are set at
500 pH and 30 m
Ω
, respectively.
Record the user limit values in the “Check Sheet” on page 51 . For the method
of recording, see “Example Entry in Check Sheet” on page 51 .
Acquiring Reference Values
To obtain reference values, measure the impedance (Rs, Ls) of the fixture
before deterioration. It is recommended to take measurements at a frequency
at which the fixture is normally used. It is necessary to obtain reference values
using electrodes and shorting bars for all sizes of DUTs that will be subject to
actual measurement.
“Acquiring reference values” is necessary in the following cases:
— When using the fixture for the first time after delivery
— After replacement of parts
Necessary
equipment
— Shorting bars (supplied as accessories)
— Impedance measuring instrument (calibrated at the 7mm connector end)
Q X R

2

fL
 
R

= =
Note that the above settings are just an example. Actually, user limit
values should be varied depending on the measuring conditions and type
of DUT.
In actual measurement, some of the effect of electrode deterioration is
canceled by SHORT compensation. However, it is recommended to set
user limit values on the assumption that deviations from the reference
values affect the entire measurement results, as shown in the above
example.
Set the fixture compensation for the measuring instrument to OFF.
Check that each shorting bar is not deformed or stained.