MW1008P, user manual
26
The
calibration
can
be
performed at a given test
frequency
or
for
all
frequencies. As a matter of
fact, the parasitic elements
may not be constant over
frequency, and the instrument
keeps in memory the 4
parasitic elements for each
frequency.
The calibration is performed
by pressing key CAL. A menu
appears and you can choose
an open-circuit calibration
(OPEN) or a short-circuit
calibration
(SHORT). The
correction
limits
are
the
following ones :
Short-circuit calibration : the maximum series
resistance of cables should be 20
while total
impedance should be < 50
Open circuit calibration : the parallel impedance
of the cable should be smaller than 10 k
.
The instrument displays the message « PASS » if the calibration succeeded, « FAILED » in
the other case.
To perform a calibration at all frequencies press key CAL long enough so that the instrument
displays the menu « OPEN SHORT » in capital letters. The instrument then starts the
calibration procedure at all frequencies, what takes a longer time. The calibration should be
performed at each measurement cable change, or for critical measurements (see above).
SMT tweezers cable :
The zeroing of the instrument can be performed by shorting the tweezers extremities. The
open circuit calibration is more critical since the spacing between contacts may vary. One
should use for this a small piece of isolating material with the same thickness than the
component to measure, and proceed to open circuit calibration.
Case of measurements on transformers
The OPEN/SHORT calibration must not be used.
Figure X : short-circuit calibration for the measurement of low
impedances.
