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Model 4277A
SECTION III
Note
When the HP I6065A, EXT Voltage Bias
Fixture, is used with the 4277A, set the
CABLE LENGTH switch to
the
Im
position.
Note
When
the
HP
16048D
Test
Leads
(standard 2m test cable) is used with
the 4277A, the CABLE LENGTH switch
must be set to the Im position and the
SA SELECT switch (SI) on
the
A1
(Logic) board must be set as shown in
Figure 3-11. The setting of this switch
can
be
changed
only
when
the
instrument is turned off.
Figure 3-11.
SA
SELECT Switch Settings for
2m Test Leads.
Note
If test leads longer or shorter than the
standard Im or 2m test leads are used,
the additional error is proportional to
the square of the frequency.
As the
characteristic impedance of the test
leads is also a factor in the propagation
loss and phase shift (and of resultant
measurement error), use of different
type test leads must be avoided.
Use
only the standard test leads available
from Hewlett-Packard.
3-51. ZERO OFFSET ADJUSTMENT
3-52. The test fixtures and test leads used to
connect samples to the instrument's UNKNOWN
terminals have inherent residual impedance and
stray admittance which, unless compensated for
in some way, affect measurement accuracy. To
minimize the effects of these residuals and
strays, the 4277A is equipped with OPEN and
SHORT Zero Offset Adjustment functions that
can be executed from the front panel or via the
HP-IB.
Each
Zero
Offset
Adjustment
is
performed at the following frequencies:
IMHz
900kHz
700kHz 505kHz
202kHz
lOOkHz
50.5Hz
20.2Hz
lOkHz
Zero Offset data for test frequencies other than
those listed above are calculated from the Zero
Offset
data
obtained
at
the
above
test
frequencies
by
using
second
degree
interpolation. Thus, Zero Offset is provided for
measurements
made
at all test
frequencies.
Brief
descriptions
of
the
Zero
Offset
Adjustments (OPEN and SHORT) are given below.
ZERO OPEN:
The procedure for performing OPEN Zero Offset
Adjustment is as follows:
(1)
Connect the test fixture or test leads to the
instrument's UNKNOWN terminals.
Note
If test leads are used, you
must
convert
the
four-
terminal pair configuration
to
a
two-terminal
configuration.
Refer
to
paragraph 3-45 and Figure
3-8.
(2)
Connect nothing as the DUT.
(3)
Press the ZERO OPEN button.
3-39
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