IET Labs, Inc. RLC Digibridge 1693, User And Service Manual, Page: 38 / 171

14
1693 RLC Digibridge
Operation
3.1.3 Zeroing
In the zeroing process, the instrument automati-
cally measures stray parameters and retains the data,
which it uses to correct measurements so that results
represent parameters of the DUT alone , without (for
example) test-fixture or adaptor capacitance.
Before measurement, zero the Digibridge as follows.:
1. Set conditions: SLOW measure rate, 1 V test
voltage (default), RANGE HELD indicator
NOT lit.
2. To measure open circuit
A. Press [FUNCTION] key (if necessary) to
select MEASURE function.
B. Press [MEASURE MODE] key (if neces-
sary) to select TRIGGERED mode.
C. Connect the remote test fixture or at least
the BNC cables and adaptors that will
contact the DUT.
D. Be sure that the test fixture is open
circuited.
If you want this “zero” process to echo a display of
0 00000 , press the [C/D] key. However doing so will
disable automatic parameter selection. (See paragraph
3.1.4, step 2.).
E. Press the following keys: [l] [6] [9] [3] [=]
[SHIFT] [OPEN]
Note: the GO indicator being lit and two zeros confirm
the previous step. Watch the GO indicator on the
keyboard; not one on any remote test fixture.
F. Keep hands and objects at least 10 cm
(4 in.) from test fixture.
G. Press the START button.
The GO indication disappears.
H. Wait for the GO indicator to be lit again.
3. To measure short circuit:
A. Short the fixture with a clean copper wire
(AWG 18 to 30), length 5 to 8 cm.
B. Press the following keys: [l] [6] [9] [3] [=]
[SHIFT] [SHORT].
Note : the GO indicator being lit and two fives confirm the
previous step.
C. Press the START button.
The GO indication disappears.
D. • Wait for the GO indicator to be lit again.
E. • Remove the short circuit.
Note: For best accuracy, repeat this procedure daily
and after changing test-fixture adaptors or frequency..
3.1.3.1 Zeroing with various test
fixtures
This section contains information on proper open and
short connections for various types of cables for use
with the 1693 Digibridge.
7000-04 Banana and 1657-9600 Extender Cables
Open and short should be performed as shown in
Figure 3-1 below when using banana plugs. When
performing Open the spacing between the pairs should
be the same as the spacing of the terminals on the DUT
or if unknown a minimum of 0.75”. Short should be
performed as shown and it is important to keep senses
and drives in the correct order.
Geometry:
If is important to maintain the spacing between the
leads during the open compensation at exactly the
same distance as the spacing is when the banana plugs
are connected to the DUT. If the spacing is not exactly
the same there will be an error in the measured value.
This is due to the fact that the four terminal Kelvin
connection stops at the connection between Drive
and Sense. The banana plugs are two-terminal so the
capacitance between the parallel spaced banana plugs
will be measured as part of the overall measurement
unless open compensation is performed to eliminate
this additional capacitance.
Figure 3-1: Open and short measurements with
banana plugs
Sense + Sense -
Drive + Drive -
Match spacing of
DUT terminals
DUT
+ -
Sense +
Sense -
Drive +
Drive -
Open
Connection
Short
Connection