Zeroing And Selecting "Dq In Ppm; Recalibration For Range 4 - IET Labs, Inc. RLC Digibridge 1693 User And Service Manual

5.9.2 Zeroing and Selecting "DQ in
PPM"
This zeroing procedure is like the routine procedure in
Operation, Chapter 3. In this process, the Digibridge
automatically measures stray parameters related to
the test fixture and associated circuits and retains the
data, which it uses in each recalibration step below
to correct measurements so that results most accu-
rately represent parameters of the external calibration
resistor alone. NOTE: Leave the I-T factor at 1 (the
power-up default) or more, NOT less. (See para 3.5.5.)
1. Press [FUNCTION) key (if necessary) to
select MEASURE function .
2. Press [MEASURE MODE) key (if necessary)
to select TRIGGERED mode.
3. Press the following keys: [1][6][9][3][=]
[SHIFT][OPEN].
4. Confirm that the GO indicator is lit.
5. Keep hands and objects at least 10 cm
(4 in.) from test fixture.
6. Press the START button.
7. Wait for the GO indicator to be lit again.
8. Press the following keys: [1][6][9][3][=]
[SHIFT][SHORT].
9. Confirm that the GO indicator is lit.
10. Press the START button.
11. Wait for the GO indicator to be lit again. The
RLC display should be .00000 ohms.
12. Disconnect the short circuit.
DQ in PPM. Press [SHIFT][DQ in PPM] keys if
necessary to light this indicator. Select "kΩ." Press
[R/Q] key. The kΩ indicator will light
Service and Maintenance

5.9.3 Recalibration for Range 4

1. Connect the 24.9-ohm calibration resistor to
the Digibridge test fixture .
2. Enter the known parameters of the calibration
resistor as in the following example, based on
the values R = 24.895 ohms and Q= 15 ppm.
NOTES: The Digibridge will accept six digits for R, even
though only five will be displayed. The Q is associated
with 'b in 00", and its value must be preceded with "-"
if the known Q is negative.)
A. Select ENTER with [FUNCTION] key
and CONTINUOUS with [MEASURE
MODE] key.
B. Press [4][=][SHIFT][SPECIAL][1]
C. Press [2][4][.][8][9][5][=][SHIFT][NOM
VALUE]
NOTE: The calibration resistance value should appear
in the left display. The DQ in PPM indicator must be lit.
D. Press [1][5][=][SHIFT][BIN NO][0][0]
NOTE: The calibration Q value should appear in the
right-hand display.
3. Enable and execute the recalibration for this
range as follows. (The following keystrokes
are the same for any range.)
A. Select MEASURE with the [FUNCTION]
key and TRIGGERED with [MEASURE
MODE] key.
B. P r e s s [ l ] [ 6 ] [ 9 ] [ 3 ] [ = ] [ 1 ] [ S H I F T ]
[CALIBRATE]
NOTE: The GO indicator being lit and a 6 in the left
and a 6 in the right displays confirm that calibration is
enabled.
C. Press START (The GO indicator remains
unlit while calibration proceeds.) Keeping
hands away from the test fixture, wait until
the GO indicator is lit again.
This completes recalibration of one range.
4. Select CONTINUOUS with the [MEASURE
MODE] key and cheek that the Digibridge
operates properly with the recalibration.
• The Digibridge should measure the calibra-
tion resistor like any ordinary resistor and
display its R and Q (ppm) values.
• The Q display can be expected to "jump"
a bit. (precision and repeatability are in the
order of 5 ppm).
• The NO-GO indicator will probably be lit;
this is normal.
5. Disconnect the calibration resistor from the
test fixture.
1693 RLC Digibridge
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