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3.3.3.2 Secondary Measurement
Results
The secondary Digibridge measurement will be
presented on the right (QDR) display panel, for each
measurement if the DISPLAY selection is VALUE,
delta%, or deltaRLC. There is no secondary display
if the selection is BIN NO.
Negative QDR. A negative QDR has the following
meanings:
Parameter
+ QDR
Selection
R/X, G/B, Z/ANG,
DUT is inductive
Q, D, or R is
L/Q, C/D, C/R
Positive
G/B, Y/ANG
DUT is capacitive
If the secondary measurement is Q, D, or R and is
negative - then there are two likely possibilities. If
the Q or D value (whichever is being displayed) is
very small, a small (acceptable) calibration and/or
measurement error can lead to a negative result. (It
should of course fall within the specified accuracy of
the instrument.)
Measurement error can be reduced by choice of
measurement conditions, averaging, etc. Another
possibility is that the DUT (as seen by the Digibridge)
really does have a negative loss factor . This situation
might occur when you are measuring certain kinds of
multi-terminal networks or active devices.
NOTE: Improper connection of extender cables can
cause a false indication of negative QDR.
D, Q or ANG IN PPM, Selected by the [SHIFT][DQ
in PPM] Keys. For D, Q or ANG values less than
.0100, selecting DQ in PPM improves the resolution
by a factor of 100. For example , if the displayed D
values of two capacitors are both 0.0001, changing
to DQ in PPM might distinguish them by providing a
reading of 138 ppm for one and 87 ppm for the other.
Operation
The ''DQ in PPM" selection applies to the Q, D or
ANG result only, and is effective for all selections
of the [DISPLAY] key except BIN NO, and for all
parameter selections except C/R, R/X, and G/B.
When this selection is in effect: the DQ INPPM in-
dicator is lit; the display is always parts per million,
without decimal point; if the display is blank, the D
or Q value is greater than 9999 ppm (to obtain the
value, cancel "DQ in PPM").
To cancel this selection, use the same keystrokes
-QDR
again: [SHIFT][DQ in PPM].
DUT is capacitive
Q, D, or R is
negative see below
DUT is inductive
If comparison is enabled, by a non-zero entry for
"nominal value" and limits in at least one bin, a GO
or NO-GO indication is provided on the keyboard,
for every measurement. GO means the measurement
falls in bin 1 through 13; NO-GO means bin 0 or 14.
3.3.4 Units, Multipliers, and Blank
Units of R, L, C, G, Z, and Y are determined entirely
by your selection of parameter. Units multipliers are
fixed by parameter, range, and frequency, except that
selection of delta% changes the RLC display to a
percentage. See Table 3-6.
Units of D and Q are dimensionless and are expressed
as a decimal ratio, without multiplier - unless you se-
lect "DQ IN PPM", in which case D or Q is expressed
in parts per million (see below). To obtain D or Qin
percent, from the regular display, move the decimal
point two places to the right. For example, a regular
display of D = .0045 is equivalent to 0.45%
3.3.3.3 Go/No-Go Indicators
Displays
1693 RLC Digibridge
39
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