OPERATION
2-1
DISPLAY
The SR715/720 displays both major and minor parameters simultaneously. In addition to the parameter
selection, the display type may also be specified. This allows results to be shown in engineering units,
deviation from a specified nominal value, or binned for sorting purposes. The display also shows values
entered from the keyboard while specifying the nominal value or bin limits. The status LED's indicate remote
programming status information.
DISPLAYED PARAMETERS
The Parameter keys ([R+Q], [L+Q], [C+D], [C+R], and [AUTO]) determine the measurement type and the
displayed parameters. The selected parameters are indicated above the two 5 digit displays.
R+Q Resistance is shown on the major parameter (left) display and the quality factor,
Q, on the minor parameter (right) display. The resistance is either the equivalent
series or parallel resistance of the device under test. The units of resistance are
Ω, kΩ, or MΩ. Q is the ratio of the imaginary part of the impedance to the real
part of the impedance and is dimensionless. Q is the same for both series and
parallel representations. If Q is positive, the reactive component of the device
under test is inductive. If Q is negative, the reactive component is capacitive.
L+Q Inductance is shown on the major parameter (left) display and the quality factor,
Q, on the minor parameter (right) display. The inductance is either the equivalent
series or parallel inductance of the device under test. The units of inductance are
µH, mH or H. Q is the ratio of the imaginary part of the impedance to the real part
of the impedance. Q is dimensionless and the same for both series and parallel
representations. If the major parameter (inductance) is negative, then the part
under test is capacitive.
C+D Capacitance is shown on the major parameter (left) display and the dissipation
factor, D, is shown on the minor parameter (right) display. The capacitance is
either the equivalent series or parallel capacitance of the device under test. The
units of capacitance are pF, nF, or µF. D is the ratio of the real part of the
impedance to the imaginary part of the impedance, or 1/Q. A good capacitor has
a large C (imaginary) and a small R (real) and thus a low D. If the major
parameter (capacitance) is negative, then the part under test is inductive.
C+R Capacitance is shown on the major parameter (left) display. The equivalent series
or parallel resistance is shown on the minor parameter (right) display. The units
for resistance are Ω unless the kΩ LED to the right of the minor parameter
display is on.
AUTO The SR715/720 determines which component model is the most accurate
representation of the device under test and chooses the appropriate parameter
pair. The determination is made as follows:
If |Q| < 0.125 the unit selects R+Q.
If Q > +0.125 the unit selects L+Q.
If Q < -0.125 and the unit is in the series mode, it selects C+R.
If Q < -0.125 and the unit is in the parallel mode, it selects C+D.
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