HP 83751A, User Manual

Page: 38 / 282

I
Externally Leveling the Sweeper
leveling with detectorslcouplerslsplitters
N O T E
The coupling factor is defined by the equation
leveled power detected power
Refer to Figure ‘2-1 for
locations of
P
lev and
P det.
After the coupling factor has been entered, the front panel knob
may be used to fine tune the displayed power to equal the actual leveled output power
Figure illustrates a typical setup for external leveling. When externally
leveled, the power level feedback is taken from the external negative detector
input rather than the internal detector. This feedback voltage controls the
ALC system to set the desired RF output.
Figure 2-2 shows the input power versus output voltage characteristics for
typical
diode detectors. From the chart, the leveled power at the diode
detector input resulting from any external level voltage setting may be
determined. The ALC feedback voltage present at the output of the detector
must be between -0.2
and -0.5 For a typical diode detector, this
corresponds to a detector input of approximately -35 to (See
Figure 2-2.)
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