Fluke 9640A Series Instruction Manual page 251

If a power sensor having different characteristics than the one specified is
used, it may be necessary to change sensors prior to this point. Consult the
power sensor manufacturer's manual for input signal level specifications.
17. Disconnect the power meter and sensor from the UUT 75 Ω Leveling Head. Connect
the 75 Ω Leveling Head to the input of the spectrum analyzer via a 75 Ω to 50 Ω
impedance-matching pad at the spectrum analyzer RF input.
The following steps facilitate the low-level flatness adjustment of the 75
Leveling Head using a spectrum analyzer/measuring receiver.
18. Set the UUT to OPER .
19. Set the spectrum analyzer reference level, span, resolution and/or video bandwidth as
necessary to make a high-quality level measurement at the applied level and
frequency.
For each frequency it is important to maintain consistent analyzer/receiver
settings as the target amplitude changes. For any given frequency the
analyzer setting can be to suit, but that setting must be maintained for all
amplitudes at that frequency after the transfer point. In particular, analyzer
attenuator, reference level and resolution bandwidth settings must not
change. Typically there are 3 or 4 amplitudes per frequency point during
which the analyzer settings must be static.
20. Using the blue arrow keys and rotary knob, edit the UUT Actual output until the
spectrum analyzer display indicates the Target value stated. Press Accept Target .
The recommended spectrum analyzer/measuring receiver is capable of
automatically compensating for the insertion loss of the 75
impedance-matching pad. If this feature is not enabled or an alternative
spectrum analyzer is used the insertion loss must be taken into account to
obtain the expected level indication on the spectrum analyzer.
21. Press Next Target .
22. Repeat steps 19 through 21 for all points requiring the use of the spectrum analyzer
until all Leveling Head adjustments are completed.
23. Press Previous Menu . The 75 Ω Leveling Head adjustment is now complete.
24. If additional Leveling Heads are to be adjusted, substitute the remaining Leveling
Head(s) for the one currently attached and perform the appropriate (50 or 75 Ω)
Leveling Head adjustment process. If not, press Exit twice to return the UUT to a
normal operating state.
Note
Note
Note.
Note
Calibration
Calibration Adjustments
Ω
Ω Ω
to 50
5
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