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144 Keysight N9938-90006 User’s Guide
Calibration for NA, CAT, and VVM Modes
Verifying Calibration and Jumper Cable Integrity
Apply Nearest (NA Mode Only)
When Apply Nearest is pressed, interpolation is turned off and the nearest
calibration point is applied when the start stop frequencies are changed for the
current sweep.
To use Apply Nearest :
— Press Cal 5
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Apply Nearest
Verifying Calibration and Jumper Cable Integrity
After calibrating, it is important to verify that the calibration is good. When
using a jumper cable, also verify that the cable is of high quality.
Verify a Calibration
— Connect a LOAD standard at the calibration reference plane (where
calibration standards were connected). This may be at the end of the
jumper cable or at FieldFox PORT 1 connector.
— In CAT Mode, select Return Loss .
— In NA Mode, select S11 with Log Mag format.
— For frequencies lower than 9 GHz , observe the trace on the FieldFox
screen:
— Lower than 35 dB indicates a GOOD calibration.
— Higher than 30 dB indicates that you should recalibrate.
Verifying Phase Accuracy
— Connect a LOAD standard at the calibration reference plane (where
calibration standards were connected).
— In NA Mode, select a S11 Reflection with Polar or Smith Chart format.
IMPORTANT!
– Apply Nearest needs to re-selected after each pair of start and stop
frequency points is entered, because the Apply Nearest feature is disabled
when a new start stop frequency pair is selected.
– Apply Nearest calculates the number of points based on the start and
stop frequency points entered.
– Apply Nearest will display the following error when there is no valid
calibration found:
“
Error: 225, The required user calibration is not present.
“