106                                                                                                                     Keysight N9938-90003 User’s Guide
Calibration for NA, CAT, and VVM Modes
Calibration Method Summary
Calibration Method Summary
— Mechanical Full 2-port Cal is ALWAYS the most accurate Cal method. The 
quality of a Mechanical Cal is completely dependent on the quality of the 
OPEN, SHORT, LOAD standards and the quality of the standard 
connections. Use the correct high quality standards to ensure the most 
accurate calibration. 
— Even with the optional Load, phase accuracy begins to degrade when 
the return loss is greater than about 20dB.
— CalReady is accurate ONLY when the DUT is directly connected at the test 
ports and most accurate at room temperature. 
— For highest accuracy, a new Mechanical Cal should be performed:
— When the temperature changes more than about 10°F (5°C)
— When the connection to the DUT requires a different jumper cable or 
adapters. 
— When any of the following measurement settings change: Frequency 
Range, Power Level, IF BW, and Resolution.