Site Master™ S331L User Guide : Calibration : Calibration Procedures : Temperature Window
 
Temperature Window
Anritsu recommends allowing the instrument to warm up for ~10 minutes to typical operating temperature before calibrating. Any applied calibration factor will automatically be turned off if the internal temperature moves outside the valid cal window. The Site Master will display: and a new cal will be required.
Save and Recall Calibration Coefficients
Calibration information is included when a setup (.stp) file is saved (even if the Cal Correction is Off). The calibration information is also recalled with a setup file and can be applied (Calibration > Cal Correction On) if the current internal instrument temperature is within the saved cal window.
Calibration information is not included when a measurement (.dat) file is saved.
Note 
The InstaCal module is not a discrete calibration component and it can not be used at the top of the tower to perform line sweep measurements.