7 Performance Tests and Calibration148 Keysight U1401B User’s and Service GuideAdjustment ConsiderationsTo adjust (calibrate) the instrument, you will need a set of test input cables andconnectors for receiving the reference signals. You will also need a shorting plug.Adjustments for each function should be performed with the followingconsiderations (where applicable):– Allow the instrument to warm up and stabilize for five minutes beforeperforming the adjustments.– Make sure that the batteries will not run low during the adjustments. Replaceor recharge the batteries before making adjustments to avoid false reading.– Consider the thermal effects as you connect the test leads between thecalibrator and this instrument. It is recommended that you wait for one minuteafter connecting the test leads before you begin the calibration.– During ambient temperature adjustment, ensure that the instrument has beenturned on for at least one hour with a K-type thermocouple connectedbetween the instrument and the calibration source.CAUTION Do not turn off the instrument during calibration. This may delete thecalibration memory for the present function.