If the displayed values are unstable increase the Running Average from the default value of 1. Maximum value is 60. Increasing the running average is useful when measuring unstable sources or when measuring near the zero calibration level described below.

To monitor and record the maximum power level over time, set Max Hold to On. The needle and numeric values will display the maximum recorded value until Max Hold is turned off.

In Cont + Run mode (Figure: Limit Setting Display Changes), the power meter is continuously measuring and updating the power reading. In Cont + Hold mode, the readings are halted.

In Single + Run mode, the power meter performs the number of readings set in Running Average (default is 1) and then places the instrument in Hold mode. Changing the mode from Hold to Run will initiate another series of readings and then returns the instrument mode to Hold once again.

Zero the sensor before making power measurements. If frequent low-level measurements are being made, it is advised to check the sensor zeroing often and repeat as necessary. Before zeroing the sensor, connect it to the DUT (device under test) test port and remove RF power from the connection to a level 20 dB below the noise floor of the power sensor.

For the MA24105A power sensor, this level is less than –20 dBm.

For the MA24106A power sensor, this level is less than –60 dBm.

For the MA24108A, MA24118A, and MA24126A, this level is less than –70 dBm.

It is preferable to leave the sensor connected to the DUT test port so that ground noise and thermal EMF (electro-magnetic fields) are zeroed out of the measurement. The sensor may also be connected to a grounded connector on the DUT or disconnected from any signal source.

This message appears if the zero operation is unsuccessful. The reason could be the presence of RF power at the input of the sensor.

Turn off the RF input to the sensor or disconnect the sensor from the RF source and try the zero operation again.