Do I have to zero the power meter before making every RF power measurement with the Agilent 8922?
The Pwr Zero function establishes a 0.0 Watt reference for measuring RF power at the RF IN/OUT port. A Pwr Zero should be performed:
- When alternately making high and low power measurements.
- High RF power applied to the RF IN/OUT connector can raise the temperature of the internal circuitry, causing measurement offsets to be generated. These offsets are small in comparison to the high level of the signal being measured. However, they can become appreciable when measuring low power levels immediately after measuring high power levels. Zeroing the power meter before making the low power measurement will compensate for these offsets and provide the best measurement accuracy.
- Before making the first RF power measurement after turning the instrument on.
- After initializing the instrument (that is, after selecting PRESET from the front panel or sending *RST on the IEEE 488 GPIB bus).
While not necessary, it is recommended that a Pwr Zero should be performed:
- After every hour of continuous use.
- Whenever there is an fast change (> 10 degrees C) in ambient temperature, such as taking the instrument from a warm inside environment to a cold outside environment.