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The user can select the appropriate sensor according to the characteristics and measurement requirements of the
measured signal and the specifications of each sensor. The main unit and power sensor models are shown in Tables 3.1
and 3.2. Please refer to Chapter 8 “Main specifications” for detailed description of specifications of each sensor.
3.2 Zeroing And Calibration Before Measurement
To improve the power measurement accuracy, the power sensor should be zeroed and calibrated during power
measurement.
The S2438 series microwave power meter contains a calibrator with a frequency of 50 MHz and power of 0dBm which
can be traced back to national standards.
The S71710 series CW power sensor, if used, should be connected to the calibrator for calibration, but the S81702 or
S81703 series peak power sensor has no such demand as they are built-in with a calibration circuit and can be calibrated
online during use.
After the user performs regular maintenance according to the recommended calibration interval, the calibrator can enable
the user to measure the CW power more accurately.
It is recommended to zero and calibrate the power sensor:
1) Every time the sensor is replaced. The sensor needs to warm up for 15 minutes for stabilization before
auto-calibration.
2) When the prompt “Channel A/B requires zeroing and calibration” is the displayed in the system state area;
3) When the temperature drift warning message is displayed in the system message area on the screen. If the
surrounding ambient temperature of the sensor changes too much, the system will display an excessive
temperature drift message. When the temperature returns to the specified range, the system will automatically clear
the warning message.
4) When the S71710 series CW sensor is used for measurement if the power of the measured object is relatively low
(<-40 dBm). After the S 71710 power sensor is connected to the device under test, disable the output of the device
under test, perform zeroing operation for the S71710 power sensor and eliminate the error caused by ground noise
between the microwave power meter and the device under test.
5) After the S81702 or S81703 series peak power sensor with a built-in zeroing and calibration function is connected to
the device under test. The online zeroing and calibration can be performed without disablement of output of the
device under test.
When the “Calibration required” function is activated, if the user is unable to perform calibration because of the
above-mentioned circumstances, then measurement cannot be carried out. Normal measurement can only continue once
auto-calibration is complete.
