Front Panel Operation
Manual 31470, Rev. E, April 2001
2-23
2.
Turn off the source output before you zero the sensor. The microwave source must output less
than -74 dBm of total noise power during RF Blanking for proper zeroing. The source signal
power should be less than -90 dBm.
3.
Press
[CAL/ZERO]
. The meter will check that the sensors are installed and calibrated, then
it will display a menu for you to select Sensor A, B or both (All) to be zeroed. Select the
sensor(s) to start the zeroing process, or press [Cancel] to abort zeroing and return to the Main
menu.
4.
The sensor should be zeroed just before recording final readings in the lower 15 dB of the power
sensor’s dynamic range.
5.
The sensor should remain connected to the signal source during zeroing. By turning off the
source instead of disconnecting the detector, the zeroing process automatically accounts for
ground line voltages and connector interface EMF.
2.3.3.1
Calibration & Zeroing for High Power Sensors with Removable
Attenuators
When using a Giga-tronics high power sensor with external attenuator, Giga-tronics power meters
automatically recognizes the sensor type and compensates for the attenuation factor. However, when
performing the front panel calibration, be sure to remove the attenuator before connecting to the
calibrator port. During measurement, you do not need to enter an offset factor to account for the
attenuator loss. The sensor frequency calibration factors automatically correct for the combined
frequency response of the sensor and attenuator. Because the sensor and attenuator are a matched set,
the serial numbers of the sensor and attenuator are identical. Do not use attenuators from other high
power sensors.
1.
Remove the high power attenuator from the sensor.
2.
Connect the sensor to be calibrated from Channel A or B to the Calibrator Output (see
Figure 2-14).
3.
Press the
[CAL/ZERO]
hardkey. The meter will automatically zero and calibrate the sensor.
4.
Reconnect the high power attenuator to the sensor.
NOTE:
Sufficient time must be allowed for the module to reach thermal
equilibrium with the source. This could be up to 15 minutes for moderate initial
temperature differences.
NOTE:
Sufficient time must be allowed for the module to reach thermal
equilibrium with the source. This could be up to 15 minutes for moderate
initial temperature differences.
NOTE:
There are alignment marks (arrows) on the sensor and attenuator. To reduce
measurement uncertainty, align the arrows when reconnecting the attenuator to the sensor.
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Summary of Contents for 8650A Series
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Page 240: ...Series 8650A Universal Power Meters Index 6 Manual 31470 Rev E April 2001 ...