Service manual

5-8 8510XF Network Analyzer Systems
System Maintenance
Conversion Loss Calibration
Conversion Loss Calibration
Purpose of the
Calibration
This is the second of the two calibrations that insure the accuracy of absolute
power levels at the test ports.
The RF-to-IF conversion loss of a mixer varies with frequency. To
compensate for these frequency-related variations, correction factors must
be applied to the level control system. Conversion loss calibration is the
process by which these correction factors are gathered.
(For more detail, see “The Leveling Loop” on page 5-15, and “Level
Calibration” on page 5-18.)
The Calibration
Process
During conversion loss calibration, the test ports are monitored with a power
meter while the 8510XF steps through its frequency range. Based on the
measured power levels, correction factors for each frequency are stored in an
EEPROM within the millimeter-wave controller.
Measurement frequencies occur at intervals of 25 MHz, up to 18 GHz.
Above 18 GHz, measurement frequencies occur at intervals of 50 MHz.
When to Calibrate Calibration is performed at the factory prior to shipment; thereafter it should
be performed as required.
NOTE Conversion loss calibration data applies only to the specific combination of
controller and test heads calibrated together as a set. The cables connecting
the test heads to the controller also become part of the calibration. If the
controller or one of the test heads is repaired or replaced, the old calibration
data will no longer be valid.
Agilent Technologies
Customer Engineering
This calibration requires expensive test instruments, software and
accessories. For this reason, conversion loss calibration is to be performed
by an Agilent Technologies Customer Engineer or the factory only. Contact
your nearest Agilent Technologies office to order this service (refer to
“Contacting Agilent” on page v).