Agilent Technologies 8590L Service Manual page 558

The frequency of the 10 MHz standard timebase, a room temperature
crystal oscillator (RTXO), is controlled by a DAC located on the A25
counterlock assembly. Refer to the 10 MHz reference procedure in
Chapter 2 to adjust the timebase DAC using
equipped with a A24 Tracking Generator (Options 010 and 011) use two
correction constants to improve the performance of the external
automatic level control (ALC). Refer to
Correction Constants for Option 010 or 011"
External ALC Error for Option 010 or 011"
about the CALTGX slope and offset correction constants.
The initial service-calibration correction constants are stored by the
factory in nonvolatile memory on the A16 assembly. After shipment,
new correction constants must be manually generated whenever an
adjustment or repair affects frequency response or A12 amplitude
control step attenuation.
Refer to "After an analyzer repair"
assemblies that affect frequency response. Whenever the A16
processor/video assembly is replaced, new correction constants must
also be generated, unless valid correction constants were saved prior to
the instrument failure.
Note that the manual generation of the new service-calibration
correction constants is a lengthy procedure. Avoid having to generate
new correction constants manually by periodically recording the
current correction constants. Refer to
backing up correction constants.
Refer to the softkey descriptions in this section for specific information
about the use and modification of the correction-constant data.
Chapter 13
Softkey Descriptions
CAL TIMEBASE
"19. Entering External ALC
and "21. Correcting for
in Chapter 2
in Chapter 4 for the specific
Chapter 3 for information about
Softkey Descriptions
.Analyzers
for details
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