Agilent Technologies 8590 Series Service Manual page 235

The analyzer may also fail the displayed average noise performance
verification test.
1. Check the REF LVL CAL DAC value using
described in "Using the Internal Service-Diagnostic Routines."
type of problem causes the DAC value to be close to the 255
maximum.
2. Measure the 321.4 MHz input to the A9 third converter assembly by
connecting the CAL OUT to the INPUT 50Ω with a BNC cable.
75 Ω input only: Connect the CAL OUT to the INPUT 75Ω with the
75 Ω BNC cable.
Then, disconnect the W9 cable assembly from the third converter
and measure at the cable output.
The 321.4 MHz input typically measures between −36 and −39 dBm
with zero input attenuation.
3. Check the signal path from the analyzer input to the output of the
A14 log amplifier assembly. Refer to
located in Chapter 5
If the displayed signal amplitude appears too
high
This problem is caused by high gain somewhere along the RF or IF
signal path. The displayed CAL OUT signal appears to have an
amplitude greater than −20 dBm. The excessive gain causes a
calibration error that makes the CAL OUT signal appear higher than
normal.
The self-calibration routine may not fail.
CAL AMPTD
• Check for a REF LVL CAL DAC value of 0 using
as described in "Using the Internal Service-Diagnostic Routines."
The values in the ERR column are 0.00 or have a negative value.
• Measure the 321.4 MHz input to the A9 third converter assembly by
connecting the CAL OUT to the INPUT 50Ω with a BNC cable.
75 Ω input only: Connect the CAL OUT to the INPUT 75Ω with the
75 Ω BNC cable.
Then, disconnect the W9 cable assembly from the third converter
and measure at the cable output.
The 321.4 MHz input typically measures between −36 and −39 dBm
with zero input attenuation.
• Check the signal path from the analyzer input to the output of the
A14 log amplifier assembly. Refer to
located in Chapter 5
Chapter 4
Isolating an RF, LO, IF, or Video Problem
"IF Power-Level Measurement"
of this service guide.
"IF Power-Level Measurement"
of this service guide.
Troubleshooting the Analyzer
as
DISPLAY CAL DATA
This
DISPLAY CAL DATA
235