Agilent Technologies 8590 Series Service Manual page 428

Analyzer Options and Block Diagrams
First LO Distribution Amplifier (LODA) 8593E, 8594E, 8594Q, 8595E, 8596E Option 009
IS THE FAILURE IN A SINGLE CHANNEL BANDWIDTH?
Comments
IS THE FAILURE WITH THE PREAMPLIFIER "ON" ONLY?
428
TREE 4: EVM Problems
Problems/Reasons
The test conditions with the
preamplifier "ON" are designed to
test the functionality of the
preamplifier and to stress the
analyzer sensitivity to low
signals. If the problem could be in
the preamplifier, the extra noise
in the RF option board path, or it
could be in the spectrum analyzer
platform DANL.
Diagnostic/Fix Action
•Evaluate the preamplifier. Refer to
"Set up to use the preamplifier" in
the "Making Measurements"
chapter of the user's guide for your
QAM analyzer.
1. Remove the 8770 test signal,
then apply the CAL signal to the
RF input.
2. Do the "Measuring the
Preamplifier Gain" procedure to
find out what suspect
preamplifier gain truly is. It
should be 23 ±3 dB. If it is not,
the problem is in the
preamplifier.
3. Test the preamplifier control
by turning the preamplifier on
and off, using PREAMP ON OFF.
•Evaluate the spectrum analyzer
platform DANL. If the DANL is out
of specification, the problem is in
the spectrum analyzer
down-conversion path.
•Swap the RF option card with a
"known" good card. Rerun the test.
If the problem is resolved, save the
bad board and the matching test
data for return to Agilent.
Chapter 10