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The on-screen amplitude level will probably not change as expected, since the
video circuitry is assumed to be faulty.
15. Monitor
while stepping the reference level from -10
to j-30
If the
voltage does not step approximately 100
per 10
step, refer to “Video MUX” in
this chapter.
16. If the Video MUX is working properly, monitor
with the oscilloscope and step
the reference level from -10
to
If the voltage does not change 100
per 10
step, refer to “Video Filter” in this chapter.
17. If the voltage at
is correct, move the oscilloscope probe to
and step the
reference level between -10
and i-30
If the voltage does not change 100
per 10
step, refer to “Video Filter Buffer Amplifier” in this chapter.
18. If the voltage at
is correct, move the oscilloscope probe to
Set the
following controls to keep the ADC MUX set to the MOD-VIDEO input during the
sweep
Sweep time
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 s
Detector mode
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sample
19. Step the reference level from -10
to i-30
while monitoring the voltage change
on the oscilloscope. If the voltage does not change 100
per 10
step, refer to “ADC
MUX” in this chapter.
20. If the voltage at
is correct, move the oscilloscope probe to
and step the
reference level between -10
and i-30
If the voltage at
is not the same
as that at
replace
21. If the voltage at
and
are equal, move the oscilloscope probe to
22.
Change the reference level from -10
to 0
The voltage change on
should be between 630
and 770
If the voltage change is outside of these limits,
refer to “Variable Gain Amplifier (VGA)” in this chapter. The gain of the VGA should be
7
Refer to function block X of A3 Interface Assembly Schematic Diagram in the
HP 8560 E-Series Spectrum Analyzer Component Level Information.
The log scales are modified using a combination of amplification and digital trace
manipulation. The video input to the A3 assembly is either 10 dB/div or linear. To obtain
the 5 dB/div scale, the CPU manipulates the trace data from the 10 dB/div scale. To obtain
the 2 dB/div scale, the video signal is amplified and offset so that top-screen in 10 dB/div
corresponds to top-screen in 2
iv. To obtain the 1 dB/div scale, the CPU manipulates
trace data from the 2 dB/div scale.
In 2
Log Offset/Log Expand amplifies the top 20
of the display. This is done by
offsetting the video signal by -0.8 V and providing a gain of 5 to the top 0.2 V of the video
signal. The -0.8 V offset is accomplished by sinking 2
through R114 by current source
I. On the spectrum analyzer, press
SPAN, (CAL), and IF
.
Section 8-15
Summary of Contents for 8562E
Page 21: ...A l HP 85623 Interconnect Block Diagram A 5 Contents 14 ...
Page 205: ...8560E Series sl131e FIGURE 5 3 PARTS IDENTIFICATION MAIN CHASSIS v ...
Page 219: ...FL 4 Bl Figure 6 9 Rear View BTl A20 SK162 Major Assembly and Cable Locations 6 l1 ...
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