Agilent Technologies HP 8719D Service Manual page 286

The analog bus consists of a source section and a receiver section. The source
can be the following:
any one of the 23 nodes described in "Analog Bus Nodes"
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the Al4 fractional-N VCO
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the Al4 fractional-N VCO divided down to 100 kHz
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The receiver portion can be the following:
the main ADC
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the frequency counter
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When analog bus traces are displayed, frequency is the x-axis. For a linear
x-axis in time, switch to CW time mode (or sweep a single band).
The Main ADC
The main ADC is located on the Al0 digital IF assembly and makes voltage
measurements in two ranges. See ~~~L~~~~ ", under "Analog In Menu".
The Frequency C4mnter
The frequency counter is located on the Al4 assembly and can count one of
three sources:
selected analog bus node
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n
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range is 100 kHz to 16 MHz)
The counts are triggered by the phase lock cycle; one at each pretune, acquire,
and track for each bandswitch. The counter works in swept modes or in CW
mode. It can be used in conjunction with TSRY,XGE .:~#tXYlS for troubleshooting
phase lock and source problems
The display and marker units (II) correspond to volts.
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About 0.750 MHz is a typical counter reading with no AC signal present.
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Anything occurring during bandswitches is not visible.
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Fast-moving waveforms may be sensitive to sweep time.
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The analog bus input
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Waveforms up to approximately 200 Hz can be reproduced.
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impedance
is about 50K ohms.
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Service Key Menus and Error Messages
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