Agilent Technologies 8720E Series Service Guide

10-22 Service Guide
Service Key Menus and Error Messages 8719ET/20ET/22ET
Analog Bus on OFF 8719ES/20ES/22ES
RF Network Analyzers
switches the counter to monitor the A14 fractional-N VCO
frequency at the node shown on the “Overall Block
Diagram,” in Chapter 4 , “Start Troubleshooting Here.”
switches the counter to monitor the A14 fractional-N VCO
frequency after it has been divided down to 100 kHz for
phase locking the VCO.
Analog Bus Nodes
The following paragraphs describe the 23 analog bus nodes. They are listed in numerical
order and are grouped by assembly. For node locations, refer to the “Overall Block
Diagram,” in Chapter 4 .
Press
, and then use the front panel keys or knob to select an analog
bus node. Terminate the entry by pressing .
A10 Digital IF
1. +0.37V (+0.37V reference)
Check for a flat line at approximately +0.37V. This is used as the voltage reference in
the Analog Bus Correction Constants adjustment for calibrating out the analog bus
high/low resolution gain and offset errors. The absolute voltage level is not critical, but
it should be the same in high and low resolution.
2. +2.50V (+2.50V reference)
Check for a flat line at approximately +2.5V. This voltage is used in the Analog Bus
Correction Constants adjustment as a reference for calibrating the analog bus low
resolution circuitry.
3. Aux Input (Rear panel input)
This selects the rear panel AUX INPUT to drive the analog bus for making voltage and
frequency measurements. It can be used to look at test points within the instrument on
the display (using the display as an oscilloscope). Connect the test point of interest to
the AUX INPUT BNC connector on the rear panel. This feature can be useful if an
oscilloscope is not available. Also, it can be used for testing voltage-controlled devices by
connecting the driving voltage of the DUT to the AUX IN connector. You can look at the
driving voltage on one display channel while displaying the DUT S-parameter response
on the other display channel.
With turned ON, you can examine analog bus nodes with external
equipment (see in “Analog In Menu” on page 10-21). See the
“Overall Block Diagram,” in Chapter 4 . For GPIB considerations, refer to “GPIB
Service Mnemonic Definitions” on page 10-31.
4. A10 Gnd (Ground reference)
This is used in “Analog Bus Correction Constants (Test 44)” on page 3-8 as a reference
for calibrating the analog bus low and high resolution circuitry.
FRAC N
DIV FRACN
System
SERVICE MENU
ANALOG BUS ON
Meas
ANALOG IN AUX INPUT
x1
AUX OUT
AUX OUT on OFF

Agilent Technologies 8720E Series Specifications

General

Brand	Agilent Technologies
Model	8720E Series
Category	Measuring Instruments
Language	English