Analog Bus On Off; Description Of The Analog Bus (Anab); The Main Adc; The Frequency Counter - Agilent Technologies 8719ET Service Manual

Service Key Menus and Error Messages

Analog Bus on OFF

Analog Bus on OFF
To access the analog bus, press
Description of the Analog Bus
The analog bus is a single multiplexed line that networks 23 nodes within the instrument.
It can be controlled from the front panel, or through GPIB, to make voltage and frequency
measurements just like a voltmeter, oscilloscope, or frequency counter. The next few
paragraphs provide general information about the structure and operation of the analog
bus. For a description of each individual node, see
see where the nodes are located in the instrument, refer to the "Overall Block Diagram," in
Chapter 4 , "Start Troubleshooting Here."
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
• the A14 fractional-N VCO
• the A14 fractional-N VCO divided down to 100 kHz
The receiver portion can be the following:

• the main ADC

• or the frequency counter on the fractional-N VCO (A14) board
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 A10 digital IF assembly and makes voltage measurements
in two ranges. See "
RESOLUTION

The Frequency Counter

The frequency counter is located on the A14 assembly and can count one of three sources:
• selected analog bus node
• A14 fractional-N VCO (FRAC N)
• A14 fractional-N VCO divided down to 100 kHz (DIV FRAC N) (frequency 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
SERVICE MODES
To read the counter over GPIB, use the command OUTPCNTR.
10-20
SERVICE MENU
System
(ANAB)
"Analog Bus Nodes" on page
"Analog Bus Nodes" on page 10-22
" under "Analog In Menu" on page
for troubleshooting phase lock and source problems.
8719ET/20ET/22ET
8719ES/20ES/22ES
RF Network Analyzers
.
10-22. To
10-21.
Service Guide