Agilent Technologies 8719ET Service Manual page 218

Source Troubleshooting
Broadband Phase Lock Problems
NOTE If 2.4 mm flexible cables and 2.4 mm power sensors are not available for the
8722ET/ES, use 3.5 mm to 2.4 mm adapters (HP/Agilent 11901D 2.4 mm (f) to
3.5 mm (m) and HP/Agilent 11901B 2.4 (f) mm to 3.5 mm (f)) to interface with
your 3.5 mm equipment.
7. If the control and bias voltages are good, use a power meter and the flexible cable from
the tool kit to troubleshoot the RF signal path. To prepare to troubleshoot, enter the
service mode by pressing the following:
SERVICE MENU
System
SRC ADJUST MENU
NOTE For ES Option 089 analyzers, press the following:
System
8. To measure RF signal of the R-channel, do the following:
For ES analyzers:
Disconnect the front panel R-channel jumper.
Connect the power sensor to the R CHANNEL OUT port and look for the following
power levels:
• For the 8719ES and 8720ES, the power should be at least −18 dBm.
• For the 8722ES, the power should be at least −27 dBm.
For ET analyzers:
On ET models, there are two ways to measure the R-channel sampler assembly power.
a. Remove the bottom cover and disconnect the semirigid cable (W74) to the
RF INPUT (J2) of the R-channel sampler. Connect a 2.4 mm (f) barrel, flexible cable,
and the power sensor to W74.
CAUTION Be careful not to damage the center pins of the semirigid cable. Some flexing
of the cable will have to be done to attach the power sensor. Do not over bend
the cable.
b. Remove the front panel and disconnect the junction between the cables W72 and
W74. Connect the power sensor to W72.
• For the 8719ET and 8720ET, the power should be at least −18 dBm.
• For the 8722ET, the power should be at least −27 dBm.
9. If the power level is correct, replace the R sampler assembly (A64). If the power level is
not correct, replace the M/A/D/S (A58).
7-10
SERVICE MODES
DAC NUM HIGH BAND
INSTR. MODE EXT R CHAN
RF Network Analyzers
4000 x1
8719ET/20ET/22ET
8719ES/20ES/22ES
Service Guide