Agilent Technologies 8719ET Service Manual page 220

Source Troubleshooting
Broadband Phase Lock Problems
7. Power greater than 10 dBm indicates there is proper power coming out of the YIG at
about 4.5 GHz. If the analyzer is not phase locking at this frequency in normal
operation, the problem is with the RF cabling, A5 (source switch) or A6 (source switch).
8. If no power is present, check the lowband YIG bias voltages on pin 3 (+15V) and
pin 2 (+22V) of the J1 connector. Pin 3 is located on the left and pin 2 is located in the
middle of the J1 connector. If the voltages are correct, replace the YIG.
8722ET/ES Models
1. Set up the ES and ET models as following:
For ES analyzers:
Disconnect the front panel R-channel jumper.
Connect the power meter to the R CHANNEL OUT port.
For ES Option 089 analyzers, press the following:
NOTE
System
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.
2. To measure the low band power, press the following:
SERVICE MENU
System
SRC ADJUST MENU
The power should be at least −32 dBm.
3. To measure mid band power, press
The power should be at least −32 dBm.
4. To measure high band power, press
The power should be at least −27 dBm.
5. You may have to change the DAC number slightly to achieve a good power reading. If
power is correct, proceed with
7-12
INSTR. MODE EXT R CHAN
SERVICE MODES
DAC NUM LOW BAND
DAC NUM MID BAND
DAC NUM HIGH BAND
"Check Reference Board (A12)" on page
4000 x1
4000 x1
4000
8719ET/20ET/22ET
8719ES/20ES/22ES
RF Network Analyzers
.
.
x1
7-13.
Service Guide