Agilent Technologies PSA Series Service Manual page 100

Troubleshooting the RF Section (E4446A, E4447A, E4448A)
RF Section Description (E4446A, E4447A, E4448A)
Verifying the A29 SBTX/FELOMA Driver Assembly
Test points are provided on the A29 SBTX/FELOMA Driver board that
allow you to confirm the DC drive levels to the FELOMA assembly are
correct. There is a label on the FELOMA assembly that lists the target
voltages in milli-volts. Access to the test points is gained by sliding the
A29 assembly out of the instrument slightly.
1. Power down the instrument to avoid shorting out the A29 assembly
2. Pull up on the stainless steel spring clip near the center of the
3. Locate test point 2 near the back of the board, and connect the DVM
4. Connect the other DVM test lead to one of the test points listed in
5. Assure the A29 assembly is supported well and cannot short out
6. Turn on the instrument and set it to zero span and set the center
7. Compare the DVM reading to the value documented on the
Table 4-4 A29 SBTX Driver Board DC Levels To Be Compared With
FELOMA Label
PSA TP5
Center VG1
Frequency (mv)
50 MHz VG1
4 GHz VG1
10 GHz VG1
20 GHz VG1
30 GHz NA
50 GHz NA
External NA
Mixing
Frequency
100
while it is being unseated from the RF chassis.
assembly, and pull forward on the A29 bracket to slide the assembly
1 to 2 inches out of the instrument.
ground lead to TP2.
Table 4-4.
against anything.
frequency to correspond to the test point chosen in
FELOMA label. The values should match ± 0.005 volts, except for
the Int B5 and Int B6 values that must be less that −275 mv, but are
usually close to the −350 mv label.
TP12
VG2
(mv)
VG2
VG2
VG2
VG2
NA
NA
NA
TP9 TP4 SBTX
LO Level Unleveled
(mv) (mv)
Band0 NA
Band1 NA
Band2 NA
Band3/4 NA
IntB5 SBTX B5
IntB5 SBTX B6
"F" Label NA
Value
Table 4-4.
TP11
"S" Sampler
Unleveled (mv)
S
S
S
S
S
S
NA
Chapter 4