Keysight Technologies N5261A, User'S And Service Manual

Page: 89 / 99

Service Information
2-
Adjust ALC Levels
Background
When a component is changed in an RF or LO signal path, it is often necessary
to adjust the ALC level for the path. See Table
2-4
on page
7 8
for required
adjustments when a part is replaced.
PNA and Power Sensor Preparation
A power sensor and power meter must be prepared to make measurements at
8 GHz. This may include calibrating the power sensor with the meter and
entering a calibration factor for 8 GHz.
1. Set the PNA to measure S12.
2. Set for CW sweep at 8 GHz.
3. Set the sweep time to 5 seconds.
4. Set the power to -8 dBm.
ALC level for Port 1 (Procedure Q)
1. Prepare the PNA and Power Sensor as described above.
2. Connect PNA Port 2 to SRC 1 IN.
3. Connect the power sensor to Port 1 RF OUT.
4. Issue the Test Set I/O commands: 32,0 and 0,1 (ALC on and Port 1 RF
OUT).
5. Identify the “Port 1 & 2 ALC Amp”, see Figure 2-10 on page 58 . Identity R7
and R3, see Figure 2-
20
on page
8 4
.
6. Adjust R7: turn full CW (may require up to 30 turns) then 5 turns CCW.
7. Adjust R3: adjust for a reading on the power meter of 12.5 dB (± 0.1 dBm).
ALC level for Port 3 (Procedure R)
1. Prepare the PNA and Power Sensor as described above.
2. Connect PNA Port 2 to SRC 2 IN.
3. Connect the power sensor to Port 3 RF OUT.
4. Issue the Test Set I/O commands: 32,0 and 0,16 (ALC on and Port 3 RF
OUT).
5. Identify the “Port 3 & 4
Mod/
Amp,” R7 and R3, see Figure 2-10 and Figure
2- 20 .
6. Adjust R7: turn full CW (may require up to 30 turns) then 5 turns CCW.
7. Adjust R3: adjust for a reading on the power meter of 12.5 dB (± 0.1
dBm).
Keysight N5261/62A User’s & Service Guide
83