Fluke 9640A Series, Instruction Manual

Page: 246 / 324

9640A
Instruction Manual
5-56
Leveling Head Adjustment – 50
Ω
Equipment required:
•
AC Measurement Standard
•
Precision feedthrough termination, 50
Ω
•
50
Ω
Type-N female-to-BNC male adapter
•
Power Meter
•
Power Sensor, Thermal, 50
Ω
•
Power Sensor, Diode, 50
Ω
•
Precision Adapter, Type-N female-to-female, 50
Ω
•
Spectrum Analyzer/Measuring Receiver
Note
Base Adjustment must be performed before attempting Head adjustment.
Once Base adjustment has been performed, Head adjustment can take place
in any order (50 Ω or 75 Ω first).
Note
If the Reference Frequency or Base Adjustment was just completed, omit
steps 2 and 3, below.
1. Ensure a 50
Ω
Leveling Head is connected to the UUT base.
2. On the UUT, press

, followed by the soft key
Calibration
and then softkey
Calibrate Instrument
.
3. Using the keypad, enter the password, followed by the
ENTER
key.
4. Press the soft key
Adjust Head
.
5. Connect the UUT Leveling Head to the input of the AC Measurement Standard via a
precision 50 Ω feedthrough termination. (If a Type-N feedthrough termination is not
available, use a 50 Ω BNC feedthrough termination and appropriate adapters.)
Note
It is recommended that for measurements made with the AC Measurement
Standard during calibration adjustment a common mode choke is used as
described in the Level Accuracy Test, with the choke input low connected to
the AC Measurement Standard chassis ground. Keep the ground connection
as short as possible and set the AC Measurement Standard to Internal
Guard.
6. Set the UUT to
OPER
.
Note
The following steps facilitate the low frequency flatness adjustment of the
50
Ω
Leveling Head using the AC Measurement Standard.
7. Using the blue arrow keys and rotary knob, edit the UUT
Actual
output until the AC
Measurement Standard indicates the
Target
value stated. Press
Accept Target
.
Note
If the AC Measurement Standard used does not read the UUT output in
dBm directly, calculate the desired value using the following formula:
( )








= Ω
−
3
2
10
50
log 10 50
V
dBm