Fluke 9640A Series, Instruction Manual

Page: 237 / 324

Calibration
Performance Test
5
5-47
Note
The 6 dB attenuator is used to minimize mismatch errors. In some cases,
additional attenuation may be required to satisfy alternative measuring
receiver maximum input limitations.
Note
Unwanted interference from signals at 10MHz due to the frequency
reference outputs of equipment operating in the vicinity of the test setup or
the equipment used during the tests can cause erroneous results. In order to
avoid such problems, it is recommended that a small offset (50kHz) is
added to the listed nominal test frequency.
2. On the UUT enable the REF FREQUENCY OUTPUT and set the UUT as follows:
Frequency 10 MHz
Level +10 dBm
Output
OPER
3. Allow the measuring receiver to tune the input signal, and then set the controls to
measure RF level, relative (dB) to the current input level.
4. At each attenuation level listed in Table 5-22, allow the measuring receiver reading
to stabilize. The indicated value is expected to be within the listed typical
performance.
5. Return the UUT attenuation to 0 dB (+10 dBm).
Table 5-22. Attenuation Accuracy (75
Ω
)
Nominal
Attenuation
Absolute Output
Level
Specification
0 dB +10 dBm Reference
-3 dB +7 dBm ±0.035 dB
-13 dB -3 dBm ±0.035 dB
-23 dB -13 dBm ±0.035 dB
-33 dB -23 dBm ±0.035 dB
-43 dB -33 dBm ±0.05 dB
-53 dB -43 dBm ±0.05 dB
-63 dB -53 dBm ±0.05 dB
-73 dB -63 dBm ±0.15 dB
-82 dB -72 dBm ±0.15 dB
-91 dB -81 dBm ±0.15 dB
-101 dB -91 dBm ±0.15 dB (typical)
6. Repeat steps 2 through 5 at the attenuation levels shown in Table 5-22 for
frequencies of 50 and 100 MHz.
7. Set the UUT to
STBY
.
8. Disconnect the 75
Ω
Leveling Head, 75
Ω
to 50
Ω
impedance-matching pad and 6
dB attenuator from the measuring receiver.