Fluke 9640A Series, Instruction Manual

Page: 199 / 324

Calibration
Performance Test
5
5-9
Note
Care must be taken to ensure that signals applied to the spectrum analyzer
do not exceed its input mixer’s optimum operating level, causing false
harmonic signal levels to be measured. It may be necessary to readjust the
analyzer’s RF attenuation to achieve the proper mixer input level.
5. Set the UUT as follows:
Mode
Leveled Sine
Frequency 20 kHz
Level +24 dBm
Output
OPER
6. On the spectrum analyzer, press MARKER
→
PEAK.
7. Set the spectrum analyzer as follows:
FREQ
40 kHz (2
nd
harmonic)
8.
Using the spectrum analyzer delta marker functions, measure the amplitude on the
spectrum analyzer for the UUT's 2
nd
harmonic relative to the fundamental. The
displayed (delta marker) value must be at least 60 dB lower (-60 dBc) than the peak
value referred to in step 5.
Note
Signal content at the required harmonic frequency may be well below the
tolerance limit, and difficult to observe on the analyzer display with the
above settings. Provided the harmonic signal is below the allowed limit the
test result may be recorded as ‘Pass’. However, if it is desired to measure
the actual signal level, reduce the analyzer resolution bandwidth setting
and/or reduce the analyzer reference level setting. Remember to restore the
analyzer reference level setting to that shown in step 4 before changing the
UUT to the next fundamental output frequency, otherwise the analyzer may
be overloaded and invalid results obtained.
9. Set the spectrum analyzer as follows:
FREQ 60
kHz (3
rd
harmonic)
MARKER
→
PEAK
10. Using the spectrum analyzer marker functions, measure the marker amplitude on the
spectrum analyzer for the UUT’s 3
rd
harmonic. The displayed (delta marker) value
must be at least 60 dB lower (-60 dBc) than the peak value referred to in step 5.