Fluke 96000 Series - Page 94

96000 Series
Service Manual
3-52
To verify the UUT’s output VSWR using a directional bridge and a Spectrum
Analyzer:
1. Connect the REF FREQUENCY OUTPUT (rear panel) from the UUT to the
Spectrum Analyzer and signal generator external reference inputs using a
BNC tee and BNC male – male cable assemblies. Set the Spectrum Analyzer
and signal generator for external frequency reference.
2. On the UUT enable the REF FREQUENCY OUTPUT at 10 MHz. Ensure the
Spectrum Analyzer and signal generator external reference frequency inputs
are enabled for input at 10 MHz.
3. Connect the signal generator RF output to the input port of the directional
bridge. Connect the directional bridge coupled (output) port to the Spectrum
Analyzer input using a 75
Ω to 50 Ω impedance-matching pad. See
Figure 3-14.
Note
To determine the reference level setting of the Spectrum Analyzer,
the UUT must initially be connected to the directional bridge.
4. Connect the UUT to the test port of the directional bridge.
5. Set the Spectrum Analyzer as follows:
PRESET
EXT REF On
REF LVL +10 dBm
FREQ 500 MHz
SPAN Zero Span
6. Set the signal generator as follows:
Frequency 500.00001 MHz
Amplitude 0 dBm
Output On
7. Set the UUT as follows:
Note
For the 96270A, ensure the Leveling Head output is selected.
Signal Leveling Head Output
Frequency 500 MHz
Level +7 dBm
Output OPER
8. Adjust the Spectrum Analyzer reference level to place the displayed trace
approximately 3 dB below the reference level line.
9. Set the UUT to STBY and disconnect it from the directional bridge. Connect
the open (75 ) termination to the directional bridge test port.
10. Set the Spectrum Analyzer display units to volts and perform a peak search.
Note the marker indication with the test port open.
11. Connect a Type-N short to the directional bridge test port. Perform a peak
search with the test port shorted and note the marker indication. Remove the
short.