Fluke 9640A Series, Instruction Manual

Page: 223 / 324

Calibration
Performance Test
5
5-33
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:
Frequency 500 MHz
Level +13 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
(50 Ω ) 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.
12. Compute the average of the values measured with the test port open and shorted.
Record this number as Z
Max
for the test frequency of 500 MHz.
13. Repeat steps 6 through 12 for the next test frequency at +13dBm listed in Table 5-17,
setting the spectrum analyzer center frequency to the test frequency and recording
Z
Max
for each test frequency.
14. Reconnect the directional bridge test port to the UUT and set it to
OPER
.
15. Set the spectrum analyzer display to linear. Set the sweep time to 5 ms, single sweep.
16. Set the UUT frequency to 500 MHz, set the signal generator frequency to 500.00001
MHz, and set the spectrum analyzer center frequency to 500MHz.
17. Initiate a single sweep. Allow the sweep to complete then perform a (maximum) peak
search. Note the marker amplitude.
18. Perform a (minimum) peak search and note the marker amplitude.
19. Calculate the difference of the maximum and minimum peak searches, dividing the
difference by 2 to determine the peak value. Record this number as Z
UUT .
Note
Because the reflected signal level is a peak to peak value and the reference
value to which it is compared is a peak value, the reflected level must be
divided by 2 to convert it to a peak value.