Keysight Infiniium 8000 Series, Service Manual

Page: 48 / 162

Chapter 3: Testing Performance
To test bandwidth
48
10
Change the signal generator output frequency to 600 MHz for the MSO/DSO8064A
or 1 GHz for the MSO/DSO8104A and set the power meter Cal Factor % to the
appropriate value from the calibration chart on the power sensor.
This step compensates the power meter reading for changes in the power sensor output
at 500 MHz with respect to 10 MHz.
11
Adjust the signal generator output amplitude for a power reading as close as
possible to 0.0 dB[REL]. Write down the actual reading. Reading = ______ dB
[REL].
The reading on the power meter will be used to correct the final bandwidth value.
12
Set the sweep speed to 1 ns/div using the horizontal sweep speed knob.
13
After the measurement settles (averaging complete), note the V
amptd(1)
reading.
14
Calculate the response using the formula:
For example:
15
Correct the result from step 14 with any difference in the power meter from
step 11. Observe signs. For example:
Result from step 14 = - 1.19 dB
Power meter reading = - 0.5 dB(REL)
then true response = (- 1.19)- (- 0.5) = - 0.69 dB
(__________) - (__________) = _________dB
16
The result from step 15 should be between +3.0 dB and - 3.0 dB. Record the
result in the Performance Test Record.
17
Switch the power splitter from the channel 1 to the channel 2 input.
18
Turn off the current channel and turn on the next channel using the channel keys.
19
Repeat steps 4 through 18 for the remaining channels, setting the parameters
of the channel being tested where appropriate.
Real Time Test
20
Select Acquisition from the Setup menu.
21
Select Real Time sampling mode, turn off Averaging, then select Close.
22
Repeat steps 4 through 19, testing all vertical channels with the upper frequency
limit as follows:
Keysight MSO/DSO8064A; 600 MHz
Keysight MSO/DSO8104A; 1 GHz
If the test fails
Failure of the bandwidth test can be caused by a faulty attenuator or main assembly, or the need for high-
frequency pulse response adjustment.
V
600 MHz or
V
1 GHz
________ mV =
response(dB)=20log
10
V
600 MHz or
V
1 GHz
V
10 MHz
---------------------------------------------
20log
10
________=_______dB =
20log
10
487 mV
559 mV
-------------------
20log
10
0.871 1.19dB – = =