Tektronix P6248, Руководство по обслуживанию

Страница: 23 / 58

Performance Verification
P6248 1.7 GHz Differential Probe Service Manual
11
Rise Time
This procedure verifies the probe meets rise time specifications.
The probe rise time is calculated from rise times obtained by measuring the test
system without the probe connected, and then the test system with the probe.
1. Connect the test equipment as shown in Figure 6.
2. Adjust the oscilloscope vertical sensitivity to 50 mV/div.
3. Adjust the oscilloscope vertical positioning to center the signal on screen.
4. Adjust the oscilloscope horizontal sensitivity to 500 ps/div.
5. Adjust the oscilloscope horizontal positioning to place the rising edge of the
signal where it crosses the second vertical and center horizontal graticule
lines.
6. Use the oscilloscope measurement capability to display rise time. Rise time
is determined from the 10% and 90% amplitude points on the waveform.
Record the rise time as
t
s.
If the measurement reading is not stable, use Average mode (16 Averages) to
improve stability.
The system rise time ( t
s
) that you measured in step 6 represents the rise time of
the test system without the probe. The system rise time is used to calculate the
probe rise time (
t
p
) in steps 21 and 29.
1103
11800
Oscilloscope
CH 1
input
CH 1
output
BNC-to-SMA
adapter
015-0572-00
SMA cable 015-0562-00
SD24
CH1
CH2
SMA cable 015-0562-00
BNC-to-SMA adapter
015-0572-00
Figure 6: Test system rise time setup
The following steps instruct you to assemble the test setup that includes the
probe, as shown in Figure 7. The system and probe rise time (
t
s+p
) that you
measure in steps 20 and 28 is used to calculate the probe rise time ( t
p
) in steps 21
and 29.