Tektronix TDS6404, Service Manual

Page: 117 / 252

Performance Tests
TDS6000 Series Service Manual
4- 61
b. Hook up the pulse generator (see Figure 4--23 on page 4--60):
H
Connect the pulse generator output to a 50
Ω
precision coaxial cable
followed by a 90
°
right-angle female to male BNC adapter, then a
50
Ω
2X attenuator. The attenuator is connected to one side of the
female BNC T connector. The other side of the BNC T is connected
to BNC male to SMA adapter. The SMA side is connected to the
male side of the SMA T connector. (Keep the distance between the
BNC T and SMA T as short as possible). Connect 20 inch
50
Ω
coaxial cables to each female side of the SMA T connector. Connect
a female to female SMA adapter to both male coaxial connectors.
Connect the SMA short, to the remaining female SMA adapter. Now
connect the male BNC T connector to
CH 1
.
H
Set the pulse generator output for a positive-going pulse with a
rise-time as shown in Table 4--7 on page 4--62 for your oscilloscope,
and for the fastest possible rep rate (at least 1 kHz).
H
Set the pulse generator output for about 500 mV. (This amplitude
can be adjusted later to get a 5-division pulse on screen.)
c.
Modify the initialized front-panel control settings:
H
Press AUTOSET . You may see both positive and negative pulses.
Adjust the Trigger LEVEL knob so the trigger level is about 50% of
the rising edge of the positive pulse.
H
From the button bar, touch the Horiz button and select the Acquisi-
tion tab. Touch the Real Time Only RT button.
H
Set the horizontal SCALE to 5 ns/division. The pulse width should
be about
6 ns
. The indicated sample rate should be 20 GS/s.
H
Adjust pulse amplitude and oscilloscope vertical scale and position
as necessary to obtain about
5 divisions of the positive pulse.
NOTE
. If you have followed the procedure, you should have a 250 mV pulse
displayed on screen. Later in this procedure you will set the instrument to
measure the pulse width at the 150 mV level.
If the pulse you supply to the instrument is not a 250 mV pulse, you may need to
set the reference level (MidRef) to something other than 150 mV. Set the
reference level near the center of the pulse, above any noise, and below any
overshoot or ringing on the pulse.
d.
Set up for statistics measurements:
H
Re-adjust the Trigger
LEVEL
knob so the trigger level is about 50%
of the rising edge of the positive pulse.