Tektronix CSA8000 Series, Service Manual

Page: 183 / 354

Electrical Sampling Modules
CSA8000 & TDS8000 Instruments and Sampling Modules
4–79
H
set Record Length to 2000 points.
H
set Position to 1
m
s.
H
set Scale to 100 ns/division.
d. In the Meas Setup dialog box:
H
make sure the channel under test is selected in the Source menu.
H
select Meas1, then choose Select Meas > Amplitude > Mean.
e. Record for later use the High measurement value in m
r
, making sure to
take down the proper sign. This will be used as HiRef, the high reference
level for aberration measurements. The low reference level is
-1.0
r
(rho).
Follow this procedure to make the aberration checks:
1. Check aberrations in the range of 10 ns to 20 ps before the edge (aberrations
within 3%.
a. Set the Horizontal Position to 0 (minimum).
b. Change the Horizontal Scale to 50 ps/division while adjusting Horizon-
tal Position to keep the rising edge of the first step waveform on screen.
c. Press the front panel FINE button to turn it on.
d. Adjust the Horizontal Position knob so the waveform crosses the center
vertical graticule at the 10% (amplitude) point of the rising edge. Since
the waveform is 2 major divisions high at 500 m
r
/div, the waveform
should be crossing the center vertical graticule at 9 minor divisions
below the center horizontal graticule. This defines the ending reference
point for pre-transition aberration measurements.
e. Press the FINE button to turn it off.
f. In the Meas Setup dialog box:
H
select Meas1, then choose Select Meas > Amplitude > Max.
H
select the Region tab.
H
set Gate G2 to 46%.
H
turn Gates on (check).
g. In the Meas Setup dialog box:
H
select Meas2.
Tests