Tektronix 7B70 Time Base Instruction Manual page 62

Performance Check/Calibration-7B70 (SN B205000 and Up)
23. CheckIAdjust .2
ps
Timing (C530L)
0
a. Set the time-mark generator for .I p s markers.
b., Set the TIMEIDIV to .2 ps.
c. CHECK-CRT display for two markers each division
over the center eight divisions. Check that sweep timing is
within 0.16 division (2%) over center eight divisions. See
Fig. 5-9.
d. ADJUST-C530L (left side, lower front) for two
markers each division. The markers at the second and tenth
vertical lines must coincide exactly with their respective
graticule lines (use the horizontal POSITION control as
necessary to line up the display).
Fig. 5-9. CRT
display showing correct
0.2
ps timing.
24. ADJUST-Sweep Start Linearity (C537)
0
Refer to following Note before attempting adjustment
of C537.
NOTE
C537 is a factory adjustment and normally should
not require readjustment unless: 1. C537 is replaced
because of breakage or other defect. 2, Associated
major components replaced. 3. C537 has accidentally
been mis-adjusted. Gross misadjustment of C537 can
result in waveform instability and sweep foldover
near the start of the sweep. C537 adjustment is
effective only with h@her performance main-frames
such as the 7900-series, and may be adjusted to
optimize the performance of the plug-in and main-
frame as a package. This adjustment should be made
with the 7B70 installed in the highest performance
main-frame it will be used with. C537 primarily
affects the first two screen diameters following the
excluded first 12 ns of sweep at the highest magnified
sweep speed.
a. Set the controls as specified under Preliminary
Control Settings except as follows:
Time-Mark Generator
Markers 5 ns
7B70
(Installed in right (B) horizontal
compartment not on extender)
-
T/D IV .02 ps
POSITION Start of sweep near first
graticule line
MAGNIFIER X I 0
7B71
Removed from the Oscilloscope
Vol ts/Div
Adjust for about 3 divisions
display amplitude
Oscilloscope
B Intensity
Adjust for visible display
Vertical Mode Left
Horizontal Mode B
b. ADJUST-C537 (bottom left side forward of center)
for best linearity of the 12 ns to 52 ns portion of the sweep
start. Position the first (excluded) 12ns portion of the
sweep off screen to the left. Adjust C537 for best overall
linearity of the next 40 ns portion of the sweep.
Scans by ArtekMedia O 2006