TB 9-6625-1979-24
(2) Set 50
TERM switch to EXT.
(3) Set oscilloscope vertical scale for 6 divisions of vertical display and sweep time to
1 ns.
(4) Adjust oscilloscope Trigger Level control for stable display. If aberrations on
oscilloscope display are not less than 2 minor divisions p-p in first 5 ns, or less than 1.5
minor divisions after first 5 ns, perform adjustments as listed in table 4.
Table 4. Aberrations
Adjustments (fig. 2)
Effects of adjustment
C358
Affects primarily front corner and first 1.5 ns of waveform
C315
Set for minimum effect unless otherwise necessary to reduce aberrations
C325
Affects first 3 ns of waveform; also has some effect on front corner amplitude
R393
Affects flatness on top of waveform after 3-ns point
R330
Transfers energy between the 1st and 2d 250 ps of the waveform. Set fully
ccw, make the adjustments, and then use R330 to minimize aberrations.
(5) Measure risetime, using standard risetime technique. Risetime will be 600 ps or
less.
b. Adjustments. See table 4.
16. Attenuator Compensation
a. Performance Check
(1) Connect TI (X10 probe) between oscilloscope Vertical 1 input and function
generator output.
(2) Set 50
TERM switch to INT.
(3) Set oscilloscope vertical scale to 10 mV and sweep time to 10 s.
vertical display on oscilloscope. If oscilloscope does not display optimum square wave,
perform b (1) below.
(5) Remove TI X10 probe and replace with X100 probe. Repeat (4) above, except
perform b (2) below if necessary.
b. Adjustments
(1) Adjust C2 (10X) (fig. 4) for optimum square wave display.
(2) Adjust C22 (100X) (fig. 4) for optimum square wave display.