Tektronix 2445, Instruction Manual

Page: 112 / 351

Performance Check— 2445 Service
p. Rotate the TRACE SEP control CCW to separate the
traces.
q. Adjust the AREF OR DLY POS control to intensify the
2nd and 10th time markers (of the A sweep) and display the
leading edges of the displayed B sweep time markers in the
center area of the graticule.
r. VERIFY—The horizontal distance between the lead­
ing edges of the B sweep time markers is within the conser­
vative guideline listed in Table 4-9. If this guideline is met,
accuracy between each marker is ensured, and the follow­
ing CHECK step need not be performed.
s. CHECK—The horizontal distance between the lead­
ing edges of the B sweep time markers is within the speci­
fied limits given in Table 4-9. The limit given is for separation
between the 2nd and 10th marker; however, separation be­
tween the 2nd marker and each suceeding marker should
also be checked, calculating the limits from the specification
as listed at the top of the table.
t. Repeat part r (and s if necessary) for each combina­
tion of A SEC/DIV, B SEC/DIV, and X I0 MAG settings list­
ed in Table 4-9. The At readout should be set to indicate
eight times the A SEC/DIV setting. At the slowest sweep
speeds, the B SEC/DIV knob will need to be pushed in
(B Sweep only) to increase the display repetition rate.
4. Check Delay Jitter.
a. Set:
TRACKING Off (button out)
A SEC/DIV 1 ms
B SEC/DIV 0.5
ii
s (knob out)
b. Select 1 ms time markers from the Time-Mark
Generator.
c. Aiign the intensified zones with the 10th time marker
using the AREF OR DLY POS and A controls. Superimpose
the zones to obtain a At readout display of 0.000 ms.
d. Push in the B SEC/DIV knob and adjust TRACE SEP
to separate the traces.
e. CHECK— For 0.8 division or less of horizontal jitter on
the rising edge of both time markers.
Table 4-9
Delayed Sweep Delta Time Accuracy
A SEC/DIV
and Time
Markers
B SEC/DIV
as Displayed
on Readout
Displayed Separation of
Delayed Time Markers
(for 2nd and 10th markers)
Conservative
Guideline
(divisions)
Specified
Limit:
(± 0 .3 % time)
interval
+0.1% of
full scale
(divisions)
0.1
ns
1 nsa 2 .4 3 .4
0 .2
ns
2 nsa 2 .4 3 .4
0 .5 ns 5 nsb 2 .4 3 .4
1 fiS 1 0 ns 2 .4 3 .4
2 ns 2 0 ns 2 .4 3 .4
5 ns 5 0 ns 2 .4 3 .4
1 0 jus 1 0 0 ns 2 .4 3 .4
2 0
ns
2 0 0 ns 2 .4 3 .4
5 0
ns
5 0 0 ns
2 .4 3 .4
0.1 m s
1
its 2 .4 3 .4
0 .2 m s 2 ns 2 .4 3 .4
0 .5 m s 5 ns 2 .4 3 .4
1 m s 1 0 ns 2 .4 3 .4
2 m s 2 0 its 2 .4 3 .4
5 ms 5 0 ns 2 .4 3 .4
10 ms 1 0 0 its 2 .4 3 .4
2 0 ms 2 0 0 ns 2 .4 3 .4
5 0 ms
5 0 0
ns 2 .4 3 .4
0.1 s 1 ms 2 .4 3 .4
0 .2 s 2 m s 6 .4 7 .4
0 .5 s
5 m s
6 .4 7 .4
a X I0 MAG On (button in).
b For remainder of Table, turn X I0 MAG off.
5. Check A and B SEC/DIV VAR Range and
Accuracy.
a. Set:
A and B SEC/DIV 10
ns
(knobs locked)
A and B SEC/DIV VAR In detent
At Off (press and release
to eliminate At
readout)
b. Select 10
ns
time markers from the Time-Mark Gener­
ator and adjust the Time-Mark Generator variable timing
control for exactly 1 time marker per division. Note the vari­
able timing % error on the Time-Mark Generator.
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