Tektronix 2445, Инструкция по эксплуатации

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Performance Check— 2445 Service
d. Set the VOLTS/DIV switch and the generator output
level to obtain the test signal amplitude indicated for the
particular combination being tested.
e. Set the SEC/DIV switch and the X I0 MAG switch to
obtain a well-defined display of the test signal.
h. Repeat the DC TRIGGER COUPLING tests of Table
4-4 while in the ADD mode.
i. Move the 50 MHz and 250 MHz signals to the CH 2
input connector and repeat the DC TRIGGER COUPLING
tests of Table 4-4 while in ADD mode.
NO TE
Normally, unless trigger sensitivity is very close to the
specified limits, it is sufficient to check each o f the
indicated frequency-coupling combinations listed in
the table in Channel 1 only; checks for Channels 2, 3
and 4 need only be done in D C COUPLING (to verify
signal path).
j. Press the CH 2 button in to select the channel and
press and release the ADD button to turn off the ADD
display.
k. Repeat the DC TRIGGER COUPLING tests of Table
4-4 while in CH 2 mode.
f. CHECK— For a stably triggered display (unless other­
wise indicated) for each of the Test Frequency-TRIGGER
COUPLING combinations listed in Table 4-4. When testing
the 250 MHz triggering, check that trigger jitter is < 50 ps
(0.05 division at 10 ns/div with X I0 MAG).
I. If trigger sensitivity is close to the specified limits given
in steps c through k above, test all of the frequency-coupling
combinations given in Table 4-4 for CH 2.
m. Move the test signal to CH 3 and CH 4 in turn and
repeat parts c through f using Table 4-5.
Table 4-4
CH 1 or CH 2 Triggering Conditions
Test
Fre­
quency
Minimum Vertical Display Levels at Which
Triggering Should Occur
TRIGGER COUPLING
DC NOISE
REJ
HF REJ LF REJ AC
60 Hz
a a a
No
Trigger,
Freeruns
0.35 Div
30 kHz
a
a
0.5 Div
a a
80 kHz
a
a a
0.5 Div
a
50 MHz 0.35 Div 1.2 Div No Trigger,
Freeruns
at 1.2 Div
0.5 Div 0.35 Div
250 MHz
(trigger
jitter
< 50 ps)
1.0 Div 3.0 Div No Trigger,
Freeruns
at 3.0 Div
1.0 Div 1.0 Div
aNot necessary to check.
Table 4-5
CH 3 or CH 4 Triggering Conditions
Test
Fre­
quency
Minimum Vertical Display Levels at Which
Triggering Should Occur
TRIGGER COUPLING
DC NOISE
REJ
HF REJ LF REJ
AC
60 Hz
a a a
No
Trigger,
Freeruns
0.18 Div
30 kHz
a a
0.25 Div
a a
80 kHz
a a a
0.25 Div
a
50 MHz 0.18 Div 0.6 Div No Trigger,
Freeruns
at 0.6 Div
0.25 Div 0.18 Div
250 MHz
(trigger
jitter
< 50 ps)
0.5 Div 1.5 Div No Trigger,
Freeruns
at 1.5 Div
0.5 Div 0.5 Div
aNoi necessary to check.
g. Press in the ADD button to select the function and
press and release the CH 1 button to turn off the CH 1
display.
n. Set:
TRIGGER
MODE
LEVEL AUTO
Fully clockwise
4-15