A Trigger Modes; Trigger Controls And Indicators - Tektronix 2247A Operator's Manual

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Controls, Connectors, and Indicators
, - -TRIGGER
(.;;\ I
H~ fF LEVEL
I
.fJ5\
~lr1f\\
{ ~~
~
V -
+
IN
®+f.o'c
-
I /"
SELE~T
TRIG'D
-o-
READY
rA----y--8
1
AUTO
AUTO
VERT
LEVEL
LEVEL
AUTO
RUNS
CH 1
DC
AFTER
NORM
NORM
CH 2
NOISE
TV
TV
CH 3
I
LINE
LINE
HF
REJ
TV
FROM
CH 4
1
FIELD
A LF
SOURCE
LINE
AC
6373
Figure 2-5. Trigger controls and Indicators.
Adjusting the LEVEL control fully counterclockwlse In AUTO LEV
Trigger MODE causes the trigger to reacquire and sets the trl r
level t~ the 10% point of the trigger signal; adjusting to the clock~~
top will cause a reacquisition to the 90% level. In either case th
ihmlts of the _Trigger LEVEL control will be the 10% and 90o/c lev~ls of
t e trigger signal. 0
@
~ODE Bu_ttons (Up- and Down-Arrows) and Indicators-Selec t
e operating modes of the A and 8 trigger systems. Pres sin th
t
Uhp-T/D,own-Arrow buttons selects the operating modes as sho!n by
e r gger MODE lights.
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2247 A Operators
I
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f
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Controls, Connectors, and Indicators
Selections avallable for the A Trigger (A/8 SELECT button lit) are:
AUTO LEVEL, AUTO, NORM, TV LINE, TV FIELD , and SGL SEQ.
Selections for the 8 Trigger (A/8 SELECT button not lit) are: AUTO
LEVEL, RUNS AFTER, NORM, TV LINE FROM A SOURCE. For RISE,
FALL, and PROP DELAY measurements, B Trigger MODE selection is
not allowed, and B Trigger MODE lights are, off.
If TV Sync Trigger Slope has been preset In the Configuration menu
( see Service Menu Features In section 3) , the A SLOPE Is set to the
preset slope when TV LINE or TV FIELD A Trigger MODE is selected.
Whenever A Trigger MODE Is set to a TV Trigger MODE , B Trigger
SLOPE will automatically be set to match A Trigger SLOPE if TV LINE
B Trigger MODE Is selected. After A SLOPE has been preset, If A
Trlgger"'MODE is then taken out of a TV Trigger MODE, A SLOPE Is
set back to Its previously selected ( non-p~eset) value. If , while doing
this, B Trigger MODE was still In TV LINE
1
the B SLOPE will be set
automatically to match . A SLOPE . If B SLOPE was set to match A
SLOPE because B Trigger MODE was TV LINE, then setting B Trigger
MODE to any other mode will cause B SLOPE to be set back to its
previously s~lected ( non-pre~et) value.
After the A SLOPE has been preset, It may then be altered as usual,
and ·B SLOPE will automatically be set to match It if B Trigger MODE Is
TV ~INE. If TV Sync ·Trigger Slope has not been preset In the Con-
figuration menu, the A SLOPE will stay at Its prior setting .
t
A Trigger Modes
AUTO LEVEL-Automatically sets the range of the Trigge'r LEVEL
control to the 10% and 90% levels of the A Trigger sburce signal and
sets the Trigger LEVEL either to the 10%, q0%, or 90% le'vel of the A
Trigger source signal, depending on the position of the Trigger LEVEL
control.
The auto-level range is reset when triggering Is lost, when the Trigger
LEVEL control Is rotated to either end stop~ or when AUTO LEVEL
Trigger MODE Is selected again. AUTO LEVEL mode is useful for
quickly locating and maintaining an appropriate triggering level.
The A sweep free-runs to produce a baseline trace when the A
Trigger source signal amplitude is too low or the triggering-source
frequency is less than 10 Hz.
AUTO- Triggers the same as the NORM Trigger MODE when an ade-
quate trigger signal is applied. However, the A sweep free-runs when
2247 A Operators
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