Tektronix 2247A

L3
aA
«
“3
4
Controls, Connectors, and Indicators
Selections avallable for the A Trigger (A/B SELECT button lit) are:
AUTO LEVEL, AUTO, NORM, TV LINE, TV FIELD, and SGL SEQ,
Selections for the B Trigger (A/B 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.
\f TV Syne 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
Trigger MODE is then taken out of a TV Trigger MODE, A SLOPE Is
set back to its previously selected (non-preset) value. If, while doing
this, B Trigger MODE was still in TV LINE, 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 selected (non-preset) 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 LINE. If TV Sync Trigger Slope has not been preset in the Con-
figuration menu, the A SLOPE will stay at Its prior setting.
A Trigger Modes
AUTO LEVEL—Automatically sets the range of the Trigger LEVEL
control to the 10% and 90% levels of the A Trigger source signal and
sets the Trigger LEVEL elther to the 10%, 50%, or 90% level 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
2247A Operators 2-15