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Controls, Connectors, and Indicators

TV LINE—Starts the A sweep at the beginning of a video signal line.

SLOPE polarity must match the composite sync polarity (i.e., - T

SLOPE for negative sync) to obtain TV LINE triggering on the horizon

tal sync pulse. Instruments Serial Numbered B020100 or above can

have the TV SLOPE polarity preset by changing the instrument con

figuration from the CONFIGURE menu (see “Service Menu Features"

in Section 3).

TV FIELD—Starts the A sweep at the beginning of a video signal field.

SLOPE polarity must match the composite sync polarity to obtain TV

FIELD triggering.

SGL SEQ (Single Sequence)—Sets up the A sweep for single-se

quence operation. Each additional press of the down-arrow MODE

button, when in single-sequence mode, resets the sweep and makes

it ready to accept a trigger. As in NORM trigger MODE, the set trig

gering level changes only when the TRIGGER LEVEL control is ad

justed to a new level setting.

When triggered, the sweep runs to produce a single sweep of each

trace as required by the setting of the VERTICAL MODE and HORI

ZONTAL MODE switches. Each displayed sweep in the sequence re

quires a distinct A sweep triggering event. The READY light remains

on until the final trace in the sequence is completed. The readout and

cursors can be set to turn on briefly at the end of the sequence when

using a camera (factory setting default mode), or they can be set to

remain on by changing the instrument configuration from the CON

FIGURE menu (see “Service Menu Features” in Section 3).

B Trig ger M odes

AUTO LEVEL—Sets the range of the Trigger Level control to the

peak-to-peak limits of an adequate B Trigger-source signal and trig

gers the B sweep.

The auto-level range is reset when triggering is lost, TRIGGER LEVEL

control is rotated to either end stop, or AUTO LEVEL Trigger MODE

Is reselected. AUTO LEVEL mode is useful for quickly locating an ap

propriate triggering level.

The B sweep operates in RUNS AFTER mode when the trigger-source

signal amplitude is too low or the frequency is below 10 Hz. Switch to

NORM triggering if the repetition rate is too slow for auto leveling. The

A Sweep must be running (free-running or triggered) for B Sweep to

trigger.

2-14

2245A Operators

Tektronix 2245A User Manual

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