Selecting Sweep Rates; Time Measurement; Display Modes - Tektronix 7B92A Maintenance Manual

Selecting Sweep Rates

The TIME/DIV OR DLY TIME switch selects
calibrated sweep rates for the delaying sweep.
DLY'D Time/Division switch selects calibrated sweep
rates for the delayed sweep. The sweep rate for the
delaying sweep is bracketed by the black lines on the
clear plastic flange of the TIM E/DIV OR DLY TIME
switch. Sweep rate of the delayed sweep is indicated by
the white line on the DLY'D Time/Division knob. When
the white line on the outer knob is set to the same
position as the lines on the inner knob, the two knobs
lock together and the sweep rate of both generators is
changed at the same time. However, when the DLY'D
Time/Division knob is pulled outward, the clear plastic
flange is disengaged and only the delayed sweep rate is
changed. This allows changing the delayed sweep rate
without changing the delaying sweep rate.
TIME/DIV OR DLY TIME switch and the DLY'D
Time/Division switch also select display modes.
Display Mode discussion in this section for further
information.
A VARIABLE control is provided concentric with
the TIME/DIV OR DLY TIME and DLY'D Time/Division
switches (see Fig. 1-3). This control can be used with
either the delaying or delayed sweeps as determined by
the Time/Div Variable Selector multi-pin connector
(internal, see Fig. 1-1 for location).
control also incorporates a two-position switch to
determine if the applicable sweep is calibrated or
uncalibrated. When the VARIABLE control is pressed in,
it is inoperative. However, when pressed and released,
the VARIABLE control is activated for uncalibrated
sweep rates. The sweep rate can be returned to the
calibrated position by pressing the VARIABLE knob in.
This feature is useful when a specific uncalibrated sweep
rate has been obtained and it is desired to switch
between calibrated and uncalibrated sweep rates.
Switching from uncalibrated to calibrated and vice-versa
does not affect the setting of the VARIABLE control. The
VARIABLE control allows the sweep rate in each
Time/Division switch position to be increased to at least
the next adjacent switch position.

Time Measurement

When making time measurements from the
graticule, the area between the second and tenth vertical
lines of the graticule provides the most linear time
measurements (see Fig. 1-5). Position the start of the
timing area to the second vertical line and adjust the
TIME/DIV OR DLY TIME switch so the end of the timing
area falls between the fourth and tenth vertical lines.

Display Modes

Four display modes can be selected by
appropriate settings of the TIME/DIV OR DLY TIME and
DLY'D Time/Division switches.
The
The
See
The VARIABLE
1-12
Fig. 1-5. Area of graticule used for most accurate time
measurements.
Normal Sweep Operation.
Normal sweep display mode, press in the DLY'D
Time/Division switch and set it to the same sweep rate
as the TIME/DIV OR DLY TIME switch.
Delayed Triggering LEVEL control clockwise into the
detent to the RUNS AFTER DELAY TIME position.
Calibrated sweep rates in the Normal sweep
display mode are 0.2 s/Div to 0.5 ns/Div. By using the
VARIABLE control (Time/Div Variable Selector connector
set for variable Delayed Sweep rates) uncalibrated
sweep rates to 0.5 s/Div are available. Triggering in the
Normal sweep display mode is controlled by the MAIN
TRIGGERING controls.
Alternate Sweep Display.
Alternate display mode, pull out the DLY'D Time/Division
knob and rotate it to a desired sweep rate faster than the
TIME/DIV OR DLY TIME switch setting. In this mode,
both an intensified sweep and a delayed sweep are
displayed (see Fig. 1-6).
The intensified trace of the Alternate sweep
display provides an intensified portion on the delaying
sweep during the time the delayed sweep is running.
The amount of delay time between the start of the
delaying sweep and the intensified portion is determined
by the TIME/DIV OR DLY TIME switch and the DELAY
TIME MULT dial. Triggering for the delaying sweep
portion of the intensified trace is controlled by the MAIN
TRIGGERING controls; triggering for the intensified
portion of the delayed sweep trace is controlled by the
Delayed Triggering controls.
Operating Instructions-7B92A
To select the
Rotate the
To select the
REV B, JUN 1978