Operators Familiarization
BASIC OPERATION
This subsection contains the basic operating information and techniques
that should be considered before attempting any measurements. For loca
tion and function of instrument controls, connectors, and indicators see
“ CONTROLS, CONNECTORS, AND INDICATORS" Section 2 of this
manual.
Readout Display
The crt readout display indicates how the instrument controls are set up.
No physical markings are on the rotating switches to indicate the control
setting. A key to the location and type of readout Information displayed is
illustrated in Figure 3-1.
Graticule
The graticule is internally marked on the crt face to provide parallax-free
viewing and enable accurate measurements (see Figure 3-2). The graticule
Is marked with eight vertical and ten horizontal major divisions. Major
divisions are further divided into five sub-divisions of 0.2 division each,
marked along the center vertical and horizontal graticule lines. Percentage
marks for rise-time and fall-time measurements are marked on the left side
of the graticule. Vertical deflection factors and horizontal timing are cali
brated to the graticule so that accurate measurements can be made
directly from the crt.
The waveform displays are calibrated to the crt graticule markings for
making quick and very accurate measurements of waveform parameters.
Voltage measurements are done by counting the vertical graticule divisions
and partial divisions occupied by the portion of the display being measured
and then multiplying by the VOLTS/DIV setting. Time measurements using
the graticule markings are done in a similar manner. Count the number of
horizontal graticule divisions and partial divisions occupied by the portion of
the waveform being measured and multiply by the SEC/DIV setting.
To improve the accuracy of the estimate, position the display to take ad
vantage of the 0.2 division minor graticule markings on the center graticule
lines. Also position one of the measurement points of the waveform as pre
cisely as possible on one of the major graticule marks to be used as a
measurement reference point.
2245A Operators
3-1
