Learning Event 3:
DESCRIBE THE CHARACTERISTICS OF THE 453 OSCILLOSCOPE
1.
One of the first things to observe concerning the 453 oscilloscope is its
dual-channel capability. That is, you can apply two signals to the scope and can
present the two signals at the same time or separately.
2.
The vertical deflection system has a frequency response from DC to 50 MHz.
Frequency response means the frequency over which the scope amplifies all
frequencies uniformly. Another characteristic of the vertical deflection system is
the deflection factor, expressed as the voltage required to produce a unit
deflection on the CRT screen.
The deflection accuracy of this scope is -+ .3
percent of the indicated deflection. When channel 1 and channel 2 are cascaded by
using an external cable, they can provide a 1-millivolt deflection factor, the
volts/div switch on both channels must be set to 5 mV.
3.
The 453 scope can also measure risetime accurately.
By properly using the
20-mV to 10-V per division switches, you can measure risetime with accuracy to
within 6.7 nanoseconds on each channel.
Stable triggering is provided over the
full range of vertical frequency response by the trigger circuits.
Triggers are
used to start the sweep generator.
4.
The horizontal sweep system provides sweep rates from 0.1 microsecond per
division to 5 seconds per division in 24 calibrated steps. Under normal operating
conditions, the sweep accuracy is +/-3 percent of the indicated sweep rate. Using
the sweep magnified characteristics, each sweep rate can be increased to 10 times
the indicated sweep rate by expanding the center division of display.
The
calibrated delay time characteristic gives a sweep delay that is continuous from 50
seconds to 1 microsecond.
5.
As we have already pointed out, this scope performs in a variety of
environmental conditions.
The instrument performs satisfactorily over a
temperature range of -15 C to +55 C degrees. A fan in the rear of the scope blows
air through the instrument. If the internal temperature exceeds a safe operating
level, an automatic resetting thermal cutoff cuts off the instrument power.
The
power automatically comes back on when the temperature returns to a safe level.
The warmup time for a given accuracy is 20 minutes. All of the characteristics of
this instrument are listed in the applicable technical manual or technical order.
6.
Front panel, left side controls for the 453 scope. The controls located to
the left of the screen in Figure 2-8 control the signal display on the screen.
Keep in mind the purpose of intensity, focus, scale illumination, trace finder,
mode, trigger, volts/division, step attenuator balance, vertical position, and AC-
GND-DC controls.
7.
The intensity control (fig 2-8a) controls the brightness of the display.
When setting the intensity control, do not set the control for more brightness than
is necessary to provide a satisfactory display. Too much intensity can damage the
CRT phosphor.
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