Tektronix 323, Инструкция по эксплуатации

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Operating Instructions— Type 3 2 3
controls so that one cycle of the reference signal covers 9
divisions of horizontal Iruce, passing through 0° at the inter­
section of the graticule center lines as in Fig. 2-14(B). This
causes each division of horizontal base line to display 40°
of the waveform being applied.
Disconnect the reference waveform from the vertical in­
put. Connect the shifted waveform to the vertical input
connector and measure the amount of separation between
the graticule center line and the waveform 0° point as in
Fig. 2-14(C). Convert the amount of separation to degrees,
using the 40°/div value which was established previously.
If the 0° point has moved to the left, the waveform leads the
reference. If it has moved to the right, the waveform lags
the reference.
©
2 0 0 Hz
Sine W ave
G enerator
Reference
w aveform
Shifted
w aveform
(A ) Circuit.
Trace
I centered
ve rtica lly
(B) Establishing a 9 d iv reference, using the generator w ave­
form.
I —------------------- 1 cycle = r 9 d l v .........................t
!____________ 1___ L 1 1
1
1
1
1 1 :
0 ° roforonce
!
i
- 4 -
1
1
1
p<
>sition
\ |
1
t
_ i _
r r
■
Vi
i
i
I
' i
i
— 5 0 ° (1 .2 5 divisions) •
phase difference
N
i i 11
, |f
Trace
centered
ve rtica lly
(C) M easuring phase re la tio n sh ip o f w aveform across the
.01 //F capacitor.
Fig. 2 -1 4 . M easuring phase relationships.
Leading and Trailing Edges of Waveforms. The sweep
in the lype 323 Oscilloscope is normally triggered by either
the increasing ( + ) slope or the decreasing (—) slope of the
applied signal. Thus, each sweep starts at a specific point
on the waveform. If the beginning of the - f or — slope
is used to trigger the sweep, the slight delay before the
sweep begins will prevent the triggering point from being
seen. If the sweep rate selected is slow enough, the next
pulse or cycle will be displayed before the sweep ends.
However, if the pulse frequency is quite low, the sweep will
not "stretch out” the area of interest enough to get a good
look at it. Three methods are suggested to improve view­
ing of the beginning of a + or — slope.
(a) If the viewed signal is dependent upon another signal
which occurs earlier, use the earlier signal to externally
trigger the sweep. Use the horizontal sweep rate, position
and magnifier controls as necessary to view the slope.
(b) Use the opposite slope to trigger the sweep; select
the sweep rate which displays the point to be observed
as near to the right of the sweep as possible (use the Hori­
zontal VARIABLE control if calibrated measurement is not
required); using the Horizontal POSITION control, set the
point of interest to the center of the graticule; expand the
sweep, using the X 1 0 HORIZ MAG control.
(c) Select a sweep rate which causes the trigger point to
be repeated once near the right side of the sweep; using the
horizontal position controls, set the repeated trigger point to
the center of the graticule. Using the horizontal magnifier,
expand the sweep.
Amplitude Measurements. The Type 323 Oscilloscope
can measure AC and DC signal amplitudes simultaneously or
separately. However, best results will generally be obtained
if they are measured separately, allowing selection of the
best deflection factor for the component being measured.
Example: Measuring the AC and DC components of a 0.02 V
ripple riding on a 75-V power supply output. Establish a
DC reference. Using DC coupling and a deflection factor
of 20 V/division, the DC component causes 3.75 divisions
of trace displacement, but the 0.02 V ripple component
amounts to 1/1000 of a division and is not discernible. AC
coupling and a deflection factor of 0.01 V/division displays
two divisions of AC ripple without interference from the DC
component.
Time Measurements. Although relatively accurate meas­
urements are provided across the entire 10 horizontal divi­
sions of the CRT, critical waveform time measurments should
be made in the center 8 divisions.
Frequency Measurements. To determine the frequency
of a recurring event, find the reciprocal of the time (in sec­
onds) it takes to complete one event. Example: With a
sweep rate of lOms/div, a sine wave completes one cycle
in 2.5 divisions (25 ms) of travel across the face of the CRT.
1/(25 X 10'3) results in a frequency of 40 cycles per sec­
ond, normally expressed as 40 Hertz (abbreviated Hz).
Arbitrary Units of Measure. The variable controls al­
low selection of arbitrary sweep rates and deflection fac­
tors. Examples follow:
TIME/DIV: Use the 5 DIV CAL SIGNAL to establish a
0.4ms/div sweep rate.
2-18