Tektronix 516 series, Инструкция по эксплуатации

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Operating Instructions — Type 516
TRIGGER INPUT connector (leave the jumper wire connected
from the CAL. OUT connector to the A VERTICAL input con­
nector). Set the black TRIGGER SELECTOR control to - f EXT.
You have now set up the oscilloscope for external triggering,
with the Calibrator supplying the external triggering signal
as well as the displayed signal.
Set the A VERTICAL VOLTS/DIV. control to 1 and the
AMPLITUDE CALIBRATOR control to 1, then to .5, then to
.2, then to .1, and then to .05. At each setting of the AMPLI­
TUDE CALIBRATOR control, set the STABILITY and TRIGGER­
ING LEVEL controls for a stable display, if possible. Note
that at the lowest settings of the AMPLITUDE CALIBRATOR
control, stable triggering becomes very difficult or impossible
to obtain. This is because there is not sufficient triggering
signal being applied to the Time-Base Trigger. Normally, an
external triggering signal of about 0.5 volt peak-to-peak
amplitude is required for proper triggering.
Set the AMPLITUDE CALIBRATOR control to 1 again. Turn
the A VERTICAL VOLTS/DIV. control counterclockwise. Note
that no matter how small the deflection on the crt becomes,
the display continues to be triggered. This is because the
setting of the VOLTS/DIV. control has no effect on an ex­
ternal triggering signal.
Set the AMPLITUDE CALIBRATOR control to 20 and the
A VERTICAL VOLTS/ DIV. control to 5. Set the black TRIG­
GER SELECTOR control to +INT., and set the STABILITY and
TRIGGERING LEVEL control for a stable display. Rotate the
TRIGGERING LEVEL control back and forth and note the
vertical- variation in the starting point of the square wave
at the left-hand edge of the screen. (It may be necessary to
move the display slightly to the right with the HORIZONTAL
POSITION control to observe this.) Note also that the dis­
play starts on a positive-going portion of the waveform. Set
the black TRIGGER SELECTOR control to —INT. and rotate
the TRIGGERING LEVEL control as before. Note that the
display now starts on a negative-going portion of the square-
wave.
With the A VERTICAL POSITION control, move the dis­
play up and down on the screen. Note that the point at
which the waveform starts at the left-hand edge of the screen
remains fixed relative to the top and bottom of the waveform
as the display moves. This is because when the red TRIGGER
SELECTOR control is set to AC, triggering occurs at a given
level relative to the average dc level of the entire signal. Set
the red TRIGGER SELECTOR control to DC, and move the dis­
play up and down on the screen with the A VERTICAL POSI­
TION control. (If the display disappears, turn the A VERTICAL
POSITION control in the opposite direction to make it re­
appear.) Note that the point at which the waveform starts
at the left-hand edge of the screen remains approximately
fixed relative to the graticule. This is because when the red
TRIGGER SELECTOR control is set to DC, triggering occurs at
a specific dc level with respect to ground.
Set the AMPLITUDE CALIBRATOR control to 10 and the
red TRIGGER SELECTOR control to AUTO. Switch the TIME/-
DIV. and VARIABLE TIME/DIV. controls through their ranges
and note the effect on the display. Note that the associated
UNCALIBRATED lamp lights when the VARIABLE TIME/DIV.
control is moved away from the CALIBRATED position. Re­
turn the TIME/DIV. control to the ,5/xSEC position and the
VARIABLE TIME/DIV. control to the CALIBRATED position.
With the HORIZONTAL POSITION control, position the dis­
play horizontally so that one of the vertical portions of the
waveform coincides with the center graticule line. Set the
HORIZ. DISPLAY switch to the MAG. position. Note that the
center portion of the waveform has been expanded. Specifi­
cally, the portion of the waveform which occupied the center
two divisons horizontally when the HORIZ. DISPLAY switch
was in the NORM, position now occupies the entire graticule.
Return the HORIZ. DISPLAY switch to the NORM, position.
Switch the A VERTICAL POLARITY switch to the NORM.
DC position. Note the change in the position of the wave­
form on the screen. This is because the dc component of the
square wave is now included in the display whereas, in the
AC position, the display showed only the variation around
the average dc level of the square wave.
To see the effect of the INV. positions of the POLARITY
switch, set the black TRIGGER SELECTOR control to +EXT.
(The jumper wire must still be connected from the CAL. OUT
connector to the TRIGGER INPUT and A VERTICAL input con­
nectors.) Now move the A VERTICAL POLARITY switch back
and forth between NORM. DC and INV. DC. Note that as
the switch moves from the NORM, positions to the INV. po­
sitions, the square wave becomes inverted on the screen.
Note further that the position of the bottom of the square
wave on the screen when the switch is at NORM. DC cor­
responds to the position of the top of the square wave on
the screen when the switch is at INV. DC. This is because
the negative portion of the Calibrator square wave is at dc
ground and the signal is being inverted about the dc ground
potential point.
The effect of all of the preceding operations is the same
when the MODE switch is in the B ONLY position except
that the B VERTICAL Channel controls must be used instead
of the A VERTICAL Channel controls. The effect of the op­
erations with the MODE switch in the ALTERNATE or CHOP­
PED positions is approximately the same, except that external
triggering should be used for best results.
Graticule Illumination
Graticule illumination can be adjusted to suit the lighting
conditions of the room by means of the POWER AND SCALE
ILLUM. control. Turning the control clockwise increases the
graticule illumination. It is possible to extinguish the graticule
illumination completely by turning the control counterclock­
wise.
The graticule of the Type 516 Oscilloscope can be illumin­
ated so that it appears to have either red or white graticule
markings. The markings can be changed from white to red
or red to white simply by removing the graticule cover and
inverting the graticule. As a general rule, white graticule
lines are superior to red for photographic purposes.
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