Tektronix 442, Instruction Manual

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Operating Instructions—442 Service
3. Position the display to the center of the crt graticule
area and adjust the Channel 1 and Channel 2 VOLTS/DIV
switches to produce a display amplitude of less than 6
divisions vertically (Y) and less than 10 divisions horizon­
tally (X). The Channel 1 VOLTS/DIV switch controls the
horizontal deflection (X) and the Channel 2 VOLTS/DIV
switch controls the vertical deflection (Y).
4. Center the display around the center graticule lines.
Measure the distance A and B as shown in Figure 2-18.
Distance A is the horizontal measurement between two
points where the trace crosses the center horizontal line.
Distance B is the maximum horizontal width of display.
5. Divide A by B to obtain the sine of the phase angle
(<p) between the two signals. The angle can then be
obtained from a trigonometric table.
6. If the display appears as a diagonal straight line, the
two signals are either in phase (tilted upper right to lower
left) or 180° out of phase (tilted upper left to lower right). If
the display is a circle, the signals are 90° out of phase.
EXAMPLE: To measure the phase of the display
shown in Figure 2-18 where A is 5 divisions and B is 10
divisions, use the formula:
Substituting the given values:
Sine 0 = —
B
Substituting the given values:
Sine 0 = JL =0.5
10
From trigonometric tables:
0 = 30°
Figure 2-18. Phase difference measurement with an X-Y display.
Oscilloscope Light Filter and Graticule Illumination
Photography Effects
The 442 Oscilloscope contains a factory installed
colored (blue) plastic light filter in front of the crt faceplate
to improve general purpose viewing contrast in ambient
lighting conditions. This device also functions as an
implosion shield.
The internal crt graticule lines in the 442 are not
illuminated, and may not be visible on a photograph of the
crt display when using ordinary photographictechniques.
If the user wishes to produce oscilloscope photographs in
which the graticule lines are visible along with the signal
display, a special oscilloscope camera such as the
TEKTRONIX C5C or C5C Option 3 is recommended.
These cameras provide an external flash illumination for
the crt graticule. Effectiveness of the external flash
illumination is somewhat degraded when used with the
blue crt light filter. A clear light filter is available as an
optional accessory for the 442 (refer to the Accessories
tab page at the back of this manual for part number and
description of the clear filter) to be installed in place of the
blue filter during oscilloscope photography.
The clear filter may also provide improved photograph
definition and contrast with reduced oscilloscope display
intensity settings (some colored filters reduce effective
display intensity as much as 75%). Linder no cir­
cumstances should the oscilloscope be operated without
either a clear or colored light filter when no other
implosion shield is provided (optional accessory mesh
filters are not intended for implosion protection and must
be removed when using an oscilloscope camera).
To order the optional clear light filter accessory,
contact your local Tektronix Field Office.
To change light filters (implosion shields): Press down
on the bottom of the black plastic light filter frame and tilt
the top of the frame away from the crt face. Pressthefront
of the existing filter to remove it from the frame and press
the new filter into the frame. Reinstall the frame and filter
on the oscilloscope by pressing the bottom of the frame
down into the bezel channel; then tilt the top of the frame
inward toward the crt face and the spring on the bottom of
the frame will push the frame assembly up into the
operating position.
Instrument Repackaging
Should reshipment become necessary, reuse the car­
ton in which your instrument was shipped. If the original
packaging is unfit for use or is not available, repackage the
instrument as follows:
1. Obtain a carton of corrugated cardboard having
inside dimensions of no less than sixinchesmorethanthe
instrument dimensions; this will allowfor cushioning. Use
a carton having a test strength of at least 275 pounds.
REV A MAY 1980
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