Tektronix 7834

Bearrmfinder
38 . Set the deflection factor of the left amplifier unit to
0 .1 volt/division . Notice that a square-wave
display
is not
visible, since the deflection exceeds the scan area of the crt .
39 . Press the BEAMFINDER push-button switch ; notice
that the display is returned to the viewing area in com-
pressed form . Release the BEAMFINDER switch and notice
that the display again disappears from the viewing area .
40 . With the BEAMFINDER switch pushed in, increase the
amplifier-unit deflection factor until the display is reduced
to about
2
divisions vertically
.
Adjust
the
position control
of the displayed amplifier unit to position the compressed
display near the center of the graticule . Release the BEAM-
FINDER switch and notice that the display remains within
the viewing area .
Calibrator
41 . Connect the CALIBRATOR output to both the left
and right vertical units with two BNC cables and a BNC T
connector . The display amplitude should be approximately
2 divisions . If not, adjust the deflection factor accordingly .
42 . Select different CALIBRATOR push buttons (labeled
4
V, 0 .4 V, 40 mV, and
4
mV) and notice that the dis-
played signal changes accordingly (CALIBRATOR output
must be terminated into more than a 100 kilohm load for
stated output) . When the CALIBRATOR output is termi-
nated into 50 ohms, the output is 0 .1 times the stated
output .
Z-Axis Input
43 . If an external signal
is
available
(2
volts
peak-to-peak
minimum), the function of the Z-AXIS INPUT can be
demonstrated . Connect the external signal to both the
input connector of the displayed amplifier unit and the
Z-AXIS INPUT connector . Set the sweep rate of the
displayed time-base unit to display about 5 cycles of
the signal . Set the amplitude of the signal generator until
intensity modulation is visible on the display (change the
amplifier unit
deflection factor as necessary to produce
an
on-screen
display) .
The
positive peaks of the waveform
should be blanked out
and
the negative peaks intensified .
Notice
that the
setting of
the
intensity controls determines
the amount of intensity
modulation that is visible . Dis-
connect the cables
.
Storage
Operation
Operating Instructions-7834
44 . Connect the 4 V CALIBRATOR output to
the input
connector
of
the left amplifier
unit
and set the deflection
factor for a 2-division display . Set the time-base unit trig-
gering mode to single sweep and set the sweep rate
for
0 .5
millisecond/division .
45 . Press the BISTABLE push button and set the AUTO
ERASE control fully counterclockwise into the detent
position .
46 . Press the ERASE push button . The calibrator signal
should be stored on the crt
.
If not, increase the A INTEN-
SITY control slightly and press the ERASE button again .
Repeat this sequence until a stored display is obtained .
47 . Press the SAVE push button . The signal stored in the
previous step should remain on the crt ; it may be necessary
to adjust the SAVE INTENSITY control to view the
display . Turn the
SAVE
INTENSITY
control
throughout
its range and observe the effect on the display .
48 . Press the ERASE button and notice that the display
cannot be erased (the SAVE mode inhibits the erase func-
tion) . Press and release the SAVE push button .
49 . Set the STORAGE LEVEL and the PERSISTENCE
controls fully counterclockwise . Press the VAR PERSIST
push button . Observe that an erase cycle and sweep occurs
(when switching between the BISTABLE and VAR
PERSIST modes) and that the screen goes dark except for
the stored display .
50 . Slowly turn the PERSISTENCE control clockwise and
notice that the stored display fades into the background
(background lighting will be observed as the PERSIST-
ENCE control is advanced clockwise) . The PERSISTENCE
control determines the time interval during which the
stored display is retained in the VAR PERSIST mode . Set
the PERSISTENCE control fully counterclockwise .
51 . Press the
ERASE push button, then set the PERSIST-
ENCE control
to
midrange
just
long
enough for the display
to fade out . Quickly turn the PERSISTENCE control fully
counterclockwise . Slowly increase the STORAGE LEVEL
(clockwise) and notice that the faded display again becomes
visible, against the background .