Leader LBO-516 Instruction Manual - page 21
1. Set the following controls as indicated. Any control not
mentioned here or in the following steps can be neglected.
PULL QUAD control (23) ........................... Pulled out
CH-2 INV switch (19) ................................. Out
VARIABLE VOLTS/DIV controls (11) Fully CW, and
pushed in
AC/GND/DC switches (16) ......................... AC
A INTEN control (3) ................................... APS*
FOCUS control (5) ...................................... APS*
POWER switch (1) ...................................... Pushed in
B TIME/DIV switch (25) .............. . 05P S
HORIZ DISPLAY switches (31) ..... A
A VARIABLE control (26) ........... Fully CW, and
pushed in
SOURCE switch (34) .................. CH-1 or CH-2**
COUPLING switch (36) ............... AC
SWEEP MODE switches (37) ........ AUTO
HOLDOFF control (42) ................ Pulled out
(PRESET level)
Horizontal POSITION control (29) .. APS*
* As previously set. ** See Step 6.
2. Press the ALT or CHOP V MODE pushbutton (21). Press
ALT for relatively high-frequency displays (A TIME/ DIV
switch set at .2 mS/div and faster); press CHOP for relatively
low-frequency displays (A TIME/DIV switch set at .5mS/div
and slower). If the CHOP pushbutton is pressed when fast
sweep speeds are used, the displayed traces will appear as
broken lines when signal is applied. Conversely, if the ALT
pushbutton is pressed when low sweep speeds are used, the
display will flicker excessively.
3. Use the vertical POSITION controls (17 and 18) to set the
CH-1 trace two graticule divisions from the bottom of the
CRT screen. This will set the sum trace (CH- 1 + CH-2) near
the center graticule line.
NOTE: The position of the sum trace is not separately
controllable.
4. Use the PULL TRIPLE control (22) to temporarily set the
CH-3 trace off screen.
5. Connect the signals to be observed to the CH-1 and CH-2 IN
connectors (14 and 15), and adjust the VOLTS/DIV switches
(10) so the displayed traces are totally on screen and well
clear of each other. Make sure both VOLTS/ DIV switches
are set to the same position, and their VARIABLE controls
(11) are detented in their CAL'D positions. If the signal
levels are very different, set both VOLTS/DIV switches to
the position suitable for the higher-level signal.
6. Set the trigger SOURCE switch (34) to match the channel
with the higher-amplitude signal.
7. Set the A TIME/DIV switch (24) so the desired number of
cycles is displayed. Be certain the display mode (ALT or
CHOP) selected is consistent with this switch setting (per
Step 2). If the signal you wish to observe is so high in
frequency that even the .02 p3 position of the A TIME/ DIV
switch results in too many cycles displayed, pull the A
VARIABLE (XI0 MAG) control (26). This increases the
effective sweep speed by a factor of I0, so .02PS/div
becomes 2 KS/div.
8. The CH-2 INV switch (19) can be pushed in to display the
difference signal between the CH-1 and CH-2 input signals
instead of their sum.
9. If your primary reason for selecting the four-trace display
mode is to view the sum or difference signal while simul-
taneously viewing the two signals from which it is derived,
leave the CH-3 trace off screen. If you need to see the time-
base trigger trace as well, use the PULL TRIPLE control to
move the CH-3 trace to a relatively vacant spot on screen.
10. If the CH-3 trace is used as a third input channel, set the
trigger SOURCE switch to 0.2 V/DIV or 2 V/DIV, as befits
the input-signal amplitude. Since this trace is also the
timebase trigger signal, some positions of the trigger
COUPLING switch (36) will distort the trace because of the
limited-bandwidth filters they insert. Therefore, use either
the DC or AC COUPLING settings in this application.
2-3-9 Delayed-timebase Operation
The LBO-516 contains two timebases, arranged so one (the
A timebase) may provide a delay between a trigger event and the
beginning of sweep by the second (B) timebase. This allows any
selected portion of a waveform, or one pulse of a pulse train, to be
spread over the entire screen. Moreover, the CRT can be
alternately swept by the two timebases, so both the full waveform
and the selected portion appear across the full CRT screen width.
The aforementioned dual-timebase displays can be used with
any of the vertical display modes (single trace, dual trace, triple
trace, or quad). The procedure is the same regardless of the
number of traces displayed.
Basic Delayed Sweep. For delayed sweep, proceed as
follows:
1. Set up the LBO-516 as directed for whatever vertical mode
you desire.
2. Make sure the START pushbutton (32) is out.
3. Press the INTEN BY B pushbutton (31). A section of the
trace(s) will intensify (brighten).
NOTE: The intensified portion will be quite small if there is
a large difference between the settings of the A and B
TIME/DIV switches. 4. Turn the B TIME/DIV control (25)
until the intensified portion of the trace widens to an amount
equal to the portion of the trace you wish to magnify (see
Figure 2-12b).
5. Turn the DLY TIME MULT control (28) to position the
intensification over the portion of the trace you wish to
magnify.
6. Press the B HORIZ DISPLAY pushbutton (31). That portion
of the trace intensified in Step 5 now appears spread over the
full width of the CRT screen. The trace now displayed is
being swept by the B timebase (Figure 2-12c).
7. If needed, additional enlargement is possible by palling the A
VARIABLE (X10 MAG) control (26) outward.
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