Leader LBO-516 Instruction Manual - page 19
2. Press either ALT or CHOP V MODE pushbutton (21). Press
ALT for relatively high-frequency displays (A TIME/DIV
switch set at .2 mS or faster); press CHOP for relatively low-
frequency displays (A TIME/DIV switch set at .5 mS or
slower). If the CHOP pushbutton is pressed when fast sweep
speeds are used, the displayed traces will appear broken (as
in Figure 2-11) when signals are applied. If the ALT
pushbutton is pressed when slow sweep speeds are used, the
display will flicker excessively.
3. Use the vertical POSITION controls (17 and 18) to set the
CH-1 trace about two divisions down from the top graticule
line, and the CH-2 trace about two divisions up from the
bottom graticule line.
The LBO-516 is set up for dual-trace operation as follows:
4. 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 signals are totally on screen
and clear of each other.
CAUTION: Do not apply signals greater than 400 V
(DC + AC peak).
5. Set the A TIME/DIV switch (24) so the desired number of
cycles are displayed. Be certain the display mode (ALT or
CHOP) selected is consistent with this sweep speed (as per
Step 2).
6. If both channels are handling signals of the same frequency,
trigger from the channel having the steepest-slope waveform.
If the signals are different but harmonically-related
frequencies, trigger from the channel carrying the lowest
frequency. Also, bear in mind that if you disconnect the
signal to the channel serving as the trigger source, the entire
display will free run.
7. If the signals are different frequencies and not harmonically
related, select the ALT trigger SOURCE position (34) and
the ALT V MODE pushbutton (21) regardless of the A
TIME/DIV switch setting.
8. If the signal you wish to observe is so weak that even the 5
mV position of the VOLTS/DIV switch cannot produce
sufficient trace height for triggering a usable display, pull the
VARIABLE (XI0 MAG) control (11) outward. This
produces 1 mV/ div sensitivity when the VOLTS/DIV switch
is set to I0 mV, and .5 mV/div when it is set to 5 mV.
9. If the signal you wish to observe is so high in frequency that
even the .02/aS position of the A TIME/DIV switch results in
too many cycles displayed. Pull the A VARIABLE (XI0
MAG) control (26) outward. This increases the effective
sweep by a factor of 10, so .02 PS/div becomes 2 KS/div,
0.1PS/div becomes .01 /PS/div, etc. The 2 KS/div sweep
speed achievable by magnification is fast enough to display a
single cycle of a 50 MHz signal across the CRT face.
10. If the signal you wish to observe is either DC or low enough
in frequency that AC coupling attenuates or distorts the
signal, flip the AC/GND/DC switch (16) to DC.
CAUTION: If the observed waveform is
low-level AC, make certain it is not riding
on a high-amplitude DC voltage.
2-3-6 Additive and Differential Operation
Additive and differential operation are forms of two-channel
operation where two signals are combined to display one trace. In
additive operation, the resultant trace represents the algebraic sum
of the CH-1 and CH-2 signals. In differential operation, the
resultant trace represents the algebraic
difference between the
CH-I and CH-2 signals.
To set up the LBO-516 for additive operation, proceed as
follows:
1. Set up the dual-trace operation per paragraph 2-3-5, Steps 1
to 6 and 8 to I0.
2. Make sure both VOLTS/DIV switches (I0) are set to the
same position; and the VARIABLE controls (11) are de-
tented in their CAL'D position. If the signal levels are very
different, set both VOLTS/DIV switches to the position
producing a large on-screen display of the
higher amplitude
signal.
3. Trigger from the channel having the biggest signal.
4. Press the ADD V MODE (21) pushbutton. The single trace
resulting is the algebraic sum of the CH- 1 and CH-2 signals.
Either or both of the vertical POSITION controls (17) and
(18) can he used to shift the resultant trace.
NOTE: If the input signals are in-phase, the amplitude
of the resultant trace will be the arithmetic sum of the
individual traces (e.g., 4.2 div + 1.2 div = 5.4 div). If the
input signals are 180° out of phase, the amplitude of the
resultant trace will be the arithmetic difference of the
two traces (e.g., 4.2 div - 1.2 div = 3.0 div).
5. If the p-p amplitude of the resultant trace is very small, mm
both VOLTS/DIV switches to increase the display height.
Make sure both VOLTS/DIV controls are set to the same
position.
To set up the LBO-516 for differential operation, proceed as
follows:
1. Set up for dual-trace operation per paragraph 2-3-5,
Steps 1 to 6 and 8 to I0.
2. Ensure that both VOLTS/DIV switches (10) are set to
the same position. If the signal levels are very different,
temporarily set both VOLTS/DIV switches to the
position needed to produce a large on-screen display of
the highest-amplitude signal.
3. Trigger from channel having the larger signal.
4. Press in the CH-2 INV pushbutton (19).
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