Leader LBO-516 Instruction Manual - page 20
5. Press the ADD V MODE pushbutton (21)· The single trace
resulting is the algebraic difference of the CH-1 and CH-2
signals. Either or both of the vertical POSITION controls
(17) and (18) can be used to shift the resultant trace.
NOTE: If the input signals are in-phase, the amplitude
of the resultant trace will be the arithmetic difference of
the individual traces (e.g., 4.2div - 1.2div = 3.0div). If
the input signals are 180° out of 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).
6. If the peak-to-peak 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.
2-3-7 Triple-trace Operation
A very useful feature of the LBO-516 is that the timebase
trigger can be displayed on the CRT screen along with the two
vertical inputs. The trigger signal appears as the third trace,
permitting continuous trigger view and/or a third input channel.
Trigger Display. To continuously display the timebase
trigger signal and two input channels, proceed as follows:
1. Set the following controls as indicated below. Any
controls not mentioned here or in the following steps can be neg-
lected.
PULL TRIPLE control (22) ......................... Pulled out
CH-2 INV switch (19) ................................. Out
VARIABLE VOLTS/DIV Fully CW, and
controls (11) pushed in
AC/GND/DC switches (16) .......................... AC
PULL QUAD control (23) ........................... Pushed in
A INTEN control (3) ................................... APS*
FOCUS control (5) ...................................... APS*
POWER switch (1) ...................................... Pushed in
HORIZ DISPLAY switches (31) .................. A
B TIME/DIV switch (25) ............................. 05/PS
A VARIABLE control (26) ......................... Fully CW, and
.................................................................... pushed in
SOURCE switch (34)................................... CH-1 or
.................................................................... CH-2**
COUPLING switch (36) .............................. AC
SWEEP MODE switches (3'7) ..................... AUTO
HOLDOFF control (42) ............................... Pulled out
.................................................................... (PRESET level)
Horizontal POSITION control (29) .. ............ APS*
* As previously set.
** See Step 7.
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 near the 90% dotted graticule line, and the CH-2
trace on the center graticule line.
4. Use the PULL TRIPLE control (22) to set the third trace near
the 10% dotted graticule line.
5. Connect the signal 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.
6. 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 fre-
quency that even the .02 PS 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 10, so .02 PS/div be-
comes 2 KS/div.
7. If CH-1 and CH-2 are both handling signals of the same
frequency, trigger from the channel haying the steepest
waveform. If the signals are different but harmonically-re-
lated frequencies, trigger from the channel carrying the
lowest frequency.
8. The third trace is the timebase trigger signal. With trigger
taken from either CH- 1 or CH-2, the trigger signal may ap-
pear to be the same as one of the vertical channels. However,
trigger COUPLING switch positions other than DC insert
frequency-selective networks into the CH-3 amplifier, so the
third trace may appear different at certain frequencies.
NOTE: If ALT trigger source is selected, the third trace
will resemble the CH-1 trace, not the composite trigger
signal.
Three Input Channels. To display three independent input
channels, proceed as follows:
1. Perform Steps 1 to 6 of the previous procedure.
2. Connect the third signal to be observed to the EXT
TRIG IN (CH-3) connector (35). If the three signals are
different but harmonically-related frequencies, apply the
lowest-frequency signal to this channel.
CAUTION: Do not apply a signal greater than 400 V
(DC + AC peak).
3. Set the SOURCE switch (34) to the 2 V/DIV position. If
the trace is less than one division high, external
amplification will be needed.
4. The third trace is the CH-3 input signal as well as the
timebase trigger, so do not use any trigger coupling
position other than AC or DC. The bandwidth-limiting
filters inserted at other positions of the COUPLING
switch (36) will distort the CRT display of the CH-3
input signal.
2-3-8 Four-trace Operation
The algebraic sum of the CH-I and CH-2 input signals is
displayed as the fourth trace in this mode of operation. To display
the CH-1 and CH-2 input signals, their algebraic sum, and the
signal triggering the timebase, proceed as follows:
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