Operating Inform ation—2445 Service
MODE Switches—Select the indicated channel (s)
fo r display when latched in. Any combination o f the
five possible signal selections can be displayed by
pressing in the appropriate push buttons. The Chan
nel 1 signal w ill be displayed if none of the MODE
switches are latched in.
The algebraic sum of Channel 1 and Channel 2 is
displayed when the ADD push button is latched in.
When both ADD and INVERT buttons are latched in,
the waveform displayed is the difference between the
Channel 1 and Channel 2 signals. The INVERT
button also inverts the polarity o f the signal output
at the CH 2 SIG OUT connector on the rear panel.
A t the same time, the Channel 2 trigger-signal
polarity is inverted so that if CH 2 is selected as the
TRIGGER SOURCE, the displayed slope w ill agree
w ith the TRIGGER SLOPE switch setting.
When m ultiple channels are selected, they are dis
played sequentially in order o f p riority. The estab
lished p riority order is: C H I, CH 2, ADD, CH 3,
then CH 4.
( l? ) POSITION Controls—Set vertical position o f the
Channel 1 and Channel 2 signal displays. Clockwise
rotation of a control moves the associated trace
upward. When the X-Y display feature is in use,
Channel 1 POSITION control moves the display
horizontally; clockwise moves it to the right. The
Channel 2, Channel 3, and Channel 4 vertical POSI
TION controls move the associated X-Y display
vertically.
CHOP-OUT: A L T Switch—Selects the vertical display
mode for multiple-channel displays.
CHOP (latched in )—When more than one channel
is selected, the vertical display switches sequen
tia lly through the selected channels at the chop
switching rate.
The chop frequency changes between 1 MHz and
2.5 MHz, depending on the SEC/DIV switch
setting. A t all sweep speeds, the chop-switching
rate is desynchronized w ith the sweep frequency
to minimize waveform breaks when viewing
repetitive signals.
OUT: A L T (released o u t)—When more than one
channel is selected, the vertical display switches
sequentially through the selected channels. A lte r
nate switching occurs during sweep-retrace times.
If both A and B Sweeps are displayed, alternate
switching occurs at the completion of the B Sweep.
The position o f this switch has no effect on the
switching rate o f m ultiple X-Y displays. When more
than one X-Y display is selected, switching occurs
at 2.5 MHz.
@ 2 0 MHz BW L IM IT Switch-Reduces upper 3 dB
bandpass o f the vertical deflection system to a lim it
o f 13 to 24 MHz when latched in. Full instrument
bandwidth is available when push button is out.
Refer to Figure 2-4 for location o f items 18 through 22.
( j? ) CH 3 and CH 4 Input Connectors—Provide for
application of external signals to Channel 3 and
Channel 4. Input coupling from these connectors is
DC only. Coding-ring contacts, identical in operation
to the CH 1 OR X and CH 2 input connectors, are
also provided. Channel 3 and Channel 4 are most
useful as digital signal and trigger signal input chan
nels, given their limited choice o f deflection factors.
POSITION Controls—Set vertical position o f the
Channel 3 and Channel 4 signal displays. The controls
operate identically to the Channel 2 POSITION con
tro l, but w ith less range on their associated traces.
@
Channel 3 and Channel 4 VO LTS/DIV Switches—
Select either o f tw o basic deflection factors fo r Chan
nel 3 and Channel 4. With the push button OUT, the
basic deflection factor (using a 1X probe or a coaxial
cable input connection) is 0.1 V per division; when it
is latched IN, deflection factor is 0.5 V per division.
Figure 2-4. Channel 3 and Channel 4 controls and connectors
and C A LIBRATO R output.
2-6
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