Tektronix 2465A Operator's Manual page 25

Operation
Channel Selection
Using the Vertical MODE buttons, you can display any combination of the
four vertical channels. To manually switch between CH 1 and another channel,
with minimum button pushing, deselect CH 1 and press the button for the other
channel to turn it on and off; CH 1 is displayed when all other verticals are off.
ADD and INVERT
Press ADD to display the algebraic sum of CH 1 and CH 2. Select INVERT
to change the sense of the CH 2 waveform or to see the difference between
CH 1 and CH 2 on the ADD trace. If you use ADD, the CH 1 and CH 2
VOL TS/DIV settings should be equal.
Choosing CHOP or AL T
With two or more channels, the display is time-shared. Chop mode displays
each channel for a short time and multiplexes during the sweep to give the
appearance of displaying all channels at once. Chop works better than Alt for
sweeps slower than 1 ms/division and for low repetition-rate signals that make
the display flicker, up to 21's/division.
Alt mode displays each channel for the duration of a complete sweep. Alt
gives a "cleaner" display of multiple channels than Chop does and is usually
preferred at moderate to high sweep speeds.
20 MHz BW Limit
This mode can give you a sharper trace by eliminating high-frequency
interference. Before using it, check to make sure it doesn't distort the
waveform.
2465A/2455A/2445A Operators 2-3