Tektronix 2205, Operator'S Manual

Page: 33 / 91

Operation
Channel Selection
With the three VERTICAL MODE selectors, you can display com­
binations of the two vertical channels. When Channel 1 is se­
lected, the other two MODE switches are not active. When CH 2
is selected, the middle MODE switch (NORM/CH 2 INVERT) be­
comes active. And when BOTH channels are selected for dis­
play, all three MODE selectors are active.
ADD and INVERT
Select ADD mode to display the algebraic sum of the CHI and
CH 2 signals. When you use ADD, the CH 1 and CH 2 VOLTS/
DIV settings should be equal.
Selecting CH 2 INVERT causes the polarity of the CH 2 waveform
to be inverted. This allows you to see the difference between
CH 1 and CH 2 signals on the ADD trace.
CHOP or ALT?
When BOTH channels are selected, the display is tim e-shared.
The CHOP mode displays each channel for a short time and mul­
tiplexes during the sweep to give the appearance of displaying
both channels at once. This mode (CHOP),works better than
ALT for sweep speeds slower than 1 ms per division and for
low-repetition-rate signals that make the display flicker (up to 2
p.s/division).
The ALT mode displays each channel for the duration of a com­
plete sweep.- It gives a cleaner display of multiple channels than
CHOP does and is usually preferred at moderate to high sweep
speeds.
Certain trigger conditions, including composite trigger selection,
can cause a display that implies a phase relationship or even
synchronization of independent waveforms. If in doubt about the
relative timing of CH 1 and CH 2 signals, experienced operators
set the TRIGGER SOURCE to either CH 1 or CH 2.
2205 Operator’ s