Tektronix 475A - Page 19

32. SOURCE—Determines the source of the trigger
signal coupled to the input of the trigger circuit.
NORM: Trigger source is displayed signal(s). It does
not indicate time relationship between CH 1 and CH 2
signals. However, stable triggering of non-time-related
signals usually can be obtained by setting VERT MODE to
ALT, SOURCE to NORM and COUPLING to LF REJ.
Carefully adjust LEVEL for a stable dispiay.
CH 1: A sample of the signal available in Channel 1 is
used as a trigger signal. CH 2 signal is unstable if it is not
time-related.
CH 2: Asample of the signal available in Channel 2 is
used as a trigger signal. CH 1 signal is unstable if itis not
time-related.
LINE (A Trigger circuit only): A sample of the power-
line frequency is used as a trigger signal. It is useful when
the input signal is time-related (multiple or submultiple) to
the line frequency or when it is desirable to provide a
stable display of a line-frequency component in a complex
waveform.
EXT: Signals connected to the External Trigger Input
connectors are used for triggering. External signais must
be time-related to the displayed signal for a stable display.
It is useful when the internal signal is too small or contains
undesired signals that could cause unstable triggering. lt
is useful when operating in CHOP mode.
EXT + 10 (A Trigger circuit only): External trigger
signal is attenuated by a factor of 10,
STARTS AFTER DELAY (B Trigger circuit only}: B
Sweep runs immediately after the delay time selected by
the DELAV-TIME POSITION control. When making
differential time measurements you must use this mode to
obtain valid measurements. On instruments equipped
with a DM44 you must use this mode to obtain valid
measurements when using the TIME or 1/TIME functions.
33. External Trigger Inputs—Input connectors for ex-
ternal trigger signals.
@ get 475A/DM44 Operators fi