Tektronix 585 - Page 16

Operating Instructions — Type 585
Fig. 2-8. Effects on the oscilloscope display produced by
4- and — settings of the TRIGGER SLOPE switch.
Using the STABILITY and TRIGGERING LEVEL
Controls
In virtually every triggering application, satisfactory opera 
tion can be obtained with the STABILITY control in the fully
counterclockwise, PRESET, position. This setting has the ad 
vantage that no further adjustment of the STABILITY control
is required when switching from one triggering signal to
another. However, if it becomes difficult to obtain stable
triggering with the STABILITY control at PRESET, it will be
Fig. 2-9. TRIG. SENS, control location.
necessary to adjust the control for proper triggering. Also
it may be necessary to adjust the PRESET ADJUST control
as described in the Calibration section of this manual.
To adjust the STABILITY control, place the TRIGGERING
LEVEL control in the fully counterclockwise position. Then
rotate the STABILITY control slowly clockwise until a trace
appears on the c rt. The correct setting is obtained by rotat 
ing the control counterclockwise three to five degrees past
the point where the trace disappears.
The TRIGGERING LEVEL control determines the point on
the triggering waveform where triggering occurs. Rotating
the control clockwise causes the sweep to trigger at more
positive points on the waveform while rotating the control
counterclockwise causes the sweep to trigger at more nega 
tive points. Setting the TRIGGERING LEVEL control at 0 will
cause the sweep to start at approximately the average 
voltage point of the waveform.
The + arid — markings for the TRIGGERING LEVEL con 
trol should not be confused with similar markings for the
TRIGGER SLOPE switch. The markings on the TRIGGER
SLOPE switch indicate only whether triggering occurs on
the rising or falling portion of the triggering waveform.
The markings for the TRIGGERING LEVEL control indicate
whether triggering occurs on the upper or lower portion of
the waveform.
2-8