Lesson 2/Learning Event 7
Control
Indicator
Function
BIAS
Arranges circuit to produce distorted signals.
DISTORTION
Signal pulses are distorted in time relationship
(rotary
only, never waveshape distortion. The waveshape
switch)
remains square; only the relative lengths of marks and
spaces change.
Either marking or spacing biased signal
signals can be transmitted, but not both simultaneously.
SW Pos
Action
ZERO
Perfect signal. When in zero position,
PERCENT DISTORTION switches do not
function.
MARKING
Marking biased signals are transmitted.
SPACING
Spacing biased signals are transmitted.
SWITCHED
Type
of
distortion
is
switched
automatically
with
each
character
transmitted,
alternating
between
marking and spacing bias distortion.
SIG
Illuminates when a mark signal is sent, goes out when a
(indicator
space signal is sent. Flashes in time with the pulses
lamp)
of a transmitted signal.
Learning Event 7: A-SCAN, MODEL 7431
Figure 2-3.
A-Scan, Model 7431, Front Panel View.
50
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