Telequipment DM64, Руководство пользователя

Страница: 10 / 63

provide triggering from the positive
or negative-going slope of a wave-
form.
obtained by releasing DC and AC
buttons.
enable the sweep to be triggered
either internally from the vertical
amplifier or externally.
relate to the coupling of the trigger
circuit. For very low input frequency
DC should be selected.
2.1.5 VERTICAL DISPLAY
OFF-ON release of these buttons,switches off
the
channel concerned. If both
channels are switched off, a straight
line
trace results which cannot be
shifted by the POSITION controls,
except when in the X-V mode.
selects triggering from either or both
channels. When alternately triggering
from both channels both INT TRIG
buttons
should be released; the
displays should be partially super-
imposed.
provide three display modes for the
vertical channels.
In the CHOP mode, the channels are
alternately switched on and off at a
frequency
of about 150 kHZ; this
mode is suitable at the lower sweep
speeds.
In the AL T mode, each
channel is alternately displayed for
the duration of a sweep; this
mode is preferable at higher sweep
speeds.
In the SUM mode, the display is the
addition of the individual signals.
CHl POSITION is used to shift the
trace, CH2 POSITION is a Fine shift
in the SUM mode.
If INVERT is depressed,the resultant
display is the difference between the
two input signals.
displaces each trace in the vertical
direction
except when both channels
are off.
In the X-V mode irrespective of
button settings CH 1 provides a verti-
cal shift and CH2 a horizontal shift.
the setting of this button determines
whether the CH2 signal is displayed in
the same polarity as the input signal
or inverted. The inverted setting is
used
to display the difference
between two signals in the SUM mode.
provides twelve steps of attenuation
of
each channel's input signal.
Calibrated sensitivities are only valid
when VARIABLE
is fully clockwise.
enables all deflection sensitivities
between that selected by the VOLTS/
DIV switch and the next below to be
covered. The control
must be fully
clockwise for a calibrated display; for
Xl0
gain the knob should be pushed
in.
selects the input signal coupling. In
the DC position, the signal from the
INPUT connector is coupled directly
to the attenuator.
In the AC position a capacitor is
inserted in series.
In the GND position the input to the
attenuator is grounded and socket
disconnected; this position enables
the 0 V D.C. level of a trace to be
ascertained.
2.1.6 INPUT AND OUTPUT CONNECTORS
1. INPUTS
BNC
2. OUTPUTS
CAL
connectors are linked to the vertical
channel attenuators via the DC-GND-
AC switch described above.
there is a BNC connector in the
sweep section of the front-panel.
This enables either external triggering
signals to be applied, or in the EXT
condition of the VARIABLE
speed it
provides the EXT X input. The con-
nector is D.C. coupled to both trigger
and horizontal amplifier circuits. An
external blocking capacitor may be re-
quired to remove the D.C. component.
Input resistance is 100 kU
A X5 amplification of the horizontal
display is obtained by pulling out
FINE position. If a dual-trace display
is required on EXT X, the vertical
display mode must be set to CHOP,
the AL T and SUM modes will provide
only one trace.
at thE; rear of the instrument and
connected via an isolating capacitor
to the CRT cathode. A negative-going
signal is thus necessary to intensify
the trace while a positive-going signal
will blank it.
socket provides a waveform for
checking the calibration of the vertical
channels.
The repetition
rate is at supply
frequency.
provides a fast-edged positive-going
rectangular
pulse lasting for the
duration of the sweep.
The gate out signal or 0.5 V peak to
peak 1 kHz squarewave is used for
calibrating probes as follows.
1. Connect the probe to INPUT 1.
2. Set VOLTS/DIV to
.1 (X10),
10 mV (Xl001.
3. Turn VARIABLE fUlly clockwise.