38
Subject to change without notice
Attention!
If a signal is applied with a pulse duty factor of approx.
400:1 or larger, an automatic signal dis-play can not be
performed. The pulse duty factor causes too low a Y
deflection coefficient (sensi-tivity too high) and too high
a time deflection coefficient (time base speed to slow)
and results in a display in which only the baseline is
visible.
In such cases it is recommended to select normal triggering
and to set the trigger point approx. 0.5div above or below the
trace. If under one of these conditions the trigger indicator
LED is lit, this indicates the presence of a signal. Then both the
time coefficient and Y deflection coefficient should be reduced.
Please note that a reduction in intensity may occur, which could
result in a blank screen when the physical limits are reached.
Mean Value Display.
The DC Mean Value is displayed in place of the cursor line
measurement, if the cursor lines are switched off, the AUTO
MEASURE menu function “DC” is activated and further
condition are met:
The signal to be measured (AC > 20 Hz) must be applied at
input CH I (25) or CH II (28) with its DC content at the measuring
amplifier; DC input coupling (26) (29) required. Yt (time base)
mode in combination with internal triggering (trigger source
CH I or CH II; not alternated triggering) must be present. AC or
DC trigger coupling must be selected.
If the above conditions are not met, ”n/a” will be displayed.
The mean value is acquired using the trigger signal amplifiers
used for internal triggering. With the exception of DUAL mode,
the indicated mean value is automatically related to the active
channel (CH I or CH II), as the channel selection also assigns the
trigger amplifier. In DUAL mode one can select between trigger
amplifier CH I or CH II for triggering. The indicated mean value
refers to the channel from which the trigger signal originates.
The DC mean value is displayed with an algebraic sign (e.g.
”dc:Y1 501mV” resp. ”dc:Y1 -501mV). Overranging is indicated
by ” < ” resp. ” > ” sign (e.g. ”dc:Y1 <1.80V” resp. ”dc:Y1
>1.80V”). Being dependent on a necessary time constant for
mean value creation, the display update requires a few seconds
after a voltage change.
The reading accuracy is dependent on the instrument
specifications (Y deflection tolerance max. 3% from 5mV/div.
to 20V/div.). Although the tolerances are significantly smaller
in reality, other deviations such as unavoidable offset voltages
must be taken into account, which may cause a display
deviating from 0 Volt without signal applied at the input.
The display shows the arithmetic (linear) mean value. The DC
content is displayed if DC or AC superimposed DC voltages
are applied. In case of square wave voltages, the mean value
depends on the pulse duty factor.
Component Tester
(Analog mode only!)
General
The instrument specific information regarding the control and
terminals are part of item (37) in section ”Controls and Readout”.
The instrument has a built in electronic Component Tester, which
is used for instant display of a test pattern to indicate whether or
not components are faulty. It can be used for quick checks of
semiconductors (e.g. diodes and transistors), resistors,
Attention:
In chopped DUAL mode, using high expansion ratios in
“del” mode, chop interference may be visible. This can
be overcome by selecting alternate DUAL mode. A
similar effect can be caused by the READOUT with the
result that parts of a signal displayed in CH I, CH II or
DUAL mode are blanked (unsyn-chronised). In such a
case the READOUT can be switched off.
AUTOSET
The instrument specific information regarding this function
is part of the section ”Controls and Readout” paragraph
AUTOSET (2)
. As also mentioned in that section, all controls
are electronically selected with the exception of the
POWER
pushbutton.
Thus automatic, signal related instrument set up in Yt (time
base) mode is possible. In most cases no additional manual
instrument setting is required.
Briefly pressing the
AUTOSET
pushbutton causes the
instrument to switch over to the last Yt mode settings
regarding
CH I
,
CH II
and
DUAL
. If the instrument was
operated in Yt mode, the actual setting will not be affected
with the exception of
ADD
mode which will be switched off.
At the same time the attenuator(s) (
VOLTS/DIV
) are
automatically set for a signal display height of approx. 6 div
in mono channel mode or if in
DUAL
mode for approx. 4 div
height for each channel. In the determination of the time
deflection coefficient, it is assumed that the pulse duty factor
of the input signal is approx. 1:1.
The time deflection coefficient is also set automatically for a
display of approx. 2 signal periods. The time base setting occurs
randomly if complex signals consisting several frequencies
e.g. video signals are present. If cursor voltage measurement
is selected, AUTOSET also affects the position of the CURSOR
lines. Please note
AUTOSET (2)
in section ”Controls and
Readout”.
AUTOSET
sets the instrument automatically to the following
operating conditions:
AC or DC input coupling unaltered
or in GND condition the last used setting
Internal triggering (channel I or channel II)
Automatic triggering
Trigger level in electrical midrange position
Optimum calibrated Y deflection coefficient(s) 5mV -
20mv/div
Optimum calibrated Time base deflection coefficient
AC trigger coupling (except if DC trigger coupling last
present
Undelayed time base mode
X x10 magnifier switched off
Optimum X and Y position settings
Trace and readout visible.
If
DC
trigger coupling had been selected, AC
AC
AC
AC
AC trigger coupling
will not be chosen and the automatic trigger is operative without
the peak value detection.
The X position is set to the CRT center as well as the Y position
in
CH I
or
CH II
mode. In
DUAL
mode the channel I trace is
set to the upper half and the channel II trace to the lower half
of the CRT.
The 1mV/div and 2mV/div deflection coefficient will not be
selected by
AUTOSET
as the bandwidth is reduced on
these settings.
AUTOSET
Mean Value Display
