Subject to change without notice
18
DTR
mode was higher than the actual value in SEA (search)
mode, the time coefficient in DEL or DTR mode is
automatically set to the value used during SEA (search)
operation.
Photo 3
MODE: DEL (DELAY)
TIME/DIV: 5ms/div
Trigger coupling: TV-F
Trigger slope: falling ( - )
Delay time: 20ms
Reducing the time coefficient (increasing the time base speed)
now expands the signal. If the signal start position is not set
to the optimum, it can still be shifted in the X direction by
turning the DEL. POS. knob. Photo 4 shows a 50 fold X
magnification caused by setting the time coefficient to 0.1ms/
div (5ms/div : 0.1ms/div = 50). The reading accuracy also
increases with higher X magnification. As already mentioned,
the time variable control must be in CAL position when
measurements are taken.
Photo 4
MODE: DEL (DELAY)
TIME/DIV: 0.1ms/div
Trigger coupling: TV-F
Trigger slope: falling ( - )
Delay time: 20ms
It is possible to trigger after the deleay time on the next
suitable slope. This avoids jitter which may occur when high
X magnification rates are used. Depressing the DELAY
pushbutton for a short time switches over from delay (DEL)
mode to triggered delay mode and the DTR LED lights. The
trigger settings ( automatic peak / normal triggering, trigger
coupling, TRIG. LEVEL and slope) already selected do not
change. In after delay triggering mode (DTR) the instrument
is automatically set to normal triggering (NM) and DC trigger
coupling (DC). Neither setting can be changed (NM, DC) and
the indicator LED‘s remain lit. Only the trigger level (TRIG.
LEVEL) and the trigger slope direction (±) can be used, for
selecting the signal part which should be used for triggering.
If the signal height is to small or the TRIG. LEVEL setting is
unsuitable, no trace appears, and the screen is dark.
Under these DELAY conditions a X position shift is possible
by varying the delay time (DEL. POS.) if the settings are
suitable. Unlike the untriggered delay mode (DEL) where a
continous shift is the result, in trigger after delay mode (DTR)
the signal jumps from one signal slope to the next with a
simple, repetitive signal, this may not be apparent in DTR
mode. In the case of TV trigger mode, triggering is possible
on line pulses and on continously repeating slopes in the
picture content.
The X magnification is limited by the decreasing trace
intensity. The 50 fold X magnification which was used for
the screen photos is just an example.
Depressing the delay pushbutton in DTR mode once again
switches back to the normal operating conditions where
no LED on the DELAY scale is lit. The instrument then is set
automatically to the operating conditions used before
switching over to DEL.
Please note: If the instrument is operated in Dual mode
under conditions where DUAL chopped mode is active, this
display mode is not switched off when time coefficients are
being reduced ( 0.2ms/div to 0.05µs/div ) for signal expansion
in DEL and DTR mode. Under certain conditions depending
on the signal frequency and the expansion rate, the unblanking
during the channel switching may become visible. The
chopper generator can be switched off under these conditions
by simultaneously depressing both arrow pushbuttons in the
TIME/DIV. sector. Any timebase change after this procedure
will switch the chopper generator on again. The chopper
generator then can be deactivated in the same way.
AUTO SET
As mentioned most of the controls and their settings are
electronically selected. The exceptions are the
POWER
and
the calibrator frequency pushbuttons, as well as the
DEL.
POS./HOLD OFF, INTENS, FOCUS
and
TR
(trace rotation)
controls. Thus automatic signal related instrument set up in
Yt (timebase) mode is possible.
In most cases no additional manual instrument setting is
required.
Brief depressing of the
AUTO SET
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. This and the following explanation
regarding the automatic time coefficient setting assumes that
the pulse duty factor 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.
AUTO SET
sets the instrument automatically to the following
operating conditions:
•
AC
input coupling
•
Internal triggering
•
Automatic peak (value) triggering
•
Trigger level (
TRIG. LEVEL
) electrical midrange position
(the mechanical position may deviate)
•
Y deflection coefficient(s) calibrated
(the fine control knob may not be in CAL position)
•
Time deflection coefficient calibrated
(the fine control knob may not be in CAL position)
•
AC
trigger coupling
•
DELAY
mode
switched off
•
X x10
magnifier
switched off
•
Automatic X und Y position settings
(the mechanical knob position may deviate)
The automatically set operating conditions in
AUTO SET
mode are taken over by the instrument regardless whether
the mechanical knob settings coincide or not. If a knob is not
in its calibrated detent (
CAL
), the LED stops blinking. Turning
the knob reverts to the actual mechanical setting.
The 1mV/div. and 2mV/div. deflection coefficient will not be
set by AUTO SET as the bandwidth is reduced in these
settings. This is indicated by red LED‘s on the scale.
