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Operating modes of the vertical amplifiers in Yt mode
have to be adjusted such that the beginning of the pulse is as
straight as possible. Overshoot or excessive rounding are
unacceptable. The adjustment is relatively easy if only one
adjusting point is present. In case of several adjusting points
the adjustment is slightly more difficult, but causes a better
result. The rising edge should be as steep as possible, with a
pulse top remaining as straight and horizontal as possible.
After completion of the HF-adjustment, the signal amplitude
displayed on the CRT screen should have the same value as
during the 1kHz adjustment.
Probes other than those mentioned above, normally have a
larger tip diameter and may not fit into the calibrator output.
Whilst it is not difficult for an experienced operator to build a
suitable adapter, it should be pointed out that most of these
probes have a slower risetime with the effect that the total
bandwidth of scope together with probe may fall far below
that of the oscilloscope. Furthermore, the HF-adjustment
feature is nearly always missing so that waveform distortion
can not be entirely excluded. The adjustment sequence must
be followed in the order described, i.e. first at 1kHz, then at
1MHz. The calibrator frequencies should not be used for time
base calibration. The pulse duty cycle deviates from 1:1 ratio.
Prerequisites for precise and easy probe adjustments, as well
as checks of deflection coefficients, are straight horizontal
pulse tops, calibrated pulse amplitude, and zero-potential at
the pulse base. Frequency and duty cycle are relatively
uncritical. For interpretation of transient response, fast pulse
risetimes and low-impedance generator outputs are of
particular importance.
Providing these essential features, as well as switch-selectable
output-frequencies, the calibrator of the instrument can,
under certain conditions, replace expensive squarewave
generators when testing or compensating wideband-
attenuators or -amplifiers. In such a case, the input of an
appropriate circuit will be connected to the CAL.-output via a
suitable probe.
The voltage provided at a high-impedance input (1MΩ II 15-
30pF) will correspond to the division ratio of the probe used
(10:1 = 20mVpp output). Suitable probes are HZ51, 52, and 54.
Operating modes of the vertical
amplifiers in Yt mode.
The most important controls regarding the operation modes
of the vertical amplifiers are the pushbuttons: CHI (16), DUAL
(17) and CH II (20). Their functions are described in the
section "Controls and Readout".
In most cases oscilloscopes are used to display signals in Yt
mode. Then the signal amplitude deflects the beam in vertical
direction while the time base causes an X deflection (from left
to right) at the same time. Thereafter the beam becomes
blanked and fly back occurs.
The following Yt operation modes are available:
Single channel operation of channel I (Mono CH I).
22
Single channel operation of channel II (Mono CH II).
Two channel operation of channel I and channel II (DUAL).
Two channel operation of channel I and channel II -displaying
the algebraic result as the sum or difference - (ADD).
The way the channel switching is determined in DUAL mode
depends on the time base setting and is described in the
section "Controls and Readout".
In ADD mode the signals of both channels are algebraically
added and displayed as one signal. Whether the resulting
display shows the sum or difference is dependent on the
phase relationship or the polarity of the signals and on the
invert function.
In ADD mode the following combinations are possible for
In-phase input voltages:
Channel II invert function inactive = sum.
Channel II invert function active = difference.
Antiphase input voltages:
Channel II invert function inactive = difference.
Channel II invert function active = sum.
In the ADD mode the vertical display position is dependent
upon the Y-POS. setting of both channels. The same Y
deflection coefficient is normally used for both channels with
algebraic addition.
Please note that the Y-POS. settings are also added but
are not affected by the INV setting.
Differential measurement techniques allow direct measure-
ment of the voltage drop across floating components (both
ends above ground). Two identical probes should be used for
both vertical inputs. In order to avoid ground loops, use a
separate ground connection and do not use the probe ground
leads or cable shields.
X-Y Operation
The important control for this mode is the pushbutton labeled
DUAL and XY (17).
In XY mode the time base is deactivated. The signal applied
to the input of channel I - front panel marking HOR. INP. (X)
- causes the X deflection. The input related controls (AC/DC,
GD pushbutton and the VOLTS/DIV knob) consequently
affect the X deflection. For X position alteration, the X-POS.
control knob must be used, as the Y-POS. I control is
automatically inactivated. The input deflection coefficient
ranges are the same for both channels, because the X x10
magnifier is inactive in XY mode.
The bandwidth of the X amplifier, is lower than the Y amplifier
and the phase angle which increases with higher frequencies,
must be taken into account (please note data sheet).
The inversion of the X-input signal is not possible.
Lissajous figures can be displayed in the X-Y mode for certain
measuring tasks:
Comparing two signals of different frequency or bringing
one frequency up to the frequency of the other signal. This
also applies for whole number multiples or fractions of the
one signal frequency.
Subject to change without notice
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