Subject to change without notice
8
DC input coupling.
If DC voltages are applied under AC input
coupling conditions the oscilloscope maximum input voltage
value remains 400V. The attenuator consists of a resistor in
the probe and the 1M
Ω
input resistor of the oscilloscope,
which are disabled by the AC input coupling capacity when
AC coupling is selected. This also applies to DC voltages with
superimposed AC voltages. It also must be noted that due
to the capacitive resistance of the AC input coupling capacitor,
the attenuation ratio depends on the signal frequency. For
sinewave signals with frequencies higher than 40Hz this
influence is negligible.
In the GD (ground coupling) setting, the signal path is
interrupted directly beyond the input. This causes the
attenuator to be disabled again, but now for both DC and AC
voltages.
With the above listed exceptions HAMEG 10:1 probes can
be used for DC measurements up to 600V or AC voltages
(with a mean value of zero volt) of 1200Vpp. The 100:1 pro-
be HZ53 allows for 1200V DC or 2400Vpp for AC.
It should be noted that its ACpeak value is derated at higher
frequencies. If a normal x10 probe is used to measure high
voltages there is the risk that the compensation trimmer
bridging the attenuator series resistor will break down causing
damage to the input of the oscilloscope. However, if for
example only the residual ripple of a high voltage is to be
displayed on the oscilloscope, a normal x10 probe is sufficient.
In this case, an appropriate high voltage capacitor (approx.
22-68nF) must be connected in series with the input tip of
the probe.
Total value of input voltage
The dotted line shows a voltage alternating at zero volt level.
If superimposed on a DC voltage, the addition of the positive
peak and the DC voltage results in the max. voltage (DC +
ACpeak).
With
Y-POS.
control (input coupling to
GD
) it is possible to
use a
horizontal graticule line as reference line for ground
potential before the measurement.
It can lie below or above
the horizontal central line according to whether positive and/
or negative deviations from the ground potential are to be
measured.
Time Measurements
As a rule, most signals to be displayed are periodically
repeating processes, also called periods. The number of
periods per second is the repetition frequency. Depending
on the time base setting indicated by one of the
TIME/DIV.
LED‘s, one or several signal periods or only a part of a period
can be displayed. The time coefficients are stated in s/div.
when the red sec-LED and the 0.5 or 0.2 LED (ms/div scale)
are lit. The
ms/div.
or
µs/div.
time coefficients are indicated
by one of the LED‘s on the ms or µs scale.
The duration of a signal period or a part of it is
determined by multiplying the relevant time (horizon-
tal distance in div.) by the time coefficient indicated
on the TIME/DIV. LED scales.
The variable time control (identified with an arrow
knob cap) must be in its calibrated position CAL. (arrow
pointing horizontally to the right). For exact time
measurements, the variable control ( VAR. 2.5:1) must
be set to its calibrated detent CAL position. When
turning the variable control ccw, the time coefficient
indicator LED starts blinking and the timebase speed
will be reduced until a maximum factor of 2.5 is
reached. Therefore any intermediate value is possible
within the 1-2-5 sequence.
With the designations
L
= displayed wave length in div. of one period,
T
= time in seconds for one period,
F
= recurrence frequency in Hz of the signal,
Tc
= time coefficient in s/div. on timebase switch and
the relation F = 1/T, the following equations can be stated:
With active X-MAG (x10) indicated by the x10 LED lit, the Tc
value must be divided by 10.
However, these four values are not freely selectable. They
have to be within the following limits:
L
between 0.2 and 10div., if possible 4 to 10div.,
T
between 0.01µs and 5s,
F
between 0.5Hz and 35MHz,
Tc
between 0.05µs/div. and 0.5s/div. in 1-2-5 sequence
(with X-MAG. (x10) inactive), and
Tc
between 10ns/div. and 20ms/div. in 1-2-5 sequence
(with X-MAG. (x10) active).
Please note that if the time coefficient is set to 0.05µs/
div. and the X magnifier is selected the time coefficient
is automatically set to 0.01µs/div.
Examples:
Displayed wavelength L = 7div.,
set time coefficient Tc = 0.1µs/div.,
required period T = 7x0.1x10
-6
= 0.7µs
required rec. freq. F = 1:(0.7x10
-6
) = 1.428MHz.
Signal period T = 1s,
set time coefficient Tc = 0.2s/div.,
required wavelength L = 1:0.2 = 5div..
Displayed ripple wavelength L = 1div.,
set time coefficient Tc = 10ms/div.,
required ripple freq. F = 1:(1x10x10
-3
) = 100Hz.
TV-line frequency F = 15625Hz,
set time coefficient Tc = 10µs/div.,
required wavelength L = 1:(15 625x10
-5
) = 6.4div..
Sine wavelength L = min. 4div., max. 10div.,
Frequency F = 1kHz,
max. time coefficient Tc = 1:(4x10
3
) = 0.25ms/div.,
min. time coefficient Tc = 1:(10x10
3
) = 0.1ms/div.,
set time coefficient Tc = 0.2ms/div.,
required wavelength L = 1:(10
3
x0.2x10
-3
) = 5div.
= ⋅
=
⋅
=
⋅
=
⋅
=
=
