Hameg HM504-2, Manual

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9
Subject to change without notice
Input voltage U = 5 V
pp
,
set deflection coefficient D = 1 V/div,
required display height H = 5:1 = 5 div.
Signal voltage U = 230 V
rms
x 2
√
2 = 651 V
pp
(voltage > 160 V
pp
, with probe 10:1: U = 65.1 V
pp
),
desired display height H = min. 3.2 div, max. 8 div,
max. deflection coefficient D = 65.1:3.2 = 20.3 V/div,
min. deflection coefficient D = 65.1:8 = 8.1 V/div,
adjusted deflection coefficient D = 10 V/div.
The previous examples are related to the CRT graticule reading.
The results can also be determined with the aid of the DV cursor
measurement
(
please note ”controls and readout”)
.
The input voltage must not exceed 400 V, irrespective of polarity.
If an AC voltage which is superimposed on a DC voltage is
applied, the maximum peak value of both voltages must not
or –400 V. So for AC voltages with a mean value of zero
volt the maximum peak to peak value is 800 V
pp
.
If attenuator probes with higher limits are used, the probes
limits are valid only if the oscilloscope is set to DC input
coupling.
If DC voltages are applied under AC input coupling conditions the
oscilloscope maximum input voltage value remains 400 V.
The attenuator consists of a resistor in the probe and the
1 MOhm input resistor of the oscilloscope, which is 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 reactance of the
AC input coupling capacitor, the attenuation ratio depends on the
signal frequency. For sine wave signals with frequencies higher
than 40 Hz this influence is negligible.
Apart from the above listed exceptions, HAMEG 10:1 probes can
be used for DC measurements up to 600 V or AC voltages (with
a mean value of zero volt) of 1200 V
pp
. The 100 :1 probe HZ53
allows for use up to 1200 V DC or 2400 V
pp
for AC.
It should be noted that its AC peak 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.
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.
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).
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
(
TIME/DIV. knob) indicated by the readout, one or several signal
periods or only a part of a period can be displayed. The time
coefficients are stated in ms/div, µs/div or ns/div. The following
examples are related to the CRT graticule reading. The results can
also be determined with the aid of the Dt and 1/Dt cursor
measurement
( please note ”controls and readout”) .
The duration of a signal period or a part of it is determined by
multiplying the relevant time (horizontal distance in div) by the
(calibrated) time coefficient displayed in the readout.
Uncalibrated, the time base speed can 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 ms, µs or ns/div and the relation
F
= 1/T, the following can be stated:
However, these four values are not freely selectable. They
have to be within the following limits:
L between 0.2 and 10 div, if possible 4 to 10 div,
T between 10 ns and 5 s,
F between 0.5 Hz and 100 MHz,
Tc between 100 ns/div and 500 ms/div in 1-2-5 sequence
(with X-MAG. (x10) inactive), and
Tc between 10 ns/div and 50 ms/div in 1-2-5 sequence (with
X-MAG. (x10) active).
Type of signal voltage