Hameg HM 1004-3 Series, Manual

Page: 9 / 36

9
Subject to change without notice
Type of signal voltage
H between 0.5 and 8div, if possible 3.2 to 8div,
U between 0.5mVpp and 160Vpp,
D between 1mV/div and 20V/div in 1-2-5 sequence.
Examples:
Set deflection coefficient D = 50mV/div 0.05V/div,
observed display height H = 4.6div,
required voltage U = 0.05x4.6 = 0.23Vpp.
Input voltage U = 5Vpp,
set deflection coefficient D = 1V/div,
required display height H = 5:1 = 5div.
Signal voltage U = 230Vrmsx2
√
2 = 651Vpp
(voltage > 160Vpp, with probe 10:1: U = 65.1Vpp),
desired display height H = min. 3.2div, max. 8div,
max. deflection coefficient D = 65.1:3.2 = 20.3V/div,
min. deflection coefficient D = 65.1:8 = 8.1V/div,
adjusted deflection coefficient D = 10V/div.
The previous examples are related to the crt graticule reading.
The results can also be determined with the aid of the
∆
V
cursor measurement ( please note “controls and readout” ).
The input voltage must not exceed 400V, independent from
the polarity.
If an AC voltage which is superimposed on a DC voltage is
applied, the maximum peak value of both voltages must not
or -400V. So for AC voltages with a mean value of
zero volt the maximum peak to peak value is 800Vpp.
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 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 frequen-
cies higher than 40Hz this influence is negligible.
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 probe
HZ53
allows for 1200V DC or 2400Vpp 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 caus-
ing 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 measure-
ment.
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 timebase 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
∆
T and 1/
∆
T 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 timebase speed can be reduced until a
maximum factor of 2.5 is reached. Therefore any intermedi-
ate 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 equations can be stated:
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 5ns and 5s,
F between 0.5Hz and 100MHz,
Tc between 50ns/div and 500ms/div in 1-2-5 sequence
(with X-MAG. (x10) inactive), and
Tc between 5ns/div and 50ms/div in 1-2-5 sequence
(with X-MAG. (x10) active).
Examples:
Displayed wavelength L = 7div,
set time coefficient Tc = 100ns/div,
required period T = 7x100x10-9 = 0.7µs
required rec. freq. F = 1:(0.7x10-6) = 1.428MHz.
Signal period T = 1s,