Reference Value (Ref_M, Ref_S); Selecting The Measurement Range; Automatic Range Selection (Auto); Manual Measurement Range Selection - Hameg R&S HM8118 Benutzerhandbuch

surement value (reference value) is displayed. The measu-
rement value deviation is shown in the appropriate units
(Ohm, Henry, etc.).
6.3

Reference Value (REF_M, REF_S)

The menu function REF_M or REF_S enables the user
to enter a reference value which will be used as a basis
for the measurement result ∆ % or ∆ ABS. Press the SE-
LECT key to use the SETUP menu function and the set-
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ting REF_M (for the main measurement value display) and
REF_S (for the secondary measurement value display) to
enter a reference value each. The applicable units will be
selected automatically depending on the selected measu-
rement function for the main measurement value display
(H, F, Ω or S) or for the secondary measurement value dis-
play (Ω, S or °). You can enter a reference value numerically
with up to five digits after the decimal point. Alternatively,
you can press the TRIG key
and the resulting measurement value will be adopted as
reference value.
6.4

Selecting the Measurement Range

The measurement range can be selected automatically or
manually. In some cases, it is useful to lock the automa-
tic measurement range function as it can take a complete
measurement cycle to determine the appropriate measure-
ment range. This can also be useful when switching similar
components. The bridge R&S®HM8118 automatically swit-
ches to the measurement range 6 and subsequently back
to the adequate measurement range if a component has
been connected to the instrument. If the automatic mea-
surement range function has been locked and the impe-
dance of a component equals more than 100 times the no-
minal value of the measurement range, the bridge will dis-
play an OVERRANGE measurement error. In this case, it
is necessary to select a suitable measurement range for
the measurement. Press the AUTO/HOLD key
between the automatic and the manual measurement
range selection.
6.4.1

Automatic range selection (AUTO)

If the automatic measurement range function is activated,
the bridge automatically selects the most suitable mea-
surement range for an exact measurement in accordance
with the connected component. The instrument will switch
to the next measurement range level below if the measure-
ment value is smaller than 22.5% of the selected measure-
ment range or 90% higher than the end value of the mea-
surement range. An integrated switching hysteresis of ap-
proximately 10% prevents the instrument from constantly
switching the measurement range if the measurement va-
During the measurement of an inductance in the AUTO mode,
it may occur that the R&S®HM8118 is constantly changing the
measurement range. This is based on the fact that the source im-
pedance is dependent on the selected measurement range so that
after switching the measurement range, the newly measured va-
lue is outside the range of the 10% hysteresis. In this case, it is
recommended to use the manual measurement range selection.
to perform a measurement,
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to switch
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lue is close to the switching threshold of a measurement
range. The following table shows the switching thresholds
for switching the measurement range (if the constant vol-
tage CST V is switched off):
Measurement Range
1 to 2
2 to 3
3 to 4
4 to 5
5 to 6
2 to 1
3 to 2
4 to 3
5 to 4
6 to 5

6.4.2 Manual Measurement Range Selection

The bridge R&S®HM8118 includes 6 measurement ran-
ges (1–6). The measurement ranges can be preselec-
ted manually or automatically. The following table indica-
tes the source resistance and the impedance of the con-
nected component for each measurement range. The spe-
cified ranges are impedance ranges, not resistance ran-
ges. Capacitators or inductances are frequency-dependent
components.
Measure- Source
ment range Impedance
1 25.0 Ω
2 25.0 Ω
3 400.0 Ω
4 6.4 kΩ
5 100.0 kΩ
6 100.0 kΩ
Additionally, the impedance of capacitators is inversely
proportionate to the frequency. Therefore, larger capaci-
tators will be measured in the lower impedance measure-
ment ranges. Consequently, the measurement range for
any given component may change as the measurement
frequency changes. If you wish to measure multiple si-
milar components, it is possible to shorten the measure-
ment time by using the AUTO/HOLD
the automatic measurement range selection to the manual
measurement range selection with the DUT (= Device Un-
der Test) connected. The AUTO/HOLD key will no longer
be illuminated. It is recommended to primarily use the ma-
The LCR bridge R&S®HM8118 does not create a 50Ω system.
Instead, it changes its internal resistance dependent on measure-
ment function and measurement range. Every cable shows losses
and distorts the original measurement result because of inductive
and capacitive properties (particularly because of its length). The
input impedance changes dependent on the selected measurement
range and the connect load impedance between 25Ω and 100kΩ.
Setting of Parameters
Component Impedance
Z > 3.00 Ω
Z > 100.00 Ω
Z > 1.60 kΩ
Z > 25.00 kΩ
Z > 1.00 MΩ
Z < 2.70 Ω
Z < 90.00 Ω
Z < 1.44 kΩ
Z < 22.50 kΩ
Z < 900.00 kΩ
Component
Impedance
10.0 µΩ bis 3.0 Ω
3.0 Ω bis 100.0 Ω
100.0 Ω bis 1.6 kΩ
1.6 kΩ bis 25.0 kΩ
25.0 kΩ bis 2.0 MΩ
2.0 MΩ bis 100.0 MΩ
key to switch from
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