Rohde & Schwarz HM8118, User Manual

Page: 57 / 76

57
Instrument Functions
The following table shows the change in the impedance
ranges when the constant voltage mode is deactivated
(CST V OFF):
Under certain circumstances, the display shows the la-
bel „OVERRANGE“. This may occur when the constant
voltage mode is activated for the bridge and the manual
measurement range selection is activated. To bypass this,
change into a higher measurement range or select the au-
tomatic measurement range selection.
7.2 CORR Menu
7.2.1 Compensation
It is recommended to perform a compensation prior to the
measurement beginning with measurement equipment to
prevent measurement errors caused by the system. You
can also compensate test leads and other parasitic effects
(capacitative impedances) with a compensation. To at-
tain the highest possible measurement accuracy, it is re-
commended to perform the compensation under the same
conditions as the later measurement of the component
(for instance, the sequence of the test leads should not
be changed after the compensation). Also, the test leads
should not be restricted, i.e. no hands or metallic items
should be nearby as these could impact the measurement.
The following compensation options can be selected in the
CORR menu:
❙ OPEN :
An open compensation is performed to compensate for
parasitic effects (impedances) caused by connections
between measurement accessories and component. To
perform the open compensation, it is essential to only
have the open-end test leads without components
connected. The open compensation is possible for
impedances greater than 10kΩ.
Measurement Range Component Impedance
1 to 2
Z
>
3.33 Ω
2 to 3
Z
>
400.00 Ω
3 to 4
Z
>
6.67 kΩ
4 to 5
Z
>
100.00 kΩ
5 to 6
Z
>
2.22 MΩ
2 to 1
Z
<
2.7 Ω
3 to 2
Z
<
324.0 Ω
4 to 3
Z
<
5.4 kΩ
5 to 4
Z
<
81.0 kΩ
6 to 5
Z
<
1.8 MΩ
Fig. 7.8: Menu function CORR display
❙ SHORT :
A short compensation is performed to compensate for pa-
rasitic effects (impedances) caused by connections
between measurement accessories and component. To
perform the short compensation, it is essential to only
have the open-end, short-circuited test leads without
components connected. The short compensation is
possible for impedances of up to 15Ω and resistances of
up to 10Ω.
❙ LOAD :
A compensation with adjustment (compensation of a
known load impedance) is suitable to calibrate measured
impedances before the actual measurement. If the load is
known, the compensation is entered after selecting the
measurement function
28
...
39
(e.g.
L-Q
) separate for the
main display LOADM (Main) and secondary display
LOADS (Sub), and it should be as close as possible to the
expected measurement value of the DUT (= Device Under
Test). It is possible to compensate known loads for
impedances and resistances within the measurement
range.
In the CORR menu, use the arrow keys
7
to se-
lect the respective compensation function to perform a
compensation, press the knob
6
(editing mode) and se-
lect the desired setting (ON/OFF) via knob. Press the knob
again to confirm the selection. The MODE function al -
lows you to determine if the OPEN or SHORT compensa-
tion should be performed only for the currently selected
measurement frequency (SGL) or for all 69 frequency in-
crements (ALL) (available with firmware version 1.35 and
higher).
If the corresponding compensation function is activated in
the CORR menu (ON) and the frequency levels are selec-
ted, the compensation can be started via OPEN
11
, SHORT
12
or LOAD
13
key. A compensation of all 69 frequency in-
crements takes approximately 90 seconds. If the com-
pensation was successful, a short signal will sound. If the
compensation was unsuccessful, an error message will be
shown in the display.
7.2.2 NUM
You can use the NUM function to select one of 5 possi-
ble load impedances (LOAD). In the CORR menu, use the
arrow keys
7
to select the NUM function to
choose the load impedance, press the knob
6
(editing
mode) and select the desired load impedance via knob.
Press the knob again to confirm the selection.
7.2.3 Measurement Frequency FRQ
You can use the FRQ function to select the measure-
ment frequency of the load impedance (LOAD) between
For a compensation with a known load, a value is entered in both
reference memories (LOADM and LOADS) (e.g. the value for the
expected inductance in LOADM and the expected quality va-
lue in LOADS). This only applies to each selected measurement
frequency.