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HOW TO USE THE INSTRUMENT 4 - 21
VERTICAL MENU 50
Ω
The 200 MHz models offer the selection of an input impedance of 50Ω on all input
channels. The EXTTRIG input has no 50Ω possibility. The impedance selection
is a subfunction in VERT MENU.
The 50Ω input impedance is used to obtain a correct impedance to match signal
sources of the same impedance. For interconnection, a coaxial 50Ω cable must
be used. The 50Ω position is indicated on the display with the Lz sign (Low Z =
Low Impedance).
- Disconnect all signals from the inputs.
- Using a 50
Ω
coaxial cable, connect a 4 Vpp, 2 kHz signal from a
generator with 50
Ω
output impedance to channel 1.
- Press the AUTOSET key.
- Press VERT MENU.
- Press the 50
Ω
CH1 softkey.
Observe that the displayed signal amplitude changes to half of the original
amplitude. This is caused by the change of the input impedance to 50Ω, which
results in a voltage division between the 50Ω output of the generator and the 50Ω
input of the oscilloscope.
- Remove the input signal from CH1.
VERTICAL PROBE RANGE INDICATOR
- Connect the probe again.
Since the 10:1 probe delivered with the instrument is a high
impedance probe, the 50Ω termination is automatically turned off.
At the same time, the sensitivity readout is adjusted automatically
when a 10:1 or 100:1 probe is used. This way you don’t have to
multiply the displayed amplitude by 10 or 100 when you use a Fluke probe with
range indication.
ST5968
9312
CH1
1V
VERT MENU
CH1
1V
L
Z
50Ω CH.
ON
OFF
CHx
detector
ST6021