HOW TO USE THE INSTRUMENT

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VERTICAL MENU

50Ω

 

 

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 50Ω coaxial cable, connect a 4 Vpp, 2 kHz signal from a generator with 50Ω output impedance to channel 1.

-Press the AUTOSET key.

-Press VERT MENU.

-Press the 50Ω CH1 softkey.

CH1

1V

VERT MENU

 

 

 

50Ω CH.

 

 

OFF

ON

 

 

 

CH1

1V

LZ

 

 

 

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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.

CHx

 

Since the 10:1 probe delivered with the instrument is a high

 

 

impedance probe, the 50Ω termination is automatically turned off.

detector

 

At the same time, the sensitivity readout is adjusted automatically

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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.

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Image 66
Fluke PM3370B Vertical Menu, Vertical Probe Range Indicator, Remove the input signal from CH1, Connect the probe again