Vertical Controls 3
Keysight InfiniiVision 3000T X-Series Oscilloscopes User's Guide 83
 
When AC coupling is selected (see “To specify channel coupling" on 
page 81) or excessive voltage is applied to the input, the oscilloscope 
automatically switches to 1M Ohm mode to prevent possible damage.
• 1M Ohm — is for use with many passive probes and for general-purpose 
measurements. The higher impedance minimizes the loading effect of the 
oscilloscope on the device under test.
This impedance matching gives you the most accurate measurements because 
reflections are minimized along the signal path.
See Also • For more information on probing, visit: www.keysight.com/find/scope_probes
• Information about selecting a probe can be found in document number 
Keysight Oscilloscope Probes and Accessories Selection Guide (part number 
5989-6162EN), available at www.keysight.com.
To specify bandwidth limiting
1 Press the desired channel key.
2 In the Channel Menu, press the BW Limit softkey to enable or disable bandwidth 
limiting.
When bandwidth limit is on, the maximum bandwidth for the channel is 
approximately 20 MHz. For waveforms with frequencies below this, turning 
bandwidth limit on removes unwanted high frequency noise from the waveform. 
The bandwidth limit also limits the trigger signal path of any channel that has BW 
Limit turned on.
To change the vertical scale knob's coarse/fine adjustment setting
1 Push the channel's vertical scale knob (or press the channel key and then the 
Fine softkey in the Channel Menu) to toggle between fine and coarse 
adjustment of the vertical scale.
You can also do this using the touchscreen. See “Turn Channels On/Off and 
Open Scale/Offset Dialogs" on page 55.
When Fine adjustment is selected, you can change the channel's vertical 
sensitivity in smaller increments. The channel sensitivity remains fully calibrated 
when Fine is on.