Agilent Technologies 54621A, 54621D, 24A, 42A, 22A, 41A manual Press the Imped impedance softkey

MegaZoom Concepts and Oscilloscope Operation

To setup the Analog channels

3Press the Imped (impedance) softkey

The 54620-series oscilloscope analog channel input impedance is always 1 MΩ . The 54640-series oscilloscope analog channel input impedance can be set to either 1M Ohm or 50 Ohm by pressing the Imped softkey.

•50 Ohm mode matches 50-ohm cables commonly used in making high frequency measurements. This impedance matching gives you the most accurate measurements since reflections are minimized along the signal path.

•1M Ohm mode is for use with probes and for general-purpose measurements. The higher impedance minimizes the loading effect of the oscilloscope on the circuit under test.

When you connect an AutoProbe self-sensing probe, the oscilloscope will automatically configure your probe to the correct impedance.

4Press the BW Limit softkey to turn on bandwidth limiting.

Pressing the BW Limit softkey turns the bandwidth limit on or off for the selected channel. When bandwidth limit is on, the maximum bandwidth for the channel is approximately 20 MHz for 54620-series and 25 MHz for 54640-series. For waveforms with frequencies below this, turning bandwidth limit on removes unwanted high frequency noise from the waveform. Bandwidth limit also limits the trigger signal path if the channel you are configuring is the trigger source.

When BW Limit is selected, “BW” is illuminated on the front panel next to the channel position knob ( ).

5Press the Vernier softkey to turn on vernier for the selected channel.

When Vernier is selected, you can change the channel sensitivity in smaller increments with the volts/division knob. The channel sensitivity remains fully calibrated when Vernier is on. The vernier value is displayed in the status line at the top of the display.

When Vernier is turned off, turning the volts/division knob changes the channel sensitivity in a 1-2-5 step sequence.

6Press the Invert softkey to inverted the selected channel.

When Invert is selected, the voltage values of the displayed waveform are inverted. Invert affects how a channel is displayed, but does not affect triggering. If the oscilloscope is set to trigger on a rising edge, it remains set to trigger on a same edge (triggers at the same point on the waveform) after the channel is inverted.

Inverting a channel will also change the result of any function selected in the Math menu or any measurement.

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