Instructions

AP033 Active Differential Probe

7. Insert and tighten the two screws which secure the end panel to the ProBus interface

housing. Avoid over tightening the screws as the cover may warp.

8. Replace the four push button caps, pressing each fully to seat the cap on the button

shaft.

J. Attenuator Matching and Final Check

1. Repeat the Performance Verification procedure to ensure compliance with the

warranted specifications.

2. Perform the Attenuator Matching Procedure listed on page 21. Apply calibration

seals in accordance with your quality procedures.

This concludes the Adjustment Procedure. Repeat the Performance Verification

procedure to complete the calibration of the AP033.

Reference Information

Differential Mode and Common Mode

Differential probes amplify the voltage difference that appears between the + and –

inputs. This voltage is referred to as the Differential Mode or Normal Mode voltage. The

voltage component that is referenced to earth ground, and is identical on both inputs, is

rejected by the amplifier. This voltage is referred to as the Common Mode voltage,

because it is common to both inputs. The common mode voltage can be expressed as:

Differential Mode Range and Common Mode Range

The Differential Mode Range is the maximum signal that can be applied between the

and

–

inputs without overloading the probe amplifier, resulting in “clipping” or distortion

of the waveform measured by the oscilloscope.

The Common Mode Range is the maximum voltage with respect to earth ground that can

be applied to either input. Exceeding the common mode range can result in unpredictable

results. Because the Common Mode signal is normally rejected and is not displayed on

the oscilloscope, you need to be careful to avoid accidentally exceeding the common

mode range.