Operator’s Manual
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21
Battery
indicates the remaining battery life. 100% is roughly equivalent to 6 hours of life.
Cable Status and Battery are updated whenever the probe dialog is opened. If you wish to
update them after the dialog has been opened, touch the Check Status button.
Probe Volts/Div and Attenuation
The front panel Volts/Div knob controls the oscilloscope’s scale factor. When the probe is
connected, the oscilloscope voltage per division settings will be limited to a minimum sensitivity
setting based on the attached tip.
Offset
Offset allows you to remove a DC bias voltage from the input signal while maintaining DC
coupling. This ensures that the probe will never be overdriven while a signal is displayed on
screen and prevents inaccurate measurements. Keep in mind that the HVFO design already
removes the common mode voltage from the measurement, so large offsets will not typically be
required for most measurements.
The total usable offset of the system is a function of three values: oscilloscope V/div setting,
oscilloscope offset at that V/div setting, and total probe attenuation (tip plus transmitter). Find
the oscilloscope front-end V/div (Vertical Scale) setting with the probe connected. This may be
calculated as:
Oscilloscope Front End V/Div = (Probe and Oscilloscope) V/Div ÷ Total Probe Attenuation
Once the oscilloscope V/div value is known, you can find the maximum offset available at that
V/div setting either by consulting the oscilloscope specifications or by selecting to Use Max
Offset with the oscilloscope set to that V/div.
Bandwidth Limiting
Probe bandwidth limit may be switched from Off (maximum bandwidth) to 20 MHz on the input
Channel (Cn) dialog.
Auto Zero
Auto Zero corrects for DC offset drifts that naturally occur from thermal effects in the amplifier.
The HVFO probe incorporates Auto Zero capability to remove the DC offset from the probe's
amplifier output to improve the measurement accuracy.
Auto Zero is invoked manually from the HVFO108 dialog that appears when the probe is
connected to the oscilloscope. Always perform Auto Zero after the probe is warmed up
(recommended warm-up is 20 minutes). Depending on the measurement accuracy desired
and/or changes in ambient temperature, it may be necessary to perform Auto Zero more often.
If the probe is disconnected from the oscilloscope and reconnected, repeat Auto Zero after a
suitable warm-up time.
CAUTION:
Disconnect the probe from the circuit before Auto Zero, or else any DC
component that is part of the Signal to be measured will be zeroed out.
