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3.6 Correcting the Probe Phase
Procedure
Explanation
3-10
1.
Turn ON the TA220 and DL1740.
2.
Set the input impedance of the DL1740 to 50 Ω. For the procedure, see the
DL1740 User's Manual.
3.
Turn OFF the equalizer of the TA220 (see section 4.3).
4.
Set the waveform acquisition conditions of the DL1740 so that approximately
two periods of the waveform can be viewed in their entirety.
5.
Insert a flat-head screwdriver to the phase adjustment hole of the probe and turn
the variable capacitor to make the waveform displayed on the waveform monitor
a correct rectangular wave (see explanation).
The Necessity of Phase Correction of the Probe
If the input capacity of the probe is not within the adequate range, the gain across
different frequencies will not be uniform. Consequently, a correct waveform cannot be
input to the measurement circuit of the TA220. The input capacity of each probe is not
necessarily all the same. Therefore, the probe has a variable capacitor (trimmer) that
allows the input capacity to be adjusted. This adjustment is called phase correction.
When using the probe for the first time, make sure to perform phase correction. The
appropriate input capacitance varies depending on the input connector of the instrument.
Therefore, phase correction must also be performed when the connected instrument is
changed.
Calibration Signal
Waveform type
Frequency
Voltage
Differences in the waveform due to the phase correction of the probe
Correct waveform
Square wave
1 kHz
1 Vp-p
Over compensated
(the gain in the high
frequency region is up)
Under compensated
(the gain in the high
frequency region is low)
IM 704610-01E
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