Tektronix TDS 644A Sprinkler User Manual


 
Probe Selection
TDS 620A, 640A & 644A User Manual
3Ć103
These probes must be terminated in a 50 W scope input. Input capacitance
is much lower than high Z passive probes, typically 1 pF, but input resisĆ
tance is also lower (500 to 5000 W typically). Although that DC loading
degrades amplitude accuracy, the lower input capacitance reduces high
frequency loading to the circuit under test. That makes Z
O
probes ideal for
timing and phase measurements when amplitude accuracy is not a major
concern.
Z
O
probes are useful for measurements up to 40 V.
High Voltage Probes
High voltage probes have attenuation factors in the 100X to 1000X range.
The considerations that apply to other passive probes apply to high voltage
probes with a few exceptions. Since the voltage range on high voltage
probes varies from 1 kV to 20 kV (DC + peak AC), the probe head design is
mechanically much larger than for a passive probe. High voltage probes
have the added advantage of lower input capacitance (typically 2Ć3 pF).
P6009
P6015A
Figure 3Ć54:ăThe P6009 and P6015A High Voltage Probes