Tektronix P5210, Руководство по обслуживанию

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Operating Basics
6
P5210 High Voltage Differential Probe Service Manual
The extension leads, however, do affect the high-frequency
performance of the probe. With longer lead length, differential noise
induced into the input leads is greater. Also, because of the added
inductance of the leads, voltage measurements at frequencies above
approximately 10 MHz may not be as precise. Figure 3 shows the
affect on HF transient response.
The extension leads do not affect the performance of the probe when
bandwidth is set to 5 MHz.
With extension leads Without extension leads
50 ns/div 50 ns/div
250
m
v/
div
250
m
v/
div
Figure 3: HF Transient Response with and without extension leads
Probe Loading
When you touch your probe tip to a circuit element, you introduce a
new resistance, capacitance, and inductance into the circuit.
Frequency and impedance of the source determine how much the
probe loads the circuit you are measuring. As the frequency of the
source starts to increase beyond 1 kHz, the input impedance of the
probe begins to decrease. The lower the impedance of the probe
relative to that of the source, the more the probe loads the circuit
under test. For a graph of frequency versus input impedance, refer to
Figure 6 on page 13 of the
Specifications section.
The probe has virtually no loading effect on sources with relatively
low impedance and low frequency.