Loading Errors (Ac Volts) - HP 34401A User Manual

Chapter 7 Measurement Tutorial

Loading Errors (ac volts)

Loading Errors (ac volts)
In the ac voltage function, the input of the HP 34401A appears as a
1 M resistance in parallel with 100 pF of capacitance. The cabling that
you use to connect signals to the multimeter will also add additional
capacitance and loading. The table below shows the multimeter's
approximate input resistance at various frequencies.
Input Frequency Input Resistance
100 Hz 1 M
1 kHz 850 k
10 kHz 160 k
100 kHz 16 k
For low frequencies:
100 x R
Error %
R 1 M
s
Additional error for high frequencies:
Error % 100 x
R = source resistance
s
F = input frequency
C = input capacitance (100 pF) plus cable capacitance
in
s
1
1 2 x F x R x C
s in
1
2
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