HP 4262A Operating And Service Manual page 48

Section III
Table 3-4
Model 4262A
Table 3-4. Unusual Operating Indications (Sheet 2 of 4).
Indication:
Cause of trouble:
When measuring a low impedance (small
inductance, resistance or high capacitance),
measurement error is excessive.
Excessive residual impedance (inductance,
capacitance or resistance) of test leads
in a two terminal measurement.
Mutual test lead induction between
current leads (Hcur and
Lour)
and
potential leads
(Hpot
and
Lpot).
What to do:
Use test leads in four-terminal con¬
figuration and measure.
Twist current leads
(Hcur
and LCUR) together.
Do the same with potential leads
(Hpot
and
Lpot).
Additional error is presented as
w2hrCx X 100 (%) for C measurement,
where:
a> = 2?rf
f = test frequency
Lr = residual inductance
Cx = unknown capacitance
Indication:
Cause of trouble:
Measurement error is excessive when high
impedance (high inductance, small
capacitance) is measured.
Measurement
Cause of error
High Inductance
Stray capacitance
between High and Low
leads.
Small
Capacitance
Stray capacitance
between High and Low
leads.
Use shielded cable for connection
between sample and 4262A UNKNOWN
terminals. Connect outer conductor
to GUARD terminal.
Adjust C ZERO ADJ control properly to
compensate for stray capacitance.