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In general, it is safe to avoid measuring with non-
shielded connecting wire. When using a shielding wire
connect one end of the shield to the earth terminal of
the oscilloscope and the other end to the grounding of
the circuit to be measured. It is deirable to use a coaxial
cable with BNC type connector,
o The following cautions must be observed when per
forming a wide band measurement.
It is necessary to terminate with the characteristic impe
dance of the cable when measuring a rapid rising wave
form or a high frequency wave.
Especially when using a long cable, the absence of a
terminating resistor will necessarily lead to a measure
ment error derived from ringing phenomenon. Some
measuring circuits require a terminating resistor equal to
the characteristic impedance of the cable also on the
measurement terminal side.
BNC type terminating resistor (50
is conveniently
used for this purpose,
o In order to perform measurement with the measuring
circuit put in proper operating state it is sometimes
necessary to terminate the cable with an impedance
which corresponds to the circuit to be measured,
o The stray capacity of the shielded wire must be taken
into account when performing measurement with a long
shielded wire. Since the shielded wire normally in use has
a capacitance of about ICQ pF per meter, its effect on
the circuit to be measured cannot be ignored. Use a
probe to minimize the effect on the circuit,
o When the length of the shielded wire used or when the
length of the non-terminated cable reaches 1/4 wave
length or its multiples within the band of V-212 [V-211]
type (1/4 wave length is about 3 meter when using a
coaxial cable at 20 MHz), oscillation may be caused at
5 m V/DIV or near range.
This is caused by the resonance between the externally
connected high-Q inductance and the input capacity
and can be avoided by reducing the Q.
Connect the cable or shielded wire to the input connector
by way of a serially connected 100f2 to 1
resistor, or
perform measurement at other VOLTS/DIV range.
(3) When observing waveform with X-Y
Set the TIME/DIV switch to X-Y. Then the instrument
works as an X-Y oscilloscope.
Each input is applied to the instrument as follows.
X-axis signal (horizontal axis signal)
CHI INPUT [TRIG or XIN]
Y-axis signal (vertical axis signal)
CH2 INPUT [ V INPUT]
In this case leave the horizontal axis magnification switch
(PULL-MAG xlO knob) at depressed position.
19
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