Hitachi V-209 Operation Manual page 25

In general. tt tS safe
shielded connecting wire. When using a shieldmg 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 coaxtal
cable with B C type connector.
The following cautions must be observed when per­
forming a wide band measurement. It ts necessary to
terminate with the characteristic impedance of the cable
when measuring a rapid nsing waveform or a high fre­
quency wave.
Especially when using a long cable. the absence of
terminating resistor will necessarily lead to a measure­
ment error derived from ringing phenomenon. Some
measunng circutls require a term mating reststor equal to
the charactensttc unpedance of the cable also on the
measurement terminal stde.
B C type terminating reststor
used for this purpose.
order to perform measurement with the measuring
c In
circuit put in proper operating state, it is sometimes
necessary to terminate the cable with
which corresponds to the circuit to be measured.
The stray capacity of the shield wire must
o
account when performing measurement with a long
shield wire. Since the shield wire normally in use has
to avoid measunng with non­
(50 Q) ts conveniently
an impedance
be taken in
a capacity of about I
circutt to be measured cannot be ignored. Use a probe to
minimize the cffection the circuit.
When the length of the shield wire is used or when the
length of the non-terminated cable reaches I 4 wave
length or its multiples within the band of V-:!09 type
(I 4 wave length is about 3 meter when using a coaxial
cable at }0 MHz),
DIY range.
This is caused by the resonance between the externally
connected high-0 inductance and the input capacity
and can be avoided by reducing
a
Connect the cable or shield wire to the input connector
by way of a senally connected I
perform measurement at other VOLT/DIY range.
10
00 pF per meter. its effect on the
oscillation may be caused near 5 mV
the Q.
OOU to I n reststor, or
21