the
amplifiers
at
2Hz
(or
10Hz,
see section 4.3). When it
is
required
to
remove
the
meter
to
some distance from
the
accelerometer position it
is
recommended
to
fit extension cables between
the
input
stage and meter
rather
than
between
the
accelerometer and input stage. Otherwise
the
load-
ing
due
to
the
cable will decrease
the
effective sensitivity
of
the
accelerome-
ter. Refer
to
the
Accelerometer instruction manual for details.
Since it
is
extremely likely
that
the
resonance frequency
of
the
acceler-
ometer
lies within
the
frequency range
of
the
Meter, it
is
necessary
to
take
special precautions when measuring signals likely
to
have a high frequency
components.
In such cases it
is
advisable
to
use
the
Octave Filter
Set
to
be
sure
that
the
non-linear frequency response
of
the
accelerometer has no
effect. Otherwise a special low-pass filter must be used.
3.6. VOLTAGE MEASUREMENTS
Voltage measurements may be made as follows:
1. Fit
the
Sound Level Meter with its
Input
Stage and
the
jack socket
adaptor
JJ
2614.
2. Fit
the
Attenuator
Scale 3
Band
turn
the
meter scale
to
VIBRATION
METER.
3.
Turn
the
METER SWITCH
to
"Batt.
(Rec.)" and check
the
condition
of
the
batteries.
4.
Turn
the
METER SWITCH
to
"Fast",
WEIGHTING NETWORK
switch
to
"Lin"
and ATTENUATOR knobs
to
"Ref."
5. Using a small screwdriver,
turn
the
GAIN
ADJ
potentiometer
so
that
a
"Sensitivity Correction"
of
"0"
is
indicated
on
the
red scale.
The
Sound
Level
Meter
is
now correctly calibrated
for
voltage measure-
ments.
24
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