"Fast"
"Imp."
"Imp.
Hold"
"Peak
Hold"
Provides the Fast meter characteristic specified in I
EC
Publica-
tion
179.
Provides the
Impulse meter characteristic in the proposed exten-
sion
to
IEC Publication 179 and
DIN
45 633 Part 2.
In this position the meter
will
hold the maximum RMS value
of
the applied signal
until
the METER RESET
button
is
depressed.
Rise
time
is
the
same
as
for
Impulse characteristics. Decay
time
is
less
than 0.05 dB/sec.
In this position the meter
will
hold the maximum
Peak
value
of
the applied signal
until
the METER RESET
button
is
depressed.
Rise
time
is
<20
fJS.
WEIGHTING NETWORK SWITCH
In
position
"Lin"
the instrument
has
linear frequency response
from
2Hz
(or
10Hz)
to
70kHz,
(see
section 4.3). In position
"D",
"A",
"B",
"C",
the appropriate frequency weighting
network
is
switched in. In posi-
tion
"Ext.
Filter"
the signal
can
be
processed by a
filter
connected across
the EXT.
FILTER
sockets. Note that in this position
of
the WEIGHTING
NETWORK
switch a meter deflection due
to
an
external electrical signal
cannot
be
obtained unless there
is
an
input
to
the meter at the
EXT.
FILTER
OUT socket.
INPUT SOCKET SWITCH
Low
frequency limits
of
2 Hz
or
10 Hz may
be
selected
by
means
of
a
screw switch located in the centre
of
the socket
for
the
input
stage
(see
Fig.4.8). With the switch turned in its
fully
clockwise position a 2
Hz
Lower
Frequency
Limit
is
selected
and
with
the switch in its
fully
anticlockwise
position a
10Hz
Lower Frequency
Limit
is
selected.
INPUT
ATIENUATOR
(Black knob)
Controls the effective gain
of
the
input
amplifier.
Used
together
with
the
OUTPUT
ATTENUATOR
to
select the measuring
range
of
the Meter.
11
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