Norsonic nor1217, Instruction Manual

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6 Chapter 4
Technical description
The lower part consists of the base, the microphone
cartridge and the preamplifier Nor1209. A normal mi-
crophone cable supplied with Norsonic sound level
meters, like Nor1408A, should be used for connec-
tion to the sound level meter instrument. An adaptor
for mounting the outdoor microphone on a tripod is
included.
The base is made of black polyacetal (POM). The
material is durable and insulating, thus preventing
electric noise from ground loops through the mast.
Drops of water from rain are kept away from the mi-
crophone diaphragm by the combined act of the tubu-
lar windscreen, the rain hood and the dust mesh. The
upper part of the microphone cartridge is air- and wa-
ter tight, and the backside is vented to the air through
the preamplifier.
The Ingress Protection Category for the assembled
microphone is IP55 according to IEC 60529.
Consider the assembly of microphone cartridge
and preamplifier as a single unit when operated in the
field. If disassembled in the field, the performance may
be reduced due to contamination from dust and hu-
midity.
When Nor1217 substitutes a normal measurement
microphone on a sound level meter, a correction of the
frequency response is needed to retain the class of
accuracy for the sound level meter, see Specifications.
Based on the correction, the reference direction may
be selected to be either horizontal or vertical. Horizon-
tal reference direction is usually selected for sound
approaching the microphone mainly along a horizon-
tal axis like noise from industry or vehicles. A vertical
reference axis is usually used for measuring the noise
from aircraft.
The sound analyser Nor140 has a correction net-
work where the reference axis for the outdoor micro-
phone Nor1217 may be selected to be horizontal or
vertical
See separate description in this manual on how to con-
figure the Nor140, Chapter 5.
Electrical description
The power to the Nor1217 will normally be supplied
from a Norsonic sound analyser Nor140 instrument
and the user does not need detailed knowledge of the
interconnection. Alternatively, the microphone unit may
be supplied either from a single supply in the range 28
V to 120 V or a symmetric supply in the range ±14 V to
±60 V. The latter alternative is recommended. Required
current is 3mA. The connection is shown on the adjacent
figure. (Outside view for the connector).
Pin 3, allocated for polarization voltage, shall be ter-
minated to signal ground (pin 2) for the microphone
cartridge Nor1227. When the microphone unit is
equipped with the Nor1225 microphone cartridge where
polarization voltage is needed, 200 V must be supplied
to this terminal.
Rain hood
Microphone
cartridge
Dust mesh
Wind screen