Norsonic nor1218, Instruction Manual

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3 Norsonic Nor1218
Instruction Manual
Screw the lock nut on the preamplifier onto the fe-
male connector on the cable. Push the preamplifier
carefully into the base unit. The preamplifier and mi-
crophone is aligned in the correct position by a spring
force. After mounting the upper protection part, the
outdoor microphone unit will be ready for use. How-
ever, we recommend that you test the unit together
with the measuring instrument by applying a calibrator
before the upper part is mounted.
Grounding and lightning protection
If the outdoor microphone assembly is the highest ob-
ject in the vicinity when mounted, it may be exposed to
lightning strokes. We recommend to use a conductive
mast and to ground it properly. A rod in proper con-
tact with the conductive mast should be made at the
side and 50 cm above the tip of the microphone. The
rod should be placed at least 25 cm to the side of the
microphone assembly and have a diameter not more
than 10 mm in order not to interfere with the directional
properties of the microphone.
Safety considerations may require the screen of the
microphone cable to be properly grounded and that
the internal conductors are clamped for high voltage
protection.
We recommend making the combined grounding
for the cable and instrument at one point only in order
to reduce the risk of pick-up of hum and electromag-
netic noise.
Verify the noise floor of the complete system after
installation is completed to ensure it is below the lower
end of the required measurement range. If a quiet lo-
cation is not available, the noise floor may be meas-
ured by substituting the microphone with a dummy mi-
crophone like Nor1448. As an alternative the Nor1447
adaptor terminated with a short-circuit or a 50 ohm
BNC termination is also a suitable device for making
this test. A sound calibrator in OFF-mode may also be
used to attenuate the external noise.