Norsonic nor1216, Instruction Manual

Page: 11 / 32

3 Norsonic Nor1216
Instruction Manual
preamplifier and mount the assembly of microphone
cartridge and preamplifier. After mounting of the
upper protection part, the outdoor microphone is
ready for use. However, we recommend you to test the
unit together with the measuring instrument by apply-
ing a calibrator before the upper part is mounted.
The unit is delivered with an adaptor for mounting
on a tripod. The cable is then led through a slot in the
side of the adaptor. The base screw has a threaded
hole like those commonly used for cameras (3/8"
UNC
) . The base screw also forms a tension relief for
the cable.
Mounting on a mast
For permanent installations we recommend to mount
the Nor1216 on a pole rather than using the 3/8” cam-
era tripod treads. Remove the optional tripod adapter
with tension relief to gain access to the pole mount
threads. The pole mount threads are standard 1” ac-
cording to ISO228-BSP (British Standard Pipe)
If the mast is high and you need to make regular
calibrations or other service operations, we recom-
mend to use a mast that can be tilted or a telescopic
mast. Norsonic can supply different masts on demand.
We recommend to place the cable to be mounted
inside the mast for protection. A cable flapping onto
the mast in windy conditions may create excessive
noise and ruin the accuracy of the measurement.
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 less than
10 mm to avoid interference with the directional prop-
erties 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. A ½” microphone
normally requiring polarization voltage may also be
used without polarization voltage. It will then have a
very low sensitivity.