3
Norsonic Nor1217
Instruction Manual
Unscrew and remove the upper part consisting of
birdspike and windscreen as one unit. Do not remove the
windscreen from this upper part as this may destroy the
weather protection and alter the acoustic performance.
The unit is delivered with an adaptor for mounting
on a tripod. The cable is 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.
Remove the base screw and slide the cable through
the base unit. Assemble the microphone cartridge to
the preamplifier and connect the preamplifier to the
cable. We recommend to mount the supplied O-ring
between the microphone cartridge and the preamp-
lifier. Screw the lock nut on the preamplifier onto the
female connector on the 1408A cable. Push the pre-
amplifier carefully into the base unit. The preamplifier
and microphone 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.
However, we recommend that you test the unit togeth-
er with the measuring instrument by applying a calibra-
tor 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 conduc-
tivemast 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. A ½” microphone
normally requiring polarization voltage may also be
used without polarization voltage. It will then have a
very low sensitivity.
NOTE:
Please note that the System
Check signal must be deactivated when
you want to calibrate the microphone with
an acoustical calibrator. Unless deacti-
vated, you will read unstable values due to the
interference between the System Check signal
and the signal from the sound calibrator.
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