Instruction manual

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Precautions
Operate the unit only as described in this manual.
The NL-42/NL-52 is a precision instrument. Protect it from shocks and
vibrations. Take special care not to touch the microphone diaphragm. The
diaphragm is a very thin metal  lm which can easily be damaged.
Use only the microphone/preampli er assembly with the number as shown
on the name plate of the unit.
Do not use the preampli er of this unit with sound level meters of other
models. It may cause the preampli er to fail.
Ambient conditions for operation of the unit are as follows: temperature
range -10 to +50°C, relative humidity 10 to 90%RH.
Protect the unit from water, dust, extreme temperatures, humidity, and
direct sunlight during storage. Also keep the unit away from air with
high salt or sulphur content, gases, and stored chemicals during storage
and use.
If it starts raining while using the unit outside, stop the measurement and
protect the unit from getting wet. In case the unit gets wet, wipe it with
a dry cloth and let it dry in a well-ventilated place.
Always turn the unit off after use. Remove the batteries from the unit if
it is not to be used for a long time.
When disconnecting cables, always grasp the plug and do not pull the
cable.
Before using the unit and before putting it away, always check that the
microphone grid has not become loose. If this has happened, refasten the
microphone grid  rmly and then use or store the unit.
Store this unit in the right place in the supplied storage case.
Up to two units can be stored in the storage case. When storing the unit
in an empty space, protect the unit by wrapping it with cushioning mate-
rial. Note that we are not responsible for any failure or damage to the unit
which occurs while the unit is stored in an empty space.