B&K 2250 Light Instrukcja Użytkownika Pobierz pdf (Strona 20)

Hand-held Analyzer 2250 Light – User Manual

2.5 Assembling 2250 Light

2.5.1 Charging the Battery for the First Time

Battery Pack QB-0061 comes charged to approximately half capacity on initial delivery.

Before using your 2250 Light for the first time, it is recommended that you fully charge the

battery pack, by connecting Mains Power Supply ZG-0426 (or ZG-0429) to the external power

socket. It should take approximately 8 – 10 hours.

The battery charge light shows a steady green light when external power is applied (and the

battery is charging), and a flashing green light when charging has finished. You can leave 2250

Light with external power on, even when the battery is fully charged. Also see section 9.3.3.

2.5.2 Making Good Measurements

The fact that you are using your 2250 Light, which fully complies with the IEC 61672–1

standard, ensures you always make good measurements. 2250 Light should be set up using the

following recommended assembly instructions. This is to minimise the influence of acoustical

reflections during measurements. All the components described below are shown in Fig.2.1

and Fig.2.4.

Another set of instructions is provided in section 2.5.3, for situations where you need to

position the microphone at a distance from 2250 Light, while still complying with the standard.

Placing the Measurement Microphone

The measurement microphone must be placed away from shielding, reflecting, or absorbing

objects. In a diffuse sound field, absorbing objects will reduce the measured sound levels. In

a free sound field, reflecting objects can change the measured sound levels. Typically, the

sound level 0.5 m from a plane reflecting wall is 3 dB higher than if there was no wall.

The operator of the system may be personally shielding, absorbing, and reflecting, and can be

an additional noise source. Measure downwind in dry conditions with a windspeed less than

5 m/s.

The optimum position for the microphone is best found by trying different positions and

observing the resulting sound levels.

Mounting the Measurement Microphone

Before mounting the measurement microphone, note the following precautions:

• When screwing on the microphone, do it gently to avoid damaging threads

• Keep dust and foreign matter off the microphone diaphragm. Do not touch the diaphragm

with anything – it is very delicate

Note: Once the measurement microphone and preamplifier have been assembled and

connected to your 2250 Light, they should normally be left connected to the instrument.

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