Instruction Manual

Sound Level Meter Types 2245 – Instruction Manual Page 39 of 110
Fig. 3.1 Setting up the signal source for an immunity test
To prevent the acoustic source from being affected by acoustic noise in the
surroundings, the following method can be used.
Insert an acoustic attenuator in the hose close to the microphone, so that the sound
pressure within the greater part of the hose is held far above the surrounding sound
level. The acoustic attenuator can easily be made from a short piece of metal tubing
with an outer diameter of ½". Squeeze a piece of paper tissue into the tube, and
compress it until the desired attenuation is obtained. Up to 40 to 60 dB of acoustic
attenuation can be obtained.
Electrical Source for Testing According to IEC 61260
The short-circuit of the input signal may be achieved by short-circuiting the electrical
substitute for microphones mounted on the sound level meter.
3.9.2 Reference Orientation
Fig. 3.2 shows the reference orientation of the sound level meter, relative to the RF-
emitter/receiver. This is common to both emission and immunity tests.
Fig. 3.2 Reference orientation of the sound level meter relative to the RF-
emitter/receiver
3.9.3 Securing of Cables During EMC Test
During test, any excessive cable is folded back on itself in an even number of figure
eights.
The cable arrangement is common for both the Emission and Immunity tests.