1. TYPE

Dynamic receiver for telephone handset.

2. ELECTRICAL CHARACTERISTICS

2.1 TEST SET UP

Shown in Fig.2

2.2 IMPEDANCE

150 ohm±20% at （at 1KHz 60mV sine wave）

2.3 SENSITIVITY

97±3dB S.P.L. （at 1KHz 60mV sine wave）

2.4 DISTORTION

<5% （300…3400Hz）

2.5 FREQUENCY RESPONSE

The frequency response relative to the 1KHz response shall Lie between the upper and lower limits show in Fig.1

3. MECHANICAL DATA

Φ35mm X 17.5mm
shown in Fig.3

A. SENSITIBITY

• Set decade resistor R to 150 ohm
• Ser switch S1 to position 1
• Set osc. frequency to 1000Hz
• Set Eg to 0.120 VRMS
• Read the S.P.L. indicator

B. FREQUENCY RESPONSE

• Set decade resistor R to 150 ohm
• Ser switch S1 to position 1
• Set osc. frequency to 1000Hz
• Set Eg to 0.120 VRMS
• Vary frequency from 100 to 5000Hz. The frequency response shall fall within the limits of Fig.1

C. AUDIBLE NOISE

• Set decade resistor R to 0 ohm
• Ser switch S1 to position 2
• Set VISUAL voltage to 0.86 VRMS
• Listen to speaker output: It must be free of audible noise （buzzes and rattles）through the 300 to 3000Hz frequency range.
  
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4. ENVIROMENTAL TESTS

4.1 GENERAL

After any following test, the response at 1KHz shall not deviate more than 3dB from the initial value.

4.2 HIGH TEMPERATURE TEST

a. Temperature: +65℃±3℃
b. Duration: 96 hours
c. Duration of recovery: 2 hours

4.3 LOW TEMPERATURE TEST

a. Temperature: -40℃±3℃
b. Duration: 96 hours
c. Duration of recovery: 2 hours

4.4 HUMIDITY TEST

a. Relative humidity: 90-95% at +40℃±2℃
b. Duration: 96 hours
c. Duration of recovery: 2 hours

4.5 TEMPERATURE CYCLING TEST

a. Temperature cycling diagram
b. Number of cycles: 4 cycles
c. Duration of recovery

4.6 VIBRATION TEST

a. Vibration direction: 3 axes
b. Frequency: 55 Hz
c. Vibration amplitude: 1.5 mm
d. Duration: 30 minute in each plane

4.7 DROP TEST

a. Unit only: The receiver shall withstand 10 random drops from a height 75cm to a concrete floor, and no mechanical damage.

b. Fixed in handset: The receiver when properly mounted in a handset, shall withstand 6 random drops from a height of 1.5 meters to a concrete floor, and no mechanical damage, and no change the 1KHz response level.