1. TYPE

Dynamic receiver for telephone handset.

2. ELECTRICAL CHARACTERISTICS

2.1 TEST SET UP

Shown in Fig.2

2.2 IMPEDANCE

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

2.3 SENSITIVITY

92±2dB S.P.L. （at 1KHz 60mV sine wave）

2.4 DISTORTION

<5% （300…3400Hz）

2.5 MAGNETIC FIELD STRENGTH

MF Intensity axial≥-19dB at 1KHz0dB: 1A/M
MF Intensity radial≥-22dB at 1KHz0dB: 1A/M
Shown in Fig.3

2.6 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

3.1 DIMENSIONS

shown in Fig.4

3.2 WEIGHT

35g

A. SENSITIBITY

• Set decade resistor R to 300 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 300 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.
  
• 

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: +70℃±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.