BK-603 is a two-wire/four-wire IFB box. It only supports 3.mm jack earphone. BK-603 also can run with four AA size battery.

Technical Specifications

BK-500 is for MS-500. Tally Light, RMK

1.Microphone Amplifier(From Microphone to Line)
Dynamic Headset Mic impedance: 200 ohm
Voltage Gain: 44±3dB
Harmonic Distortion:<1%(1000Hz)
2. Headphone Amplifier(From Line to Load)
Load impedance: 50-600 ohm
Voltage Gain: 31±3dB
Harmonic Distortion:<2%(1000Hz)
3. Power Requirements
24V DC,60mA±10mA
Power Range:12-30V DC
4. Environment
-10~55°C
5. Dimension
High:105mm ,Wide:87mm , Deep:48mm

Technical Specifications

1.Microphone Amplifier(From Microphone to Line)
Dynamic Headset Mic impedance: 200 ohm
Voltage Gain: 44±3dB
Harmonic Distortion:<1%(1000Hz)
2. Headphone Amplifier(From Line to Load)
Load impedance: 50-600 ohm
Voltage Gain: 31±3dB
Harmonic Distortion:<2%(1000Hz)
3. Power Requirements
24V DC,60mA±10mA
Power Range:12-30V DC
4. Environment
-10~55°C
5. Dimension
High:105mm ,Wide:87mm , Deep:48mm
6. Compatibility
The BK-501 is compatible with TELEX and Clear-Com Party-Line intercoms.

Technical Specifications

1.Microphone Amplifier(From Microphone to Line)
Dynamic Headset Mic impedance: 200 ohm
Voltage Gain: 44±3dB
Harmonic Distortion:<1%(1000Hz)
2. Headphone Amplifier(From Line to Load)
Load impedance: 50-600 ohm
Voltage Gain: 31±3dB
Harmonic Distortion:<2%(1000Hz)
3. Power Requirements
24V DC,60mA±10mA
Power Range:12-30V DC
4. Environment
-10~55°C
5. Dimension
High:105mm ,Wide:87mm , Deep:48mm
6. Compatibility
The BK-601 is compatible with TELEX and Clear-Com Party-Line intercoms.