Beltpack:

A portable headset station, consisting of a line bridging amplifier, an audio amplifier, and a microphone amplifier. When equipped with a headset it is capable of communicating with other beltpacks, fixed headset stations, master stations, or loudspeaker stations. Production Intercom manufacturers beltpacks in one and two circuit versions. 
 

Performance: The BP-1 portable headset station may be worn on the belt or hung on the wall by its sturdy belt-clip. Soft plastic strips on the underside help hold it in place when set on top of a console. The matte black finish minimizes visibility.
Frequency response has been carefully shaped to optimize both intelligibility and long-term listening comfort. A microphone limiter circuit reduces overload distortion. The high bridging impedance ensures that system and sidetone levels do not vary as other stations are switched in and out of the circuit.

The top panel contains controls for switching the microphone on and off, for controlling listening level, and for signaling. They are easily identifiable by touch. A recessed, screwdriver-adjust control is provided for varying the level of the user’s voice to be heard in his own earphone (Sidetone). A long-life, extremely bright, 4-segment LED serves as the signal light.

The bottom panel provides a 3-pin female XLR for connection to the system; a 3-pin male XLR for looping onwards to the next station, and; a 4-pin male XLR for connection of any standard communications headset with a dynamic microphone.

Durability: The ribbed, extruded aluminum case; glass-filled nylon end bezels; internal support system for the PC board; best-quality XLR-type connectors, and; recessed controls, all contribute to the outstanding ability of the BP-1 to withstand rough usage.

Value: The comparatively low price of the BP-1 is made possible by the minimized assembly cost resulting from simplicity of construction. Simple construction also affords the use of higher quality components, and increases the ease (thus lowering the cost) of servicing.

Compatibility: The BP-1 is plug-in compatible with Clear-Com® and other popular headset intercom systems.

Technical Specifications: (Subject to change without notice.)

Power requirement:            24~30 VDC, 10 mA quiescent, 30 mA max. (with signal lamp lit)
Headphone output:             8~4k ohms acceptable, 200 ohms ideal
Microphone input:              200~600 ohms, Dynamic
Sidetone rejection:             >50dB
Audio bridging impedance: 200 ohms, unbalanced
Size:                                  3.70 x 4.30 x 2.50 in. (93.98 x 109.22 x 63.5 mm)
Weight:                             13.5 oz. (0.385kg)

Accessories:
OG904                            Remote Override Generator Card