The Series 3800 Vehicle Intercom System is engineered to solve the problem of communicating in high-noise environments with a mobile vehicle platform. Fire apparatus, rescue vehicles, ambulances, command and control vehicles, airline deicers and paint stripers are but a few applications that currently benefit from the Series 3800 system. The U3811 is designed to provide isolated radio transmit function for one headset and radio receive function for all users within the Series 3800 Intercom System. It contains one radio PTT switch, one headset jack and headset listen level control, one system input connection and one radio input connection. It is designed for use at the end of a series of headset stations, as there are no available connections for "daisy-chaining" additional modules. With a modular design, rugged and weather-resistant enclosures and functional versatility, the Series 3800 intercom system is an ideal solution for any mobile environment requiring crisp, clear communication and effective hearing protection.