Figure 8-30. - A solid, circular beam of microwave energy extends from a transmitter to the receiver over a range of up to 1,500 feet (457 m).

Figure 8-31. - Structure of a heat-sensor cable.

channels of the dialer permit two distinct dialing and message programs. Although labeled as, and most commonly used for, separate burglar and fire alarms the two channels can be connected and programmed for any application: medical emergency, heating-system failure, freezer warmup, and water-pressure failure.

It is important to understand the priority relationship between the two channels before making trigger connections. The priority arrangement ensures

Figure 8-32. - Curve showing relationship of resistance to temperature.

transmission of the vital fire-alarm program (or other priority program on the FIRE channel) in three ways.

1. If the dialer is already operating on the BURGLAR channel when the FIRE channel is triggered. the dialer immediately switches to FIRE- channel transmission 8-18