User Manual Part 1

Horn Alert

To use the horn alert, a Horn option switch, Cadence Style, and Auxiliary B Horn output

must be programmed. Refer to Section 4.7 of the operating manual (see Section 3) and the

programming manual referenced in Section 4 for more information. (The Aux B output is

programmed on page 2 of the Global screen.)

When the horn alert sounds, Pin 4 of the accessory connector goes low. If a relay is used, a

diode should be connected across the relay coil with the cathode toward the battery side. This

protects Q6 on the logic board from the voltage spike produced when the relay de-energizes. A

horn circuit example is shown in Figure 2-6.

Figure 2-6 Horn Circuit Example

Siren Backlight

The “Backlight” function of the Auxiliary B output is programmed when the optional siren

is used. The siren control head backlight then turns on and off with the radio control head

backlight. A separate siren control pigtail cable is installed and provides the Auxiliary B output

signal to the siren controller (Pin 4 of the accessory connector is not used).

Site Trunking

The “Site Trunking” function of the Auxiliary B output provides an external indication such

as a light when site trunking is occurring. This function is available with SmartZone and Project

25 trunked operation.

2.5.5 EXTERNAL PUBLIC ADDRESS (PIN 7)

An external public address system can be connected to Pin 7 of the accessory connector. The

PA option switch is required to control this feature. In the public address mode, microphone

audio is always routed to the PA system, and the transceiver can be programmed so that receive

audio is also routed. This is a low-level output, so some type of amplifier is required.

2.5.6 AUXILIARY B INPUT (PIN 8)

This input can be programmed for the following functions. This input is activated by a high

voltage and deactivated by a low voltage or no signal (high impedance).