E F Johnson Company 2425372 Benutzerhandbuch

The microphone hanger can be connected to chassis ground and the radio programmed to 
detect an off-hook condition (Hangup Box Monitor selected). The following operation 
then occurs when the microphone is taken off-hook:

Conventional Channel Selected - Scanning temporarily halts (if applicable) and the 
Monitor Mode described in Section 5.2 is enabled. However, the receiver unsquelches 
only if a carrier is detected.

SMARTNET/SmartZone/P25 Trunked Channel Selected - Scanning temporarily 
halts if applicable.

If the off-hook condition is not detected (Hangup Box Monitor not selected), the 
microphone hook state has no affect on radio operation.

If the Surveillance mode is programmed, the backlight, all alert tones, and front panel 
LED indicator are totally disabled in all operating modes.

This feature can be turned on and off by the user if the SURVLC option switch is 
programmed. The user selected mode permanently overrides the programmed mode if 
applicable.

An external public address system can be connected to pin 7 of the radio accessory pigtail 
cable. This is a low level output, so some sort of PA amplifier is required. The External 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 
radio can be programmed so that receive audio is also routed. When the PA is enabled/
disabled, “Ext PA On/Off” is displayed momentarily. The radio can also be programmed 
to display “Ext PA On” continuously.

Scanning monitors the channels in the scan list for messages the radio is programmed to 
receive. When a message is detected, scanning stops and the message is received. Shortly 
after the message is complete, scanning resumes (unless it has been disabled).