EFJohnson 002-9750-003 User Manual

With conventional operation, selecting a system actually selects a specific radio channel. Then selecting a group (if 

available) selects the mobile or group of mobiles being called or from which calls are received on that channel. There 
are no tones or display messages to indicate busy or out-of-range conditions. Therefore, a busy channel must be 
detected as described in the next section, and an out-of-range condition may exist if you are unable to get a response 
from the mobile you are calling.

Before transmitting in the conventional mode, government regulations require that you monitor the channel before 

transmitting to make sure that it is not being used by someone else. If you were to transmit while someone else was 
talking, you would probably disrupt their conversation.

If the Transmit Disable On Busy feature is programmed (see description on page 16), monitoring is performed 

automatically. If it is not used, monitoring is performed as follows:

•

When not system or group scanning, note if “BUSY” is being displayed. If it is not, the channel is free and a 
message can be sent.

•

Enable the monitor mode by taking the microphone off-hook or pressing the MON switch if available. The 
monitor mode is indicated by “MON” in display, and it disables any programmed squelch control features so that 
all messages are heard. It also halts scanning if applicable. 

•

If equipped with the CG option switch, both transmit and receive Call Guard squelch or other squelch control 
features can be disabled on the selected group only. The disable mode is indicated by a triangle ( 

∆ ) in the display 

under the switch.

The transceiver can also be programmed so that a microphone off-hook condition is not detected. The Transmit 

Disable On Busy feature or MON/CG switches must then be used to perform monitoring.

The Time-Out Timer automatically disables the transmitter if it is keyed continuously for longer than the 

programmed time. It is usually programmed by your system operator for 0.5-5 minutes. When this timer times out, the 
transmitter is automatically disabled, the intercept tone sounds, and “TX TIMEOUT” is displayed.

Five seconds before time-out occurs, a warning beep sounds. The timer is reset by releasing the PTT switch. One 

use of this feature is to prevent a blocked channel caused by an accidentally keyed transmitter. Another use is to prevent 
possible transmitter damage caused by transmitting for extended periods.

The call indicator is the word “CALL” in the display. The purpose of this indicator is to show when a call is 

received while you were away from the vehicle. It can be programmed by your system operator to come on only when 
calls are received on specific groups. To turn this indicator off, change any front panel control, take the microphone off-
hook, press the PTT switch, or turn power off and then on again.