21 
Circuit Board Jumpers, Adjustment Controls, Indicators and Switches 
 
Figure 14.  Base Station Circuit Board 
Jumpers 
J1 and J2  Set for the type of menu sign in the system.  Jumper pins 1 and 2 on both jumpers for menu 
signs having a speaker only.  Jumper pins 2 and 3 on both jumpers for menu signs having a 
speaker and a microphone. 
J3  Set to designate the number of the lane in the system.  Jumper pins 1 and 2 to select lane 1. 
Jumper pins 2 and 3 to select lane 2. 
J4  Set for the type of vehicle detector in the system.  Jumper pins 1 and 2 for an air switch 
detector.  Jumper pins 2 and 3 for a loop/sodar detector. 
J5  Set to designate the type of communication operation.  Jumper pins 2 and 3 for standard 
operation.  Jumper pins 1 and 2 for duplex operation. 
J6  MENU PWR SEL – STD or DPLX 
STD – applies power to outbound speaker amplifiers only when the TALK switch is pressed. 
Note: for Standard (half–duplex) operation J6 MUST be placed in the STD position. 
DPLX – applies power to outbound speaker amplifiers constantly.  This will reduce the click 
that is sometimes heard in duplex mode when the TALK button is pressed. 
J9 
TALK MON LVL 
REDUCE – reduces the volume to the Monitor Speaker by 16dB while TALK is activated.  
This decreases the chance of feedback when a headset is operating near the Monitor Speaker in 
duplex mode. 
FULL – unreduced volume to monitor speaker in all modes. 
*Note 
This setting may cause feedback when a headset is operating near the monitor 
speaker in duplex mode. 
J10  SWT THLD – HIGH or NRML 
SWT THLD refers to Switch Threshold.  This jumper is used to change the dynamic gain