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Mounting on the panel requires that you insert the jack from the back
of the panel. Test jack(s) for clearance and fit. Leave room behind -
the jack expands when headset plug is inserted. Make sure the back
of the jack does not interfere with any moving parts of the vehicle.
Drill a ½ inch hole in the panel. Install jack with mounting washers
and nut as in Figure 3. Both jack insulating washers must be used.
The Jacks have to be insulated from mounting spot to minimize
electrical noise getting into intercom system. No need to tighten
the jack now. You may have to remove the jack to connect the wires.
PTT Switch Installation:
In order for the Driver, Officer and on US-LAC6 Crew #4 positions
to transmit on the radios, they will each need two Push-To-Talk
(PTT) switches.
The PTT switches should be placed within easy reach of the users. It is
also helpful if they can be easily seen by the users. The PTT switches
can be mounted in the blue ptt mounting boxes or directly into a
panel. If using the ptt boxes, set the box on the mounting surface in
the selected area and mount with two of the hex head self drilling
screws. For most applications* these screws can be installed with no
pre drilling. Just power in the screws with a standard electric driver
with a 5⁄16 inch hex bit.
* No pre drilling required for aluminum and
steel. A
1⁄8
inch pilot hole will still be required with some stainless steels.
If mounting the PTT switches directly into a panel the switch is
mounted from the front and the panel can have a maximum thick-
ness of 3⁄16 of an inch.
In the selected spot, drill a 5⁄8 inch hole. Mount the switch into the
hole but only loosely install the provided lock washer and nut from
the back. The PTT switch will likely have to be removed to connect
the wires later. The nut requires a 7⁄8 inch wrench
III. HEADSET JACK AND PTT SWITCH WIRING
The wiring of the headset jacks and PTTs is straight forward. In
general, the 4 foot Headset Jack and PTT Switch Cable gets wired to
the four conductor Hook-up Wire (gray) and then the Hook-up wire
connects to the jacks and the PTT switches. For US-LAC4 models, this
cable has a 12 pin / 12 wire connector (J1 – P1). For the US-LAC6, there
is a 15 pin / 13 wire (J1 – P1) connector and a 3 pin / 3 wire (J4 – P4)
connector. Before going on, plug the cable(s) into the Intercom unit.
Flexible six conductor hook-up wire is provided with each system to
connect each headset jack and PTT switch to the UltraSound unit’s
Headset Jack and PTT Switch Cable. Enough wire is provided for a
typical vehicle installation. If required, additional hook-up wire can
be purchased through your Sigtronics dealer.
Each headset jack requires three wires. Each PTT switch requires two.
Refer to the UltraSound Wiring Diagram for the exact wiring infor-
mation. Figure 4 for US-LAC4 intercoms. Figure 5 for US-LAC6
intercoms.
The connections between the Headset Jack and PTT Switch Cable
and the hook-up wire should be soldered and insulated for reliability.
Do not use crimp type splices. They can become intermittent over
time. Use a good quality electrical tape, or better yet, use heat shrink
tubing to cover the soldered connections. The connections to the
headset jacks and PTT switches will also have to be soldered. See
Figure 3 for jack terminal identification.
We also do not recommend using screw type terminal strips for
intercom connections. There have been several instances where
terminal strips introduced high levels of electrical noise like alter-
nator whine into the intercom system. It is acceptable however
to tie the intercom red and green power wires to existing vehicle
terminal strips.
The best place to run the wiring between the unit and the jack and
PTT switches is out of sight. It should be run behind vehicle panels
and/or up in the headliner. This will reduce the chance of personnel
or equipment catching on or damaging the wiring. Wire routing
should take into account normal vehicle operations. Wires should
not interfere with any of the vehicle’s controls, compartments, or
doors. If the vehicle’s cab tilts up for engine servicing, run wiring
along the existing vehicle wiring bundle. Make sure that wiring does
not interfere or restrict the tilting operation. Also, make sure that
the tilting operation will not cut or sever the wiring.
Make sure that the wiring does not rest on sharp edges. Over time
the vehicle’s vibration may cause a sharp edge to cut into the wire.
Use the provided wire grommets wherever the four conductor wire
goes through the hole into a jack box. Use wire ties or tie wraps to
secure and strain relieve the wire.
At this time do not put the covers on the jack boxes or tighten up
the PTT switches. You will need to verify the correct operation of
the system before you close everything up.
Power Connections:
The UltraSound unit will run on 11-16 VDC. CAUTION: UltraSound
units are designed for negative ground vehicles only. They can
be used on positive ground vehicles only if a Sigtronics Positive
Ground Adapter is used. Contact your Sigtronics dealer on pricing
and availability.
Make sure that the vehicle power is turned off before connecting
the UltraSound power wire. The power for the UltraSound unit
comes in on the red and green wires on the Headset Jack and PTT
Switch Cable.
Connect the red wire to vehicle power. (Try not to use a power buss
that also runs electrical motors such as fans or light bars with rotat-
ing lights.) Connect the green wire to the vehicle chassis ground.
RING
BARREL
SHOULDER
INSULATING
WASHER
FLAT
INSULATING
WASHER
FLAT
METAL
WASHER
VEHICLE
PANEL
HEADSET JACK
TIP
NUT – OR – SPLASH COVER AND NUT
FIGURE 3
