Sigtronics EAI Operating Instructions - Manual (Page 9)

between the vehicle power and the EAI red wire will usu-
ally accomplish the same thing. Do not use the type of filter
that installs on or near the alternator. NOTE: This solution
should not be considered a permanent fix. Vehicle charging
system problems of this type will eventually cause other
equipment failure as well as shorten the life of the vehicle’s
batteries.
2. The other type of noise is that generated by equipment
that uses the vehicle’s power. This type of noise is usually
constant and does not vary with engine rpm. It does, how-
ever, go away completely if the offending equipment is
shut off or disconnected. Electrical motors in fans or light
bars with rotating lights are two common examples.
Several things can be done to rectify this type of electrical
noise:
a) Find a better (less noisy) vehicle power source for the EAI
unit. Move the EAI red wire to another power buss. Try
not to use a power buss that also runs electrical motors
such as fans or light bars with rotating lights.
b) Move the EAI ground connection (green wire) to
another ground point on the vehicle.
c) Install an electrical noise filter on the power line going
to the equipment causing the noise. Contact the com-
pany that makes the offending equipment for a recom-
mendation on the type of filter to use.
If something does not work as described, go back over the
wiring and correct before going on. If all is well, you can
tighten all headset jacks and secure all jack box covers
with the supplied hardware. Also, tighten and secure all PTT
switches. On the EAI unit, turn down the intercom VOLume
control to approximately 1/3 position.
V. RADIO HOOK UP
The connection of the EAI unit to the vehicle’s radio(s) should
be done by someone familiar with the radio(s) such as your
radio installer. Refer to the EAI Wiring Diagram -Figure 4 on
page 6 for EAI-S4 or EAI-S6 units or for EAI-D4 or EAI-D6 see
Figure 5 on page 7. Only the radio functions are shown for
the radio end of the EAI Radio Interface Cable. Because the
connector(s) used by radio manufacturers varies widely, you
will have to consult the radio manual or manufacturer for
the connector(s) and pin assignments used. Sigtronics has
extensive radio interface experience and can assist with any
question you might have concerning this or any other aspect
of the EAI system. See our installation hot line number located
on the last page of this manual.
Using the radio manuals and the EAI Wiring Diagram, iden-
tify the correct signal wires or connector pins to attach the
respective EAI wires. For most radios, these connections are at
the back of the radio or radio control head. For some radios,
the only place to connect the MIC HI and LO and PTT HI and
LO wires is to the hand-held microphone connector.* It is best
to wire in such a way that the radio hand microphone can
still be used as normal. Make sure that you do not physically
tie the EAI MIC LO and SPEAKER LO wires to the same pin on
the radio, even if they are tied together inside the radio. As
in the headset wiring, the connections between the EAI and
radios should be soldered and insulated for reliability. Do not
use crimp type splices.
Use a good quality electrical tape or heat shrink tubing to
cover the soldered connections.
* For the more popular radios of this type Sigtronics manu-
factures plug in “Y” adapters to make these connections easy.
Contact your Sigtronics dealer for pricing and availability.
For dual radio units (EAI-D4 or EAI-D6), hook up Radio 1 first
and test before moving on to Radio 2.
Connect the six wires from the Radio 1 / Power Interface
Cable to the appropriate connections on the vehicle’s radio.
Once that is done you will need to adjust the Radio 1 Transmit
Mic Level.
Radio transmit mic level adjustment for the radio (or both
radios for EAI-D4 and EAI-D6) is provided through a hole (or
holes) on the side of the Radio Adapter unit. The adjustment(s)
sets the microphone audio level going to the radio(s) during
transmit. The radio transmit mic level adjustment(s) will need
to be initially set to your particular radio(s). The level(s) once
set, should never need adjustment again unless the type of
radio(s) used are changed. The following simple procedures
take you through the adjustment of the mic level(s).
Radio Transmit Mic Level Adjustment can be made with
a small, flat blade screwdriver. Clockwise rotation increases
the output level to the radio. Counter-clockwise rotation
decreases it. The basic adjustment concept is simple. You
will be setting the level and clarity of outgoing radio trans-
missions through the EAI unit headsets, to match or exceed
that of transmissions using the radio’s standard hand micro-
phone. To do this, you will need to transmit and receive on the
vehicle’s radio to a remote station. Arrange to have someone
nearby with a radio compatible to the radio you are using
with the EAI. Then
1. Set the EAI ON / OFF switch to the “ON” position. Plug a
headset into the Captain’s jack. Make sure that the volume
control on the headset is turned up to full. It is not neces-
sary to connect the other headsets (or Radio 2 on EAI-D4 or
EAI-D6 units) for this adjustment. On dual radio units (EAI-
D4 or EAI-D6), set RADIO 1/ RADIO 2 switch to “RADIO 1”
and the AUTO / BOTH switch to “AUTO”.
2. Set the headset aside for a moment. With the radio’s hand
mic, transmit as normal, to the remote station. Transmit
long enough so that the receiving station can get “cali-
brated” to your transmission (voice) level.
3. Put on the Captain’s headset and position the headset
microphone as normal. Verify radio reception. If OK, use
Captain’s PTT to transmit to your receiving party. If receiv-
ing station reports weak transmission, use the screwdriver
to turn the RADIO TRANSMIT MIC LEVEL clockwise a small
amount. If they report garbled, broken, or noisy transmis-
sions, turn the RADIO TRANSMIT MIC LEVEL counter-
clockwise a small amount. Repeat as necessary until the
receiving party reports that transmissions through the EAI
sound as good or better then when using the radio hand
microphone. That’s all there is to it!
Once the mic level is set also check radio operation with the
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