Sigtronics EAI Operating Instructions - Manual (Page 11)

the background noise pick up is coming from this active
hand mic. If you have this type of hand mic then it is best
to contact the radio manufacturer for instructions on a
possible microphone modifica-tion to fix the problem.
Some radio manufacturers can supply a compatible
microphone that does not have this problem.
b) Adjust the EAI Radio Transmit Mic Level Adjustment. If
the mic level is set too low, you will get reports of weak
transmissions. If the mic level is too high, you will get
reports of noisy or garbled transmissions. See “Radio
Transmit Mic Level Adjustment” on page 9.
Radio 2 Hook Up:
Plug in J4 of the Radio 2 Interface Cable into P4 of the Radio
Adapter unit. (This cable has a six pin connector.) Using the
radio manual and Figure 5 on page 7, connect the six wires
to the appropriate connections on the vehicle’s radio. Once
that is done you will need to adjust the Radio 2 Transmit Mic
Level.
The Radio 2 Transmit Mic Level Adjustment is the right one
of the two located on the Radio Adapter unit. The adjustment
procedure is very similar to that of the Radio 1 Transmit Mic
Level adjustment. Arrange to have someone nearby with a
radio compatible with your Radio 2. Then, proceed as fol-
lows:
1. Set the EAI ON / OFF switch to the “ON” position. Again,
Plug in a headset into Captain’s jack. Make sure that the
volume control on the headset is turned up to full. (Radio
1 and the other headsets are not needed for this adjust-
ment.) Set the RADIO 1/ RADIO 2 switch to “RADIO 2”
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 2 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 2 TRANSMIT MIC LEVEL clockwise a
small amount. If they report garbled, broken, or noisy trans-
missions, turn the RADIO 2 TRANSMIT MIC LEVEL coun-
terclockwise 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.
If Radio 2 does not operate as it should, use the “Radio Trouble
shooting Guide” on page 10 to find and fix the problem. This
completes the EAI installation.
SYSTEM OPERATION
The following describes how to use the EAI System as well as
adjust the EAI controls. It also explains exactly how the EAI
unit operates. This will allow you to easily set all unit func-
tions to your specific needs. If you are not familiar with the
EAI operation, perform the next few steps while the vehicle
is not in motion.
HEADSETS
Put on the headset(s) and position the boom mike close to
the mouth, as is the practice with a hand-held mike. For best
voice clarity, the headset microphone must be positioned to
one side of the mouth and 1/4 inch from the lips. Turn the
volume control on the headset ear cup to maximum. Turn
down for individual hearing needs if necessary only after
intercom and radio volumes have been set correctly. (see
below)
Intercom operation and adjustment can be performed by
the following procedure:
1. Set the ON / OFF switch to the “ON” position.
2. Turn the intercom SQuelch control to the maximum
clockwise position. For best system performance set the
intercom VOLume control as low as possible. On most
systems this will be approximately between 1/4 to 1/3
open. Note: the intercom volume control only adjusts the
volume of conversation between the headsets inside the
vehicle. It does not affect the level at which you hear the
dispatch radio. (see Radio Volume below) You should now
hear yourself and others on the intercom.
3. To adjust the Intercom SQuelch for voice activated opera-
tion (VOX), it is helpful to have some background noise
(truck engine or ...). Turn intercom SQuelch control all the
way counter-clockwise. Now, without speaking, rotate the
SQuelch control clockwise until you hear the background
noise in your headset. Next, rotate it counterclockwise in
small amounts until the background noise disappears.
Finally, make small adjustments until your voice triggers
the unit at comfortable speaking levels. This procedure
is necessary because the squelch is a “Fast-on, Slow-off’
system.
When you speak, your voice will be heard in the headsets
but the sound will cut off about a second after you stop
speaking. Minor readjustment of the Squelch may be nec-
essary if the background noise level changes significantly
(engine idling to cruise power with siren on).
RADIO OPERATION
With the EAI System, your radio(s) are heard through the
headsets as well. Adjust the volume level of the dispatch
radio(s) in the headsets with the volume control on the
radio as normal. Note that the radio volume does not effect
the intercom volume and visa versa.
Transmitting (talking to dispatch) from the selected headset
positions is possible on a one-at-a-time basis. For a typical EAI
installation the Captain or Engineer positions can transmit
at any time simply by pressing their PTT switch. The Crew
positions cannot transmit on the radios. When one position
transmits, several things take place automatically:
• All headset microphones, except for the transmitting posi-
tion, are muted.
• The selected radio is put into transmit mode.
• The headset microphone audio (your voice) is sent to the
selected radio.
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