Installation; Before Starting; Negative Ground; Pre-Existing Conditions - Setcom IM-900 Installation And Operation Manual

5 Installation

5.1 Before Starting

Prior to installing hardware, be sure you have an overall understanding of the system
you are installing. Compare the number of stations, headsets, and model of radio to the
System Drawing prepared for your order and ensure they agree with the hardware you have
received. The IM-900 will interface with the radio make and model identified at the time of
purchase without need of any internal adjustments. If the radio model is changed before
installation, a different radio interface device (MAC or Radio Cable) may be required to allow
the IM-900 to correctly modulate this new radio. You will need to call our toll-free service line 1-
888-673-8266 ext 603 (888-6SETCOM ext 603) to determine the correct radio interface device
required for the new radio. If you wish to exchange components, now is the time to contact the
factory. Once components have been installed they are no longer considered as new. After
you have determined that all components, including cable lengths, are correct; you are ready
to start.

5.2 Negative Ground

The Setcom IM-900 is designed for 12Vdc negative ground electrical system. If vehicle
has a positive ground, a DC converter must be used to power the radio and the same source
can be used for the Intercom.
Note: The IM-900 is grounded through the radio cable to the radio.

5.3 Pre-existing Conditions

Due to the fact the headset will reduce background noise by over 90%, any alternator
whine or other objectionable noise will become more noticeable. Presence of such noise can
be detected prior to intercom installation by placing your ear directly against the radio speaker
with a normal volume setting on your radio, and with the vehicle engine running. Check both
with a modulated carrier being received and with the radio in the standby mode. In some
instances, it may be necessary to connect a set of headphones across the speaker if it is not
possible to listen directly to the speaker itself. If a problem exists, and you have a Motorola or
M/A-COM radio with a remote control head, first check the power leads. These radios will
normally have two leads for power. The orange wire (Motorola) is connected to the ignition
switch; the green lead is connected to a continuously hot 12-volt power source. The green
wire typically powers the audio speaker amplifier. Connecting a suitable noise filter in line with
the green lead will usually reduce alternator whine to an acceptable level. If there is detectable
whine in the transmitted signal, a similar filter should be installed in series with the orange
lead.
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