Instruction Manual

7.2
Checking the Physical Installation of Radio Ground and Radio
Accessory Wiring
Dash and Remote Mount Configurations
• Scrape away paint on the chassis at the place where you are making the ground connection, and
try to keep the ground lead as short as possible.
• Verify that the red A+ lead is connected directly to the positive terminal of the battery and the black
ground lead is connected to the vehicle chassis using a wire with practical length.
• Ensure that the mobile radio antenna is the minimum required distance (three feet) from the mobile
radio equipment to prevent radio frequency interference (RFI).
• For vehicles that have other types of electronic equipment installed such as lights, flashers,
computers, siren/PA, and others, use a separate ground for the mobile radio equipment.
• Do not coil up any excess length of the red A+ lead. Doing this may produce a large transient
voltage when there is a high current drain for example, during transmit. This could cause the radio
to reset when the push-to-talk (PTT) is depressed.
Motorcycle Configuration
• Ensure that the antenna ground connection is solid. An intermittent ground connection can distort
the transmission when the motorcycle engine is running.
• Do not coil up any excessive length of antenna cable. It may affect the receive performance of the
radio.
• If an extra length of cable is used to extend the microphone, ensure that the added capacitance
does not interfere with the operation of the radio.
7.3
Improving the Electrical Quality of the Power and Ignition Lines
• Use a relay to isolate the vehicle ignition switch point (ACC) from the radio ignition sense point.
Control this relay from the vehicle ignition switch point (ACC). Supply a cleaner voltage from the
positive terminal of the battery into the relay, which will now be attached to the radio ignition sense
point. Now the ACC line toggles the relay, instead of directly toggling the radios ignition sense line.
• Install a Power Line Filter between the A+ lead and the positive terminal of the battery. The Power
Line Filter filters the battery power applied to the transmitter power amplifiers. Pay extra caution to
this because the series filter introduces a negative spike when the radio transmits that may cause
problems with radio operation. Lock-up issues have been seen with the dual control head MCS
2000 configuration.
• For vehicles that use electromechanical relays to control external devices (lights, motors, switch
boxes, and others), isolate these relay circuits as best as possible from the mobile radio equipment.
Also, use diode suppression across the relay coil to minimize the noise produced by the collapsing
magnetic field.
• If the ignition sense switch is used, ensure that there is not a large voltage drop between the A+
point (usually the positive terminal of the battery) and the ignition sense point. In general, the
voltage difference between these two points, should not be greater than 1.5 V when all accessories/
air-conditioner are turned on. Refer to the Basic Service Manual for specifications for minimum and
maximum voltage levels. Typical battery voltage levels are 13.6 V +/- 20%.
MN005720A01-AB
Chapter 7: Best Practices: Installation and Troubleshooting
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