MM-007024-001
27
8
RADIO DC POWER INSTALLATION
Refer to the wiring diagrams at the end of this manual. The diagram in section 19 (page 61) includes
mobile radio with the CH-103 Control Head. The diagram in section 20 (page 63) is nearly the same with
the exception of the three cables designed for use with the CH-103PA Control Heads. Power connections
to either head are exactly the same.
8.1 ON/OFF POWER WIRING CONFIGURATIONS
The mobile radio can be wired in a motor vehicle in various ways to accommodate the user’s preferences.
In all cases, its red power wire must be connected through an in-line fuse to raw battery power (positive
battery terminal). The white ignition wire of the radio’s DC Power Cable is only used for the Data-Only
(i.e., no Control Head) radio and it is the only means for turning its power on. An in-line switch for
switched battery power to the radio must never be considered unless the user has the discipline to turn off
the radio through the Control Head’s on/off button or through a separate switch wired to the ignition
sense wire. Failure to wait for the radio to completely power down before disconnecting battery power
will not damage the radio; however, it
will
result in the loss of settings that have changed (e.g., channel
number, volume setting, etc.) during the operating session.
Integral to the power management system of the CH-103 and CH-103PA Control Heads is a 60-second
power-off Time-Delay Relay (part number MAMROS0088). The addition of this relay is required to
remove the relatively high standby (off-state) quiescent-current (30 mA) consumed by the Control Head
that would otherwise reduce the charge state of the vehicle’s battery. The radio by itself does not require
the relay, as its standby quiescent-current is typically below 1 mA. This is especially true in the case of
the Data-Only radio configuration since it has no control head. However, because the CH-103 and
CH-103PA do require the relay, it is advisable to connect the relay so both the radio and Control Head are
shut down together. This relay reduces quiescent-current for the radio/control head pair below 2 mA and,
if installed correctly, will work in conjunction with all on/off power configurations described below.
On/Off power functions for the radio are controlled by the Control Head or, in the case of a Data-Only
radio, within the radio itself. The following power wiring configurations are supported:
•
Radio turns on automatically with vehicle’s ignition switch/key
— The white sense wire of the
Control Head’s (or Data-Only radio’s) DC Power Cable is connected to a fused switched power
source, typically identified as “Accessory” power. This source must switch on (up to + battery
voltage potential) when the vehicle’s ignition switch/key turns on, and it must switch off (to near zero
volts) when the ignition switch/key turns off. The required fuse rating is 2 amperes. An ATM fuse
holder and fuse are included with the applicable fuse kit.
•
Radio turns on with a manual switch
— The white sense wire of the Control Head’s (or Data-Only
radio’s) DC Power Cable is connected to one side of a manual toggle switch and the other side of this
switch is connected to a fused vehicle power source. This configuration is used when, for example,
the radio must remain on even when the ignition key must be removed from the vehicle and a
separate on/off switch is acceptable. The required fuse rating is 2 amperes if no other devices share
the switch. If other devices share the switch, the 2-ampere ATM fuse must be spliced in the white
wire on the load/switched power side of the switch.
•
Radio turns on with Control Head’s on/off button (“hot wired”)
— Standard software
configurations allow turning on the radio with the Control Head’s on/off button. This configuration
may be desired if, for example, the radio must remain on even when the ignition key must be
removed from the vehicle. In this case, the white sense wire of the Control Head’s DC Power Cable is
connected to vehicle chassis ground and the Time-Delay Relay’s white wire is connected to the
relay’s red (power input) wire. In fact, the Time-Delay Relay’s function is rendered useless, so the