TM8260 Installation and Programming Guide
Installing a Dual-Radio System
27
© Tait Limited
October 2014
3.6
Connecting the Power Cables to a Power Source
To provide power to dual radio systems, you must connect each radio body
separately to a power source or sources. Dual radio systems do not currently
support a single lead-to-battery connection.
It is important to ensure that both radio bodies have a solid and secure power
supply. Unexpected behavior can arise if the power supply to one body
operates at a lower voltage than the other, or is momentarily interrupted, as
might occur with a poorly formed or intermittent wiring termination.
Notice
Each radio is designed to operate from a nominal 12V negative
ground supply. Each radio may draw up to 15A of current. Each radio
will tolerate a supply voltage range of 10.8V to 16.0V at the radio.
Selecting the Power
Source
In passenger vehicles, the radio is always connected directly to the battery
using the power cable provided.
Notice
Do not connect the radio to the center tap of two 12V batter-
ies! This may result in damage to the radio due to earth loops, in partic-
ular when the negative lead is disconnected from the vehicle battery.
It may also result in overcharging or undercharging of the batteries,
reducing their service life.
In trucks, where direct connection to the battery is often not possible, each
radio can be connected to a suitable terminal inside the fuse box that is
connected directly to the battery.
24V-to-12V
Converter
In vehicles with a supply voltage larger than 16.0V, such as many trucks, it
is essential to provide a suitably rated 24V-to-12V converter. This will
isolate the radios from excessive battery voltage and provide the correct DC
operating conditions. Note that most 24V-to-12V converters already fitted
are not rated sufficiently.
Table 3.3
Radio body power connector—pins and signals
Pinout
Pin
Signal name
Description
Signal type
1
AGND
Earth return for radio body power
source
Ground
2
SPK–
External speaker output. Balanced load
configuration
Analog
3
SPK+
External speaker output. Balanced load
configuration
Analog
4
13V8 BATT
DC power input for radio body and
control head
Power
rear view
>25W radio
1
2
3
4
rear view
25W radio
