INSTALLATION
The 805 Microphone requires 9VDC to 18VDC as a power source. If your 805 was
shipped with a factory installed connector, then refer to the Application Note that is
included, if any, for further instructions on modification of the radio to route this power
source to the radio microphone connector jack. Some radio models have this power
source already available and no modification is necessary. If your 805 was shipped
with no connector installed, refer to Table 1. and wire a connector that mates with the
radio microphone jack. Also refer to the radio service manual and schematic diagram
for the appropriate connector pin number for each function.
Table 1. - 805 Microphone Wiring Connections
Cable Conductor Function
Blue
Red
White
Black
Shield
Yellow
+12 VDC
PTT (Push-To-Talk)
TX Audio Input
CTCSS Monitor Hang Up
Audio Ground
Power Ground
Microphone Power Source
Some transceivers will require a modification to bring a switched +9 to +18 VDC source voltage
from the radio power switch or power regulator. This modification can easily be performed by a
two-way radio technician. On most transceivers, a 'spare' or otherwise unused pin on the
microphone jack is often available, such as a handset audio function. If using a pin that already
has a functional purpose, ensure that this connection path or wire is disconnected from the
microphone connector before routing the B+ source voltage for the 805 microphone. If the
source pin to be used has a series resistor of more than 22 ohms, then bypass this resistor.
After wiring the microphone connector, verify proper connections before applying power. Use an
ohmmeter between the +12 VDC connection and ground(s) with and without the microphone
connected. The resistance reading should not change appreciatively, and in particular should not
show a low resistance reading with the microphone connected.
If presence of alternator whine or other vehicular noise is apparent upon placing the 805 into
service, remove the jumper JPR2 on the 805 printed circuit board. Refer to the Component
Layout illustration for location of this jumper.
Note: The 805 Series DTMF Microphones have been engineered to provide optimum
performance with virtually all land mobile radio transceivers. However, if using the 805
with a radio that does not incorporate pre-emphasis (sometimes this is done in the
original radio microphone) the resulting transmitted modulation will sound 'bassy'. If this
is the case, then change the 805 audio output coupling capacitor C10 to .001 uF. If
difficulty remains, contact CES Customer Service.
