User's Manual

Table Of Contents

Technical Manual Installation & Operation

2.3.2.5 Configure Digital I/O

The MX800 has 16 digital inputs and 8 general-purpose outputs. The inputs

are +5V CMOS logic compatible and are buffered by a 10K resistor in series

with each input. JMP19 on the Micro-Controller selects whether these inputs

are internally pulled up or internally pulled low. The active state of the input

is set up through MXTOOLS. Of the 16 inputs the 8 input port B inputs are

allocated to the Channel Select function. Two of the input port A inputs (bit 0

and bit 1) are allocated to a power control function (see Table 2-3 below),

two (bit 2 RX and bit 3 TX) are allocated to CTCSS control and the other 4

are allocated as address bits for the MX800 network mode (software V2.8.1

and higher).

Bit 1 Bit 0 RF O/P Power

0 0 100%

0 1 50%

1 0 20%

1 1 10%

Table 2-3 Power Control Function Settings

An auxiliary voltage (either +5V or GND dependant upon the setting of

JMP15) is available on CN3 pin one for wiring convenience.

The 8 general-purpose outputs are +5V CMOS logic compatible and are

buffered by a series 1K resistors.

2.3.3 Adjustments

There are two categories of adjustable parameters in the MX800. Those that

are controlled by conventional potentiometers, which may be manually

adjusted, and those controlled by digital potentiometers, which are under the

control of the Micro Controller. The latter category of items comprises TX

power, TX VCO deviation, TX reference oscillator deviation and TX

reference oscillator frequency. All of these are adjusted with the aid of

MXTOOLS and all except TX power should only be adjusted as a part of a

full TX VF path alignment procedure.

Following adjustment of a digipot controlled parameter the value must then

be saved to the radio to make the change permanent.

Refer to section 5 ‘Alignment and Testing’ for details.