Technical Manual Technical Description
© SPECTRA ENGINEERING 2006 Revision 4.2.3
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4.4.5 User Interface
All user interfaces to the MX800 except the RF connections is made by way
of the Micro Controller board.
Output latch IC18 drives the six LED indicators on the front panel. The
function is described in section 1.1.1.
Input latch IC14 serves to accept the programmed status of the 8-bit binary
channel select DIP switch SW1. Refer section 7.3 for programming
instructions.
Input latch IC13 serves to accept the programmed status of the 6-bit binary
mode select DIP switch SW2. Refer section 2.2.2.2 for mode selection
instructions.
Input latches IC48 and IC47 provide two eight bit +5V CMOS compatible
digital input ports (ports A and B respectively). The inputs may be either
internally pulled high and active low or internally pulled low and active high.
Port B inputs are configured as external channel select inputs. The inputs are
buffered by 10kΩ series resistors.
Output latch IC46 provides 8 uncommitted +5V CMOS compatible digital
outputs. Each output is buffered by a 1kΩ series resistor.
IC60 is a 1-Watt speaker amplifier, which drives the internal speaker. This IC
includes the volume control function connecting to the front panel.
Microphone audio is fed via amplifier IC61A to a compressor (IC34B). This
VF is pre-emphasised and filtered before being fed to the main TX VF path.
IC22 provides CMOS to RS232 conversion for the serial port.
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