MITSUBISHI ELECTRONICS AMERICA, INC.
ST200 Series Technical Support Manual
16
January 2000
dialing keys, and eight other unique keys including a power button and two volume control
buttons on the side of the handset. Users can input up to 28 characters or numbers for placing a
call or memory storage in one of 99 locations (two screens required to see the entire location).
The interface between the standard handset and the cradle is a special 8-wire interface using RJ-
45 connections. The interface consists of three audio lines, two serial data lines, a power-on
signal line, +12V DC power, and ground. The serial data lines transmit keypad strokes and
receive and display commands from the handset and CTU.
The curl cord stretches to a maximum length a 5 feet (1.5m). Do not attempt to fabricate a
replacement or alternate cable, or modify the length of the curl cord provided. Although
standard RJ-45 extension cables exist, Mitsubishi Electronics does not endorse these extension
cables or guarantee MT product performance and reliability with these cables.
The connection of the Handset curl cord at the cradle must be firmly secure. Loose or improper
connections may render the terminal inoperable (not able to power on) or result in error
messages.
4.9 Push-to-Talk Handset
The Push-To-Talk handset, or PTT microphone, is an optional accessory providing access to the
wide-area dispatch service known as net radio. The PTT handset lets users select up to 15
different networks, or talkgroups. The MSAT service provider configures these channels, which
operate in a half-duplex manner like a standard two-way radio. The PTT handset also allows
users to automatically scan through configured talk groups and select active networks. The PTT
handset plugs into the junction box with the optional external speaker (needed for received
audio).
The interface between the PTT handset and the junction box is a special 8-wire interface using
RJ-45 connections. The interface comprises one audio line, two serial data lines, a PTT signal
