Midland Radio SD250U2 Users manual

SD-250

User Guide

Contents

Introduction --- 2
Preparing for use

Unpacking and inspection --- 3
Description of modem --- 4
Features --- 5
External Connections --- 6
Pin Outs --- 7

Operation

Channel Selection --- 9
Transmit/Receive Operation --- 10
Serial Commands --- 10

Rev. 0B

Status Indicators --- 12
Programming --- 13

Installation

Antennas --- 14
Power sources --- 14
Cabling --- 15

Fixing --- 15
Safety and general information --- 16
Warranty and repairs --- 18
Care of the equipment --- 18
Disposal / Recycling --- 18

1

Rev. 0B

Introduction

The SD250 range is a 1 to 6 Watts RF data module at VHF and UHF frequencies.

The SD250 is housed in a rugged cast-aluminum box sealed to IEC 529 (IP54)
making it suitable for a wide range of mobile and fixed applications.

All SD250 RF data module units meet the essential requirements of the relevant
directives. In order to maintain this compliance the installation and safety
information must be adhered to at all times.

• The SD250 RF data module must only be installed where unintentional contact
cannot be made. The surface of the device may be hot to touch under certain
transmit conditions. The SD250 is not designed for permanent transmission. If
prolonged transmission periods are used, the unit will become hot and will
require an additional heat-sink to be fitted.

• When fitting the module into a fixed installation, care must be taken in the
routing of all cabling such that the insulation cannot become damaged.

• The recommended supply sources for use with the SD250 is a standard 12V /
2A dc supply, but is capable of operating in the range 9V - 18V.

2

Preparing for use

Unpacking and inspection

Unpack the modem and check that you have received the following items:

• SD250 RF data module

• User Guide (this document)

Rev. 0B

If any of these items are missing, please contact your supplier.

3

Rev. 0B

Description of modem

The SD250 is a network free, point to point RF data module that offers great
flexibility in varied applications where wireless data or voice communication is
needed.
It can be used as a transparent radio, with no internal modem fitted, to allow
users to facilitate the use of their own modem and protocol. The correct signal
levels need to be used with the use of separate control lines, see the pin out
table below.

The SD250 can also be fitted with below a few different modems

• Bell 202 / V.23 modem (1200 baud rate)

• FFSK modem (4800 baud rate)

• GMSK modem (9600 baud rate)

The internal modem allows communication with a pc using RS 232 for the data
and control lines. For further details, please refer to the modem manual.

SD250 has standard radio features available which are associated with a private
radio. This includes CTCSS and DCS, software controlled squelch, time out timer
options and busy channel lockout as listed below (not all available with option
modem fitted). There is a microphone input and speaker output to allow speech
to be transmitted and received.

4

Features

• Compact and rugged die cast box

• Resistant to dirt, dust and water ingress (IP54 rated)

• Network free, point to point communication

• 1 / 6 watt programmable output power

• Synthesized operation with 16 channel capability

• SAT when used with Bell 202 / V.23 and FFSK modem or speech

• Programmable 12.5 / 25kHz channel spacing

• External modem / Direct FM

• Internal modem options available: Bell 202 / V.23, FFSK, GMSK

• ‘Busy’ output (can be set active high or low)

• 9 – 18 volt supply input

Rev. 0B

• Busy Channel lockout

• Time out timer

5