LBI-39061A
Installation Manual
DTMF Encoder
344A4209P23 (MHDE5U)
ericssonz
TABLE OF CONTENTS
Page
INTRODUCTION...................................................3
GENERAL DESCRIPTION.................................3
PROGRAMMING................................................3
THEORY OF OPERATION....................................3
INSTALLATION AND ALIGNMENT.......................4
10 CHANNEL VERSION ....................................4
4/16 CHANNEL VERSION .................................8
PARTS LIST ..........................................................12
SCHEMATIC DIAGRAM........................................14
NOTICE!
This manual covers Ericsson and General Electric
products manufactured and sold by Ericsson Inc.
This manual is published by
to this manual necessitated by typographical errors, inaccuracies of current information, or
improvements to programs and/or equipment, may be made by
without notice. Such changes will be incorporated into new editions of this manual. No part of
this manual may be reproduced or transmitted in any form or by any means, electronic or
mechanical, including photocopying and recording, for any purpose, without the express
written permission of
Coriht © A
ril 1994
Ericsson Inc.
Ericsson Inc.
Ericsson GE Mobile Communications Inc.
, without any warranty. Improvements and changes
Ericsson Inc.
, at any time and
2
INTRODUCTION
GENERAL DESCRIPTION
The Dual-Tone Multi-frequency (DTMF) encoder
allows DTMF operation in the
Portables.
When installed, the DTMF encoder will provide the
radio with ability to use all of the combinations found on
the DTMF keypad.
PROGRAMMING
Programming of the DTMF encoder is not neces sary
or required.
THEORY OF OPERATION
All tone frequency generation is provided by U2. U2
is a standard generic 5098 DTMF encoder device
commonly used in telephone circuitry. Internally the
device contains a crystal oscillator which operated on
3.579 MHz (commonly known as the clock), two
programmable down-counters which divide the clock
output frequencies to provide DTMF tones which are
added together when a keypad button is depressed. The
resulting sine wave output is enabled by either the XMIT
ENABLE or it's inverse.
Monogram™ Series
The speaker output provides an amplitude which
may be heard on the speaker.
3
The DTMF OUTPUT is adjustable with R8 and
routed to the audio input within the radio.
A regulated 5.0 VDC source for U2 is provided by
U1. Beyond the regulator, decoupling capacitors are
provided to keep RF out of the circuit.
INSTALLATION AND ALIGNMENT
NOTE
The installation and alignment instructions assume
the radio has been properly programmed, aligned and
deviati on cor rec tl y set pri or t o the i ncor pora ti on of t he
DTMF option.
10 CHANNEL VERSION
1. Remove the battery.
2. Remove the two front cover retaining screws from
the bottom of the unit as shown in Figure 1.
3. Remove the front cover and disconnect the 4-pin
plug from CON 406.
NOTE
Retain the front cover and screws for future use or as
a source of replacement parts.
4
Figure 1 - Bottom of Radio
4. Remove solder jumper from LK7.
5. Add solder jumper to LK6.
6. Remove the solder jumper from LK3 and install the
supplied 10K ohm resistor (R29/060-103-8Z) in its
place.
7. Add the supplied 470 pF chip capacitor (R29/134711-9) to the trace at the lower portion of LK3 as
shown.
NOTE
Instal lation of the 470 pF chip c apacitor requires the
removal of the soldermask from the printed wiring
board. USE CAUTION WHILE REMOVING TO
AVOID DAMAGING THE PRINTED WI RING BOARD
TRACES.
5
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