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Ericsson MGM 148 Maintenance Manual

Vhf mobile radio monogram series
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LBI-38864B
Maintenance Manual
Monogram
Series
VHF MOBILE RADIO
MODEL MGM 148 & 160
ericssonz

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Summary of Contents for Ericsson MGM 148

  • Page 1 LBI-38864B Maintenance Manual Monogram Series VHF MOBILE RADIO MODEL MGM 148 & 160 ericssonz...

  • Page 2: Table Of Contents

    MONOGRAM SERIES LBI-38864B TABLE OF CONTENTS TABLE OF CONTENTS SPECIFICATIONS ............... . . 1-4 Receiver (PER EIA RS-204-C) .
  • Page 3 MONOGRAM SERIES LBI-38864B TABLE OF CONTENTS Suggested Test Equipment ............. . 19 Pre-Alignment Notes: .

  • Page 4: Specifications

    MONOGRAM SERIES LBI-38864B SPECIFICATIONS SPECIFICATIONS GENERAL Frequency Range VHF Low Band 136-150 MHz VHF Mid Band 148-165 MHz VHF High Band 160-174 MHz Channel Capability 16 max Channel Spacing 25 or 30 kHz Input Voltage 13.8 VDC negative ground Current Drain Standby 0.4 Amps (max) Receive...

  • Page 5: Receiver (Per Eia Rs-204-C)

    MONOGRAM SERIES LBI-38864B SPECIFICATIONS RECEIVER (PER EIA RS-204-C) RF Input Impedance 50 ohms nominal Sensitivity EIA 12 dB SINAD 0.30 mV 0.50 µV 20 dB QUIETING Squelch Sensitivity 0.25 mV threshold Selectivity -70 dB Inter modulation -70 dB ± 7.5 kHz Modulation Acceptance Bandwidth Spurious and Image 70 dB mx...

  • Page 6: Transmitter (Per Eia Rs-152-B)

    MONOGRAM SERIES LBI-38864B SPECIFICATIONS TRANSMITTER (PER EIA RS-152-B) RF Power Output 40 W (adjustable) RF Output Impedance 50 ohms Spurious and Harmonics -70 dBc Modulation 16 K0F3E FM Hum and Noise -45dB nominal Audio Distortion < 3 % @ 1000 Hz ±...

  • Page 7: Options And Accessories

    MONOGRAM SERIES LBI-38864B SPECIFICATIONS OPTIONS AND ACCESSORIES CONTROL STATION OPTIONS: Power Supply MGPS5V External Speaker MGZM7C Desk Microphone MGMC5H NOT SHOWN: Antenna - MGAN1A Relay Kit - MGSU1C Noise Suppression Kit - MGPD1A Page -4- Nov. 94...

  • Page 8: Unpacking

    MONOGRAM SERIES LBI-38864B UNPACKING UNPACKING Check the carton and packing material carefully for the following items: Transceiver Unit Microphone DC power Cord Mobile Mounting Bracket Assembly Hardware Operating Guide Styrofoam not used Inner packing is now cardboard tray box. FIGURE 1 - Unpacking Diagram Page -5- Nov.

  • Page 9: General Description

    MONOGRAM SERIES LBI-38864B GENERAL DESCRIPTION GENERAL DESCRIPTION Introduction The Conventional Monogram Series Radio is a rugged, two-way FM mobile radio which operates in either the 148-165 MHz band split or the 160-174 MHz band split. The Monogram is a synthesized radio utilizing microcomputer technology to provide reliable high-quality simplex two-way mobile communications.

  • Page 10: Description Of Controls

    MONOGRAM SERIES LBI-38864B DESCRIPTION OF CONTROLS DESCRIPTION OF CONTROLS FRONT PANEL CONTROLS 1. SQUELCH Control: The squelch control will silence the receiver when no signal is being received. 2. ON/OFF/VOLUME Control: This is the main power switch and volume control. 3.

  • Page 11: Rear Panel Controls

    MONOGRAM SERIES LBI-38864B DESCRIPTION OF CONTROLS BACK PANEL CONNECTORS 1. External Speaker Connector: This 3.5mm diameter jack is provided for a 4 ohm external speaker. The internal speaker is silenced when the external speaker is connected. 2. Auxiliary Speaker Connector: This 3.5mm diameter jack is provided for an auxiliary speaker (Option MGSU1C Relay Kit is required).

  • Page 12: General Operation

    MONOGRAM SERIES LBI-38864B GENERAL OPERATION GENERAL OPERATION • NOTE: The following description briefly outlines the operation of your VHF synthesized mobile radio. Consult the operator’s manual for a complete description of all the modes of operation. RADIO ON/OFF, POWER UP 1.

  • Page 13: Digital Channel Guard

    MONOGRAM SERIES LBI-38864B GENERAL OPERATION DIGITAL CHANNEL GUARD Channel Guard provides a means of restricting calls to specific radios through the use of a CTCSS (Continuous Tone Coded Squelch) or DCS (Digitally Coded Squelch). The tone frequencies range from 67 Hz to 250.3 Hz and there are 83 programable codes.

  • Page 14: Circuit Analysis

    MONOGRAM SERIES LBI-38864B CIRCUIT ANALYSIS CIRCUIT ANALYSIS RECEIVER RF Amplifier Incoming signals from the antenna jack are routed backwards through the transmitter lowpass filter in PIN diode switch D12. In receive mode, D12 conducts allowing a low impedance path through the diode to the receiver front end circuitry.

  • Page 15: Transmitter

    MONOGRAM SERIES LBI-38864B CIRCUIT ANALYSIS Squelch The presence of an RF carrier is determined by noting the level of ultrasonic noise at the detector output (pin 9) of IC2. When a carrier is present, the noise level drops. The audio at pin 9 of IC2 is filtered by a two-pole bandpass filter formed around L5, L6 C48 and C50.
  • Page 16 MONOGRAM SERIES LBI-38864B CIRCUIT ANALYSIS Reference Oscillator Crystal X3, varactor diode D119, a thermistor/resistor network and oscillator stage of IC108 from a temperature compensated 10.24 MHz oscillator. This frequency is divided by 2084 to generate the 5 kHz reference frequency for the PLL frequency synthesizer.

  • Page 17: Preventive Maintenance

    MONOGRAM SERIES LBI-38864B PREVENTIVE MAINTENANCE PREVENTIVE MAINTENANCE To ensure high operating efficiency and to prevent mechanical and electrical failures from interrupting system operations, routing checks should be made of all mechanical and electrical parts at regular intervals. Preventive maintenance should include the following checks: CONNECTIONS Ground connections to the voltage source should be periodically checked for tightness.

  • Page 18: Disassembly

    MONOGRAM SERIES LBI-38864B DISASSEMBLY DISASSEMBLY TOP AND BOTTOM COVERS There are no screws used to secure the top and bottom covers. Both top and bottom covers are removed with a flat blade screwdriver or similar tool. On each side of the radio there are two small slots (one at the top and one at the bottom).

  • Page 19: Digital Board

    MONOGRAM SERIES LBI-38864B DISASSEMBLY DIGITAL BOARD 1. Remove the (6) M3 x 18 machine screws that secure the Top Panel shield to the chassis. 2. Unplug and remove the Auxillary Relay P.C.B. at PL5. 3. Remove the (6) machine screws (3 on top and 3 on bottom) that secure the Front Panel to the chassis. •...

  • Page 20: Programming Instructions

    MONOGRAM SERIES LBI-38864B PROGRAMMING INSTRUCTIONS PROGRAMMING INSTRUCTIONS The VHF synthesized mobile radio is equipped with a personality EEPROM. All customer information such as the customer frequencies, customer tones and customer options are stored in the EEPROM. The EEPROM contains all information to tailor the operation of the radio to the user’s requirements. The EEPROM is programmed by using an IBM compatible personal computer with MSDOS, Programming Cable TQ-3376 and Programming software TQ-3375.

  • Page 21: Test Equipment Setup

    MONOGRAM SERIES LBI-38864B TEST EQUIPMENT SETUP TEST EQUIPMENT SETUP Figure 4 - Test Equipment Setup * Optional Test Equipment Page -18- Nov. 94...

  • Page 22: Alignment Procedure

    MONOGRAM SERIES LBI-38864B ALIGNMENT PROCEDURE ALIGNMENT PROCEDURE • WARNING: Any repairs or adjustments should be made under the supervision of a certified technician. SUGGESTED TEST EQUIPMENT The following equipment, or its equivalent, is required for proper alignment of your VHF synthesized mobile radio: 1.

  • Page 23: Pll Alignment

    MONOGRAM SERIES LBI-38864B ALIGNMENT PROCEDURE 4. The middle RX/TX frequencies should be halfway between the lowest and the highest frequencies. • NOTE: There should be 4 channels programmed with a total of 3 different frequencies. PLL ALIGNMENT 1. Connect an RF dummy load or power attenuator (50 watt minimum rating) to the antenna connector. 2.
  • Page 24 MONOGRAM SERIES LBI-38864B ALIGNMENT PROCEDURE • WARNING: To prevent damage to the radio, avoid keying the radio for periods longer than 1 minute. Allow a 5 minute cool down period after keying the radio for 1 minute. 7. Repeat step 6 above for the lowest, middle, and highest frequency transmit channel with the goal to achieve the least variation in power output across the band.

  • Page 25: Receiver Alignment

    MONOGRAM SERIES LBI-38864B ALIGNMENT PROCEDURE Modulation Deviation Adjustment 1. Connect an RF deviation meter to the radio through a power attenuator. 2. Set the CHANNEL selector to a transmit channel which has a DCS code pre-programmed (should be a mid-frequency channel). 3.
  • Page 26 MONOGRAM SERIES LBI-38864B ALIGNMENT PROCEDURE 9. Adjust T6 and T7 for maximum sensitivity. These adjustments have a very broad range where little change in sensitivity is noted while the adjustment is being made. The slugs should be set in the middle of this range.

  • Page 27: Alignment Points 406041-F Issue:h Digital Board

    MONOGRAM SERIES LBI-38864B ALIGNMENT POINTS 406041-F Issue:H DIGITAL BOARD ALIGNMENT POINTS 406041-F Issue:H DIGITAL BOARD Page -24- Nov. 94...

  • Page 28: Alignment Points 406039-E Issue:h Rf Board

    MONOGRAM SERIES LBI-38864B ALIGNMENT POINTS 406039-E Issue:H RF BOARD ALIGNMENT POINTS 406039-E Issue:H RF BOARD Page -25- Nov. 94...

  • Page 29: Performance Test

    MONOGRAM SERIES LBI-38864B PERFORMANCE TEST PERFORMANCE TEST TRANSMITTER PERFORMANCE TEST Power Output 1. Set the power supply voltage to 13.8 VDC (measured at the radio during transmit). 2. Connect an RF wattmeter and dummy load to the antenna connector. 3. Press the PTT switch. 4.

  • Page 30: Receiver

    MONOGRAM SERIES LBI-38864B PERFORMANCE TEST Spectrum Test 1. Connect a spectrum analyzer to a sampled RF output of the radio. 2. Press the PTT switch. Observe the output spectrum on the spectrum analyzer. 3. All spurious and harmonics should be at least 60 dB below the carrier level. 4.
  • Page 31 MONOGRAM SERIES LBI-38864B PERFORMANCE TEST Audio Output 1. Increase the RF signal generator/service monitor RF level to 1000 µV. 2. Connect a 4 ohm audio dummy load to the AUXILIARY speaker jack. 3. Connect a true RMS audio volmeter (the audio distortion analyzer may include this function) to the speaker leads.

  • Page 32: Component Replacement

    MONOGRAM SERIES LBI-38864B COMPONENT REPLACEMENT COMPONENT REPLACEMENT SURFACE MOUNT COMPONENTS Surface mount components should always be replaced using a temperature controlled soldering system. The soldering tools may be either a temperature controlled soldering iron or a temperature controlled hot-air soldering station.

  • Page 33: Surface Mount Component Replacement

    MONOGRAM SERIES LBI-38864B COMPONENT REPLACEMENT SURFACE MOUNT COMPONENT REPLACEMENT 1. "Tin" one terminal end of the new component and the corresponding pad of the PCB. Use as little solder as possible. 2. Place the component on the PCB pads, observing proper orientation for capacitors, diodes, transistors, etc. 3.

  • Page 34: Electrical Parts List

    ELECTRICAL PARTS LIST NOTE Only those items indicated by shading will be stocked by After Market Services. All other items are for reference only. When ordering parts for your Monogram Series radio, precede all part numbers with the prefix "R29/" Page -31- Nov.

  • Page 35: Printed Circuit Board Layouts

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  • Page 59 PRINTED CIRCUIT BOARD LAYOUT Page -32.0- Nov. 94...

  • Page 60: Top View 406041-F Issue: H / Digital Board

    MONOGRAM SERIES LBI-38864B TOP VIEW 406041-F ISSUE: H / DIGITAL BOARD TOP VIEW 406041-F ISSUE: H / DIGITAL BOARD Page -32.1- Nov. 94...

  • Page 61: Bottom View 406041-F Issue: H / Digital Board

    MONOGRAM SERIES LBI-38864B BOTTOM VIEW 406041-F ISSUE: H / DIGITAL BOARD BOTTOM VIEW 406041-F ISSUE: H / DIGITAL BOARD Page -32.2- Nov. 94...

  • Page 62: Top View 406039-E Issue: H / Rf Board

    MONOGRAM SERIES LBI-38864B TOP VIEW 406039-E ISSUE: H / RF BOARD TOP VIEW 406039-E ISSUE: H / RF BOARD Page -32.3- Nov. 94...

  • Page 63: Bottom View 406039-E Issue: H / Rf Board

    MONOGRAM SERIES LBI-38864B BOTTOM VIEW 406039-E ISSUE: H / RF BOARD BOTTOM VIEW 406039-E ISSUE: H / RF BOARD Page -32.4- Nov. 94...
  • Page 64 MONOGRAM SERIES LBI-38864B PRINTED CIRCUIT BOARDS PRINTED CIRCUIT BOARDS DISPLAY BOARD TOP VIEW DISPLAY BOARD BOTTOM VIEW VOLUME BOARD BOTTOM VIEW VOLUME BOARD TOP VIEW Page -32.5- Nov. 94...
  • Page 65 MONOGRAM SERIES LBI-38864B PRINTED CIRCUIT BOARDS PRINTED CIRCUIT BOARDS 406-969-F (DIG. PCB) BOTTOM 406-969-F (DIG. PCB) TOP 406-968-C (RF. PCB) TOP 406-968-C (RF. PCB) BOTTOM 406-973-A TOP 406-973-A BOTTOM Page -32.6- Nov. 94...
  • Page 66 MONOGRAM SERIES LBI-38864B VOLTAGE CHARTS VOLTAGE CHARTS Page -32.7- Nov. 94...
  • Page 67 MONOGRAM SERIES LBI-38864B VOLTAGE CHARTS VOLTAGE CHARTS Page -32.8- Nov. 94...
  • Page 68 MONOGRAM SERIES LBI-38864B VOLTAGE CHARTS VOLTAGE CHARTS Page -32.9- Nov. 94...
  • Page 69 MONOGRAM SERIES LBI-38864B VOLTAGE CHARTS VOLTAGE CHARTS Page -32.10- Nov. 94...

  • Page 70: Exploded View

    EXPLODED VIEW EXPLODED VIEW PARTS LIST NOTE Only those items indicated by shading will be stocked by After Market Services. All other items are for reference only. When ordering parts for your Monogram Series radio, precede all part numbers with the prefix "R29/" Page - 33.0 - Oct.
  • Page 71 MONOGRAM SERIES LBI-38864B EXPLODED VIEW PARTS LIST EXPLODED VIEW PARTS LIST Page - 33.1 - Oct. 94...
  • Page 72 MONOGRAM SERIES LBI-38864B EXPLODED VIEW PARTS LIST EXPLODED VIEW PARTS LIST Page - 33.2 - Oct. 94...
  • Page 73 MONOGRAM SERIES LBI-38864B MGM-148 / MGM-160 EXPLODED VIEW MGM-148 / MGM-160 EXPLODED VIEW Page - 33.3 - Oct. 94...

  • Page 74: Schematics

    SCHEMATICS Ericsson Inc. Private Radio Systems Mountain View Road Lynchburg,Virginia 24502 1-800-528-7711 (Outside USA, 804-528-7711) Printed in U.S.A. Page -34- Nov. 94...
  • Page 75 LBI-38864B RF BOARD R29/406039-E 34.1...
  • Page 76 LBI-38864B DIGITAL BOARD R29/406041-F 34.2...

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