Maxon Telecom SM-2000 service manual General Description

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MAXON SM-2000 MOBILE

GENERAL DESCRIPTION

GENERAL DESCRIPTION

The Maxon SM-2000 is a rugged two way FM mobile radio which operates from 136-174 MHz (VHF) in two bands & 400-512 MHz (UHF) in five bands. The SM-2000 is a synthesized radio utilizing microcomputer technology to provide reliable high quality simplex two-way mobile communications. The SM-2000 transmitter output power level is 25 watts over a wide bandwidth, with a receiver operational bandwidth that covers the specified frequency band. The basic radio package includes the following features:

Microprocessor Control

Synthesized RF Channel Selection (Frequency Control)

CTCSS Encode / Decode

DCS Encode / Decode

Priority Channel Scan

5 PPM Frequency Stability (SM-2150/VHF)

2.5 PPM Frequency Stability (SM-2450/UHF)

Field Programmable with PC

Internal 4 watt speaker, with Volume Control

Busy Channel Lockout

The small size of the SM-2000 radio makes it ideal for front mounting in conventional vehicles. The radio is operated with a simple hand held microphone in combination with the operating controls described in the following section.

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December 98

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Contents SM-2000 Page Table of Contents Maxon SM-2000 MobileSchematics and Block Diagrams PCB LayoutsSM-2000 Exploded View Specifications Transceiver Nominal PerformanceGeneral Operational Bandwidth BandTransmitter Specfications TX Tone Modulation Characteristics SUB Audible Tones DCSReceiver RX Tone Demodulation Characteristics AccessoriesSubaudible tones CTCSS/DCS Reliability AnalysisIntroduction Unpacking Information Check the carton carefully for the following itemsGeneral Description Description of Controls Description of ControlsSM-2000 Rear Panel Theory of Operation Digital CircuitryCTCSS/DCS Decode Circuits CTCSS/DCS Encoder CircuitEeprom PLL RF Section SM-2150/VHF RX VCO TX VCOOut of Lock Detector PrescalerReceiver RF AmplifierReceiver Audio Circuit Low Pass FilterAudio Amplifier Noise Detect Circuit SQ BoardRF Section SM-2450/UHF UHF TransmitterFrequency Synthesizer Circuit Voltage Controlled Oscillator Circuit First MixerSecond Oscillator- Mixer- Limiter and FM Detector Squelch Mute Circuit Squelch Noise Band Pass FilterNoise Detector Speaker Audio AmplifierTest Setup Transmit TestsSM-2150/VHF Alignment Procedure PLL AlignmentDiscriminator Tuning Receiver Alignment RFSquelch Adjustment Automatic Power AdjustmentCTCSS/DCS Deviation Adjustment Modulation Deviation AdjustmentAlignment Points Diagram SM-2150/VHF SM-2450/UHF Alignment Procedure Page-28 December ∙ Note Release the PTT button when changing channels Page-30 December Alignment Points Diagram SM-2450/UHF Component Replacement Surface Mount ComponentsSurface Mount Removal Surface Mount Component Replacement Surface Mounted Integrated Circuit ReplacementParts List Common to SM-2000 REF # DescriptionDigital Parts Common on Both VHF & UHF Digital Section Band Chart REF # Description FRONT-END PCB Assembly Main Board PartsPage-38 December Page-39 December Page-40 December Page-41 December SM-2450A UHF Band SM-2450C UHF Band SM-2450D UHF Band Band Chart SM-2450E UHF BandPage-44 December Page-45 December Page-46 December Page-47 December Component Pinout Page-49 December Page-50 December Voltage Charts SM-2150/VHF IC409Page-52 December Transistor Voltage Chart Voltage Charts SM-2450/UHF IC404 Page-56 December Trouble Shooting Chart SM-2000 Status Indications & Audible TonesPage-58 December Replacement Module Schematics MMBV109MA-4472 Microphone Schematic Page-61- December Page-62- December Page-63- December Page-64- December SW5 SM-2000 Control HeadSM-2150/VHF Main Board Assy Page-66 DecemberSM-2450/UHF Main Board Assy FrontSM-2000 SM-2150/VHF Exploded View Parts List Intentionally Left Blank