Midland Radio service manual SP-300INTRODUCTION, Features

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SP-300INTRODUCTION

The SP-300 Series of portable radios from Maxon, utilizes the latest technology in its design and manufacturing. Both the VHF and UHF models are PLL (Phase Lock Loop Syn- thesizer) / microprocessor controlled, and offer 1 or 5 watts of power with 4 & 16 channel capability. Multiple functions including Scan, CTCSS / DCS signaling and 12.5 & 25 kHz channel spacing are standard in these fully programmable wide bandwidth handheld units.

MAXON

SP-300 Series HAND HELD

FEATURES

Main Features

•Wideband

•Scan Mode

•Busy Channel Lockout/Marked Idle Enable

•Standard/Non-Standard CTCSS/DCS Signaling

•Transmit Time-Out Timer/Tx Inhibit

•Beep Tone Enable/Disable

•Low Battery Indication

•Memory Protect

•External Option Detect

•5/1 Watts Programmable RF Power

•Battery Save Circuitry

•Locking Accessory Connector

Wideband

This software is made to work and control the wide band receiver/transmitter boards.

Scan Mode

During programming of the radio, any channel can be selected as a scanned channel. When a channel is selected as a scanned channel, it becomes part of the scan list. The scan list will be activated by switching to the channel that was selected as the scan channel during programming of the sys- tem parameters.

The channel that was selected as the scan channel can still be used as a receive only channel when in scan mode or receive and transmit channel if the channel has been programmed for “Priority Scan TX”.

Scan Channel Delete

When the unit is in scan mode the monitor button can be pushed to delete a channel from the scan list. If the monitor button is pushed while scanning has stopped to monitor an active channel, that channel will be deleted from the scan list. The channel will remain inactive in the scan list until the scan mode is re-initiated by switching off the scan list channel and switching back to the scan list channel. Any number of channels can be deleted from the scan list in this way. The scan list is always initiated with all the scan list channels active.

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May 2001

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Contents Service Manual Table of Contents Board Layout Exploded View Specifications Temperature RangeGeneral Current ConsumptionDimensions WeightAdjacent Channel Power Frequency BandsReceiver Peak Deviation @ 1 kHz Nom. Dev +20dBRX Tone Demodulation Characteristics Features SP-300INTRODUCTIONBusy Channel Lockout VCO Lock Time Description of Controls DescriptionTheory of Operation Digital CircuitsRF Circuits RF Circuits PLL Synthesizer Squelch mute Circuit KHz Band Pass FilterNoise Detector Speaker Audio AmplifierMaintenance and Repair Removing & Replacing the Belt ClipRemoving the belt clip To replace the belt clipRemoving & Replacing the Battery To remove the batteryTo replace the battery To remove the PTT assemblyRemoving & Replacing the ACCES- Sory Connector Removing & Replacing the Antenna & Control KnobsTo replace the Back Cover Removing & Replacing the Back CoverTo remove the Back Cover Removing & Replacing the Main Board To remove the Main BoardTo replace the Main Board Removing & Replacing the Speaker Component ReplacementRemoving & Replacing the DAUGH- TER Boards Surface Mount Component Replacement Surface Mounted Integrated Circuit ReplacementCloning Alignment ProcedureProgramming RX VCO Test Equipment Setup S.G. @ 1kHz AudioAlignment Points Diagram TP1Troubleshooting Guide Symptoms Causes Counter MeasuresVoltage Charts Main CircuitReceive State Transmit State SP-300 Series UHF & VHF Digital Section Parts List REF# Description PART#-30- May SP-300 Series VHF RF Section Parts List REF # Description Replacement Modules-32- May -33- May SP-300 Series UHF RF Section Parts List -35- May -36- May -37- May Component Pinout KTA1504SY-39- May Base Diagram PIN Description VHF Power AMP UHF Power AMPVHF FRONT-END UHF FRONT-ENDVHF V.C.O UHF V.C.OFuse ACC-200 BatteryTcxo SP-300 Series VHF RF Schematic UHF RF Schematic -47- May Board Layout Top Main Board Assembly 416121B -49- May
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