Maxon Telecom SM-2000 service manual Page-30 December

Page 34

MAXON SM-2000 MOBILE

SM-2450/UHF ALIGNMENT PROCEDURE

Modulation Deviation Adjustment

1.Connect a power meter and a coupler to the radio.

2.Connect an AF generator to the test box.

3.Set the audio output to 30mV and the audio frequency to 1kHz .

4.Using the channel switch, select the highest transmit channel that does not have CTCSS or DCS programmed.

5.Press and hold the PTT switch.

6.Adjust RV402 for 90% of maximum, system deviation.

6a. Adjust RV402 for 2.25kHz for narrow band (12.5kHz).

6b. Adjust RV402 for 4.5kHz for wide band (25kHz).

7.Using the channel switch, select the lowest transmit channel that does not have CTCSS or DCS programmed.

8.Press and hold the PTT switch.

9.Measure and check that the deviation is not below 3.8k . If the deviation is below 3.8k, adjust RV402 to 3.8k .

10.Return to highest transmit channel having a sub- audible tone and verify deviation does not exceed 5k.

11.At the channel that highest deviation is found, sweep the audio frequency between 300kHz and 3kHz . Adjust RV402 to ensure deviation is below peak system deviation at all frequencies.

12.Set the PTT switch to the OFF position.

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December 98

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Contents SM-2000 Page Table of Contents Maxon SM-2000 MobilePCB Layouts Schematics and Block DiagramsSM-2000 Exploded View Transceiver Nominal Performance SpecificationsGeneral Band Operational BandwidthTransmitter Specfications SUB Audible Tones DCS TX Tone Modulation CharacteristicsReceiver Subaudible tones CTCSS/DCS RX Tone Demodulation CharacteristicsAccessories Reliability AnalysisIntroduction Unpacking Information Check the carton carefully for the following itemsGeneral Description Description of Controls Description of ControlsSM-2000 Rear Panel CTCSS/DCS Decode Circuits Theory of OperationDigital Circuitry CTCSS/DCS Encoder CircuitEeprom PLL RF Section SM-2150/VHF RX VCO TX VCOReceiver Out of Lock DetectorPrescaler RF AmplifierAudio Amplifier Receiver Audio CircuitLow Pass Filter Noise Detect Circuit SQ BoardUHF Transmitter RF Section SM-2450/UHFFrequency Synthesizer Circuit First Mixer Voltage Controlled Oscillator CircuitSecond Oscillator- Mixer- Limiter and FM Detector Noise Detector Squelch Mute CircuitSquelch Noise Band Pass Filter 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 Surface Mount Components Component ReplacementSurface 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