Maxon Telecom SP200 Common RF Circuits, Battery Low Indicator Circuit, LEDs and indicators, Vco

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SP200/210

Maxon SP200/210 Radio

Battery Low Indicator Circuit

When the battery voltage drops below 5.6 VDC a Battery Low indication is given. Due to the volts drop across D403, a voltage below 5.6V on the battery gives a voltage less than 5V on the base of Q405. , Q405 switches on its when base is below 5v (current flow through R413), which switches on Q404, so driving pin 52 of the microcontroller low (normally tied high). The micro controller disables the transmitter and at the same time enables the red LED and sends an alert tone to warn the user. The battery should be replaced or recharged at this time (one transmission is allowed after the low battery warning).

LEDs and indicators

The red and green LEDs are switched on, via Q407and Q411, by control lines from the microcontroller. Both the red and green LEDs being lit indicate the condition ‘busy’ i.e. orange. Both the LCD and backlight are driven from the microcontroller.

The alert tones are generated in the microcontroller and are fed through a filter to the volume control via link 27. There is an option of routing the tones directly to the audio amp via link28.

5.5 Common RF Circuits

PLL Synthesiser

The PLL synthesiser circuit is common to both the transmitter and receiver.

The synthesiser comprises:

TCXO

DC - DC

Converter

Data

IC 2
PLL	Charge Pump
	Charge Pump

Loop Filter

Tx or Rx

VCO

~

RF Out

Figure 5-2 – Synthesiser Block Diagram

12.8 MHz TCXO

The TCXO contains a crystal oscillator, which has 2-stage thermistor network compensation, and a modulation port. Accuracy is +/-2.5 PPM from -30°C to +60°C. Frequency adjustment is provided by TC701.

VCO

The VCO is configured as a Colpitts oscillator using transistor Q202, varactor diodes D201 / 202, frequency setting inductor L203 and associated components. Cascade bias is provided by Q201.

The frequency of operation is controlled by reverse biasing D201 in the range of 1 to 12 V dc (from the PLL). During receive Q9 is switched on by the Rx enable (active low), so switching D203 in circuit (via Q203), which puts C208 (variable capacitor) in parallel with the varactor diodes and adjustable inductor.

Issue 1.0	DETAILED FUNCTIONAL DESCRIPTION
03/01	Page 5-5

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Contents SP200/210 NSW Australia Tel +61 0 2 9707 Issue No Effective Date Reason for Change Signature Amendment Record SheetAmendment Record Sheet Maxon SP200/210 Radio Table of Contents 11.4 Default Settings 11-8 SL100 UHF Parts List10-1 11-1List of Tables Maxon SP200/210 Radio Issue 03/01 Introduction Using this ManualAmendments to this Manual Category C Engineering BulletinContact Information General SpecificationsPhysical Dimensions Synthesiser Environmental Operating Temperature RangeVibration ESD EMCAccessories & Options Pre-Install Check AccessoriesOptions Accessories & Options Installation INSTALLATION, Commissioning & AlignmentINSTALLATION, Commissioning & Alignment ConnectionsRecommended Test Equipment CommissioningCommissioning Kit Commissioning EquipmentDiscrete Test Equipment Test Equipment Set-up using Discrete Test EquipmentSK 3100 Service Kit Test Equipment Connection Transmitter Performance TestsReceiver Performance Tests Power Adjustment SquelchAudio Output Alignment Tests without DisassemblyPreparation VHFDisassembly and Re-assembly of the Radio Removing and Replacing BatteryRemoving and Replacing the Belt Clip Removing and Replacing the Main Assembly Location of Adjustment PointsPLL Alignment Squelch Sensitivity Transmitter AlignmentTcxo Radiocommunications Test SET Balance Adjustment Audio deviation adjustmentCtcss / DCS deviation Audio Volume Level At maximum volume, nominal distortion is 10%Receiver Alignment Introduction Detailed Functional DescriptionCommon Circuits EepromAudio Asic Audio Signal PathMiscellaneous Signals and Controller Sat Signal PathAudio/SAT Circuits LEDs and indicators Battery Low Indicator CircuitCommon RF Circuits PLL SynthesiserOut-of-Lock Detector PLL ICCharge Pump and Loop Filter DC to DC ConverterAutomatic power control APC circuits Antenna SwitchTransmitter PA moduleFront End ReceiverSecond mixer, Second IF, FM detector First MixerSquelch Mute Circuit 16kHz Band Pass FilterNoise detector circuit AF Output Low Pass FilterSpeaker Audio Amplifier Diagnostic Function TroubleshootingDiagnostics TroubleshootingIf IC Troubleshooting ChartVoltage Charts Transistors Main CircuitMain Circuit Transistor Voltages Integrated Circuits Integrated Circuit Voltages ReceiveIntegrated Circuit Voltages Transmit Troubleshooting Troubleshooting Troubleshooting Troubleshooting SMP6100 ProgrammingIntroduction Getting StartedScanning Select Features MenuProgram/Print/Save Program RadioSave Data to Disk Print DataMaxon SP200/200 Radio SP200/210 Parts List Exploded Mechanical Drawings & Parts ListsExploded Mechanical Drawings & Parts Lists Spare PartsSL100V2 SL100U2For details on servicing, please refer to Section Mechanical PartsLCD TTR 1866 Dpfdpw Parts List for Exploded Mechanical DrawingSKPT-110VA PCB LCDSML-020MLTT86 SMD NUT M7 BsbmPCB VCO PCB RF Bsbm M2.6 AldcSL100 VHF Parts List V2 Control Circuit05B-000-5Z Chip Ceramic 0.001UF GRM39 X7R102K 50V P Diode Switching KDS181S A3Chip Ceramic 0.012UF GRM39 X7R123K 25V P Chip Ceramic 0.0022UF GRM39 X7R222J 50V PSW Tact SKPT-1101VA 2 V2 RFRES.CHIP Trimmer 10K RH03E1C14X RES.CHIP Trimmer 1K RH03E1C13XThermistor Chip 33KNTCCS32163SH333KC TH1 Elect Capacitor 10UF 16V 20%Chip Ceramic 39PF GRM40 COG390J 50V P RE Power Module GNOK-M68776-E01 IC9Chip Ceramic 43PF GRM40 COG430J 50V P Chip Ceramic 47PF GRM39 COG470J 50V PTcxo Assembly 5 V2 Front End 4 V2 VCOU2 Control Circuit SL100 UHF Parts ListConnector Waffer Chip Resistor 12K 2 U2 RFChip Resistor 18K Chip Resistor 39KChip Ceramic 0.0015UF GRM39 X7R152K 50V P RES.CHIP Trimmer K RH03E1C13XChip Ceramic 10PF GRM40 COG100C 50V P Chip CeramicChip Ceramic 2.2PF GRM40 COG2R2C 50V P Power Mpduleuhf M68732HGNOK IC9Chip Ceramic 470PF GRM40 COG471J 50V P Chip Ceramic 4.7PF GRM40 COG4R7C 50V PCoil Chip 18NHLL2012-F18NM TcxoCoil Spring X0.35X7TR Coil Spring 2X0.75X3TL SMD4 VCO Maxon SP200/210 Radio Circuit Diagrams & PCB Layouts Circuit Diagrams & PCB LayoutsRF PCB TcxoCircuit Diagrams & PCB Layouts Digital Board Layout Top Side Digital Board Layout Bottom Side RF Board Layout Top Side Issue RF Board Layout Bottom Side P406787a Front End Front-End Board Layout Tcxo Board Layout Spare Parts & Maintenance Policy 10SPARE Parts10.1Spare Parts Surface mount component replacement Component ReplacementSurface mount components Surface mount removalSurface mounted integrated circuit replacement Spare Parts & Maintenance Policy 11.1Purpose 11APPENDIX ACC-2003 Alignment BOX11.2Test Equipment 11.3Calibration ProgramAppendix a ACC-2003 Alignment BOX Calibration Program Primary ScreenAsic Control Screen Rx Adjustment of Asic values TXTRIM2TXTRIM3 RX VOL Transmit Adjustments SAT BalanceSAT Deviation Audio Output Level Receive Adjustments11.4.1 V1 Band Default Settings 11.4Default SettingsV1 Default Frequency Table V1 Default Asic Settings11.4.2 V2 Band Default Settings V2 Default Frequency TableV2 Default Asic Settings 11.4.3 U1 Band Default Settings U1 Default Frequency TableU1 Default Asic Settings 11.4.4 U2 Band Default Settings U2 Default Frequency TableU2 Default Asic Settings