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Motorola GP320 Service Information

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Professional Radio
GP Series
UHF (403 - 470MHz)
Service Information
Issue: June 2002

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   Summary of Contents for Motorola GP320

  • Page 1

    Professional Radio GP Series UHF (403 - 470MHz) Service Information Issue: June 2002...

  • Page 2: Computer Software Copyrights

    Accordingly, any copyrighted Motorola computer programs contained in the Motorola products described in this manual may not be copied or reproduced in any manner without the express written permission of Motorola. Furthermore, the purchase of Motorola...

  • Page 3: Table Of Contents

    Table of Contents Chapter 1 MODEL CHART AND TECHNICAL SPECIFICATIONS 1.0 GP320/GP340/GP360/GP380 Model Chart............1-1 2.0 GP140 Model Chart .....................1-2 3.0 GP640/GP680 Model Chart .................1-2 4.0 GP1280 Model Chart ...................1-3 5.0 GP240/GP280/GP540/GP580 Model Chart............1-4 6.0 Technical Specifications ..................1-5 Chapter 2 THEORY OF OPERATION 1.0 Introduction ......................2-1...

  • Page 4

    Chapter 4 UHF PCB/SCHEMATICS/PARTS LISTS 1.0 Allocation of Schematics and Circuit Boards ............4-1 1.1 Controller Circuits ................... 4-1 1.2 Voice Storage Facility..................4-1 2.0 UHF PCB 8480450Z03 / Schematics ..............4-3 3.0 UHF PCB 8480450Z03 / PCB 8480587Z01 Parts List ........4-11 4.0 UHF PCB 8480587Z01 (GP1280) ..............

  • Page 5: Gp320/gp340/gp360/gp380 Model Chart

    Chapter 1 MODEL CHART AND TECHNICAL SPECIFICATIONS GP320/GP340/GP360/GP380 Model Chart Professional GP300 Series (UHF) Model Description MDH25RDC9AN0_E GP320 UHF 403-470MHz 4W 1-Ch MDH25RDC9AN3_E GP340 UHF 403-470MHz 4W 16-Ch MDH25RDF9AN5_E GP360 UHF 403-470MHz 4W 255-Ch MDH25RDH9AN6_E GP380 UHF 403-470MHz 4W 255-Ch...

  • Page 6: Gp140 Model Chart

    MODEL CHART AND TECHNICAL SPECIFICATIONS GP140 Model Chart Professional GP140 (UHF) Model Description MDH25RDC9AA3_E GP140 UHF 403-470 MHz 4W 16 Ch Item Description PMLE4130_ *GP140 UHF Back Cover Kit 6864110B25 GP140 Basic User Guide NAE6483_ UHF Whip (403-470 MHz) Antenna HNN9008_ Battery, NiMH Standard x = Indicates one of each is required.

  • Page 7: Gp1280 Model Chart

    GP1280 Model Chart GP1280 Model Chart Professional GP1280 (UHF) Model Description MDH25RDN9CK8_E GP1280 UHF 403-470 MHz 4W Item Description PMLE4142_ *GP1280 UHF Back Cover Kit 6864110B20 GP1280 Basic User Guide NAE6483_ UHF Whip (403-470 MHz) Antenna HNN9008_ Battery, NiMH Standard x = Indicates one of each is required.

  • Page 8

    MODEL CHART AND TECHNICAL SPECIFICATIONS GP240/GP540/GP280/GP580 Model Chart Professional GP200/GP500 Series (UHF) Model Description MDH25RDC9GC3 GP540 UHF 403-470 MHz 4W MDH25RDH9GC6 GP580 UHF 403-470 MHz 4W MDH25RDC9GB3 GP240 UHF 403-470 MHz 4W MDH25RDH9GB6 GP280 UHF 403-470 MHz 4W Item Description *PMLE4192_ GP240/GP540 UHF Back Cover Kit *PMLE4193_...

  • Page 9: Technical Specifications

    Technical Specifications Technical Specifications Data is specified for +25°C unless otherwise stated. General Specifications Channel Capacity GP140 GP240, GP280 128 in conventional Mode GP320 GP340 GP360, GP380 GP540, GP580 128 in conventional Mode GP640, GP680, GP1280 16 (Conventional) Power Supply Rechargeable battery 7.5v...

  • Page 10

    MODEL CHART AND TECHNICAL SPECIFICATIONS Transmitter *Frequencies - Full Bandsplit UHF 403-470 MHz Channel Spacing 12.5/20/25 kHz Frequency Stability ±1.5 ppm (-25°C to +55°C, +25° Ref.) Power 403 - 470 MHz:1-4W ±2.5 @ 12.5 kHz Modulation Limiting ±4.0 @ 20 kHz ±5.0 @ 25 kHz FM Hum &...

  • Page 11: Introduction

    Chapter 2 THEORY OF OPERATION Introduction This Chapter provides a detailed theory of operation for the UHF circuits in the radio. For details of the theory of operation and trouble shooting for the the associated Controller circuits refer to the Controller Section of this manual.

  • Page 12: Antenna Switch

    THEORY OF OPERATION The LDMOS PA is capable of supplying an output power of 7W with an input signal of 0.3W. The current drain is typically 1300mA while operating in the frequency range of 403-470MHz. The power output can be varied by changing the bias voltage. Antenna Switch The antenna switch circuit consists of two pin diodes (CR101 and CR102), a pi network (C107, L104 and C106), and two current limiting resistors (R101 and R170).

  • Page 13: Uhf Receiver

    UHF Receiver UHF Receiver The UHF receiver consists of a front end, back end, and automatic gain control circuits. A block diagram of the receiver is shown in Figure 2-2. Detailed descriptions of these features are contained in the paragraphs that follow. Antenna Pin Diode Varactor...

  • Page 14: Receiver Back-end

    THEORY OF OPERATION The output of the bandpass filter is coupled to the RF amplifier transistor Q301 via C307. After being amplified by the RF amplifier, the RF signal is further filtered by a second varactor tuned bandpass filter, consisting of L306, L307, C313, C317, CR304 and CR305. Both the pre and post-RF amplifier varactor tuned filters have similar responses.

  • Page 15: Automatic Gain Control (agc)

    UHF Receiver Automatic Gain Control (AGC) (Refer to the UHF Receiver Front End and Receiver Back End schematic diagrams) The front end automatic gain control circuit provides automatic reduction of gain, of the front end RF amplifier via feedback. This action is necessary to prevent overloading of backend circuits. This is achieved by drawing some of the output power from the RF amplifier output.

  • Page 16: Frequency Generation Circuit

    THEORY OF OPERATION Frequency Generation Circuit (Refer to Figure 2-3 and the UHF Frequency Synthesizer schematic diagram) The frequency generation circuit, shown in Figure 2-3, is composed of Fractional-N synthesizer U201 and VCO/Buffer IC U241. Designed in conjunction to maximize compatibility, the two ICs provide many of the functions that normally require additional circuitry.

  • Page 17: Synthesizer

    Frequency Generation Circuit Synthesizer (Refer to Figure 2-4 and the UHF Synthesizer schematic diagram) The Fractional-N synthesizer, shown in Figure 2-4, uses a 16.8MHz crystal (FL201) to provide a reference for the system. The LVFractN IC (U201) further divides this to 2.1MHz, 2.225MHz, and 2.4MHz to be used as reference frequencies.

  • Page 18: Voltage Controlled Oscillator (vco)

    THEORY OF OPERATION Voltage Controlled Oscillator (VCO) (Refer to Figure 2-5 and the UHF Voltage Controlled Oscillator schematic diagram) The VCOB IC (U241), shown in Figure 2-5, in conjunction with the Fractional-N synthesizer (U201) generates RF in both the receive and the transmit modes of operation. The TRB line (U241 pin 19) determines which oscillator and buffer are enabled.

  • Page 19

    Frequency Generation Circuit Table 2-1 Level Shifter Logic Desired AUX 4 AUX 3 Mode High (@3.2V) High (@4.8V) High Battery Saver Hi-Z/Float (@2.5V) In the receive mode, U241 pin 19 is low or grounded. This activates the receive VCO by enabling the receive oscillator and the receive buffer of U241.

  • Page 20: Voice Storage (gp1280 Only)

    2-10 THEORY OF OPERATION Voice Storage (GP1280 Only) (Refer to Figure 2-6 and the UHF Voice Storage schematic diagram) The Voice Storage feature is offered as standard in the GP1280 and as an Option board for GP340/GP360/GP380 and GP640/GP680 models. The Voice Storage feature enables users to: Record and Playback Personal Memo (Reminders, Notes, etc.).

  • Page 21

    Voice Storage (GP1280 Only) 2-11 Audio routing to the Voice Storage circuitry during receive message recording, message playback, personal memo recording and voice prompt transmit over the air are as follows: Received Message Recording The receive audio is tapped from the Rx_Aud_Rtn pin of the ASFIC_CMP during receive mode. Message Playback Message playback is via the FLAT_RX_SND pin of ASFIC_CMP.

  • Page 22

    2-12 THEORY OF OPERATION...

  • Page 23: Troubleshooting Flow Chart For Receiver (sheet 1 Of 2)

    Chapter 3 TROUBLESHOOTING CHARTS Troubleshooting Flow Chart for Receiver (Sheet 1 of 2) START Bad SINAD Bad 20dB Quieting No Recovered Audio udio Check Controller at pin 27 of U301? Spray of inject 1st IF into XTAL Filter IF Freq: 45.1MHz Check Q320 bias circuitry for faults.

  • Page 24: Troubleshooting Flow Chart For Receiver (sheet 2 Of 2)

    TROUBLESHOOTING CHARTS Troubleshooting Flow Chart for Receiver (Sheet 2 of 2) Inject RF into J101 Q302 Trace IF signal collector OK? IF Signal from L311 to IF signal at L311? Q302. Check for present? bad XTAL filter. Before replacing U301, check U301 voltages;...

  • Page 25: Troubleshooting Flow Chart For Transmitter

    Troubleshooting Flow Chart for Transmitter Troubleshooting Flow Chart for Transmitter START No Power Is There B+ Bias for Check Q111 Ant switch CR101 Is Current Check PCIC Is Control Voltage High or Low at C119 High 1. Check Pin Diodes Check Drive to 2.

  • Page 26: Troubleshooting Flow Chart For Synthesizer

    TROUBLESHOOTING CHARTS Troubleshooting Flow Chart for Synthesizer 3.3V at Check U248, Start U201 pins 5, L201 & L202 20, 34& Check CR201, Visual U210, U211, Correct check of the C258, C259 & Problem Board OK? C228 Is U201 16.8MHz 16.8MHz at pin 6 of Pin47 AT = Replace...

  • Page 27: Troubleshooting Flow Chart For Vco

    Troubleshooting Flow Chart for VCO Troubleshooting Flow Chart for VCO START No LO? U241 Check R245 TRB = Pin 10 for dry joint 5V? @U241 Carrier? >1V? or faulty Pin 19 VCO OK L253 Change Open L253 Circuit? AUX 3 Check High? R260...

  • Page 28

    TROUBLESHOOTING CHARTS...

  • Page 29: Allocation Of Schematics And Circuit Boards

    Chapter 4 UHF PCB/SCHEMATICS/PARTS LISTS Allocation of Schematics and Circuit Boards Controller Circuits The UHF circuits are contained on the printed circuit board (PCB) which also contains the Controller circuits. This Chapter shows the schematics for the UHF circuits only, refer to the Controller section for details of the related Controller circuits.The PCB component layouts and the Parts Lists in this Chapter show both the Controller and UHF circuit components.

  • Page 30

    UHF PCB/SCHEMATICS/PARTS LISTS Table 4-2 UHF GP1280 Diagrams and Parts Lists PCB : 8480587Z01 Main Board Top Side Page 4-15 Main Board Bottom Side Page 4-16 SCHEMATICS Controls and Switches Page 4-5 Receiver Front End Page 4-6 Receiver Back End Page 4-7 Synthesizer Page 4-8...

  • Page 31

    Allocation of Schematics and Circuit Boards Table 4-4 UHF Diagrams and Parts Lists PCB : 8480450Z13/14 Main Board Top Side Page 4-31 Main Board Bottom Side Page 4-32 SCHEMATICS Controls and Switches Page 4-33 Receiver Front End Page 4-34 Receiver Back End Page 4-35 Synthesizer Page 4-36...

  • Page 32

    UHF PCB/SCHEMATICS/PARTS LISTS...

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