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Motorola GP Series Service Information

Motorola GP Series Service Information

Professional radio, lowband 29.7-42mhz and 35-50mhz
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See also: Detailed Service Manual , Service Information
Professional Radio
GP Series
Lowband (29.7-42MHz and 35-50MHz)
Service Information
Issue: June 2002

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Summary of Contents for Motorola GP Series

  • Page 1 Professional Radio GP Series Lowband (29.7-42MHz and 35-50MHz) Service Information Issue: June 2002...
  • Page 2 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 GP340/GP380 Model Chart .................1-1 2.0 Technical Specifications ..................1-2 Chapter 2 THEORY OF OPERATION 1.0 Lowband Transmitter ...................2-1 1.1 Power Amplifier (PA) ..................2-1 1.2 Antenna Switch....................2-2 1.3 Harmonic Filter ....................2-2 1.4 Antenna Matching Network ................2-2 1.5 Power Control Integrated Circuit (PCIC) ............2-2 1.6 Temperature Cut Back Circuit ................2-2...

  • Page 5: Model Chart And Technical Specifications

    Chapter 1 MODEL CHART AND TECHNICAL SPECIFICATIONS GP340 / GP380 Model Chart Professional GP300 Series (LB) Model Description MDH25BEC9AN3_E GP340 LB1 29.7-42 MHz 6W 16-Ch MDH25BEH9AN6_E GP380 LB1 29.7-42 MHz 6W 255-Ch MDH25CEC9AN3_E GP340 LB2 35-50 MHz 6W 16-Ch MDH25CEH9AN6_E GP380 LB2 35-50 MHz 6W 255-Ch Item Description...

  • Page 6: Technical Specifications

    MODEL CHART AND TECHNICAL SPECIFICATIONS Technical Specifications Data is specified for +25°C unless otherwise stated. General Specifications Channel Capacity GP340 GP380 Power Supply Rechargeable battery 7.5v Dimensions: H x W x D (mm) Height excluding knobs With standard high capacity NiMH battery 137 x 57.5 x 37.5 With ultra high capacity NiMH battery 137 x 57.5 x 40.0...
  • Page 7 Technical Specifications Transmitter LB1 29.7-42 MHz *Frequencies - Full Bandsplit LB2 35-50 MHz Channel Spacing 12.5/20/25 kHz Frequency Stability ±10ppm (-25°C to +55°C, +25° Ref.) 1-6W Power ±2.5 @ 12.5 kHz Modulation Limiting ±4.0 @ 20 kHz ±5.0 @ 25 kHz FM Hum &...
  • Page 8 MODEL CHART AND TECHNICAL SPECIFICATIONS...

  • Page 9: Theory Of Operation

    Chapter 2 THEORY OF OPERATION Introduction This chapter provides a detailed theory of operation for the radio RF circuits. Refer to the relevant section of this manual for details of the operation of the Controller Circuits. Lowband Transmitter (Refer to Figure 2-1 and the Lowband Transmitter schematic diagram) The Lowband transmitter consists of the following basic circuits : Power amplifier (PA).

  • Page 10: Antenna Switch

    THEORY OF OPERATION The LDMOS PA is capable of supplying an output power of 8W with an input signal of 0.3W. The current drain is typically 2000 mA while operating in the frequency range of 29.7 - 50 MHz. The final stage gate is bias by a voltage from PCIC pin 24.

  • Page 11: Lowband Receiver

    Lowband Receiver Lowband Receiver (Refer to Figure 2-2 and the Receiver Front End and Receiver Back End schematic diagrams) The Lowband receiver consists of a front end, back end, and automatic gain control circuits. Detailed descriptions of these stages are contained in the paragraphs that follow. Antenna Lowpass Lowpass...

  • Page 12: Receiver Back-End

    THEORY OF OPERATION Receiver Back-End (Refer to the Receiver Back End schematic diagram) The output of crystal filter FL301 is connected to the input of IF amplifier transistor U301. Components L303 and C348 and R301 form the termination for the crystal filter and the signal is coupled to one gate of U301 by C303.

  • Page 13: Frequency Generation Circuit

    Frequency Generation Circuit Frequency Generation Circuit (Refer to Figure 2-3, the Synthesizer and Voltage controlled Oscillator schematic diagrams) The frequency generation circuit is composed of Low Voltage Fractional-N synthesizer U205 and discrete RX VCO, TX VCO and buffers as well other supporting circuitry. The synthesizer block diagram illustrates the interconnect and support circuitry used in the region.

  • Page 14: Synthesizer

    THEORY OF OPERATION Synthesizer (Refer to Figure 2-4 and the Synthesizer schematic diagram) The Fractional-N synthesizer, shown in Figure 2-4, uses a 17.0 MHz crystal (Y201) to provide a reference for the system. Along with being used in the LVFracN, the 17.0 MHz signal is provided at pin 19 of U205 for use by the ASFIC and LVZIF.

  • Page 15: Voltage Control Oscillator (Vco)

    Frequency Generation Circuit Voltage Controlled Oscillator (VCO) (Refer to the Voltage Controlled Oscillator schematic diagram) 4.2.1 Receive VCO The receive VCO is a Colpitts type design and using two active devices in parallel, Q202 and Q204. The oscillator is powered off of the 4.3 volt super filter supply when the AUX3 line goes low. The oscillator operates from 139 to 152 MHz for range 1 and 145 to 160 MHz for range 2.
  • Page 16 THEORY OF OPERATION...

  • Page 17: Troubleshooting Charts

    Chapter 3 TROUBLESHOOTING CHARTS Receiver (Sheet 1 of 2) START Bad SINAD Bad 20dB Quieting No Recovered Audio Audio at Check Controller pin 27 of U303? Spray of inject 1st IF into XTAL Filter IF Freq: 109.65 MHz Check Q301 bias circuitry for faults.

  • Page 18: Receiver (Sheet 2 Of 2)

    TROUBLESHOOTING CHARTS Receiver (Sheet 2 of 2) Inject RF into J101 Trace IF signal U301 drain signal at from L301 to U301. L301? Check for bad IF signal XTAL filter. present? Before replac- ing U303, check U303 voltages; 1st LO O/P trace IF signal Signal Check FGU...

  • Page 19: Transmitter

    Transmitter Transmitter START No Power Is control voltage Is Current Check PCIC at U101 Pin 1 > 5 ~ 2 A? Check input to U101, Pin 16 1. Check Pin Diodes 2. Check Harmonic Filter 3. Check PA Bias Troubleshoot Is voltage >...

  • Page 20: Synthesizer

    TROUBLESHOOTING CHARTS Synthesizer Check U400 3.3V at U205 Start and L225 pins 5, 20, 34 & 36 Visual Correct check of the Problem Board OK? Check C247, C249, Is U205 Is 17.0 MHz 17.0MHz C283-C286, Replace Pin 47 at D210, D211, Signal at signal at U205...

  • Page 21: Voltage Controlled Oscillator

    Voltage Controlled Oscillator Voltage Controlled Oscillator No RX LO or No No TX LO or No signal at U205 Pin signal at U205 Pin 32 in RX 32 in TX Check signal at Check signal at collector of Q201 collector of Q201 Check L204, L211, L212, Level >...
  • Page 22 TROUBLESHOOTING CHARTS...

  • Page 23: Schematics

    Chapter 4 LOWBAND PCB/SCHEMATICS/PARTS LIST Allocation of Schematics and Circuit Boards Controller Circuits The Lowband circuits are contained on the printed circuit board (PCB) which also contains the Controller circuits. This chapter shows the schematics for the Lowband circuits only, refer to the Controller section for details of the related Controller circuits.
  • Page 24 Lowband PCB/SCHEMATICS/PARTS LIST...

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Gp 300 seriesGp340Gp380

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