Motorola Gm328 Gm338 Gm398 Detailed 6804112j18 E Manual
Have a look at the manual Motorola Gm328 Gm338 Gm398 Detailed 6804112j18 E Manual online for free. It’s possible to download the document as PDF or print. UserManuals.tech offer 249 Motorola manuals and user’s guides for free. Share the user manual or guide on Facebook, Twitter or Google+.
GM328/GM338/GM398 Mobile Radios VHF (136-174MHz) Service Information Issue: December, 2003
Computer Software Copyrights The Motorola products described in this manual may include copyrighted Motorola computer programs stored in semiconductor memories or other media. Laws in the United States and other countries preserve for Motorola certain exclusive rights for copyrighted computer programs, including the exclusive right to copy or reproduce in any form, the copyrighted computer program. 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 products shall not be deemed to grant, either directly or by implication, estoppel or otherwise, any license under the copyrights, patents or patent applications of Motorola, except for the normal non-exclusive royalty- free license to use that arises by operation of law in the sale of a product.
i Table of Contents Section 1 Model Chart and Technical Specifications 1.0 GM328/GM338/GM398 Model Chart ................................................................... 1-1 2.0 Technical Specifications ...................................................................................... 1-2 Section 2 Theory of Operation 1.0 Introduction .......................................................................................................... 2-1 2.0 VHF (136-174 MHz) Receiver.............................................................................. 2-1 2.1 Receiver Front-End ........................................................................................ 2-1 2.2 Front-End Band-Pass Filters & Pre-Amplifier ................................................. 2-2 2.3 First Mixer and High Intermediate Frequency (IF) .......................................... 2-2 2.4 Low Intermediate Frequency (IF) and Receiver Back End ............................. 2-3 3.0 VHF (136-174 MHz) Transmitter Power Amplifier (PA) 25 W .............................. 2-3 3.1 First Power Controlled Stage.......................................................................... 2-4 3.2 Power Controlled Driver Stage ....................................................................... 2-4 3.3 Final Stage ..................................................................................................... 2-4 3.4 Directional Coupler ......................................................................................... 2-5 3.5 Antenna Switch............................................................................................... 2-5 3.6 Harmonic Filter ............................................................................................... 2-5 3.7 Power Control ................................................................................................. 2-5 4.0 VHF (136-174 MHz) Frequency Synthesis .......................................................... 2-6 4.1 Reference Oscillator ....................................................................................... 2-6 4.2 Fractional-N Synthesizer ................................................................................ 2-6 4.3 Voltage Controlled Oscillator (VCO) ............................................................... 2-7 4.4 Synthesizer Operation .................................................................................... 2-8 Section 3 Troubleshooting Charts 1.0 Troubleshooting Flow Chart for Receiver ............................................................ 3-1 2.0 Troubleshooting Flow Chart for 25W Transmitter ................................................ 3-3 3.0 Troubleshooting Flow Chart for Synthesizer ........................................................ 3-6 4.0 Troubleshooting Flow Chart for VCO ................................................................... 3-7
ii Section 4 VHF PCBs/Schematics/Parts Lists 1.0 Allocation of Schematics and Circuit Boards ....................................................... 4-1 1.1 Controller Circuits ........................................................................................... 4-1 2.0 VHF 1-25W PCBs / Schematics / Parts Lists ...................................................... 4-3 VHF (136-174 MHz) 1-25W 8486172B06 Top Side .............................................. 4-3 VHF (136-174 MHz) 1-25W 8486172B06 Bottom Side ......................................... 4-4 VHF (136-174 MHz) Power Amplifier 1-25W.......................................................... 4-5 VHF (136-174 MHz) FRACN .................................................................................. 4-6 VHF (136-174 MHz) Voltage Controlled Oscillator ................................................. 4-7 VHF (136-174 MHz) Receiver Front End ............................................................... 4-8 VHF (136-174 MHz) IF ........................................................................................... 4-9 VHF PCB 8486172B06 Parts List 1-25W ............................................................. 4-10 VHF (136-174 MHz) 1-25W 8486172B07 Top Side ............................................ 4-13 VHF (136-174 MHz) 1-25W 8486172B07 Bottom Side ....................................... 4-14 VHF (136-174 MHz) IF ......................................................................................... 4-15 VHF (136-174 MHz) FRACN ................................................................................ 4-16 VHF PCB 8486172B07 Parts List 1-25W ............................................................. 4-17
1-1 Section 1 MODEL CHART AND TECHNICAL SPECIFICATIONS 1.0 GM328/GM338/GM398 Model Chart GM Series, VHF 136-174 MHz Model Description AZM25KHC9AA1GM328 136-174 MHz 1-25W AZM25KHF9AA5 GM338 136-174 MHz 1-25W AZM25KHN9AA8GM398 136-174 MHz 1-25W Item Description X GCN6112_ GM328 Control Head Direct Mount XGCN6114_GM338 Control Head Direct Mount X GCN6115_ GM398 Control Head Direct Mount XXIMUD6010_Tanapa WM 136-174 MHz 1-25W X IMUD6023_ Tanapa WM 136-174 MHz 1-25W XXXRAD4198_BNC 136-144 MHz, 1/4 Wave Roof Mount XXXRAD4199_ BNC 146-150.8 MHz, 1/4 Wave Roof Mount XXXRAD4200_BNC 150.8-162 MHz, 1/4 Wave Roof Mount XXXRAD4201_ BNC 162-174 MHz, 1/4 Wave Roof Mount XXXRAD4202_BNC 146-172 MHz, 3dB Gain Roof Mount X 6804113J74 GM328 User Guide X6804112J06GM338 User Guide X 6804112J07 GM398 User Guide x = Indicates one of each is required.
1-2Technical Specifications 2.0 Technical Specifications Data is specified for +25°C unless otherwise stated. General Specifications Channel Capacity GM328 GM338 GM398 4 128 160 Power Supply 13.2Vdc (10.8 - 15.6Vdc) Dimensions: H x W x D (mm) Depth excluding knobsGM328 56mm x 176mm x 177mm (add 8mm for Volume Knob) Dimensions: H x W x D (mm) Depth excluding knobsGM338 59mm x 179mm x 186mm (1 - 25W) 59mm x 179mm x 198mm (25 - 45W) (add 9mm for Volume Knob) Dimensions: H x W x D (mm) Depth excluding knobsGM398 72mm x 185mm x 188mm (add 7mm for Volume Knob) Weight GM328/GM338 1400 g Weight GM398 1500 g Sealing: Withstands rain testing per MIL STD 810 C/D /E and IP54 Shock and Vibration: Protection provided via impact resistant housing exceeding MIL STD 810-C/D /E Dust, Salt & Fog Protection provided via environment resistant housing exceeding MIL STD 810 C/D /E
Technical Specifications1-3 *Availability subject to the laws and regulations of individual countries.Transmitter VHF *Frequencies - Full BandsplitVHF 136-174 MHz Channel Spacing12.5/20/25 kHz Frequency Stability (-30°C to +60°C, +25° Ref.)±2.5 ppm Power 1-25W Modulation Limiting ±2.5 @ 12.5 kHz ±4.0 @ 20 kHz ±5.0 @ 25 kHz FM Hum & Noise-40 dB @ 12.5kHz -45 dB @ 20/25kHz Conducted/Radiated Emission (ETS)-36 dBm 1 GHz Adjacent Channel Power-60 dB @ 12.5 kHz -70 dB @ 25 kHz Audio Response (300 - 3000Hz)+1 to -3 dB Audio Distortion @1000Hz, 60% Rated Maximum Deviation65 dB Base Mode: >70dB (1-25W model only) Adjacent Channel Selectivity (ETS) 65 dB @ 12.5 kHz 75 dB @ 20 kHz 80 dB @ 25 kHz Spurious Rejection (ETS)75 dB @ 12.5 kHz 80 dB @ 20/25 kHz Rated Audio3W Internal 13W External Audio Distortion @ Rated Audio
1-4Technical Specifications THIS PAGE INTENTIONALLY LEFT BLANK
2-1 Section 2 THEORY OF OPERATION 1.0 Introduction This Chapter provides a detailed theory of operation for the VHF circuits in the radio. For details of the theory of operation and troubleshooting for the the associated Controller circuits refer to the Controller Section of this manual. 2.0 VHF (136-174 MHz) Receiver 2.1 Receiver Front-End The receiver is able to cover the VHF range from 136 to 174 MHz. It consists of four major blocks: front-end bandpass filters and pre-amplifier, first mixer, high-IF, low-IF and receiver back-end. Two varactor-tuned bandpass filters perform antenna signal pre-selection. A cross over quad diode mixer converts the signal to the first IF of 44.85 MHz. High-side first injection is used. Figure 2-1 VHF Receiver Block Diagram Demodulator 1. Crystal Filter Mixer Va r a c t o r Tuned Filter RF Amp Va r a c t o r Tuned Filter Antenna Control Voltage from PCICFirst LO from FGU Recovered Audio RSSI IF Second LO 2. Crystal Filter 455kHz Filter (25kHz)455kHz Filter (25kHz) 455kHz Filter (12.5kHz)455kHz Filter (12.5kHz)SwitchSwitchSwitchSwitch Limiter 1. IF Amp 2. IF Amp Filter Bank Selection from Synthesizer IC Pin Diode Antenna Switch RF Jack Harmonic Filter
2-2VHF (136-174 MHz) Receiver There are two 2-pole 44.85 MHz crystal filters in the high-IF section and 2 pairs of 455 kHz ceramic filters in the low-IF section to provide the required adjacent channel selectivity. The correct pair of ceramic filters for 12.5 or 25kHz channel spacing is selected via control line BWSELECT. The second IF at 455 kHz is mixed, amplified and demodulated in the IF IC. The processing of the demodulated audio signal is performed by an audio processing IC located in the controller section. 2.2 Front-End Band-Pass Filters & Pre-Amplifier The received signal from the radio’s antenna connector is first routed through the harmonic filter and antenna switch, which are part of the RF power amplifier circuitry, before being applied to the receiver pre-selector filter (C3001, C3002, D3001 and associated components). The 2-pole pre- selector filter tuned by the dual varactor diode D3001 pre-selects the incoming signal (RXIN) from the antenna switch to reduce spurious effects to following stages. The tuning voltage (FECNTL_1) ranging from 2 volts to 8 volts is controlled by pin 20 of PCIC (U3501) in the Transmitter section. A dual hot carrier diode (D3003) limits any inband signal to 0 dBm to prevent damage to the pre- amplifier. The RF pre-amplifier is an SMD device (Q3001) with collector-base feedback to stabilize gain, impedance, and intermodulation. Transistor Q3002 compares the voltage drop across resistor R3002 with a fixed base voltage from divider R3011, R3000 and R3012, and adjusts the base current of Q3001 as necessary to maintain its collector current constant at approximately 15-20 mA. Operating voltage is from the regulated 9.3V supply (9V3). During transmit, 9.1 volts (K9V1) turns off both transistors Q3002 and Q3001. This protects the RF pre-amplifier from excessive dissipation during transmit mode. A switchable 3dB pad (R3022, R3024, R3016 and R3018) controlled via Line FECNTL_2 and Q3021 stabilizes the output impedance and intermodulation performance. A second 2-pole varactor tuned bandpass filter provides additional filtering of the amplified signal. The dual varactor diode D3004 is controlled by the same signal FECNTL_1, which controls the pre- selector filter. 2.3 First Mixer and High Intermediate Frequency (IF) The signal coming from the front-end is converted to the high-IF frequency of 44.85 MHz using a cross over quad diode mixer (D3031). Its ports are matched for incoming RF signal conversion to the 44.85 MHz IF using high side injection. The high-side injection signal (RXINJ) from the frequency synthesizer circuitry has a level of approximately 13 dBm and is injected via matching transformer T3002. The mixer IF output signal (IF) from transformer T3001 pin 2 is fed to the first two pole crystal filter FL3101. The filter output in turn is matched to the following IF amplifier. The IF amplifier Q3101 is actively biased by a collector base feedback (R3101, R3106) to a current drain of approximately 5 mA drawn from the voltage 5V. Its output impedance is matched to the second two pole crystal filter FL3102. The signal is further amplified by a preamplifier (Q3102) before going into pin 1 of IFIC (U3101). A dual hot carrier diode (D3101) limits the filter output voltage swing to reduce overdrive effects at RF input levels above -27 dBm.