Motorola GP640 Service Information

iii
Table of Contents
Chapter 1 MODEL CHART AND TECHNICAL SPECIFICATIONS
1.0 GP640/GP680 Model Chart .................................................................................1-1
2.0 GP1280 Model Chart ...........................................................................................1-1
3.0 Technical Specifications ......................................................................................1-2
Chapter 2 THEORY OF OPERATION
1.0 Introduction ..........................................................................................................2-1
2.0 UHF2 Transmitter ................................................................................................2-1
2.1 Power Amplifier ..............................................................................................2-1
2.2 Antenna Switch...............................................................................................2-2
2.3 Harmonic Filter ...............................................................................................2-2
2.4 Antenna Matching Network ............................................................................2-2
2.5 Power Control Integrated Circuit (PCIC) ........................................................2-2
3.0 UHF2 Receiver ....................................................................................................2-3
3.1 Receiver Front-End ........................................................................................2-3
3.2 Receiver Back-End.........................................................................................2-4
3.3 Automatic Gain Control (AGC) .......................................................................2-5
4.0 Frequency Generation Circuit ..............................................................................2-6
4.1 Synthesizer.....................................................................................................2-7
4.2 Voltage Control Oscillator (VCO)....................................................................2-8
5.0 Voice Storage (GP1280 Only) ...........................................................................2-10
Chapter 3 TROUBLESHOOTING CHARTS
1.0 Troubleshooting Flow Chart for Receiver (Sheet 1 of 2)......................................3-1
2.0 Troubleshooting Flow Chart for Receiver (Sheet 2 of 2)......................................3-2
3.0 Troubleshooting Flow Chart for Transmitter ........................................................3-3
4.0 Troubleshooting Flow Chart for Synthesizer........................................................3-4
5.0 Troubleshooting Flow Chart for VCO...................................................................3-5
Chapter 4 UHF2 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 UHF2 PCB 8485641Z02 / Schematics ................................................................4-3
3.0 UHF2 PCB 8485641Z02 / PCB 8485677Z01 Parts List ...................................4-11
4.0 UHF2 PCB 8485677Z01 (GP1280) ...................................................................4-15
3.0 UHF2 PCB 8485677Z01 / PCB 8485641Z02 Parts List ..................................4-11
5.0 UHF2 PCB 8485677Z01 Voice Storage Parts List (GP1280)............................4-18

Motorola GP640 Specifications

Power

power supply	7.5 V
power 136-174	1-5W
power 403-470	1-4W
power 450-527	1-4W

Battery

average battery life with standard high capacity NiMH battery low power	11 hours
average battery life with standard high capacity NiMH battery high power	8 hours
average battery life with ultra high capacity NiMH battery low power	14 hours
average battery life with ultra high capacity NiMH battery high power	11 hours
average battery life with NiCD battery low power	12 hours
average battery life with NiCD battery high power	9 hours
average battery life with Li-lon battery low power	11 hours
average battery life with Li-lon battery high power	8 hours

Operating Environment

operating temperature	-20°C to +55°C
frequency stability	±2.5 ppm (-25°C to +55°C, +25°Ref.)
sealing	MIL STD 810 C/D/E and IP54

Transmitter

frequencies full bandsplit VHF	136-174 MHz
frequencies full bandsplit UHF 1	403-470 MHz
frequencies full bandsplit UHF 2	450-527 MHz
channel spacing	12.5/20/25 kHz
modulation limiting	±2.5 @ 12.5 kHz, ±4.0 @ 20 kHz, ±5.0 @ 25 kHz
FM hum & noise	-40 dB typical

Receiver

sensitivity (12 dB SINAD) EIA	.25 µV typical
sensitivity (20 dB SINAD) EN	.50 µV typical
intermodulation EIA	70 dB
adjacent channel selectivity	60 dB @ 12.5 kHz, 70 dB @ 20/25 kHz
spurious rejection	70 dB
rated audio	0.5W

Weight and Dimensions

dimensions with standard high capacity NiMH battery	137 x 57.5 x 37.5 mm
dimensions with ultra high capacity NiMH battery	137 x 57.5 x 40.0 mm
dimensions with NiCD battery	137 x 57.5 x 40.0 mm
dimensions with Li-lon battery	137 x 57.5 x 33.0 mm
weight with standard high capacity NiMH battery	420 gm
weight with ultra high capacity NiMH battery	500 gm
weight with NiCD battery	450 gm
weight with Li-lon battery	350 gm