Motorola CDM1250 Service Manual

Section 11: i
6881091C63-F
Section 11: VHF (136–174 MHz) 25–45 W LDMOS
Service Information
Table of Contents
Chapter 1 Model Charts and Technical Specifications
1.0 VHF (136–174 MHz) 25–45 W LDMOS Model Charts ...................................11:1-1
1.1 CDM Series Model Chart ..........................................................................11:1-1
1.2 PRO Series Model Chart...........................................................................11:1-2
2.0 Technical Specifications .................................................................................11:1-2
Chapter 2 Theory of Operation
1.0 Introduction.....................................................................................................11:2-1
2.0 VHF (136–174 MHz) 25–45 W LDMOS Receiver Front-End .........................11:2-1
2.1 Receiver Front-End ...................................................................................11:2-1
2.2 Front-End Bandpass Filters and Pre-Amplifier..........................................11:2-2
2.3 First Mixer and 1st Intermediate Frequency (IF) .......................................11:2-2
2.4 2nd Intermediate Frequency (IF) and Receiver Back-End........................11:2-2
3.0 VHF (136–174 MHz) 25–45W LDMOS Transmitter Power Amplifier
(PA) 45 W .......................................................................................................11:2-3
3.1 Power Controlled Stage ............................................................................11:2-3
3.2 Driver Stage ..............................................................................................11:2-4
3.3 Final Stage ................................................................................................11:2-4
3.4 Antenna Switch .........................................................................................11:2-4
3.5 Harmonic Filter..........................................................................................11:2-5
3.6 Directional Coupler....................................................................................11:2-5
3.7 Power Control............................................................................................11:2-5
4.0 VHF (136–174 MHz) 25–45 W LDMOS Frequency Synthesis.......................11:2-5
4.1 Reference Oscillator..................................................................................11:2-6
4.2 Fractional-N Synthesizer...........................................................................11:2-6
4.3 Voltage Controlled Oscillator (VCO)..........................................................11:2-7
4.4 Synthesizer Operation...............................................................................11:2-8
Chapter 3 Troubleshooting Charts
1.0 Troubleshooting Flow Chart for Receiver .......................................................11:3-1
2.0 Troubleshooting Flow Chart for 45 W Transmitter..........................................11:3-3
3.0 Troubleshooting Flow Chart for Synthesizer...................................................11:3-6
4.0 Troubleshooting Flow Chart for VCO..............................................................11:3-7

Motorola CDM1250 Specifications

General

Display	Alphanumeric
IP Rating	IP54
Frequency Range	VHF: 136-174 MHz, UHF: 403-470 MHz
Signaling	PL, DPL, MDC1200, Quick Call II
Operating Temperature	-22°F to +140°F (-30°C to +60°C)
Power Output	VHF: 1-25W; UHF: 1-25W