Pace CB 123A User Manual

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Pace CB123A Service Manual
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Pace CB 123A Specifications

General

Brand	Pace
Model	CB 123A
Category	Transceiver
Language	English

Summary

General Information

General Description

Overview of the PACE Model CB 123A Mobile Transceiver features and design.

Technical Specifications

Details the performance parameters and electrical characteristics of the transceiver.

Crystal Information

Explains crystal usage, types, and their role in frequency synthesis for channel selection.

Other Pertinent Information

Covers type acceptance and compliance with regulatory standards.

Principles of Operation

Section II Overview

Introduces the section detailing the internal circuitry and operational concepts.

Transmitter Description

Explains the frequency generation, driver, and power amplifier stages of the transmitter.

Receiver Description

Details the double conversion superheterodyne receiver architecture and its functional blocks.

Noise Limiter

Describes the noise limiting circuit and its operation in clipping signal amplitude.

Squelch Amplifier

Explains how the squelch sensing voltage controls the audio amplifier gain.

Audio Amplifier

Details the AC coupled push-pull audio amplifier stage and its components.

Transmit-Receive Switching

Explains the relay-controlled system for switching between transmit and receive modes.

Oscillator Description

Details the three crystal oscillators and their role in channel frequency synthesis.

Maintenance

Section III Overview

Introduces the maintenance procedures for the transceiver.

Tools and Techniques

Lists recommended tools and general techniques for performing maintenance operations.

Parts Identification

Guides users to illustrations and schematics for identifying and locating components.

Preventive Maintenance

Recommends electrical checks for maintaining optimal operating efficiency.

Corrective Maintenance

Covers checks, adjustments, and component-level repairs for malfunctions.

Troubleshooting

Suggests a functional analysis approach to locate and resolve malfunctions.

Modulation Check

Provides methods for checking the audio modulation percentage of the transmitter.

Adjustment and Alignment

Section IV Overview

States the transceiver was factory aligned and when realignment is necessary.

Test Equipment

Lists the necessary instruments for performing alignment and service procedures.

Transmitter Alignment

Details the steps for tuning transmitter stages to ensure optimal performance.

Transmitter Preliminary Set-Up

Outlines the initial setup steps before performing transmitter adjustments.

Driver Alignment

Provides instructions for adjusting the driver stage for proper RF output.

Intermediate Power Amplifier Alignment

Details the procedure for aligning the IPA stage for maximum RF output.

Power Amplifier Alignment

Explains how to adjust the PA stage for optimal RF power output.

Receiver Alignment

Describes the process for aligning receiver stages using the S-meter indicator.

Receiver Preliminary Set-Up

Outlines the initial setup steps required before receiver alignment.

Receiver Alignment Steps

Details the specific steps to align receiver tuning stages for maximum signal indication.

Receiver Sensitivity Check

Explains how to verify receiver sensitivity using a signal generator.

Oscillator Adjustment

Provides instructions for adjusting the transceiver's oscillators for correct frequencies.

Q6 Oscillator Adjustment

Details the procedure for adjusting the Q6 oscillator circuit.

Q7 Oscillator Adjustment

Details the procedure for adjusting the Q7 oscillator circuit.

Q16 Oscillator Adjustment

Details the procedure for adjusting the Q16 oscillator circuit.

Meter Set Adjustment

Covers the calibration of the S-meter and RF meter using VR3 and VR5.

VR3 Adjustment

Details the procedure for adjusting VR3 for the initial meter indication.

VR5 Adjustment

Details calibrating the RF meter scale against a wattmeter reading.

Squelch Adjustment

Explains how to adjust the squelch control for effective noise muting.

Illustrations and Parts List

Section V Overview

Introduces the section containing diagrams and a list of electronic components.

Accessories