Signal Generators: Applications and Use--Intro and Article Index

Sections of this Guide

SECTION 1: BASIC PRINCIPLES

Signal-Generator Features - Mode of Operation - Amplitude Modulation - General Shielding Considerations - Uhf Signal Generators - Transistorized Signal Generators - Signal Generator and Signal Tracer - Frequency-Synthesizer Generators

SECTION 2: GENERATOR ACCURACY AND CALIBRATION

Frequency Calibration and Accuracy Ratings - Low-Band Calibration - High-Band Calibration - Dual-Crystal Calibrators - Inter-harmonic Beats--Equalization of Harmonic Amplitudes Measurement of Generator Output Voltage - Measurement of Harmonic Amplitudes--Counter Calibration

SECTION 3: MODULATION OF GENERATOR SIGNAL

Sine-Wave Amplitude Modulation-Maximum R-f Output-Variable Modulating Frequency - Harmonic Distortion - Square Wave Modulation of Signal Generator-Frequency Modulation of Signal Generators - Video Sweep Modulation-Specialized Types of Pulse Modulation

SECTION 4: UHF SIGNAL GENERATORS

Oscillator Tuning-Feedback Considerations-Plate-Tuning Considerations-Effect on Frequency-Lead Inductance-Transit Time--Uhf Tubes-Limitations in External Circuits-Klystron Oscillator-Electrical Tuning-Attenuators-Uhf Signal Generator Modulation

SECTION 5: FM STEREO MULTIPLEX SIGNAL GENERATORS

Fundamentals of Stereo Multiplexing-Formation of L and R Signals- FM Stereo Multiplex Signal Generator-Stereo-Signal Generation With Balanced Modulators

SECTION 6: SPECIALIZED TYPES OF SIGNAL GENERATORS

Accuracy Considerations-Operation as a Heterodyne Frequency Meter-Operation as a Wavemeter-Operation as an Auxiliary Signal Generator-Modulation of a Grid-Dip Meter-Harmonic Response of Stubs-Analyzer Type of Generator-Transistor Radio Analyzer-Radio Test Sets

SECTION 7: SUPERSONIC GENERATORS

Basic Circuitry-Wien-Bridge Oscillator-Beat-Frequency Generators

(NOTE: This guide is based on the 1965 Howard W. Sams book: Know Your Signal Generators by ROBERT G. MIDDLETON. Although dated, much of the theoretical material is applicable to modern signal generator design.)

Overview

Signal generators are some of the most frequently used test equipment in modern electronics work: AM generators are used for alignment and signal-injection tests of broadcast radio receivers. Standard signal generators are used in maintenance and troubleshooting of two-way radio units and other communications equipment. Marker generators with crystal calibrating facilities are often combined with FM generators for alignment of FM radio and TV receivers, and uhf signal generators are finding increased application. FM stereo multiplex generators are required for adjusting and troubleshooting stereo-broadcast receivers and adapters. Specialized types of signal generators, such as dip meters, long favored by radio amateurs, are also widely used in radio and TV service shops.

Another specialized signal generator, called an analyzer, has recently found wide acceptance.

Because of the extensive applications of generators, a thorough understanding of the operating principles, capabilities, and maintenance of the various types of signal generators is essential. Since electronics technology is expanding rapidly, newcomers are entering the field at an unprecedented rate.

Hence, this guide is written for the beginner as well as the old-timer who wants to know what makes the newer types of generators "tick." In this guide you will find explanations of generator circuits, some of the more basic applications, how to calibrate the various bands, analysis of common troubles, and practical tips on how to keep a generator in top operating condition.

Most signal generators employ vacuum tubes; however, there is a definite trend toward the use of transistorized circuitry, particularly in FM stereo multiplex generators. Accordingly, this topic is given appropriate coverage. Semiconductor-diode modulators are also detailed, inasmuch as they are now used extensively in service shops and laboratories.

There is also a definite trend toward the use of all-electronic FM generator circuitry, and consideration is given to permeability-tuned oscillators, as well as junction-diode frequency modulators.

Topical treatment is practical throughout, with a minimum of mathematics. It is assumed that the reader has a basic knowledge of Ohm's law for DC and AC circuits. Theory is presented only when it is necessary to clarify practical considerations. Professional technicians, apprentices, students in technical schools, hams, and hobbyists will find that this guide "speaks their language."

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