Radiotron Designer's Handbook

CHAPTER HEADINGS

PREFACE & ACKNOWLEDGEMENTS

PART 1: THE RADIO VALVECHAPTER PAGE 1 INTRODUCTION TO THE RADIO VALVE 1 2 VALVE CHARACTERISTICS 13 3 THE TESTING OF OXIDE-COATED CATHODE HIGH-VACUUM RECEIVING VALVES 68

PART 2: GENERAL THEORY AND COMPONENTS 4 THEORY OF NETWORKS 128 5 TRANSFORMERS AND IRON-CORED INDUCTORS 199 6 MATHEMATICS 254 7 NEGATIVE FEEDBACK 306 8 WAVE MOTION AND THE THEORY OF MODULATION 403 9 TUNED CIRCUITS 40710 CALCULATION OF INDUCTANCE 42911 DESIGN OF RADIO FREQUENCY INDUCTORS 450

PART 3: AUDIO FREQUENCIES12 AUDIO FREQUENCY VOLTAGE AMPLIFIERS 48113 AUDIO FREQUENCY POWER AMPLIFIERS 54414 FIDELITY AND DISTORTION 60315 TONE COMPENSATION AND TONE CONTROL 63516 VOLUME EXPANSION, COMPRESSION AND LIMITING 67917 REPRODUCTION FROM RECORDS 70118 MICROPHONES, PRE-AMPLIFIERS, ATTENUATORS AND MIXERS 77519 UNITS FOR THE MEASUREMENT OF GAIN AND NOISE 80620 LOUDSPEAKERS 83121 THE NETWORK BETWEEN THE POWER OUTPUT STAGE AND THE LOUDSPEAKER 880

PART 4: RADIO FREQUENCIES22 AERIALS AND TRANSMISSION LINES 89023 RADIO FREQUENCY AMPLIFIERS 91224 OSCILLATORS 94725 FREQUENCY CONVERSION AND TRACKING 96226 INTERMEDIATE FREQUENCY AMPLIFIERS 102027 DETECTION AND AUTOMATIC VOLUME CONTROL 107228 REFLEX AMPLIFIERS 114029 LIMITERS AND AUTOMATIC FREQUENCY CONTROL 1147

PART 5: RECTIFICATION, REGULATION, FILTERING AND HUM30 RECTIFICATION 116131 FILTERING AND HUM 119232 VIBRATOR POWER SUPPLIES 120233 CURRENT AND VOLTAGE REGULATORS 1213

PART 6: COMPLETE RECEIVERS34 TYPES OF A-M RECEIVERS 122335 DESIGN OF SUPERHETERODYNE A-M RECEIVERS 122836 DESIGN OF F-M RECEIVERS 128737 RECEIVER AND AMPLIFIER TESTS AND MEASUREMENTS 1297

PART 7: SUNDRY DATA38 TABLES, CHARTS AND SUNDRY DATA 1328

See next page for detailed List of Contents.SUPPLEMENT 1475

INDEX 1433(ix)

CONTENTS

PART 1 : THE RADIO VALVE

CHAPTER 1. INTRODUCTION TO THE RADIO VALVESECTION PAGE 1. ELECTRICITY AND EMISSION 1 2. THE COMPONENT PARTS OF RADIO VALVES 4

(i) Filaments, cathodes and heaters 4(ii) Grids 5(iii) Plates 5(iv) Bulbs 5(v) Voltages with valve operation 5

3. TYPES OF RADIO VALVES 6(i) Diodes 6(ii) Triodes 7(iii) Tetrodes 7(iv) Pentodes 7(v) Pentode power amplifiers 8(vi) Combined valves 8(vii) Pentagrid converters 8

4. MAXIMUM RATINGS AND TOLERANCES 9(i) Maximum ratings and their interpretation 9(ii) Tolerances 9

5. FILAMENT AND HEATER VOLTAGE/CURRENT CHARACTERISTICS 10 6. VALVE NUMBERING SYSTEMS 10 7. REFERENCES 12

CHAPTER 2. VALVE CHARACTERISTICS 1. VALVE COEFFICIENTS 13 2. CHARACTERISTIC CURVES 15

(i) Plate characteristics 15(ii) Mutual characteristics 17(iii) Grid current characteristics 18(iv) Suppressor characteristics 21(v) Constant current curves 22(vi) "G" curves 23(vii) Drift of characteristics during life 23(viii) Effect of heater-voltage variation 24

3. RESISTANCE-LOADED AMPLIFIERS 24(i) Triodes 24(ii) Pentodes 26

4. TRANSFORMER-COUPLED AMPLIFIERS 27(i) With resistive load 27(ii) Effect of primary resistance 28(iii) With i-f voltage amplifiers 28(iv) R-F amplifiers with sliding screen 28

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CONTENTSSECTION PAGE

(v) Cathode loadlines 29(vi) With reactive loads 30

5. TRIODE OPERATION OF PENTODES 34(i) Triode operation of pentodes 34(ii) Examples of transconductance calculation 34(iii) Triode amplification factor 35(iv) Plate resistance 36(v) Connection of suppressor grid 36

6. CONVERSION FACTORS, AND THE CALCULATION OF CHARACTERISTICS OTHERTHAN THOSE PUBLISHED 36

(i) The basis of valve conversion factors 36(ii) The use of valve conversion factors 37(iii) The calculation of valve characteristics other than those pub-

lished 40(iv) The effect of changes in operating conditions 42

7. VALVE EQUIVALENT CIRCUITS AND VECTORS 45(i) Constant voltage equivalent circuit 45(ii) Constant current equivalent circuit 46(iii) Valve vectors 47

8. VALVE ADMITTANCES 49(i) Grid input impedance and admittance 49(ii) Admittance coefficients 50(iii) The components of grid admittance-input resistance-

input capacitance-grid input admittance 51(iv) Typical values of short-circuit input conductance 55(v) Change of short-circuit-input capacitance with transconduct-

ance 55(vi) Grid-cathode capacitance 56(vii) Input capacitances of pentodes (published values) 56(viii) Grid-plate capacitance 57

9. MATHEMATICAL RELATIONSHIPS 57(i) General 57(ii) Resistance load 58(iii) Power and efficiency 59(iv) Series expansion; resistance load 61(v) Series expansion; general case 63(vi) The equivalent plate circuit theorem 63(vii) Dynamic load line-general case- 64(viii) Valve networks-general case- 64(ix) Valve coefficients as partial differentials 64(x) Valve characteristics at low plate currents 65

10. REFERENCES 66

CHAPTER 3. THE TESTING OF OXIDE-COATED CATHODEHIGH-VACUUM RECEIVING VALVES

1. BASIS OF TESTING PRACTICE 68(i) Fundamental physical properties 69(ii) Basic functional characteristics 70(iii) Fundamental characteristic tests 73(iv) Valve ratings and their limiting effect on operation 75

(A) Limiting ratings 75(B) Characteristics usually rated 75(C) Rating systems 77(D) Interpretation of maximum ratings 77(E) Operating conditions 80

(v) Recommended practice and operation 80(a) Mounting 80(b) Ventilation 81

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(c) Heater-cathode insulation 81(d) Control grid circuit resistance 82(e) Operation at low screen voltages 84(f) Microphony 84(g) Hum 84(h) Stand-by operation 84

2. CONTROL OF CHARACTERISTICS DURING MANUFACTURE 85(i) Importance of control over characteristics 85(ii) Basic manufacturing test specification 85(iii) Systematic testing 86(iv) Tolerances on characteristics 88

3. METHODS OF TESTING CHARACTERISTICS 89(i) General conventions 90(ii) General characteristics 91

(a) Physical dimensions 91(b) Shorts and continuity 91(c) Heater (or filament) current 93(d) Heater to cathode leakage 94(e) Inter-electrode insulation 94(f) Emission 94(g) Direct inter-electrode capacitances 95

(iii) Specific diode characteristics 99(a) Rectification test 99(b) Sputter and arcing 100(c) Back emission 100(d) Zero signal or standing diode current 101

(iv) Specific triode, pentode and beam tetrode characteristics 101(A) Reverse grid current 101(B) Grid current commencement voltage 102(C) Positive grid current 102(D) Positive voltage electrode currents 103(E) Transconductance or mutual conductance 103(F) Amplification factor 104(G) Plate resistance 104(H) A.C. amplification 105(I) Power output 105(J) Distortion 106(K) Microphony 107(L) Audio frequency noise 107(M) Radio frequency noise 107(N) Blocking 107(O) Stage gain testing 108(P) Electrode dissipation 108

(v) Specific converter characteristics 108(A) Methods of operation including oscillator excitation 108

(1) Oscillator self-excited 108(2) Oscillator driven 109(3) Static operation 109

(B) Specific characteristics 109(a) Reverse signal grid current 109(b) Signal-grid current commencement 109(c) Mixer positive voltage electrode currents 109(d) Mixer conversion transconductance 109(e) Mixer plate resistance 111(f) Mixer transconductance 111(g) Oscillator grid current 111

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(h) Oscillator plate current 113(i) Oscillator transconductance 113(j) Oscillator amplification factor 113(k) Oscillator plate resistance 113(1) Signal-grid blocking 113(m) Microphony 113(n) R-F noise 113

(vi) Tests for special characteristics 113(A) Short-circuit input admittance 113(B) Short-circuit feedback admittance 117(C) Short-circuit output admittance 117(D) Short-circuit forward admittance 117(E) Perveance 117

(vii) Characteristics by pulse methods-point by point - 118(viii) Characteristics by curve tracer methods 119

4. ACCEPTANCE TESTING 120(i) Relevant characteristics 120(ii) Valve specifications 120(iii) Testing procedure 120

5. SERVICE TESTING AND SERVICE TESTER PRACTICE 121(i) Purpose and scope of service testing and discussion of as-

sociated problems 121(ii) Fundamental characteristics which should be tested 122(iii) Types of commercial testers 122(iv) Methods of testing characteristics in commercial service testers 123

(a) Shorts testing 123(b) Continuity testing 123(c) Heater to cathode leakage 123(d) Emission testing 123(e) Mutual conductance testing 123(f) Plate conductance testing 124(g) Reverse grid current testing 124(h) Power output testing 124(i) Conversion conductance testing 124(j) Oscillator mutual conductance testing 124(k) Noise testing 124(1) A.C. amplification testing 124

(v) A.C. versus d.c. electrode voltages in testers 124(vi) Pre-heating 125(vii) Testing procedure 125

6. REFERENCES 125

PART 2: GENERAL THEORY AND COMPONENTSCHAPTER 4. THEORY OF NETWORKS

1. CURRENT AND VOLTAGE 128(i) Direct current 128(ii) Alternating current 129(iii) Indications of polarity and current flow 130

2. RESISTANCE 130(i) Ohm's Law for d.c. 130(ii) Ohm's Law for a.c. 131(iii) Resistances in series 131(iv) Resistances in parallel 132(v) Conductance in resistive circuits 133

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CONTENTSSECTION PAGE 3. POWER 133

(i) Power in d.c. circuits 133(ii) Power in resistive a.c. circuits 133

4. CAPACITANCE 134(i) Introduction to capacitance 134(ii) Condensers in parallel and series 135(iii) Calculation of capacitance 135(iv) Condensers in d.c. circuits 136(v) Condensers in a.c. circuits 137

5. INDUCTANCE 140(i) Introduction to inductance 140(ii) Inductances in d.c. circuits 141(iii) Inductances in series and parallel 141(iv) Mutual inductance 142(v) Inductances in a.c. circuits 142(vi) Power in inductive circuits 143

6. IMPEDANCE AND ADMITTANCE 144(i) Impedance, a complex quantity 144(ii) Series circuits with L, C and R 144(iii) Parallel combinations of L, C and R 147(iv) Series-parallel combinations of L, C and R 149(v) Conductance, susceptance and admittance 153(vi) Conversion from series to parallel impedance 157

7. NETWORKS 158(i) Introduction to networks 158(ii) Kirchhoff's Laws 160(iii) Potential dividers 161(iv) Thevenin's Theorem 164(v) Norton's Theorem 165(vi) Maximum Power Transfer Theorem 165(vii) Reciprocity Theorem 165(viii) Superposition Theorem 165(ix) Compensation Theorem 166(x) Four-terminal networks 166(xi) Multi-mesh networks 167(xii) Non-linear components in networks 170(xiii) Phase shift networks 170(xiv) Transients in networks 171(xv) References to networks 171

8. FILTERS 172(i) Introduction to filters 172(ii) Resistance-capacitance filters, high-pass and low-pass 172(iii) Special types of resistance-capacitance filters 176(iv) Iterative impedances of four terminal networks 176(v) Image impedances and image transfer constant of four ter-

minal networks 177(vi) Symmetrical networks 179(vii) "Constant k " filters 179(viii) M-derived filters 182(ix) Practical filters 184(x) Frequency dividing networks 184(xi) References to filters 185

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CONTENTSSECTION PAGE9. PRACTICAL RESISTORS, CONDENSERS AND INDUCTORS 186

(i) Practical resistors 186(ii) Practical condensers 191(iii) Combination units 197(iv) Practical inductors 197(v) References to practical resistors and condensers 198

CHAPTER 5. TRANSFORMERS AND IRON-CORED INDUCTORS 1. IDEAL TRANSFORMERS 199

(i) Definitions 199(ii) Impedance calculations-single load- 200(iii) Impedance calculations-multiple loads- 201

2. PRACTICAL TRANSFORMERS 204(i) General considerations 204(ii) Effects of losses 205

3. AUDIO-FREQUENCY TRANSFORMERS 206(i) General considerations 206(ii) Core materials 207(iii) Frequency response and distortion

(a) Interstage transformers 209(b) Low level transformers 210(c) Output transformers 211

(iv) Designing for low leakage inductance 217(v) Winding capacitance 219(vi) Tests on output transformers 227(vii) Specifications for a-f transformers 228

4. MAGNETIC CIRCUIT THEORY 229(i) Fundamental magnetic relationships 229(ii) The magnetic circuit 231(iii) Magnetic units and conversion factors 232

5. POWER TRANSFORMERS 233(i) General 233(ii) Core material and size 234(iii) Primary and secondary turns 235(iv) Currents in windings 236(v) Temperature rise 236(vi) Typical design 237(vii) Specifications for power transformers 241

6. IRON-CORED INDUCTORS 242(i) General 242(ii) Calculations-general- 242(iii) Effective permeability 243(iv) Design with no d.c. flux 243(v) Design of high Q inductors 245(vi) Design with d.c. flux 247(vii) Design by Hanna's method 248(viii) Design of inductors for choke-input filters 249(ix) Measurements 250(x) Iron-cored inductors in resonant circuits 251

7. REFERENCES 252

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CHAPTER 6. MATHEMATICS 1. ARITHMETIC AND THE SLIDE RULE 255

(i) Figures 255(ii) Powers and roots 255(iii) Logarithms 255(iv) The slide rule 257(v) Short cuts in arithmetic 258

2. ALGEBRA 259(i) Addition 260(ii) Subtraction 260(iii) Multiplication 260(iv) Division 260(v) Powers 260(vi) Roots 261(vii) Brackets and simple manipulations 261(viii) Factoring 262(ix) Proportion 262(x) Variation 262(xi) Inequalities 262(xii) Functions 263(xiii) Equations 263(xiv) Formulae and laws 265(xv) Continuity and limits 265(xvi) Progressions, sequences and series 266(xvii) Logarithmic and exponential functions 267(xviii) Infinite series 268(xix) Hyperbolic functions 269(xx) General approximations 271

3. GEOMETRY AND TRIGONOMETRY 272(i) Plane figures 272(ii) Surfaces and volumes of solids 275(iii) Trigonometrical relationships 275

4. PERIODIC PHENOMENA 278

5. GRAPHICAL REPRESENTATION AND j NOTATION 279(i) Graphs 279(ii) Finding the equation to a curve 281(iii) Three variables 281(iv) Vectors and j notation 282

6. COMPLEX ALGEBRA AND DE MOIVRE'S THEOREM 285(i) Complex algebra with regular coordinates 285(ii) Complex algebra with polar coordinates 286(iii) De Moivre's Theorem 287

7. DIFFERENTIAL AND INTEGRAL CALCULUS 289(i) Slope and rate of change 289(ii) Differentiation 291(iii) Integration 294(iv) Taylor's Series 298(v) Maclaurin's Series 299

8. FOURIER SERIES AND HARMONICS 299(i) Periodic waves and the Fourier Series 299(ii) Other applications of the Fourier Series 302(iii) Graphical Harmonic Analysis 302

9. REFERENCES 304

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CHAPTER 7. NEGATIVE FEEDBACK 1. FUNDAMENTAL TYPES OF FEEDBACK 306

(i) Feedback positive and negative 306(ii) Negative voltage feedback at the mid-frequency 307(iii) Negative current feedback at the mid-frequency 312(iv) Bridge negative feedback at the mid-frequency 313(v) Combined positive and negative at the mid-frequency 314(vi) Comparison between different fundamental types at the mid-

frequency 315 2. PRACTICAL FEEDBACK CIRCUITS 316

(i) The cathode follower 316(ii) The cathode degenerative amplifier and phase splitter 327(iii) Voltage feedback from secondary of output transformer 330(iv) Voltage feedback from plate-transformer input- 332(v) Voltage feedback from plate-r.c.c. input- 332(vi) Voltage feedback over two stages 334(vii) Voltage feedback over three stages 344(viii) Cathode coupled phase inverters and amplifiers 347(ix) Hum 348(x) Some special features of feedback amplifiers 352(xi) Combined positive and negative feedback 352(xii) Choke-coupled phase inverter 355

3. STABILITY, PHASE SHIFT AND FREQUENCY RESPONSE 356(i) Stability and instability 356(ii) Conditions for stability 356(iii) Relationship between phase shift and attenuation 359(iv) Design of 1 and 2 stage amplifiers 364(v) Design of multistage amplifiers 365(vi) Effect of feedback on frequency response 378(vii) Design of amplifiers with flat frequency response 379(viii) Constancy of characteristics with feedback 388(ix) Effect of feedback on phase shift 389

4. SPECIAL APPLICATIONS OF FEEDBACK 389 5. VALVE CHARACTERISTICS AND FEEDBACK 390

(i) Triode cathode follower 390(ii) Pentode cathode follower 393(iii) Triode with voltage feedback 394(iv) Pentode with voltage feedback, transformer coupled 395(v) Cathode degenerative triode 397(vi) Cathode degenerative pentode 399(vii) Cathode-coupled triodes 399(viii) Feedback over two stages 399

6. REFERENCES TO FEEDBACK 399 7. OVERLOADING OF FEEDBACK AMPLIFIERS ON TRANSIENTS 1477

CHAPTER 8. WAVE MOTION AND THE THEORY OFMODULATION

1. INTRODUCTION TO ELECTROMAGNETIC WAVES 403(i) Wave motion 403(ii) Electromagnetic spectrum 404(iii) Wave propagation 404

2. TRANSMISSION OF INTELLIGENCE 405(i) Introduction 405(ii) Radio telegraphy 405(iii) Radio telephony 405

3. REFERENCES 406

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CHAPTER 9. TUNED CIRCUITS 1. INTRODUCTION 407 2. DAMPED OSCILLATIONS 408 3. SERIES RESONANCE 409 4. PARALLEL RESONANCE 410 5. GENERAL CASE OF SERIES RESONANCE 412 6. SELECTIVITY AND GAIN 412

(i) Single tuned circuit 412(ii) Coupled circuits-tuned secondary- 413(iii) Coupled circuits-tuned primary, tuned secondary- 414(iv) Coupled circuits of equal Q 415(v) Coupled circuits of unequal Q 416

7. SELECTIVITY-GRAPHICAL METHODS- 416(i) Single tuned circuit 416(ii) Two identical coupled tuned circuits 417

8. COUPLING OF CIRCUITS 418(i) Mutual inductive coupling 418(ii) Miscellaneous methods of coupling 418(iii) Complex coupling 420

9. RESPONSE OF IDENTICAL AMPLIFIER STAGES IN CASCADE 42110. UNIVERSAL SELECTIVITY CURVES 42111. SUMMARY OF FORMULAE FOR TUNED CIRCUITS 42312. REFERENCES 427

CHAPTER 10. CALCULATION OF INDUCTANCE 1. SINGLE LAYER COILS OR SOLENOIDS 429

(i) Current-sheet inductance 429(ii) Solenoids wound with spaced round wires 430(iii) Approximate formulae 432(iv) Design of single layer solenoid 433(v) Magnitude of the differences between Ls and Lo 435(vi) Curves for the determination of the " current-sheet" induc-

tance 437(vii) Effect of concentric, non-magnetic screen 438

2. MULTILAYER SOLENOIDS 441(i) Formula for current sheet inductance 441(ii) Correction for insulation thickness 442(iii) Approximate formulae 442(iv) Design of multilayer coils 443(v) Effect of a concentric screen 444

3. TOROIDAL COILS 445(i) Toroidal coil of circular section with single layer winding 445(ii) Toroidal coil of rectangular section with single layer winding 445(iii) Toroidal coil of rectangular section with multilayer winding 445

4. FLAT SPIRALS 445(i) Accurate formulae 445(ii) Approximate formulae 446

5. MUTUAL INDUCTANCE 446(i) Accurate methods 446(ii) Approximate methods 448

6. LIST OF SYMBOLS 448 7. REFERENCES 448

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CHAPTER 11. DESIGN OF RADIO FREQUENCY INDUCTORS 1. INTRODUCTION 450

2. SELF-CAPACITANCE OF COILS 451(i) Effects of self-capacitance 451(ii) Calculation of self-capacitance of single-layer solenoids 451(iii) Measurement of self-capacitance 453

3. INTERMEDIATE-FREQUENCY WINDINGS 453(i) Air-cored coils 453(ii) Iron-cored coils 454(iii) Expanding selectivity i-f transformers 455(iv) Calculation of gear ratios for universal coils 456(v) Miscellaneous considerations 458

4. MEDIUM WAVE-BAND COILS 459(i) Air-cored coils 459(ii) Iron-cored coils 460(iii) Permeability tuning 461(iv) Matching 462

5. SHORT-WAVE COILS 463(i) Design 463(ii) Miscellaneous features 468

6. RADIO-FREQUENCY CHOKES 474(i) Pie-wound chokes 474(ii) Other types 475

7. TROPIC PROOFING 476(i) General considerations 476(ii) Baking 476(iii) Impregnation 477(iv) Flash dipping 477(v) Materials 477

8. REFERENCES 478

PART 3: AUDIO FREQUENCIESCHAPTER 12. AUDIO FREQUENCY VOLTAGE AMPLIFIERS

1. INTRODUCTION 481(i) Voltage amplifiers 481

2. RESISTANCE-CAPACITANCE COUPLED TRIODES 482(i) Choice of operating conditions 482(ii) Coupling condenser 483(iii) Cathode bias 484(iv) Fixed bias 487(v) Grid leak bias 489(vi) Plate voltage and current 489(vii) Gain and distortion at the mid-frequency 490(viii) Dynamic characteristics 491(ix) Maximum voltage output and distortion 491(x) Conversion factors with r.c.c. triodes 493(xi) Input impedance and Miller effect 493(xii) Equivalent circuit of r.c.c. triode 494(xiii) Voltage gain and phase shift 494(xiv) Comments on tabulated characteristics of resistance-

coupled triodes 495

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CONTENTSSECTION PAGE 3. RESISTANCE-CAPACITANCE COUPLED PENTODES 496

(i) Choice of operating conditions 496(ii) Coupling condenser 496(iii) Screen by-pass 496(iv) Cathode bias 499(v) Fixed bias 501(vi) Dynamic characteristics of pentodes 504(vii) Gain at the mid-frequency 506(viii) Dynamic characteristics of pentodes and comparison with

triodes 508(ix) Maximum voltage output and distortion 510(x) Conversion factors with r.c.c. pentodes 511(xi) Equivalent circuit of r.c.c. pentode 512(xii) Voltage gain and phase shift 512(xiii) Screen loadlines 513(xiv) Combined screen and cathode loadlines and the effect of toler-

ances 515(xv) Remote cut-off pentodes as r.c.c. amplifiers 516(xvi) Multigrid valves as r.c.c. amplifiers 516(xvii) Special applications 516(xviii) Comments on tabulated characteristics of resistance-

coupled pentodes 517 4. TRANSFORMER-COUPLED VOLTAGE AMPLIFIERS 517

(i) Introduction 517(ii) Gain at the mid-frequency 517(iii) Gain at low frequencies 517(iv) Desirable valve characteristics 517(v) Equivalent circuits 518(vi) Gain and phase shift at all frequencies 518(vii) Transformer characteristics 518(viii) Fidelity 518(ix) Valve loadlines 518(x) Maximum peak output voltage 518(xi) Transformer loading 518(xii) Parallel feed 518(xiii) Auto-transformer coupling 520(xiv) Applications 520(xv) Special applications 520

5. CHOKE-COUPLED AMPLIFIERS 521(i) Performance 521(ii) Application 521

6. METHODS OF EXCITING PUSH-PULL AMPLIFIERS 521(i) Methods involving iron-cored inductors 521(ii) Phase splitter 522(iii) Phase inverter 524(iv) Self-balancing phase inverter 524(v) Self-balancing paraphase inverter 524(vi) Common cathode impedance self-balancing inverters 526(vii) Balanced output amplifiers with highly accurate balance 527(viii) Cross coupled phase inverter 527

7. PUSH-PULL VOLTAGE AMPLIFIERS 527(i) Introduction 527(ii) Cathode resistors 527(iii) Output circuit 527(iv) Push-pull impedance-coupled amplifiers—mathematical treat-

ment 528(v) Phase compressor 528

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CONTENTSSECTION PAGE8. IN-PHASE AMPLIFIERS 529

(i) Cathode-coupled amplifiers 529(ii) Grounded-grid amplifiers 529(iii) Inverted input amplifiers 529(iv) Other forms of in-phase amplifiers 529

9. DIRECT-COUPLED AMPLIFIERS 529(i) Elementary d-c amplifiers 529(ii) Bridge circuit 530(iii) Cathode-coupled 531(iv) Cathode follower 531(v) Phase inverter 532(vi) Screen coupled 532(vii) Gas tube coupled 532(viii) Modulation systems 532(ix) Compensated d.c. amplifiers 533(x) Bridge-balanced direct current amplifiers 533(xi) Cascode amplifiers 533

10. STABILITY, DECOUPLING AND HUM 535(i) Effect of common impedance in power supply 535(ii) Plate supply by-passing 535(iii) Plate circuit decoupling 535(iv) Screen circuit decoupling 537(v) Grid circuit decoupling 538(vi) Hum in voltage amplifiers 538

11. TRANSIENTS AND PULSES IN AUDIO FREQUENCY AMPLIFIERS 540(i) Transient distortion 540(ii) Rectangular pulses 540

12. MULTISTAGE VOLTAGE AMPLIFIERS 541(i) Single-channel amplifiers 541(ii) Multi-channel amplifiers 541

13. REFERENCES 542

CHAPTER 13. AUDIO FREQUENCY POWER AMPLIFIERS 1. INTRODUCTION 544

(i) Types of a-f power amplifiers 544(ii) Class of operation 545(iii) Some characteristics of power amplifiers 545(iv) Effect of power supply on power amplifiers 547

2. CLASS A SINGLE TRIODES 548(i) Simplified graphical conditions, power output and distortion 548(ii) General graphical case, power output and distortion 550(iii) Optimum operating conditions 555(iv) Loudspeaker load 558(v) Plate circuit efficiency and power dissipation 559(vi) Power sensitivity 559(vii) Choke-coupled amplifier 559(viii) Effect of a.c. filament supply 560(ix) Overloading 560(x) Regulation and by-passing of power supply 560

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CONTENTSSECTION PAGE 3. CLASS A MULTI-GRID VALVES 560

(i) Introduction 560(ii) Ideal pentodes 561(iii) Practical pentodes-operating conditions- 561(iv) Graphical analysis-power output and distortion- 563(v) Rectification effects 565(vi) Cathode bias 565(vii) Resistance and inductance of transformer primary 566(viii) Loudspeaker load 566(ix) Effects of plate and screen regulation 568(x) Beam power valves 569(xi) Space charge tetrodes 569(xii) Partial triode (" ultra-linear") operation of pentodes 570

4. PARALLEL CLASS A AMPLIFIERS 570 5. PUSH-PULL TRIODES CLASS A, AB1 571

(i) Introduction 571(ii) Theory of push-pull amplification 573(iii) Power output and distortion 577(iv) Average plate current 579(v) Matching and the effects of mismatching 580(vi) Cathode bias 582(vii) Parasitics 582

6 PUSH-PULL PENTODES AND BEAM POWER AMPLIFIERS, CLASS A, AB1 583(i) Introduction 583(ii) Power output and distortion 583(iii) The effect of power supply regulation 584(iv) Matching and the effects of mismatching 584(v) Average plate and screen currents 584(vi) Cathode bias 585(vii) Parasitics 585(viii) Phase inversion in the power stage 585(ix) Extended Class A 587(x) Partial triode (" ultra-linear ") operation 587

7. CLASS B AMPLIFIERS AND DRIVERS 587(i) Introduction 587(ii) Power output and distortion—ideal conditions—Class B2 588(iii) Power output and distortion—practical conditions—Class B2 588(iv) Grid driving conditions 590(v) Design procedure for Class B2 amplifiers 592(vi) Earthed-grid cathode coupled amplifiers 592(vii) Class B1 amplifiers—quiescent push-pull 592

8. CLASS AB2 AMPLIFIERS 593(i) Introduction 593(ii) Bias and screen stabilized Class AB2 amplifier 593(iii) McIntosh amplifier 594

9. CATHODE-FOLLOWER POWER AMPLIFIERS 59610. SPECIAL FEATURES 596

(i) Grid circuit resistance 596(ii) Grid bias sources 597(iii) Miller Effect 598(iv) 26 volt operation 598(v) Hum from plate and screen supplies 599

11. COMPLETE AMPLIFIERS 599(i) Introduction 599(ii) Design procedure and examples 599(iii) Loudspeaker load 600

12. REFERENCES 601(xxii)


CHAPTER 14. FIDELITY AND DISTORTION 1. INTRODUCTION 603

(i) Fidelity 603(ii) Types of distortion 604(iii) Imagery for describing reproduced sound 604

2. NON-LINEAR DISTORTION AND HARMONICS 605(i) Non-linearity 605(ii) Harmonics 606(iii) Permissible harmonic distortion 607(iv) Total harmonic distortion 609(v) Weighted distortion factor 610(vi) The search for a true criterion of non-linearity 610

3. INTERMODULATION DISTORTION 611(i) Introduction 611(ii) Modulation method of measurement—r.m.s. sum 612(iii) Difference frequency intermodulation method 613(iv) Individual side-band method 613(v) Modulation method of measurement—peak sum 614(vi) Le Bel's oscillographic method 614(vii) Comparison between different methods 616(viii) Synthetic bass 616

4. FREQUENCY DISTORTION 617(i) Frequency range 617(ii) Tonal balance 617(iii) Minimum audible change in frequency range 617(iv) Sharp peaks 618

5. PHASE DISTORTION 618

6. TRANSIENT DISTORTION 619(i) General survey 619(ii) Testing for transient response 619

7. DYNAMIC RANGE AND ITS LIMITATIONS 620(i) Volume range and hearing 620(ii) Effect of volume level on frequency range 621(iii) Acoustical power and preferred listening levels 623(iv) Volume range in musical reproduction 623(v) The effect of noise 624

8. SCALE DISTORTION 625

9. OTHER FORMS OF DISTORTION 626(i) Frequency-modulation distortion 626(ii) Variation of frequency response with output level 626(iii) Listener fatigue 626

10. FREQUENCY RANGE PREFERENCES 627(i) Tests by Chinn and Eisenberg 627(ii) Tests by Olson 627(iii) Single channel versus dual-channel tests 627(iv) Summing up 628

11. SPEECH REPRODUCTION 628(i) The characteristics of speech 628(ii) Articulation 628(iii) Masking of speech by noise 629(iv) Distortion in speech reproduction 629(v) Frequency ranges for speech 630

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CONTENTSSECTION PAGE12. HIGH FIDELITY REPRODUCTION 630

(i) The target of high fidelity 630(ii) Practicable high fidelity 630(iii) The ear as a judge of fidelity 632

13. REFERENCES 632

CHAPTER 15. TONE COMPENSATION AND TONE CONTROL 1. INTRODUCTION 635

(i) The purpose of tone compensation 635(ii) Tone control 636(iii) General considerations 636(iv) Distortion due to tone control 636(v) Calculations involving decibels per octave 637(vi) Attenuation expressed as a time constant 638(vii) The elements of tone control filters 639(viii) Fundamental circuit incorporating R and C 639(ix) Damping of tuned circuits 639(x) Tolerances of elements 639

2. BASS BOOSTING 640(i) General remarks 640(ii) Circuits not involving resonance or negative feedback 640(iii) Methods incorporating resonant circuits 644(iv) Circuits involving feedback 645(v) Regeneration due to negative resistance characteristic 648

3. BASS ATTENUATION 649(i) General remarks 649(ii) Bass attenuation by grid coupling condensers 649(iii) Bass attenuation by cathode resistor by-passing 649(iv) Bass attenuation by screen by-passing 650(v) Bass attenuation by reactance shunting 650(vi) Bass attenuation by negative feedback 651(vii) Bass attenuation by Parallel-T network 651(viii) Bass attenuation using Constant k filters 652(ix) Bass attenuation using M-derived filters 652

4. COMBINED BASS TONE CONTROLS 653(i) Stepped controls 653(ii) Continuously variable controls 653

5. TREBLE BOOSTING 653(i) General remarks 653(ii) Circuits not involving resonance or negative feedback 653(iii) Methods incorporating resonant circuits 654(iv) Circuits involving feedback 655

6. TREBLE ATTENUATION 655(i) General remarks 655(ii) Attenuation by shunt capacitance 655(iii) Treble attenuation by filter networks 657(iv) Treble attenuation in negative feedback amplifiers 657

7. COMBINED TREBLE TONE CONTROLS 658 8. COMBINED BASS AND TREBLE TONE CONTROLS 658

(i) Stepped controls-general— 658(ii) Quality switch 659(iii) Universal step-type tone control not using inductors 660(iv) Universal step-type tone control using inductors 661(v) Fixed bass and treble boosting 662

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(vi) Step-type tone control using negative feedback 662(vii) Continuously-variable controls—general 662(viii) Single control continuously-variable tone controls 662(ix) Ganged continuously-variable tone controls 664(x) Dual control continuously-variable tone controls 664

9. FEEDBACK TO PROVIDE TONE CONTROL 669(i) Introduction 669(ii) Amplifiers with feedback providing tone control 669(iii) Whistle filters using feedback 672

10. AUTOMATIC FREQUENCY-COMPENSATED VOLUME CONTROL 672(i) Introduction 672(ii) Methods incorporating a tapped potentiometer 672(iii) Methods incorporating step-type controls 673(iv) Method incorporating inverse volume expansion with

multi-channel amplifier 67311. WHISTLE FILTERS 673

(i) Resonant circuit filters 673(ii) Narrow band rejection filter 675(iii) Crystal filters 675(iv) Parallel-T network 675(v) Filters incorporating L and C 676

12. OTHER METHODS OF TONE CONTROL 676(i) Multiple-channel amplifiers 676(ii) Synthetic bass 676

13. THE LISTENER AND TONE CONTROL 67714. EQUALIZER NETWORKS 67715. REFERENCES 677

CHAPTER 16. VOLUME EXPANSION, COMPRESSION ANDLIMITING

1. GENERAL PRINCIPLES 679(i) Introduction 679(ii) An ideal system 680(iii) Practical problems in volume expansion 680(iv) Distortion 681(v) General comments 681

2. VOLUME COMPRESSION 681(i) Introduction 681(ii) Peak limiters 682(iii) Volume limiters 683(iv) Distortion caused by peak limiters or volume limiters 683(v) Volume compression 683(vi) Volume compression plus limiting 684(vii) Compression of commercial speech 684

3. GAIN CONTROL DEVICES 684(i) Remote cut-off pentodes 684(ii) Pentagrids and triode-hexodes 685(iii) Plate resistance control 685(iv) Negative feedback 685(v) Lamps 685(vi) Suppressor-grid control 686

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CONTENTSSECTION PAGE 4. VOLUME EXPANSION 686

(i) Introduction 686(ii) Expanders incorporating lamps 687(iii) Expanders utilizing feedback 688(iv) Expanders incorporating remote cut-off pentodes 688(v) Expanders incorporating remote cut-off triodes 689(vi) Expanders incorporating suppressor-grid controlled pentodes 689(vii) Expanders incorporating valves with five grids 691(viii) Expanders incorporating plate resistance control 692

5. PUBLIC ADDRESS A.V.C. 693 6. SPEECH CLIPPERS 693 7. NOISE PEAK AND OUTPUT LIMITERS 694

(i) Introduction 694(ii) Instantaneous noise peak limiters 694(iii) Output limiters 698(iv) General remarks 699

8. REFERENCES 699

CHAPTER 17. REPRODUCTION FROM RECORDS 1. INTRODUCTION TO DISC RECORDING 701

(i) Methods used in sound recording 701(ii) Principles of lateral recording 702(iii) Frequency range 704(iv) Surface noise and dynamic range 704(v) Processing 705(vi) Turntables and driving mechanism 705(vii) Automatic record changers 705

2. DISCS AND STYLI 706(i) General information on discs 706(ii) Dimensions of records and grooves 706(iii) Styli 709(iv) Pinch effect 711(v) Radius compensation 711(vi) Record and stylus wear 712

3. PICKUPS 714(i) General survey 714(ii) Electro-magnetic (moving iron) pickups 717(iii) Dynamic (moving coil) pickups 719(iv) Piezo-electric (crystal) pickups 720(v) Magnetostriction pickups 721(vi) Strain-sensitive pickups 721(vii) Ribbon pickups 722(viii) Capacitance pickups 722(ix) Eddy-current pickups 723

4. TRACKING 723(i) General survey of the problem 723(ii) How to design for minimum distortion 725(iii) The influence of stylus friction 726

5. RECORDING CHARACTERISTICS, EQUALIZERS AND AMPLIFIERS 727(i) Recording characteristics 727(ii) Pre-amplifiers for use with pickups 732(iii) Introduction to equalizers 732(iv) High-frequency attenuation (scratch filter) 737(v) Equalizers for electro-magnetic pickups 738

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(vi) Equalizers for crystal pickups 741(vii) Equalizers applying negative feedback to the pickup 743(viii) Miscellaneous details regarding equalizing amplifiers 743(ix) Complete amplifiers 744(x) Pickups for connection to radio receivers 751(xi) Frequency test records 752

6. DISTORTION AND UNDESIRABLE EFFECTS 757(i) Tracing distortion and pinch effect 757(ii) Playback loss 760(iii) Wow, and the effects of record warping 760(iv) Distortion due to stylus wear 761(v) Noise modulation 761(vi) Pickup distortion 762(vii) Acoustical radiation 762(viii) Distortion in recording 762

7. NOISE REDUCTION 763(i) Analysis of noise 763(ii) High-frequency attenuation 763(iii) High-frequency pre-emphasis and de-emphasis 763(iv) Volume expansion 763(v) Olson noise suppressor 763(vi) Scott dynamic noise suppressor 764(vii) Price balanced clipper noise suppressor 765

8. LACQUER DISC HOME RECORDING (DIRECT PLAYBACK) 766(i) General description 766(ii) Recording characteristic 766(iii) Cutting stylus 767(iv) Cutter head 767(v) Equalization of cutter 767(vi) Motor and turntable 767(vii) Amplifier 767(viii) Pickups for use on lacquer discs 768(ix) Recording with embossed groove 768

9. REPRODUCTION FROM TRANSCRIPTION DISCS 769(i) Introduction 769(ii) Characteristics of record material, wear and noise 769(iii) Sound track 770(iv) Recording characteristics and equalization 770(v) Translation loss and radius compensation 770

10. REFERENCES TO LATERAL DISC RECORDING 771

CHAPTER 18. MICROPHONES, PRE-AMPLIFIERS,ATTENUATORS AND MIXERS

1. MICROPHONES 775(i) General survey 775(ii) Carbon microphones 777(iii) Condenser microphones 778(iv) Crystal and ceramic microphones 778(v) Moving coil (dynamic)microphones 779(vi) Pressure ribbon microphones 779(vii) Velocity ribbon microphones 779(viii) Throat microphones 780(ix) Lapel microphones 780(x) Lip microphones 780

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(xi) The directional characteristics of microphones 780(xii) The equalization of microphones 781(xiii) Microphone transformers 781(xiv) Standards for microphones 781

2. PRE-AMPLIFIERS 782(i) Introduction 782(ii) Noise 782(iii) Hum 784(iv) Microphony 786(v) Valves for use in pre-amplifiers 786(vi) Microphone pre-amplifiers 788(vii) Pickup pre-amplifiers 793(viii) Gain-controlled pre-amplifiers 793(ix) Standard pre-amplifiers for broadcasting 793(x) Standard pre-amplifiers for sound equipment 793

3. ATTENUATORS AND MIXERS 794(i) Potentiometer type attenuators (volume controls) 794(ii) Single section attenuators-constant impedance— 795(iii) Single section attenuators-constant impedance in one direction—

only 795(iv) Multiple section attenuators 796(v) Electronic attenuators 797(vi) Mixers and faders—general 798(vii) Non-constant impedance mixers and faders 798(viii) Constant impedance mixers and faders 801

4. REFERENCES 804

CHAPTER 19. UNITS FOR THE MEASUREMENT OF GAINAND NOISE

1. BELS AND DECIBELS 806(i) Power relationships expressed in bels and decibels 806(ii) Voltage and current relationships expressed in decibels 807(iii) Absolute power and voltage expressed in decibels 807(iv) Microphone output expressed in decibels 808(v) Pickup output expressed in decibels 810(vi) Amplifier gain expressed in decibels 810(vii) Combined microphone and amplifier gain expressed in decibles 811(viii) Loudspeaker output expressed in decibels 812(ix) Sound system rating 812(x) Tables and charts of decibel relationships 813(xi) Nomogram for adding decibel-expressed quantities 821(xii) Decibels, slide rules and mental arithmetic 822

2. VOLUME INDICATORS AND VOLUME UNITS 823(i) Volume indicators 823(ii) Volume units 824

3. INDICATING INSTRUMENTS 825(i) Decibel meters 825(ii) Power output meters 825(iii) Volume indicators 825(iv) Acoustical instruments 825

4. NEPERS AND TRANSMISSION UNITS 825(i) Nepers 825(ii) Transmission units 826

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CONTENTSSECTION PAGE5. LOUDNESS 826

(i) Introduction to loudness 826(ii) The phon 826(iii) Loudness units 827

6. THE MEASUREMENT OF SOUND LEVEL AND NOISE 827(i) Introduction 827(ii) The sound level meter 828(iii) The measurement of noise in amplifiers 829(iv) The measurement of radio noise 829

7. REFERENCES 830

CHAPTER 20. LOUDSPEAKERS 1. INTRODUCTION 831

(i) Types of loudspeakers 831(ii) Direct radiator loudspeakers 831(iii) Horn loudspeakers 832(iv) Headphones 832(v) Loudspeaker characteristics 833(vi) Amplitude of cone movement 834(vii) Good qualities of loudspeakers 834(viii) Loudspeaker grilles 835

2. CHARACTERISTICS OF MOVING-COIL CONE LOUDSPEAKERS 835(i) Rigid (piston) cone in an infinite flat baffle 835(ii) Practical cones 835(iii) Special constructions for wide frequency range 836(iv) Impedance and phase angle 837(v) Frequency response 838(vi) Efficiency 839(vii) Directional characteristics 839(viii) Field magnet 840(ix) Hum bucking coil 840(x) Damping 840

3. BAFFLES AND ENCLOSURES FOR DIRECT-RADIATOR LOUDSPEAKERS 842(i) Flat baffles 842(ii) Open back cabinets 842(iii) Enclosed cabinet loudspeakers 843(iv) Acoustical phase inverter (" vented baffle ") 845(v) Acoustical labyrinth loudspeakers 850(vi) The R-J loudspeaker 850(vii) Design of exterior of cabinet 850

4. HORN LOUDSPEAKERS 851(I) Introduction 851(ii) Conical horns 851(iii) Exponential horns 851(iv) Hyperbolic exponential horns 853(v) Horn loudspeakers-general— 854(vi) Folded horn loudspeakers 856(vii) High-frequency horns 858(viii) Combination horn and phase inverter loudspeakers for personal

radio receivers 859(ix) Material for making horns 859

5. DUAL AND TRIPLE SYSTEM LOUDSPEAKERS 860(i) Introduction 860(ii) Choice of the cross-over frequency 860

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(iii) The overlap region 861(iv) Compromise arrangements 861

6. LOUDSPEAKERS IN OPERATION 861(i) Loudness 861(ii) Power required 861(iii) Acoustics of rooms 864(iv) Loudspeaker placement 865(v) Stereophonic reproduction 865(vi) Sound reinforcing systems 866(vii) Open air Public Address 867(viii) Inter-communicating systems 867(ix) Background music in factories 867

7. DISTORTION IN LOUDSPEAKERS 868(i) Non-linearity 868(ii) Frequency-modulation distortion in loudspeakers 869(iii) Transient distortion 869(iv) Sub-harmonics and sub-frequencies 871(v) Intermodulation distortion 871

8. SUMMARY OF ACOUSTICAL DATA 871(i) Definitions in acoustics 871(ii) Electrical, mechanical and acoustical equivalents 872(iii) Velocity and wavelength of sound 872(iv) Musical scales 873

9. STANDARDS FOR LOUDSPEAKERS 874(i) Voice coil impedance for radio receivers 874(ii) Loudspeaker standard ratings for sound equipment 874

10. REFERENCES TO LOUDSPEAKERS 876

CHAPTER 21. THE NETWORK BETWEEN THE POWER VALVEAND THE LOUDSPEAKER

1. LOUDSPEAKER "MATCHING" 880(i) Loudspeaker characteristics and matching 880(ii) Optimum plate resistance 880(iii) Procedure for " matching " loudspeakers to various types of

amplifiers 881 2. MULTIPLE AND EXTENSION LOUDSPEAKERS 882

(i) Multiple loudspeakers—general 882(ii) Sound systems 883(iii) Extension loudspeakers 883(iv) Operation of loudspeakers at long distances from amplifier 886

3. LOUDSPEAKER DIVIDER NETWORKS 887 4. REFERENCES 889

PART 4: RADIO FREQUENCIESCHAPTER 22. AERIALS AND TRANSMISSION LINES

1. INTRODUCTION 890 2. THE TRANSMISSION LINE 890

(i) Introduction 890(ii) The correct termination for a transmission line 890(iii) Impedance-transforming action of a transmission line 891

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CONTENTSSECTION PAGE3. AERIALS AND POWER TRANSFER 892

(i) Introduction 892(ii) Power transfer 892

4. CHARACTERISTICS OF AERIALS 893(i) Effective area of a receiving aerial 893(ii) The power gain of an aerial 894(iii) The beam-width of an aerial 894

5. EFFECTS OF THE EARTH ON THE PERFORMANCE OF AN AERIAL 894(i) Introduction 894(ii) A perfectly-conducting earth 894(iii) An imperfectly conducting earth 896(iv) The attenuation of radio waves in the presence of an imper-

fectly-reflecting earth 896 6. THE EFFECT OF THE IONOSPHERE ON THE RECEPTION OF RADIO SIGNALS 901 7. THE IMPEDANCE OF AN AERIAL 901

(i) Introduction 901(ii) Resistive component of impedance 902(iii) Reactive component of impedance 903(iv) Characteristic impedance of aerial 903(v) Examples of calculations 903(vi) Dipoles 904(vii) Loop aerials 905

8. DUMMY AERIALS906 9. TYPES OF AERIAL USED FOR BROADCAST RECEPTION 907

(i) Introduction 907(ii) Medium-frequency receiving aerials 907(iii) Short-wave receiving aerials 908(iv) V-H-F aerials 909

10. REFERENCES 911

CHAPTER 23. RADIO FREQUENCY AMPLIFIERS 1. INTRODUCTION 912

(i) Aerial coupling 912(ii) Tuning methods 913(iii) R-F amplifiers 913(iv) Design considerations 914

2. AERIAL STAGES 915(i) Difficulties involved 915(ii) Generalized coupling networks 915(iii) Mutual inductance coupling 916(iv) Tapped inductance 920(v) Capacitance coupling 921(vi) General summary 921

3. R-F AMPLIFIERS 922(i) Reasons for using r-f stage 922(ii) Mutual-inductance-coupled stage 922(iii) Parallel tuned circuit 923(iv) Choke-capacitance coupling 924(v) Untuned and pre-tuned stages 924(vi) Grounded grid stages 925

4. IMAGE REJECTION 925(i) Meaning of image rejection 925(ii) Image rejection due to aerial stage 926(iii) Other considerations 926

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CONTENTSSECTION PAGE 5. EFFECTS OF VALVE INPUT ADMITTANCE 927

(i) Important general considerations 927(ii) Input loading of receiving valves at radio frequencies 928

(A) Input conductance 929(B) Cold input conductance 929(C) Hot input conductance 930(D) Change in input capacitance 932(E) Reduction of detuning effect 933

6. VALVE AND CIRCUIT NOISE 935(i) Thermal agitation noise 935(ii) Shot noise 936(iii) Induced grid noise 939(iv) Total noise calculations 940(v) Sample circuit calculations 941(vi) Conclusions 942

7. INSTABILITY IN R-F AMPLIFIERS 942(i) Causes of instability 942(ii) Inter-electrode capacitance coupling 943(iii) Summary 944

8. DISTORTION 944(i) Modulation envelope distortion 945(ii) Cross modulation distortion 945

9. BIBLIOGRAPHY 945

CHAPTER 24. OSCILLATORS 1. INTRODUCTION 947 2. TYPES OF OSCILLATOR CIRCUITS 949

(i) Tuned plate oscillator 949(ii) Tuned grid oscillator 950(iii) Hartley oscillator 951(iv) Colpitts oscillator 952(v) Electron-coupled oscillator 953(vi) Negative transconductance oscillators 953

3. CLASS A1 B AND C OSCILLATORS 954 4. CAUSES OF OSCILLATOR FREQUENCY VARIATION 955

(i) General 955(ii) Changes due to supply voltage 955(iii) Temperature and humidity changes 955(iv) Oscillator harmonics 956

5. METHODS OF FREQUENCY STABILIZATION 957 6. UNSTABLE OSCILLATION 958 7. PARASITIC OSCILLATION 959 8. METHODS USED IN PRACTICAL DESIGN 959 9. BEAT FREQUENCY OSCILLATORS 96010. BIBLIOGRAPHY 961

CHAPTER 25. FREQUENCY CONVERSION AND TRACKING

1. THE OPERATION OF FREQUENCY CONVERTERS AND MIXERS 962(i) Introduction 962(ii) General analysis of operation common to all types 964(iii) The oscillator section of converter tubes 968(iv) The detailed operation of the modulator or mixer section of the

converter stage 968

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(v) Conclusion 984(vi) Appendix 985

2. CONVERTER APPLICATIONS 987(i) Broadcast frequencies 987(ii) Short waves 990(iii) Types of converters 996

3. SUPERHETERODYNE TRACKING 1002(i) General 1002(ii) (A) Formulae and charts for superheterodyne oscillator

design 1005(B) Worked examples 1011

(iii) (A) Padded signal circuits 1013(B) Worked example 1015

4. REFERENCES 1017

CHAPTER 26. INTERMEDIATE FREQUENCY AMPLIFIERS 1. CHOICE OF FREQUENCY 1020

(i) Reasons for selection of different frequencies 1020(ii) Commonly accepted intermediate frequencies 1021

2. NUMBER OF STAGES 1021 3. COMMONLY USED CIRCUITS 1022

(i) Mutual inductance coupling 1023(ii) Shunt capacitance coupling 1023(iii) Composite i-f transformers 1024

4. DESIGN METHODS 1025(i) General 1025(ii) Critically-coupled transformers 1026

(A) Design equations and table 1026(B) Example 1028(C) Design extension 1029(D) Conclusions 1030(E) k measurement 1030

(iii) Over-coupled transformers 1031(A) Design equations and table 1031(B) Example 1033(C) k measurement (when k is high) 1033

(iv) Under-coupled transformers and single tuned circuits 1034(A) Single tuned circuit equations 1034(B) Example 1035(C) Under-coupled transformer equations 1035(D) Example 1036

(v) F-M i-f transformers 1037(vi) I-F transformer construction 1041(vii) Appendix: Calculation of coupling co-efficients 1043

5. VARIABLE SELECTIVITY 1048(i) General considerations 1048(ii) Automatic variable selectivity 1049

6. VARIABLE BANDWIDTH CRYSTAL FILTERS 1050(i) Behaviour of equivalent circuit 1050(ii) Variable bandwidth crystal filters 1052(iii) Design of variable bandwidth i-f crystal filter circuits 1053

(A) Simplifying assumptions 1053(B) Gain 1053(C) Gain variation with bandwidth change 1054(D) Selectivity 1055

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(E) Crystal constants 1056(F) Position of filter in circuit 1057(G) Other types of crystal filters 1057

(iv) Design example 1057 7. DETUNING DUE TO A.V.C. 1061

(i) Causes of detuning 1061(ii) Reduction of detuning effects 1062

8. STABILITY 1065(i) Design data 1065(ii) Neutralizing circuits 1065

9. DISTORTION 1067(i) Amplitude modulation i-f stages 1067(ii) Frequency modulation i-f stages 1068

10. REFERENCES 1069

CHAPTER 27. DETECTION AND AUTOMATIC VOLUMECONTROL

1. A-M DETECTORS 1072(i) Diodes 1072

(A) General 1072(B) Diode curves 1075(C) Quantitative design data 1075(D) Miscellaneous data 1081

(ii) Other forms of detectors 1082(A) Grid detection 1082(B) Power grid detection 1084(C) Plate detection 1084(D) Reflex detection 1085(E) Regenerative detectors 1086(F) Superregenerative detectors 1087

2. F-M DETECTORS 1088(i) Types of detectors in general use 1088(ii) General principles 1088(iii) Phase discriminators 1088

(A) General 1088(B) Design data 1090(C) Design example 1091

(iv) Ratio detectors 1095(A) General 1095(B) Operation 1097(C) Types of circuit 1098(D) Design considerations 1099(E) Practical circuits 1101(F) Measurement on ratio detectors 1102

3. AUTOMATIC VOLUME CONTROL 1105(i) Introduction 1105(ii) Simple a.v.c. 1105(iii) Delayed a.v.c. 1106(iv) Methods of feed 1109(v) Typical circuits 1111(vi) A.V.C. application 1111(vii) Amplified a.v.c. 1112(viii) Audio a.v.c. 1113(ix) Modulation rise 1114

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(x) A.V.C. with battery valves 1114(xi) Special case with simple a.v.c. 1115(xii) The a.v.c. filter and its time constants 1115(xiii) A.V.C. characteristics 1117(xiv) An improved form of a.v.c. characteristic 1118(xv) Design methods 1120

4. MUTING (Q.A.V.C.) 1125(i) General operation 1125(ii) Typical circuits 1125(iii) Circuits used with F-M receivers 1128

5. NOISE LIMITING 1130 6. TUNING INDICATORS 1132

(i) Miscellaneous 1132(ii) Electron Ray tuning indicators 1133(iii) Null point indicator using Electron Ray tube 1134(iv) Indicators for F-M receivers 1135

7. CRYSTAL DETECTORS 1136(i) Old type crystal detectors 1136(ii) Fixed germanium crystal detectors 1136(iii) Fixed silicon crystal detectors 1137(iv) Theory of crystal rectification 1138(v) Transistors1138

8. REFERENCES 1138

CHAPTER 28. REFLEX AMPLIFIERS 1. GENERAL DESCRIPTION 1140

(i) Description 1140(ii) Advantages and disadvantages of reflex receivers 1140

2. SOME CHARACTERISTICS OF REFLEX SUPERHET. RECEIVERS 1142(i) Playthrough (residual volume effect) 1142(ii) Over-loading 1142(iii) Automatic volume control 1142(iv) Reduction in percentage modulation 1143(v) Negative feedback 1143(vi) Operating conditions of reflex stage 1143

3. DESIGN OF PLATE REFLEX SUPERHET. RECEIVERS 1143(i) General considerations 1143(ii) Full a.v.c. applied to both stages 1143(iii) Fractional a.v.c. applied to both stages 1143(iv) Full a.v.c. on converter, fractional a.v.c. on reflex stage 1144

4. DESIGN OF SCREEN REFLEX SUPERHET. RECEIVERS 1145(i) Screen reflex receivers 1145(ii) Comparison between plate and screen reflexing 1146

5. DESIGN OF T.R.F. REFLEX RECEIVERS 1146 6. REFERENCES TO REFLEX AMPLIFIERS AND REFLEX RECEIVERS 1146

CHAPTER 29. LIMITERS AND AUTOMATIC FREQUENCYCONTROL

1. LIMITERS 1147(i) General 1147(ii) Typical circuits for F-M receivers 1149

2. AUTOMATIC FREQUENCY CONTROL 1150(i) General principles 1150(ii) Discriminators for a.f.c. 1152(iii) Electronic reactances 1156

3. REFERENCES 1160

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PART 5: RECTIFICATION, REGULATION, FILTERING ANDHUM

CHAPTER 30. RECTIFICATION 1. INTRODUCTION TO RECTIFICATION 1161

(i) Principles of rectification 1161(ii) Rectifier valves and types of service 1164(iii) The use of published curves 1165(iv) Selenium and copper oxide rectifiers 1169

2. RECTIFICATION WITH CONDENSER INPUT FILTER 1170(i) Symbols and definitions 1170(ii) Rectification with condenser input filter 1170(iii) To determine peak and average diode currents 1174(iv) To determine ripple percentage 1177(v) To determine the transformer secondary r.m.s. current 1177(vi) Procedure when complete published data are not available 1177(vii) Approximations when the capacitance is large 1180(viii) Peak hot-switching transient plate current 1180(ix) The effect of ripple 1181

3. RECTIFICATION WITH CHOKE INPUT FILTER 1182(i) Rectification with choke input filter 1182(ii) Initial transient current 1185

4. TRANSFORMER HEATING 1185 5. VOLTAGE MULTIPLYING RECTIFIERS 1186

(i) General 1186(ii) Voltage doublers 1186(iii) Voltage triplers 1187(iv) Voltage quadruplers 1187

6. SHUNT DIODE BIAS SUPPLIES 1188

CHAPTER 31. FILTERING AND HUM 1. INDUCTANCE-CAPACITANCE FILTERS 1192 2. RESISTANCE-CAPACITANCE FILTERS 1194 3. PARALLEL-T FILTER NETWORKS 1194 4. HUM—GENERAL 1196

(i) Hum due to conditions within the valves 1196(ii) Hum due to circuit design and layout 1198(iii) Hum levels in receivers and amplifiers 1199

5. HUM NEUTRALIZING 1200 6. REFERENCES 1201

CHAPTER 32. VIBRATOR POWER SUPPLIES 1. VIBRATORS—GENERAL PRINCIPLES 1202

(i) Operation 1202(ii) Vibrator types 1202(iii) Choice of vibrator 1203(iv) Coil energizing 1204(v) Waveform and time efficiency 1205(vi) Standards for vibrators for auto-radio 1205

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CONTENTSSECTION PAGE 2. VIBRATOR TRANSFORMER DESIGN 1205

(i) General considerations 1205(ii) Transformer calculations 1206(iii) Standards for vibrator power transformers 1207

3. TIMING CAPACITANCE 1207(i) The use of the timing capacitance 1207(ii) Calculation of timing capacitance value 1207(iii) Percentage closure 1208(iv) Effect of flux density on timing capacitance value 1208

4. ELIMINATION OF VIBRATOR INTERFERENCE 1210 5. 12, 24 AND 32 VOLT VIBRATOR SUPPLIES 1211

CHAPTER 33. CURRENT AND VOLTAGE REGULATORS 1. CURRENT REGULATORS 1213

(i) Barretters 1213(ii) Negative temperature coefficient resistors (Thermistors) 1214

2. VOLTAGE REGULATORS 1214(i) Gaseous tube voltage regulators 1214(ii) Valve voltage regulators 1215

3. REFERENCES 1222

PART 6: COMPLETE RECEIVERSCHAPTER 34. TYPES OF A-M RECEIVERS

1. INTRODUCTION AND SIMPLE RECEIVERS 1223(i) Types of receivers 1223(ii) Crystal sets 1223(iii) Regenerative receivers 1223(iv) Superheterodyne receivers 1224(v) Tuned radio-frequency receivers 1224

2. THE SUPERHETERODYNE 1225 3. THE SYNCHRODYNE 1226 4. REFERENCES 1227

CHAPTER 35. DESIGN OF SUPERHETERODYNE A-MRECEIVERS

1. INTRODUCTION 1228 2. SPECIFICATIONS AND REQUIREMENTS 1229 3. GENERAL DESIGN 1229

(i) A.V.C. and noise 1229(ii) Audio-frequency response 1234(iii) Hum 1239(iv) Microphony 1241(v) Instability 1243(vi) The local oscillator 1244(vii) Cabinet design 1248(viii) Ratings 1249(ix) Field testing 1250

4. FREQUENCY RANGES 1250(i) Medium frequency receivers 1250(ii) Dual wave receivers 1251(iii) Multiband receivers 1252(iv) Bandspread receivers 1253

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CONTENTSSECTION PAGE 5. A.C. OPERATED RECEIVERS 1256

(i) Four valve receivers 1256(ii) Five valve receivers 1259(iii) Larger receivers 1260(iv) Communication receivers 1260

6. A.C./D.C. RECEIVERS 1264(i) Series-resistor operation 1264(ii) Barretter operation 1266(iii) Dial lamps 1266(iv) Miscellaneous features 1267

7. BATTERY OPERATED RECEIVERS 1268(i) General features 1268(ii) Vibrator-operated receivers 1270(iii) Characteristics of dry batteries 1272

8. CAR RADIO 1275(i) Interference suppression 1275(ii) Circuit considerations 1276(iii) Valve operating conditions 1277

9. MISCELLANEOUS FEATURES 1278(i) Spurious responses 1278(ii) Reduction of interference 1279(iii) Contact potential biasing 1280(iv) Fuses 1281(v) Tropic proofing 1282(vi) Parasitic oscillations 1283(vii) Printed circuits 1283(viii) Other miscellaneous features 1285

10. REFERENCES 1285

CHAPTER 36. DESIGN OF F-M RECEIVERS 1. F-M RECEIVERS 1287

(i) Comparison with A-M 1287(ii) Aerial and r-f design 1287(iii) Local oscillator design 1289(iv) I-F amplifier 1290(v) F-M detection and A-M rejection 1292

2. F-M/A-M RECEIVERS 1294(i) R-F section 1294(ii) I-F amplifier 1294(iii) General considerations 1295

3. REFERENCES 1296

CHAPTER 37. RECEIVER AND AMPLIFIER TESTS ANDMEASUREMENTS

1. A-M RECEIVERS 1297(i) Introduction 1297(ii) Definitions 1297(iii) Equipment required 1298(iv) Measurements and operating conditions 1300(v) Measurements 1301(vi) Tests 1302

2. F-M RECEIVERS 1314(i) Definitions 1314(ii) Testing apparatus 1315

(xxxviii)


(iii) Test procedures and operating conditions 1315(iv) Receiver adjustments 1316(v) Performance tests 1317

3. AUDIO FREQUENCY AMPLIFIERS 1321(i) Equipment and measurements 1321(ii) Tests 1321

4. MEASUREMENTS ON COILS 1325(i) Measurement of coefficient of coupling 1325(ii) Measurement of primary resonant frequencies of aerial and r-f

coils 1325(iii) Measurement of distributed capacitance across coils 1325

5. REFERENCES 1327

PART 7: SUNDRY DATACHAPTER 38. TABLES, CHARTS AND SUNDRY DATA

1. UNITS 1329(i) General physical units 1329(ii) Electrical and magnetic units 1331(iii) Photometric units 1334(iv) Temperature 1334

2. COLOUR CODES 1335(i) Colour code for fixed composition resistors 1335(ii) Colour code for fixed wire wound resistors 1336(iii) Table of R.M.A. colour code markings for resistors 1337(iv) Colour code for moulded mica capacitors 1340(v) Colour code for ceramic dielectric capacitors 1341(vi) Colour code for i-f transformers 1342(vii) Colour code for a-f transformers and output transformers 1342(viii) Colour code for power transformers 1342(ix) Colour code for loudspeakers 1343(x) Colour code for chassis wiring 1343(xi) Colour code for battery cables 1344(xii) Colour code for metallized paper capacitors 1344

3. STANDARD RESISTORS AND CAPACITORS 1344(i) Standard fixed composition resistors 1344(ii) Standard fixed wire wound resistors 1346(iii) Fixed paper dielectric capacitors in tubular non-metallic cases 1347(iv) Metal encased fixed paper dielectric capacitors for d.c. appli-

cation 1349(v) Standard fixed mica dielectric capacitors 1351(vi) Standard ceramic dielectric capacitors 1352(vii) Standard variable capacitors 1354(viii) Standard variable composition resistors 1356(ix) Standard metallized paper dielectric capacitors 1357(x) Standard electrolytic capacitors 1357(xi) References to standard resistors and capacitors 1358

4. STANDARD FREQUENCIES 1361(i) Standard frequency ranges 1361(ii) Frequency bands for broadcasting 1361(iii) Standard intermediate frequencies 1361

5. WAVELENGTHS AND FREQUENCIES 1362(i) Wavelength-frequency conversion tables 1362(ii) Wavelengths of electromagnetic radiations 1363

6. STANDARD SYMBOLS AND ABBREVIATIONS 1363(i) Introduction 1363(ii) Multipliers1363

(xxxix)


(iii) Some units and multipliers 1363(iv) Magnitude letter symbols 1364(v) Subscripts for magnitude letter symbols 1364(vi) Magnitude letter symbols with subscripts 1365(vii) Mathematical signs 1366(viii) Abbreviations 1366(ix) Abbreviations of titles of periodicals 1367(x) References to periodicals 1369(xi) References to standard symbols and abbreviations 1369

7. STANDARD GRAPHICAL SYMBOLS 1370 8. PROPERTIES OF MATERIALS AND CHEMICAL AND PHYSICAL CONSTANTS 1372

(i) Properties of insulating materials 1372(ii) Properties of conducting materials 1374(iii) Composition of some common plastics 1375(iv) Weights of common materials 1375(v) Resistance of a conductor at any temperature 1376(vi) References to properties of materials 1376(vii) Chemical and physical constants 1376

9. REACTANCE, IMPEDANCE AND RESONANCE 1377(i) Inductive reactances 1377(ii) Capacitive reactances 1378(iii) Impedance of reactance and resistance in parallel 1380(iv) Impedance of reactance and resistance in series 1382(v) Resonance 1386(vi) Approximations in the calculation of impedance for reactance

and resistance in series and parallel 1386(vii) Reactance chart 1387

10. SCREW THREADS, TWIST DRILLS AND SHEET GAUGES 1388(i) Standard American screws used in radio manufacture 1388(ii) B.A. screw threads 1389(iii) Whitworth screw threads 1389(iv) Unified screw threads 1390(v) Drill sizes for self-tapping screws 1391(vi) Wood screws 1391(vii) Twist drill sizes 1392(viii) Sheet steel gauges 1393

11. TEMPERATURE RISE AND RATINGS 139412. FUSES 139513. CHARACTERISTICS OF LIGHT; PANEL LAMPS 1396

(i) Visibility curves of the human eye and relative spectral energycurves of sunlight and tungsten lamp 1396

(ii) Velocity of light 1396(iii) American panel lamp characteristics 1397

14. GREEK ALPHABET 139715. DEFINITIONS 139816. DECIMAL EQUIVALENTS OF FRACTIONS 140417. MULTIPLES AND SUB-MULTIPLES 140518. (i) Numerical values 1406

(ii) Factorials 140719. WIRE TABLES 140820. LOGARITHM TABLES 141821. TRIGONOMETRICAL TABLES 1420

Hyperbolic sines, cosines and tangents 142122. LOG SCALES AND LOG SCALE INTERPOLATOR 1422

(xl)

CHAPTER I.

INTRODUCTION TO THE RADIO VALVE

by F. LANGFORD-SMITH, B.Sc., B.E.

Section Page ... ... ... ... 1. Electricity and emission ... ... 1

... 2. The component parts of radio valves ... ... ... 4

... 3. Types of radio valves ... ... ... ... ... 6 ... ... 4. Maximum ratings and tolerances ... ... 9

5. Filament and heater voltage/current characteristics ... ... 10 6. Valve numbering systems ... ... ... ... ... 10

... ... 7. References ... ... ... ... ... ... 12

SECTION 1 : ELECTRICITY AND EMISSION

The proper understanding of the radio valve in its various applications requires some knowledge of the characteristics of the electron and its companion bodies which make up the complete structure of atoms and molecules.

All matter is composed of molecules which are the smallest particles preserving the individual characteristics of the substance. For example, water is made up of molecules that are bound together by the forces operating between them. Molecules are composed of atoms that are themselves made up of still smaller panicles. Ac- cording to the usual simplified theory, which is sufficient for this purpose, atoms may be pictured as having a central nucleus around which rotate one or more electrons in much the same manner as the planets move around the sun. In the case of the atom, however, there are frequently several electrons in each orbit. The innermost orbit may have up to 2, the second orbit up PO 8, the third orbit up to 18, the fourth orbit up to 32, with decreasing numbers in the outermost orbits (which on'y occur with elements of high "atomic numbers "). We do not know the precise shape and positions of the orbits and modern theory speaks of them as " energy levels " or "shells." The electronsforming the innermost shell are closely bound to the nucleus but the forces become progressively less in the outer shells. Moreover, the number of electrons in the outermost shell may be less than the maximum number that this shell is capable of accommodating. In this case, the substance would be chemically active ; examples of such are sodium and potassium.

In a metal the various atoms are situated in close proximity to one another, so that the electrons in the outermost shells have forces acting upon them both from their " parent " nucleus and their near neighbour. Some electrons are free to move about throughout the substance and are, therefore, called "free electrons." If an electric potential is applied between two points in the meral, the number of electrons moving from the negative to the positive point will be greater than those moving in the opposite direction. This constitutes an electric current, since each electron carries an electric charge. The charge on the electron is defined as unit negative charge and the accepted direction of current flow is opposite to the net electron movement.

I

CHAPTER 4

THEORY OF NETVVORKS

by F. LANGFORD-SMITH, B.Sc., B.E.

Section p%e 1. Current and voltage . . . . . . . . . . . . ... ... 128 2. Resistance .. . ... ... . . . . . . ... ... ... 130 3. Power . . . ... . . , . . . . . . . . . ... ... 133 4. Capacitance . . . . . . . . . ... . . . . . . ... 134 5. Inductance . . . ... ... ... . . . ... . . . ... 140 6. Impedance and admittance . . . . . . ... ... ... 144 7. Networks . . . ... ... ... . . . . . . ... ... 158 8. Filters .. . ... ... ... ... ... . . . ... 172 9. Practical resistors, condensers and inductors ... ... ... 186

For ease of reference Mathematics see Chapter 6 Mathematical symbols see Chapter 38 Sect. 6 Electrical and magnetic units see Chapter 38 Sect. 1 Electrical and magnetic symbols and abbreviations see Chapter 38 Sect. 6 Standard graphical symbols see Chapter 38 Sect. 7 Charts for calculation of reactance and impedance see Chapter 38 Sect. 9 Greek alphabet see Chapter 38 Sect. 14 Definitions see Chapter 38 Sect. 15 Trigonometrical and hyperbolic tables see Chapter 38 Sect. 21

SECTION 1 : CURRENT AND VOLTAGE

(i) Direct current (ii) Alternating current ( i i i ) Indications o f polarity and current flow.

(i) Direst current We speak of the flow of an electric current in s A T r t a y

more or less the same way that we speak of the flow of water, but we should remember that the cu?sTfr:~l LoAo C;yT,"' conventional direction of current is opposite to the actual flow of electrons. In most electrical circuit theory however, it is sufficient to consider only the conventional direction of current flow. ,, ,. ,, , -

I n Fig. 4.1 there is a battery connected to a load ; the current flows from the positive ( i - ) terminal, Fig. 4. Flow of current wit,, through the load, to the negative (-) terminal, battery and load. and then through the battery to the positive terminal.

CHAPTER 5.

TRANSFORlMERS AND IRON-CORED INDUCTORS

by G . Builder, B.Sc., Ph.D., F.Inst.P., I. C. Hansen, Member I.R.E. (U.S.A.), and F. Langford-Smith, B.Sc., B.E.

Section Page ... ... ... I. Ideal transformers.. . ... ... ... 199

... ... ... ... 2. Practical transformers ... ... 204 ... ... ... ... 3. Audio-frequency transformers ... 206

... ... ... ... 4. Magnetic circuit theory ... ... 229 ... ... ... 5. Power transformers ... ... ... 233

... ... ... ... 6. Inductors, iron-cored ... ... 242 ... ... ... ... ... 7. References ... ... 252

SECTION 1 : IDEAL TRANSFORMERS

(i) Definitions (ii) Impedance calculations-single load (iii) Impedance calcda- lions-mulriple loads.

(i) Definitions An ideal transformer is a transformer in which the winding reactances are

infinite, and in which winding resistances, core loss, leakage inductances and winding capacitances are all zero. In such a transformer the voltage ratio between any two windings is equal to the turns ratio of the windings, under all conditions of loading, as illustrated in Fig. 5.1. Also, in such a transformer the currents in any two windings are inversely p:oportional to the ratio of turns in the windings under all load conditions.

Fig. 5.1. Ideal two-windinf transformer. E , and E z are alternating voltages r . m . s ) I , and I , are alternating currents (r.m.s.) but the indicated directions of current flow are at a chosen instant and correspond to the direc~ion of voltage at

that instant. Similar remarks apply to Fig. 5.2.

Modern iron-cored transformers often approach so closely to perfection for their parricular purposes that their analysis on the basis of ideal transformer theory may give useful practical approximations for design purposes.

A double-wound transformer is one in which, as illustrated in Fig. 5.1, separate primary and secondary windings are used to permit isolation of the primary and secondary circuits except through mutual inductive coupling.

199

CHAPTER 6

MATHEMATICS

By F. Langford-Smith, B.Sc., B.E.

Section 1. 2. 3. 4. 5. 6. 7. 8. 9.

... Arithmetic and the slide rule ... ... ... ... ... Algebra ... ... ... Geometry and trigonometry ... ... ... Periodic phenomena ... ...

Graphical representation and j notation ... Complex algebra and De Moivre's Theorem Differential and integral calculus ... ... Fourier Series and harmonics ... ... ...

... ... ... References ... .. . For ease in

Mathematical slgns Greek letters Definitions Decimal equivalents of fractions Numerical values Logarithm tables Trigonometrical and hyperbolic tables Log. scales and log. scale interpolator

reference see Chapter 38 Sect. 6(vii) see Chapter 38 Sect. 14 see Chapter 38 Sect. 15 see Chapter 38 Sect. 16 see Chapter 38 Sect. 18 see Chapter 38 Sect. 20 see Chapter 38 Sect. 21 see Chapter 38 Sect. 22

Mathematics, to the radio engineer, is merely a tool to be used in his design work. For this reason it is often used in a slovenly manner or with insufficient precision or understanding.

There are normally three stages in the solution of a problem- 1. Transferring the mechanical or electrical conditions into a mathematical form. 2. Solving the marhematics. 3. Interpreting and applying the mathematical solution.

The first stage is dealt with in Chapter 4 ; the second stage is the subject of this chapter, while the third stage requires careful consideration of all the relevant conditions. A solution only applies under the conditions assumed in stage one, which may involve some approximations and limits. In all cases the solution should be checked either experimentally or theoretically to prove that it is a true solution.

This chapter is not a textbook on mathematics, although it is in such an easy form that anyone with the minimum of mathematical knowledge should be able to follow it. It has been written primarily for those who require assistance in " brushing up " their knowledge, and for the clarification of points which may be imperfectly under- stood. I t is " basic " rather than elementary in its introduction, and could therefore be read with advantage by all.

Sufficient ground is covered for all normal usage in radio receiver design, except for that required by specialists in network and filter design.

Reference data have been included for use by all grades

CHAPTER 7

NEGATIVE FEEDBACK

By F. LANGFORD-SMITH, B.Sc., B.E.

Section 1. Fundamental types of feedback

... 2. Practical feedback circuits 3. Stability and maximal flatness 4. Special applications of feedback 5. Valve characteristics and feedback 6. References ... ... ... 7. Overloading of feedback amplifiers

Page ... ... ... ... 306 ... ... ... ... 316 ... . . . . ... 356 ... ... ... ... 389 ... ... ... ... 390 . . ... ... ... 399

... ... ... ... 1475

SECTION 1 : FUNDAlMENTAL TYPES OF FEEDBACK

( i ) Feedback, positive and negative (ii) Negative voltage feedback at the mid-frequency (iii) Negative current feedback at the mid-frequency (iv) Bridge negative feedback at the mid-frequency ( v ) Combined positive and negative feedback at the mid-frequency ( v i ) Comparison bemeen different fundamental types at the mid- frequency.

(i) Feedback, positive and negative . .

Feedback may be applied to any amplifier, at any frequency, and may be either positive or negative. The application is illustrated in Fig. 7.1 where an amplifier, with voltage amplification A, develops a voltage E, across its load. Portion of the voltage across the load (BE,) is fed back in series with the input terminals, so that the input voltage E; differs from the voltage (E,) across the input terminals of the amplifier itself. I t is obvious that

Eo = AEi and that Eif = Ei PE,, the sign in front of BE0 taking account of phase relationships. The quantity p is sometimes called the transfer coefficient.

INPUT OUTPUT

AMPLIFIER

Fig. 7.1. Block diagram of an

"- amplifier with feedback.

The effective overall amplification with feedback is therefore E En A' = O = --. Ei' Ei & PEn

If the effect of feedback is to increase the gain, the feedback is positive* ; if it decreases the gain, the feedback is negative. Positive feedback is used to convert

*If BEo is much greater thzn E, th in the gain will theorerically be reduced irrespective of the sign in front of BEo

306

1424 INDEX

AA-battery, definition, 1398A.C./D.C. receiver, definition, 1398Abampere, 1332, 1333Abbreviations, 1366–1367

titles of periodicals, 1367–1369Abcoulomb, 1332, 1333Abfarad, 1332, 1333Abhenry, 1332, 1333Abmho, 1332, 1333Abohm, 1332, 1333Abscissa, 279Absolute magnitude of complex quan-

tity, 140, 285Absolute maximum system, 9, 77Absolute system, definition, 1331Absolute temperature, 1334Absolute value, definition, 1398Absolute zero, 1334Abvolt, 1332, 1333Acceptance testing of values, 120Accumulator operation, valves ratings

for, 78, 79Acoustical absorption coefficient, 863Acoustical damping to eliminate standing

waves in loudspeaker enclosures, 843-845,849

Acoustical data, summary of, 871–874Acoustical, electrical and mechanical

equivalents, 872Acoustical feedback, avoidance of, 866Acoustical feedback, definition, 1398Acoustical labyrinth loudspeakers, 850Acoustical phase inverter (vented baffle)

loudspeakers, 845-850Acoustical power of orchestra, peak, 623Acoustical QUAD amplifer, 544, 596Acoustical radiation by pickup, 714, 718, 719,

760, 762Acoustical tests on receivers, 1314Acoustics and music, references, 634Acoustics of rooms, 864–865Activation of cathode, 69Addition, 260Admittance and impedance, 144–158Admittance as reciprocal of impedance, 154Admittance circle diagram, 156Admittance coefficents, 50–55Admittance, grid input, 49–53Admittance, grid input, components of, 51–53Admittance, grid input, effects of, 927–934Admittance neutralization, stable, 389Admittance of arms and networks, 153–158Admittance of parallel connections of L,

C and R, 147–149Admittance of series connections of L,

C and R, 144–147Admittance of series-parallel connections

of L, C and R, 149–153Admittance, short-circuit feedback, 50–55Admittance, short-circuit feedback,

methods of increasing in i-f ampli-fiers, 1064

Admittance, short-circuit feedback, testfor, 117

Admittance, short-circuit forward, 50–55Admittance, short-circuit forward, test

for, 117Admittance, short-circuit input, 50–55Admittance, short-circuit input, test for, 113–117Admittance, short-circuit output, 50–55

Admittance, short-circuit output, test for, 117Admittance, signal grid input, of con-

verters, 970, 973, 976-978, 980-981Admittances, short circuit, 69Admittances, valve, 49–57, 69, 70Aerial coin gain, 916–917, 920Aerial coupling, 912–913Aerial coupling capacitance, 921Aerial coupling transformer, mutual

inductance, 916–920Aerial coupling transformer, tapped in-

ductance, 920–921Aerial coupling transformer, three special

cases for, 918–920Aerial coupling units, generalised, 915–916Aerial primary windings of short-wave

coils, 474Aerial stages, 912–913, 915–922Aerial stages, fixed tuned, 921Aerials (Chapter 22), 890–911Aerials and power transfer, 892–893

beam width of, 894broadside array, 893–894car radio, aerials for 1276–1277characteristics of, 893–894dipoles, 892–895, 898, 904–906, 908–911, 919

effect of spacing between aerial andreflector, 905–906

discone, 910dummy, 906–907, 1299, 1315, 1316effective area of receiving, 893–894, 896effects of earth on performance of 894–900

height above earth, desirable, 895imperfectly conducting earth, 896–900

attenuation between transmitterand receiver, 896–900

attenuation charts, 897–900attenuation of radio waves due

to, 896–900conductivity of earth, 896–900effective area with, 896field intensity at receiver—

charts, 897–900height of receiving aerial above

earth, effect of—charts, 898–900power-flux per unit area at re-

ceiver, 896-897resistivity of earth, 896space waves, 896, 897surface wave, 896, 897

perfectly-conducting earth, 894–895vertical and horizontal aerials, com-

parison between, 895, 896equivalent circuit of aerial and input

circuit of receiver, 904equivalent circuit of aerial-earth system, 903field intensity of wave, electric, and

power-flux per unit area, relation be-tween, 896

F-M receivers, aerials for, 1288, 1294function of a receiving, 892half wave dipole, 893, 919half wave dipole, folded, 910–911horizontal, 895–896, 910impedance of, 901–906

characteristic, 903equivalent series loss resistance, 902example of calculations, 903–904

input impedance, 904voltage at receiver terminals, 904

INDEX 1425

Aerials and power transfer (continued)power that can be extracted from

aerial with resistive losses, 902radiation efficiency, 903radiation resistance, 902, 905, 906

base radiation resistance, 902reactive component of, 903resistive component of, 902

indoor, 908inverted L, 901, 902, 903–904, 907inverted T, 907ionosphere, effect on reception, 901

fading due to interference betweenreflected and ground waves 901, 908

reflected waves, 901reflecting layers in, 901

loop aerials, 901, 905, 908, 918–919loop aerials, directly tuned, 921–922loop aerials, measuring Q of, 919magnetic and electric fields of wave,

relation between, 897power available at receiver, 893power gain of, 894power-flux per unit area and electric

field intensity of wave, relation be-tween, 896

power transfer between two straightdipole aerials, 892–893

quarter-wave, 909–910references, 911sensitivity-test input, definition, 1297space, intrinsic resistance of, 897standard, definition, 1298standard 300 ohm, 1315types used for broadcast reception, 907–911

medium frequency, 907–908short-wave, 908–909v-h-f,909–911

vertical, 892, 893, 895, 896, 901, 904, 907,909–910

wave antenna, 908wave tilt, 908

Air-core, definition, 1398Air-cored i-f coils, design of, 453–454,

1041–1043Air-cored medium waveband coils, de-

sign of, 459–460Algebra, 259–272Algebra, complex, 285–287Algebra, complex, polar coordinates, 286–287Algebra, complex, rectangular coordin-

ates, 285–286Algebraic sum, definition, 1398Aligned grids, 8Alignment of converter stage, short-

wave, 990–991Alternating current, 129–130Alternating current, definition, 1398Alternating current generator, 129Alternating current, sine wave, 129, 130, 278Alternating current, 3 phase, 129Alternating current waveform, standard, 130Ambient temperature, definition 1398Ambient temperatures of composition

resistors, 187Ambient temperatures of electrolytic con-

densers, 193Ampere,

1332, 1333Ampere-turn, 1332, 1333Ampere-turn per inch, 1332, 1333Ampere-turn per metre, 1332, 1333Ampere-turn, per weber, 1332, 1333Amplification, a.c., test for, 74, 105, 124Amplification by valve, 13Amplification, definition, 1398Amplification factor, definition, 13, 72Amplification factor, effective, with

feedback, 311, 313, 314, 315, 316Amplification factor, graphical determina-

tion, 15, 16, 18Amplification factor of r.c.c. triodes, 493Amplification factor plate to screen, 35–36Amplification factor screen to control grid, 35Amplification factor, tests for, 74, 104, 113Amplification factor, triode, of pentodes, 35–36Amplified a.v.c. 1112-1113

Amplifier gain expressed in decibels, 810–811Amplifiers, a-f, complete

acoustical QUAD, 544, 596bias and screen stabilized amplifier, 593–594design procedure and examples, 599–600feedback—see Chapter 7,

combined positive and negative, togive any desired positive, zero ornegative plate resistance, 354–355

positive, to offset loss of gain byomission of by-pass condensers, 354

2 stages, 331, 334–343, 353, 3543 stages, 343–347, 353, 370, 377

McIntosh amplifier, 544, 594–596reproduction of sound, complete am-

plifiers for, 744–751Walsh, Lincoln, amplifier, 600Williamson—see under Williamson am-

plifier.Amplifiers, a-f direct-coupled, 529-534

bridge balanced, 533bridge circuit, 530cascode amplifiers, 533–534cathode-coupled amplifiers, 348, 529, 531cathode-coupled phase inverter, 347–348, 532cathode follower, 531changes in filament and place voltages,

compensation for, 533drift of valve characteristics, 23–24, 530, 533drift of valve characteristics, com-

pensation for, 533gas-tube coupled, 532maximum gain in, 65modulation systems, 532phase-splitter with positive feedback, 354references, 543screen-coupled, 532

Amplifiers, a-f, in-phase, 529cathode-coupled amplifiers, 348, 529, 531grounded-grid amplifiers, 529inverted input amplifiers, 325, 529

Amplifiers, a-f power (Chapter 13) 544–602back bias, in, 547, 597–598back bias, sources of, 597–598cathode (self) bias in, 547, 552–553, 565–566,

582, 585cathode-follower power amplifiers, 596

cathode-follower as driver, 591, 596cathode-follower as output stage, 596

Class A, definition, 545, 572Class A, limiting, definition, 545, 572Class A, regulated grid bias for, 1215Class A single multi-grid valves, 560–570

beam power valves, 569cathode bias, 565–566fifth harmonic distortion, effect on

power output 565graphical analysis, power output and

distortion 563–565ideal pentodes, 561inductance of transformer primary, 212–214leakage inductance in output trans-

former, effects of, 566load resistance, 561loudspeaker load, 566–567oscillation or parasitics, 562overload characteristics, 563partial triode operation of pentodes 570plate circuit efficiency, 562power output, 561power output and distortion of typical

beam power amplifier v's load re-sistance, 570

practical pentodes, operating con-ditions, 561–563

ratio between plate and screen cur-rents, 562

rectification, correcting loadline for,568–569

rectification effects, 561rectification effects, fixed bias 565rectification effects, cathode bias, 566regulation, plate and screen, effects

of,568–569resistance of transformer primary,

effect of, 566

1426 INDEX

Amplifiers, a-f power (continued)screen current, 562screen dissipation, 562screen source regulation, 562shunt filter, 567, 636space charge tetrodes, 569third harmonic distortion, effect on

power output, 564Class A single triodes, 548–560

a.c. filament supply, effect of, 560calculating gain and distortion at

high inputs from measurements ofgm and gp at low inputs 554, 555

cathode bias, 552–553cathode by-passing, 554choke-coupled amplifier, 559–560graphical conditions, power output

and distortion, 548–554inductance of transformer prim-

ary, 212–214, 550limitations of operating point, 559loudspeaker load, 558, 566–567, 600–601,

881–882optimum grid bias, 557optimum load resistance, 557–558optimum operating conditions, ideal

characteristics 555-558optimum operating conditions, prac-

tical characteristics, 557–558optimum plate current, 557overloading, 560plate circuit efficiency, 559plate dissipation, 559power output and distortion of

typical triode v's load resistance, 558rectification effects, cathode bias, 553–554rectification effects, fixed bias, 551–552,

565regulation of power supply, effect of, 551resistance of transformer primary,

effect of, 550sensitivity, power, 559

Class A1, distortionless, power andefficiency in, 59–61

Class AB, 545Class AB1, 572Class AB2 amplifiers, 593–596

bias and screen stabilized amplifier, 593–594McIntosh amplifier, 594–596

Class B,545Class B amplifiers and drivers, 587–593

Class B amplifier, definition, 587Class B1 amplifiers, quiescent push-

pull, 592–593design procedure for Class B2 am-

plifiers, 592distortion in, 587earthed-grid cathode-coupled ampli-

fiers, 592grid driving conditions, Class B2, 590–591

driver transformer, design of, 591driver valve curved loadline, 591instability due to negative input

resistance of valve, 590leakage inductance of driver trans-

former, effect of, 590leakage inductance of driver trans-

former, method of minimizingeffects of, 590

minimum grid input resistance, 590minimum variational grid resistance, 590peak grid input power, 590

plate circuit efficiency, Class B2, 589plate dissipation and power output,

Class B2, relation between, 589power output and distortion, Class

B2, 588–590power output, ideal conditions, Class

B2, 588classes of operation, 545, 572complete amplifiers, 599–601

automatic bias control, 572, 600design procedure and examples, 599–600Lincoln Walsh amplifier, 600

distortion in—see under Distortion.driver stage, 547, 590–591

Amplifiers, a-f power (continued)effective plate resistance (output re-

sistance), optimum, 546fixed bias in, 547, 597fixed bias, sources of, 597feedback in—see under Feedback.grid circuit resistance, 566, 596–597grid circuit resistance with back bias, 597hum from plate and screen supplies, 599load resistance, critical, 546loudspeaker load, 546, 558, 566–567, 600–601,

881-882Miller effect, 598output transformer efficiency, 567parallel Class A amplifiers, 570–571parasitic oscillation, 547, 562, 590plate efficiency, definition, 545power output, 545push-pull pentodes and beam power

amplifiers Class A, AB1 583–587cathode bias, 585extended Class A (triode and pentode

in parallel on each side), 587matching and effects of mismatching

in valves, 584phase inversion in the power stage, 585–586

common cathode impedance, 585Parry cathamplifier, 586phase inverter, 585screen resistance coupling, 585

plate and screen currents, average, 584power output and distortion, 583–584regulation of power supply, effect of 584

push-pull triodes, Class A, AB1, 571–582automatic bias control, 572, 600cathode bias, 582classes of operation, 572common impedance, effects of, 574composite characteristics, 574–577, 581equivalent circuit for push-pull am-

plifier, 576–577fundamental principles of push-

pull, 571–573hum in plate and grid supplies, effect

of, 573–574leakage inductance of output trans-

former, effect of, 572–573matching and effects of mismatching

in valves, 580–582permissible unbalance, 582plate current, average, 579–580plate dissipation at max. signal, 578power output and distortion, 577–579rate of change of current near cut-off,

effect of, 572–573regulation of power supply, effect

of, 572, 582theory of push-pull amplification

based on infinite series, 573–577references to power amplifiers, 601–602regulation of power supply, effect of

547–548, 551, 562, 568–569, 572, 582, 584self bias—see under Cathode bias.sensitivity, power, definition, 545some characteristics of power ampli-

fliers, 545–547special features of power amplifiers, 596–599testing of, 548, 1321–1325

see also under Amplifiers, a-f, tests andmeasurements.

triode operation of pentodes, 547types of, 544–54528 volt operation, 598

Amplifiers, a-f, push-pull, methods ofexciting, 521–527

balanced output amplifiers with highlyaccurate balance, 527

common cathode impedance self-bal-ancing inverters, 347–348, 526–527

cross-coupled phase inverter, 527, 663–664methods involving iron-cored inductors,

521–522paraphase, common plate impedance, 525–526paraphase, floating, 524–525, 534paraphase inverter, 524paraphase inverter, see-saw self-balancing, 526

INDEX 1427

Amplifiers, a-f, push-pull, methodsof exciting (continued)paraphase inverter, self-balancing, 524-526phase inverter, 524phase inverter, self-balancing, 524phase splitter, 329-330, 522-524phase splitter, with positive feedback, 354, 523references, 542-543Schmitt phase inverter, 526, 670

Amplifiers, a-f push-pull, voltage, 527-528cathode resistors, 527output circuit, 527-528phase compressor, 527, 528push-pull impedance-coupled ampli-

fiers, mathematical treatment, 528Amplifiers, a-f, tests and measurements,

548, 1321-1325distortion, total harmonic, 1321-1322equipment, 1321feedback, special effects with, 1324frequency response, 1323-1324

output levels for measurements, 1323gain, 1323hum distortion, 1322-1323intermodulation distortion, 1322microphony, 1311, 1324noise level, 1324operating conditions for tests, 1321output, power, 1323references, 1327square wave testing, 1324stability, 1324tests, 1321-1325

Amplifiers, a-f, transformer coupled, 27-34,517-520

applications of, 520auto-transformer coupling, 520cathode loadlines, 29-30desirable valve characteristics, 517distortion, core, 206, 207, 210, 211, 212,

214-217, 227distortion, valve, 518, 519elliptical loadlines, 30-34, 64, 213equivalent circuits, 204, 205, 518frequency response, 209, 212-214, 517, 518gain at mid-frequency, 517input impedance, unloaded transformer, 517loading of transformer, 519maximum peak output voltage, 518-519parallel feed, 519, 520parallel feed, bass boosting with, 519peak response at high frequencies, 209, 518phase shift at high frequences, 518phase shift at low frequencies, 206, 207, 214primary inductance—see under Induct-

ance, transformer primary.reactive loads, 30-34

Amplifiers, a-f voltage (Chapter 12), 481-543choke-coupled amplifiers, 521direct-coupled amplifiers, 529-534

see also under Amplifiers, a-f direct-coupled.

feedback in—see under Feedback.in-phase amplifiers, 529

see also under Amplifiers, a-f, in-phase.

methods of exciting push-pull ampli-fiers, 521-527

see also under Amplifiers, a-f push-pull, methods of exciting.

multistage voltage amplifiers, 541multi-channel amplifiers, 541single-channel amplifiers, 541

phase splitter, 329-330, 354, 522-524phase splitter with positive feedback, 354, 523pre-amplifiers—see under Pre-amplifiers.push-pull voltage amplifiers, 527-528

see also under Amplifiers, a-f push-pull voltage.

references, 542-543resistance-capacitance-coupled pento-

des, 496-517attenuation (gain/frequency) charac-

teristics with incomplete screen by-passing. 496-497

Amplifiers, a-f voltage (continued)bias, increase required with low re-

sistance screen supply, 506cathode by-passing, incomplete, effect

on gain when screen is adequatelyby-passed, 499-501

cathode and screen incompletely by-passed, effect on gain and phaseshift, 498-500

choice of operating conditions 496combined screen and cathode load-

lines and the effect of tolerances, 515-516comments on tabulated characteris-

tics, 517conversion factors applied to complete

amplifier stage, 512conversion factors with, 511coupling condenser, 496curves of constant plate/screen cur-

rent ratio, 515data for types 6J7 and 6SJ7, 507-508,

510-511distortion, comparison between triode

and pentode, 511dynamic characteristics, 503-506dynamic characteristics, comparison

with triodes, 508-509equivalent circuit, 512fixed bias, 501–502 , 506gain calculated from dynamic char-

acteristic, 506gain/frequency characteristic, 512gain at mid-frequency, 506-508gain in terms of gm and gp, 507gains, typical, 506grid resistor, maximum, 496grid resistor, maximum, cathode bias, 501grid resistor, maximum, fixed bias, 502-503load resistance, 496load resistance to give maximum gain

with specified following grid re-sistor, 507

maximum output voltage and dis-tortion, 510-511

multi-grid valves as r.c.c. amplifiers, 516mutual conductance at operating

point. 506, 507-508, 511optimum operating conditions, 504-505phase shift/frequency characteristic, 512phase shift/frequency characteristics

with incomplete screen by-pass-ing, 498-499

plate resistance, 507-508, 511-512plate supply voltage, 496references, 542remote cut-off pentodes as r.c.c. am-

plifiers, 516screen by-pass, 496-499screen loadlines, 513-514screen supply, 496screen supply from voltage divider, 506series screen and cathode bias resis-

tors, determination of, 505-506slope of dynamic characteristic, 506,

507-508special applications, 516unbypassed screen and unbypassed

cathode resistors, relation be-tween, 498-499

variations in plate/screen currentratio, 514-515

resistance-capacitance-coupled triodes,482-495

attenuation (gain/frequency) charac-teristic, 494-495

cathode bias, 484-487cathode bias attenuation (gain/fre-

quency) characteristics, 484-485cathode bias loadlines, 29-30, 486-487cathode bias, phase shift, 485-486cathode bias resistor, choice of 486comments on tabulated characteristics, 495comparison between cathode and

fixed bias, 488conversion factors with, 493

1428 INDEX

Amplifiers, a-f voltage (continued)coupling condenser, 483-484damping due to positive grid current, 489dynamic characteristics, 25-26, 491equivalent circuit, exact, 494fixed bias, 487-489gain and distortion at mid-fre-

quency, 490-491grid leak bias, 489, 786, 1280-1281grid resistor, maximum, 482-483, 487, 488input impedance and Miller effect, 493-494load resistance, 482maximum output voltage and dis-

tortion, 491-493operating conditions, 482-483optimum grid bias, 487-488phase shift/frequency characteris-

tic, 494-495plate supply voltage, 482plate voltage and current relation-

ships, 489-490references, 542

resistance loaded valves, 24-27, 58-59,482-517

dissipation of triode, 26stability, decoupling and hum, 535-540

effect of common impedance inpower supply, 535

grid circuit decoupling, 538hum in voltage amplifiers, 538-540plate circuit decoupling 535-537plate supply by-passing, 535references, 543screen circuit decoupling, 537

transformer-coupled amplifiers, 517-520see also under Amplifiers, a-f, trans-

former coupled.transients and pulses, 540-541

rectangular pulses, 540-541references, 543transient distortion in amplifiers, 540

unbypassed cathode resistor, 327-329Amplifiers, cathode degenerative, 327-330Amplifiers, feedback—see under Feedback.Amplifiers, intermediate frequency, 1020-1071

cathode resistor, unbypassed, use of, 330, 1064commonly used circuits, 1022-1025composite i-f, F-M/A-M, 1024-1025crystal filters, variable bandwidth, 1050–1061

behaviour of equivalent circuit, 1050-1051design of, 1053-1061

crystal constants, 1056-1057example, 1057-1061gain, 1053-1054gain variation with bandwidth, 1054overloading arising from, 1121position in receiver, 1057selectivity, 1055-1056types other than bridge, 1057

damping due to diode circuits, 1036, 1074,1077-1078

degenerative cathode impedance, 330, 1064design methods, 1025-1048

calculation of coupling coeffici-ents, 414-416, 419-421, 1043-1048

critically-coupled transformers, 1026-1031design and table, 1026-1030k-measurement, 1025, 1030-1031

f-m i-f transformers, 1037-1041general, 1025-1026i-f transformer construction, 1041-1043over-coupled transformers, 1031-1034

design and table, 1031-1033k-measurement (when k is high)

1033-1034, 1102under-coupled transformers and single-

tuned circuits, 1034-1037single-tuned circuits, 1034-1035under-coupled transformers, 1035-1037

detuning due to a.v.c., 1061-1064causes of, 1061-1062reduction of effects, 1062-1064

diodes, valves incorporating three, 1024distortion, 1067-1069

in a-m i-f stages, 1067-1068

Amplifiers, intermediate-frequency (continued)in f-m i-f stages, 1068-1069

in f-m receivers, 1022, 1024, 1290-1292in portable battery receivers, 1021in short-wave receivers, 1022intermediate frequencies commonly ac-

cepted, 1021intermediate frequency, choice of, 1020-1021limiters, 1023, 1040mixed coupling, 1025, 1044-1048modulation hum in, 1119mutual inductance coupling, 1023, 1025-1041,

1046, 1048-1050neutralizing, 1065-1067, 1291number of stages, 1021-1022ratio detector, 1022, 1024, 1095-1105references, 1069-1071regeneration or degeneration due to

coupling between diode detector andsignal grid, 1081

selectivity of, 1026-1028, 1031-1033,1035-1037

shunt capacitance coupling, 1023-1024sliding screen, effect on distortion, 1067sliding screen, effect on gain, 28-29stability and instability, 1065-1067, 1116criterion for choice of valve, 1065stage gain, maximum, 1028, 1032, 1036stagger tuning, 1026transformers, i-f, see also under Trans-

formers, i-f.valve characteristics and loadlines, 28variable (expanding) selectivity, 455-456,

1048-1050automatic, 1049-1050

Amplifiers, pre-, see under Pre-Amplifiers.Amplifiers, radio frequency(Chapter

23), 912-946aerial stages, 912-913, 915-922

aerial coupling, 912-913aerial coupling, car radio, 1276-1277capacitance coupling, 921difficulties involved, 915fixed tuned aerial stages, 921F-M receivers, 1287-1288general summary, 921-922generalized aerial coupling units, 915-916loop, directly tuned, 921-922mutual inductance coupling, 916-920

aerial coil gain, 916-917, 920coefficient of coupling, 918-920selectivity, 917-918three special cases for the aerial

coupling transformer, 918-920tapped inductance aerial transformer,

920-921gain and selectivity, 920input loading, minimizing, 921

degenerative cathode impedance, 330,933-934

distortion in, 944-945cross modulation distortion, 945modulation envelope distortion, 944-945

image rejection, 925-927due to aerial stage, 926meaning of, 925-926other considerations, 926-927

introduction, 912-915design considerations, 914-915

references, 945-946r-f amplifiers, 913-914, 922-925

choke-capacitance coupling, 924F-M receivers, 915-946, 1287-1289grounded grid stages, 529, 592, 925

gain, voltage, 925load impedance, optimum, 925noise factor, 925resistance loading, 925

mutual inductance coupled, 922-923coefficient of coupling, 923high impedance primary, 923low impedance primary, 922stage gain, 923top capacitance coupling, 923

parallel tuned circuit, 923-924gain, 924

INDEX 1429

Amplifiers, radio frequency (continued)reasons for using r-f stage, 922untuned and pre-tuned stages, 924-925

sliding screen, effect on gain, 28-29stability in, 942-944, 1116

causes of instability, 942-943inter-electrode capacitance coup-

ling, 943-944maximum permissible grid-plate

capacitance for stability, 943summary, 944

tuning methods, 913valve and circuit noise, 935-942

conclusions, 942equivalent noise resistance, 783, 937-938induced grid noise, 939-940shot effect noise, 783, 787, 936-938thermal agitation noise, 935-936total noise calculations, 940-942

valve input admittance, effects of, 927-934general considerations, 927-928

determination of loading effects,experimental, 927-928

figure of merit for valves, 927valves with two cathode connections, 928

input loading of receiving valves atradio frequencies, 928-934

detuning, reduction of, 933-934input capacitance, change in, 932-933input conductance, 929input conductance, cold, 929-930input conductance, hot, 930-932unbypassed cathode resistance,

effect of, 933-934Amplitude, critical, in recording, 704, 708Amplitude discriminator, 1088Amplitude limiting, 1088, 1090, 1095, 1098,

1099Amplitude modulation, 405Amplitude of modulation in recording,

peak, 702-703, 709Amplitude recording, constant, 703-704, 727Amplitude rejection

by gated beam discriminator 6BN6, 1293by detector, 1293

see also under Limiters, amplitude.by ratio detector, 1095-1096, 1103-1104testing any type of detector, method of

measurement, 1104testing F-M receivers, 1318testing, standard signal generator for, 1316

Angle, phase, 139-140Angles, measures of, 1330Angles of a triangle, 272Angles of any magnitude, trignometrical

relationships, 276Angstrom unit, 404, 1329, 1396Angular velocity, 278Angular velocity, definition, 1398Anode, 2Anode current, 2, 6

(see also under Plate current).Anode, definition, 1398Anode-grid 9Anode resistance—see under Plate re-

sistance.Antennas—see under Aerials.Antinode, definition, 1398Anti-resonance, 151Approximations, 258-259, 271-272Approximations, use of Binomial Theorem

for, 268-269Arc sine, arc cos, arc tan etc., 277Arcing, 3Arcing in rectifier valves, 100Area, cooling, for power transformers, 237Area of receiving aerial, effective, 893-894, 896Area, units of, 1329Areas by integration, 296Areas, calculation of, 274-275, 280, 296Argand diagram, 284Arithmetic and the slide rule, 255-259Arithmetic, short cuts in, 258-259

Arithmetical mean, 266-267Arithmetical-mean tracking 1010, 1014-1017Arithmetical progression, 266-267Arm of network, definition, 159Arm, series, 159Arm, shunt, 159Armature of pickup, 702Articulation index, 629Articulation of speech, 628-629, 630Asymmetrical, definition, 1398Atmosphere, pressure due to, 1330Atomic structure, references to, 12Atoms, 1Attack time of peak limiters, 682-683, 684Attenuation and phase angle characteris-

tics, 360, 361Attenuation and phase angle, relationship

between, 359-364Attenuation band of filter, 180Attenuation, bass—see also under Bass

attenuation.Attenuation, bass, with enclosed cabinet

loudspeakers, 844-845Attenuation between transmitter and re-

ceiver, 896-900Attenuation characteristics and subsidiary

voltages, summation of, 372-375Attenuation characteristics of multistage

amplifiers, 541Attenuation characteristics, r.c. filters, 173-176Attenuation characteristics, r.c.c. triodes,

incomplete cathode by-passing, 484-485Attenuation characteristic, total slope of, 362Attenuation, definition, 1398Attenuation expressed as time constant, 638Attenuation (gain/frequency) characteristic

r.c.c. pentode, 512r.c.c. pentode with incomplete cathode

and screen by-passing 498-500r.c.c. pentode with incomplete cathode

by-passing, 499-501r.c.c. pentode with incomplete screen

by-passing, 496-497r.c.c. triode, 494-495

Attenuation in tone control, definition, 636Attenuation of radio waves due to earth, 896-900Attenuation, ultimate, 174, 359-364, 637Attenuators, 794-798

electronic, 389, 797-798ladder, 796-797multiple section, 796-797potentiometer type (volume controls), 794single section, constant impedance, 795single section, constant impedance, one

direction, 795-796use of, in receiver testing 1299

Audak Polyphase pickup, 719Audibility curves for the ear, 606, 620, 621Audio a.v.c., 1113-1114, 1120, 1127, 1128, 1142Audio a.v.c., public address, 693Audio frequency, definition, 1398Audio frequency transformers—see under

Transformers, a-f.Auto-transformers, 200Auto-transformer coupling, 520Automatic frequency-compensated volume

control, 672-674Automatic frequency control, 1150-1160

electronic reactances, 1151, 1156-1160Miller effect circuits, 1157quadrature circuits, 1157-1160

design procedure, 1159-1160references, 1160resistance in series with capacit-

ance, 1156-1157frequency discriminators, 1151, 1152-1156

Foster-Seeley (phase), 1153-1156discriminator transformer, de-

sign, 1154-1156equivalent circuit, 1154

references, 1160Round-Travis, 1153

ratio detector, a.f.c. voltage from, 1098use in F-M receivers, 1289, 1293

1430 INDEX

Automatic gain control—see under Auto-matic volume control.

Automatic record changers, 705-706, 727Automatic variable selectivity, 1048-1050Avoirdupois, 1329Automatic volume control, 1105-1125,

1229-1334a.v.c. characteristics, conventional,

1113-1114, 1117-1118a.v.c. characteristics, preferred, 1229-1234,

1251-1252a.v.c. characteristics, Scroggies, 1114, 1232a.v.c. characteristics, tests for, 1307, 1318a.v.c. voltage from primary of i-f trans-

former, 1074, 1077-1078, 1234effect on a.c. shunting across detector

diode, 1074effect on damping of primary, 1077-1078

amplified a.v.c., 1112-1113, 1263audio a.v.c., 1113-1114, 1118, 1120, 1127,

1128, 1142bass frequency anti-modulation, 1116battery receivers, use in, 1269, 1271battery valves, special considerations

with, 1114-1115circuit for 3/4 valve receiver, 1257communication receivers, use in, 1262-1263delayed a.v.c., 1106, 1111, 1113, 1114, 1232design methods, 1120-1125detuning due to, 927, 928, 932-934, 993,

1061-1064, 1112reduction of effects, 1062-1064

differential distortion, 1074, 1107, 1108, 1113circuits to eliminate, 1108, 1113

disconnected for heterodyne reception, 961distortion due to insufficient by-passing, 1314dual a.v.c. system, 1108effect on input capacitance, 927, 928, 932-934,

971, 978, 984, 1061-1062effect on input conductance, 1062effect on input loading, 971effects of contact potential in diode, 1106,

1108, 1118F-M receivers, use in, 1097, 1099, 1112,

1288, 1291-1296feed, parallel (shunt), 1109, 1110-1111feed, series, 1109-1110flutter due to, 1245-1246grid circuit resistance, maximum, 1110-1111modulation rise, 1112, 1114, 1117, 1118, 1232noise curve of receiver shown on a.v.c.

characteristics, 1114, 1118, 1119, 1232, 1307oscillator frequency variation due to, 963,

993-994public address a.v.c., 693quiet a.v.c. (muting), 1125-1130ratio detector, use with, 1097, 1099references, 1139reflex receivers, design for, 1142, 1258-1259short-wave operation, limitations on use

with some converters, 975, 997, 998, 1000,1111-1112

signal to noise ratio of receiver, effecton, 1108, 1114

sinking diode circuit, 1108, 1117simple a.v.c., 1105-1106, 1111, 1115staggering of, 1107-1108tests on receivers, 1307, 1318time constant of filter circuits, 1105-1106,

1109, 1115-1117, 1233charge, 1106, 1116-1117discharge, 1106, 1116-1117effect of too small time constant, 1233suitable values for, 1116vibrator-operated receivers, use in, 1271

Average values by definite integrals, 297-298 Average voltage, current, power, 134 Axial leads, definition, 1398 Axis, imaginary, 285 Axis, real, 285

BB-battery, definition, 1398B-supply, definition, 1398B.A. screw threads, 1389Back bias, grid circuit resistance with, 597Back bias, sources of, 597-598Back bias in power amplifiers, 547, 597-598Back emission, diodes, test for, 74, 100Background music in factories, 867Background noise—see under Noise.Baffles, loudspeaker, 842-851Baffles, loudspeaker flat, 842Baffles, loudspeaker vented, 845-850Baking of coils, 476-477Balanced armature loudspeaker, 831-832Balanced input voltage, 571Balanced output push-pull amplifiers with

highly accurate balance, 527Balanced output transformer, 571Band, definition, 1398Band elimination filter, definition, 172Band-pass, definition, 1398Band-pass filters, definition, 172Band-spread, definition, 1398Band-spread receivers, design of, 1253-1256Band-spreading, design of oscillator for

tracking with, 1013-1017Band-width between peaks, 415, 416, 426Band-width, constant, in coupled tuned

circuits, 420Band-width, critical, of noise, 621Band-width, definition, 1298Band-width requirements of F-M i-f

transformers, 1037-1038Banded tone frequency test records, 752,

753-756Barretters, 1213-1214, 1266Bass attenuation, 649-652

by cathode resistor by-passing, 370, 484-485,499-501, 649-650

by constant k filters, 652by grid-coupling condensers, 173, 370,

483-484, 495, 649-650,661-662by M-derived filters, 652by negative feedback, 378-379, 651, 744-749by parallel - T network, 651, 744-749by RC network, 660-661by reactance shunting, 650by resonant primary with parallel feed,

360, 519-520, 645, 650by screen by-passing, 370, 496-500, 650by step-type control, 660-661rumble filters, 744-749to provide special attenuation charac-

teristics by feedback, 671-672with enclosed cabinet loudspeakers, 844-845

Bass boosting, general, 640-648, 1234-1239automatic frequency-compensated tone

control—see under Tone Compensa-tion.

circuits involving feedback, 336, 347, 379,645-647, 669-671, 734-736, 741, 748-751,

1235-1239negative current feedback, 645-646simple circuits with decreased feedback

at bass frequencies, 646-647definition, 1398effect on distortion, 606, 636-637effect on loudness, 640effect on overloading, 640in reflex receivers, 1141, 1146methods incorporating resonant cir-

cuits, 644-645, 666-667, 736parallel resonant circuits, 644-645series resonant circuits, 645transformer primary resonance

(parallel feed), 519-520, 645methods not involving resonance or

feedback, 640-644, 660-661, 664, 733-734, 739-740, 1234-1235

continuously variable boosting, 642-643,644, 664, 667-668, 739-740

conventional circuit (plate shuntcompensation), 640-643, 660-661,

733-734

INDEX 1431

Bass boosting, general (continued)frequency characteristics, 641-643grid series compensation, 643multiple channels, 739-740plate series compensation (plate de-

coupling), 536, 643-644methods used for record reproduction,

732-736, 739-741methods used in A-M receivers, 1234-1239regeneration due to negative resistance, 648step-type control, 660-662

Bass, definition, 1398Bass frequency anti-modulation in re-

ceivers, 1116Bass reflex loudspeaker, 845-850Bass resonant frequency of loudspeaker, 836,

837-841, 844-845, 848-849Bass response in high-fidelity sound

systems, importance of improved, 631Bass, synthetic, 616, 676Batteries, dry, characteristics of, 1272-1274Batteries, dry, rechargeable, 1274Batteries in series and parallel, 129Battery end-of-life tests on receivers, 1313Battery operation, valve ratings for, 78, 79, 80Battery valves, a.v.c. with, 1114-1115Beam power amplifiers, power output and

distortion vs. load resistance, 570Beam power amplifiers, push-pull Class A,

AB1, 583-587Beam power valves, 8, 569Beam power valve characteristics, specific

tests for, 101-108Beam-width of aerials, 894Beat frequency oscillators, 954, 960-961, 1263Beating, definition, 1398Beat-note component of co-channel inter-

ference. 1317Bels and decibels, 806-823BH characteristics, 230Bias and screen stabilized amplifier, 593-594Bias, back, sources of, 597-598Bias, cathode—see under Cathode bias.Bias, contact potential, 1280-1281Bias, control on power amplifiers, auto-

matic, 572, 600Bias, definition, 1398Bias, diode, 1280, 1281Bias, fixed, r.c.c. pentodes, 501-502, 506Bias, fixed, r.c.c. triodes, 487-489Bias, fixed, sources of, 597Bias, grid leak, 489, 786, 1280-1281Bias, optimum, r.c.c. triodes, 487-488Bias, r.c.c. triodes, comparison between

cathode and fixed, 488Bias, self—see under Cathode bias.Bias sources in battery receivers, 1269Bi-directional microphones, 779-780Bifilar transformer windings, 594, 595Bilateral elements, 159Binomial series and theorem, 268-269Binomial theorem, use for approxima-

tions,268-269Biphase half-wave rectification, 7, 1161Bleeder resistor, definition, 1398Blocking, definition, 1398Blocking, grid, 21, 84, 1110Blocking, grid, tests for, 107,113Blocking interference, 1304Blue glow, 4Bode's method of feedback amplifier de-

sign, 365-366, 367-369Bogie, definition, 1399Boiling point of water, 1334Boltzmann's constant, 935, 1308, 1376Boonton converter oscillator test circuit, 112Boosting, bass—see under Bass boosting.Boosting in tone control, definition, 636Boosting, treble—see under Treble boost-

ing.Bottom bend of valve characteristics, 57Bottom bend rectification, 1084-1085Brackets in algebra, use of, 261-262Bradley F-M detector, 1088Branch of network, definition, 159Bridge-balanced direct-coupled amplifiers, 533

Bridge circuit direct-coupled amplifiers, 530Bridge feedback—see under Feedback.Bridging amplifier, gain of, 810-811Bridging gain, 810-811Brierley ribbon pickup, 722Briggs system of logarithms, 267Brockelsby's method of designing feed-

back amplifiers with flat frequencyresponse, 382-385

Bubbling in receivers, 1141, 1142Bucking, definition, 1399Build of winding in transformers, 236Bulb diameters, maximum (footnote), 97Bulbs, 5Bunet's formula for inductance of coils, 443Buzz, 715, 722, 759By-pass condenser, definition, 1399By-pass condensers, series resonant, 944, 1289,

1291By-passing radio or ultrasonic frequencies

in a-f amplifiers, 636By-passing—see under Plate, Screen, Grid,

Cathode, etc.

CC-battery, definition, 1399C.G.S. electromagnetic system, 1331, 1332C.G.S. electrostatic system, 1331, 1332Cabinet, design of, 850, 1248-1249Cables, battery, colour codes, 1344Calculus, differential and integral, 289-299Candle, measure of light intensity, 1334Cans for i-f transformers, 1043Capacitance, general, 134-140

calculation of, cylindrical condenser, 136calculation,of parallel plates, 135-136coupled aerial transformer, 921coupling, interelectrode, 943, 944coupling, shunt, in i-f transformers,

1023-1024coupling, top, in r-f amplifiers, 923distributed, across coils, measuring,

1325-1326grid-cathode, published values of, 56grid input, 49-53grid input, components of, 51grid-plate, 7grid-plate, maximum permissible for

stability, 943heater-cathode, effect of variation in, on

Hartley oscillator, 957, 959input capacitance, effect of space charge

on, 51input, of cathode follower, 323, 325input, of high-mu r.c.c. triodes, 656input, of i-f pentodes, effect of neutral-

ization on, 1063input, of pentodes, published values of 56input, of pentodes with feedback to

screen, 345input, of receiving valves at radio fre-

quencies, change in, 927, 932-933interelectrode, 73interelectrode, effect of, 7, 46, 51, 53, 69interelectrode, ratings, 75interelectrode, tests for, 73, 95-99output, of cathode follower, 323-324, 325resistors, of, 189self, of coils, 451-453self, of coils, measurement of, 453self, of short-wave coils, 472-474short-circuit input, change with a.v.c.,

927, 928, 932-934, 971,978, 984, 1061-1062short-circuit input, change with trans-

conductance, 55timing, for vibrators, 1207-1209units of, 1332

Capacitive coupling within valve, hum due to, 788, 1196-1197, 1198Capacitive reactance, 138Capacitive reactance, sign of, 50 Capacitive susceptance, sign of, 50 Capacitor (condenser), 134 see also under Condenser.

1432 INDEX

Capacitor, definition, 1399Carbon microphones, 775, 777-778Carbon resistors, characteristics of, 186

cracked, characteristics of, 186, 190Cardioid microphones, 780Carrier frequency, definition, 1399Carrier wave, definition, 1399Cartesian coordinates, 279Cascade, definition, 1399Cascode amplifiers, 533-534, 914Catenoidal horn loudspeakers, 854Cathamplifier, Parry, 586Cathode and screen by-passing, r.c.c.

pentodes, incomplete, attenuationand phase shift characteristics, 498-501

Cathode bias in power amplifiers, 547, 552-553,565-566, 582, 585

Cathode bias loadlines, r.c.c. triodes, 29-30,486-487

Cathode bias operation, determination ofmaximum grid circuit resistance, 82-84

Cathode bias, r.c.c. triodes, 484-487Cathode bias resistor, r.c.c. pentode, de-

termination of, 505-506Cathode bias resistor, r.c.c. triodes, choice

of, 486Cathode bias, single Class A pentodes, 565-566Cathode bias with push-pull Class A,

AB1, 582, 585Cathode by-passing, attenuation slope and

phase angle, 360Cathode by-passing, incomplete, effect

on hum, 786Cathode by-passing of r.c.c. pentodes,

incomplete, attenuation characteris-tics, 499-501

Cathode by-passing of r.c.c. triodes, in-complete, attenuation characteris-

tics, 484-485Cathode by-passing of r.c.c. triodes, in-

complete, phase shift, 485-487Cathode by-passing of single Class A

triodes, 554Cathode connections, two, valves with, 928Cathode-coupled amplifiers, 348, 529, 531Cathode-coupled phase inverter, 347-348, 532Cathode current, average, maximum, 75Cathode current characteristics of pen-

todes, 16-17Cathode current, definition, 1399Cathode current, peak, maximum, 75Cathode current, total available peak and

average, 73Cathode current—see also Space current.Cathode definition, 1399Cathode degenerative amplifier, 327-329Cathode emission—see under Emission.Cathode follower 316-327Cathode follower as driver for Class B

stage, 591, 596Cathode follower as low-noise pre-ampli-

fier input stage, 789-790Cathode follower as transformerless

driver, 591, 596Cathode follower, direct-coupled, 531Cathode follower power amplifiers, 596Cathode injection circuit for converters, 969Cathode loadlines, 29-30Cathode neutralization in a-f circuits, 1285Cathode resistor, unbypassed, in r-f and

i-f amplifiers, 933-934, 1064, 1288, 1292Cathode resistor, unbypassed, to give

compensation of input capacitancechange with grid bias, 56

Cathode resistors in push-pull voltageamplifiers, 527

Cathode to heater leakage—see underHeater to cathode leakage.

Cathodes, general, 4, 5activation of, 69as negative electrode, 2, 80directly heated (filaments), 4-5on a.c. supply, 6indirectly heated, 4-5ion bombardment of, 3

Cathodes, general (continued)oxide coated, 2

low temperature operation, 3temperature of, 2

sleeve, 2, 5thermal expansion of, 51valves with two or more cathode leads, 928virtual, 3, 70, 71, 973, 978, 986

Cells (batteries) in series and parallel, 129Celsius, 1334Centigrade, 1334Centimetre, unit of length, 1329, 1331, 1332,

1333Centre tracking frequency, 1004Ceramic dielectric condensers, 196Ceramic piezo-electric microphones, 779Change in operating conditions, effect

of, 26, 42-44Changes in filament and plate voltages in

d.c. amplifiers, compensation for, 533Changes in supply voltage, effect on os-

cillator frequency variation, 949, 953, 955Channel, definition, 1399Characteristic curves, valve, 15-24see also under Valve characteristic curves.Characteristic impedance of aerial, 903Characteristic impedance of 4-terminal

networks, 179Characteristics—see under Valve charac-

teristics, etc.Charge on condenser, energy stored in, 135Charge, units of, 1332Charging characteristic of condenser, 136-137Charts, tables and sundry data, 1329-1423Chatter (needle talk), 714, 718, 719, 760, 762Chemical and physical constants, 1376Choke-capacitance coupling in r-f ampli-

fiers, 924Choke coil, definition, 1399Choke-coupled a-f amplifiers, 521Choke-coupled power amplifier, Class A

triode, 559-560Choke input filters for rectifiers, 1162-1164, 1167-1169, 1182-1185Choke, swinging, 249-250, 1182Chokes, r-f, checking resonant frequencies, 944Chokes, r-f, design of, 474-475Chokes, r-f, self resonant, 475Chokes, r-f, pie-wound, 474Circuits used for tracking analysis, 1002Circular mil, 1329Circle, 273Circle, equation to, 280Clippers, speech, 693-694Closure, percentage, of vibrator, 1208Co-axial and co-planar loudspeaker

mounting, 860Co-axial, definition, 1399Co-channel interference in F-M re-

ceivers, tests for, 1317-1318Coefficient of coupling in tuned circuits—

see under Coupling factor.Coercive force, 231Coil data (table) for power transformers, 240Coil design, oscillator, 947-957, 959-960Coil magnification factor, 144Coil, oscillator, position in receiver, 957Coils

baking of, 476-477flash dipping of, 477i-f, air-cored, design of, 453-454, 1041-1043i-f, amount of coupling, 458i-f, direction of winding, 458i-f, iron-cored, design of, 454-455, 1041-1043impregnation of, 477measurements on, 1325-1326

coefficient of coupling, 1025, 1030-1031,1033-1034, 1102

distributed capacitance across coils,1325-1326

primary resonant frequencies of aerialand r-f coils, 1325

medium wave-band, air-cored 459-460medium wave-band, design of, 459-463medium wave-band, iron-cored, 460-461multilayer, design of, 443-444

INDEX 1433

Coils (continued)multilayer, inductance of, 441-444r-f, design of, 450-480r-f, self-capacitance of, 451-453short wave, aerial primary windings, 474short wave, design charts, 466-473short wave, design of, 463-468short wave, matching, 468-471short wave, self-capacitance, 472-474tropic proofing of, 476-478universal, gear ratios for, 456-457universal, inductance of, 444see also Inductors, Solenoids.

Colpitts oscillator, 952-953Colour codes, 1335-1344

cables, battery, 1344capacitors, ceramic dielectric, 1341capacitors, metallized paper, 1344capacitors, moulded mica, 1340-1341loudspeakers, 1343resistors, fixed, 1335-1336transformers, a-f, 1342transformers, i-f, 1342transformers, output, 1342transformers, power 1342-1343wiring, chassis, 1343-1344

Common logarithms, 267Communication receivers—see under Re-

ceivers, communication.Commutator, 129Compensated diode detector, 1074Compensation for changes in filament and

plate voltages in d-c amplifiers, 533Compensation for drift in valve charac-

teristics in d-c amplifiers, 533Compensation, grid series, 643Compensation, plate series 536, 643-644Compensation, plate shunt, 640–643, 660–661,

733–734Compensation of input capacitance change

with bias change, value of cathoderesistor for, 56

Compensation theorem, 166Compensators (trimmer condensers), 197Complementary angles, 272Complex algebra, 285-287Complex algebra with polar coordinates,

286-287Complex algebra with rectangular co-

ordinates, 285-286Complex quantities, 139, 140, 285-287Complex quantity, absolute magnitude

(modulus) of, 140, 285Complex quantity, real and imaginary

parts of, 140, 285Compliance at stylus tip, 712, 717-722Compliance, definition, 1399Compliance in cone suspension, 836Composite characteristics, 574-577Composite i-f transformers, F-M/A-M,

1024-1025Composite loadlines, 576Composition resistors, characteristics of, 186Compression characteristics, 682, 684Compression of speech, 684Compression ratio, 682Compression, volume, 679-681, 681-684Concentric folded horns, 856-857Condenser (capacitor), 134Condenser charge and discharge charac-

teristics, 136-137Condenser, coupling, of r.c.c. amplifier,

483-484, 496Condenser, definition, 1399Condenser input filters for rectifiers, 1161-1163,

1165-1167, 1169, 1170-1182Condenser loudspeakers, 832Condenser microphones, 778Condensers, characteristics of, 191-198

ceramic dielectric condensers, 196colour codes, 1341standard ceramic dielectric capacitors,

1352-1354combination units, 197compensators, 197

Condensers, characteristics of (continued)electrolytic, 192-194

ambient temperature, 193capacitance tolerances, 192dissipation factor, 193dry types, 192-193

etched foil anodes, 192, 193plain foil electrodes, 192, 193reversible, 193tantalum electrodes, 192

effect of being left idle, 193effect of frequency on capacitance, 192effect of temperature on capacitance, 192leakage currents, 193power factor, 193ripple current ratings, 193-194, 1358ripple current through, 1181-1182self-healing properties, 193series operation, 193series resistance, 192standard electrolytic capacitors, 1357-1358surgeproof types, 193use as first filter condensers, 193wet types, 193

use as voltage regulators, 193gang condensers, 197, 1289

standard variable capacitors, 1354-1356vibration of plates, 958-959

metallized paper dielectric condensers, 195colour codes, 1344standard metallized paper dielectric

capacitors, 1357mica dielectric condensers, 196

colour codes, 1340-1341standard fixed mica dielectric capaci-

tors, 1351-1352paper dielectric condensers, 194-195

standard fixed paper capacitors intubular non-metallic cases, 1347-1349

standard metal encased fixed paperdielectric capacitors for d.c. ap-plication, 1349-1351

references, 198, 1358-1360r-f by-pass, checking by Q-meter, 944service life, 192shunting large condensers by small ones,

effects of, 959silvered mica dielectric condensers, 196

applications in receivers, 1023, 1041summary of characteristics, 191trimmer condensers, 197, 1356variable, tuning—see above under

gang condensers.Condensers, ideal, 136Condensers in a.c. circuits, 137-140Condensers in d.c. circuits, 136-137Condensers in parallel and series, 135Conductance, definition, 14

conversion transconductance, definitions, 14,109

conversion transconductance of conver-ter valves, 966-967

conversion transconductance of modu-lator or mixer valves, 964-966

grid variational, 20input, of receiving valves at radio fre-

quencies, 929-932input, variation with a.v.c. 1062input, signal grid, of frequency con-

verters, 976-978, 980-981, 982, 985-986,987-988

mutual, definition, 14mutual, graphical determination of, 15, 16, 17mutual—see also Transconductance

grid-plate.mutual, tests for, 74, 103-104, 113, 123, 124mutual, triode, of pentode, 34of arms and networks, 153-154plate, definition, 14plate, testing of, 124short-circuit input, typical values of, 55,

1028, 1029Conductance and susceptance from re-

sistance and reactance, chart for de-termining, 155, 156

1434 INDEX

Conductance, grid input, 49-53Conductance in resistive circuits, 133Conductance, signal grid input, of con-

verters, 976-978, 980-981, 982, 987-988Conductance, units of, 1332Conducting materials, properties of, 1374Conductivity of earth, 896-900Conductivity, units of, 1332Cone movement, amplitude of loudspeaker, 834Cone, volume of, 275Cones, practical loudspeaker, 834, 835-836,

839Conical horn loudspeakers, 851, 854Conjugate impedances, 165Connections to valve sockets, 80, 81Connoisseur pickup, 718Constancy of characteristics with feed-

back, 388Constant amplitude recording, 703-704, 727Constant bandwidth, coupled tuned cir-

cuits, 420Constant current curves, 22-23Constant, definition, 1399Constant k filters, 179-182Constant velocity recording, 703-704, 727Constants, chemical and physical, 1376Constants in algebra, 265Consonance, definition, 1399Contact potential

biasing, 1280-1281diode, effects of, 1079, 1080, 1082, 1106,

1108, 1118drift during life, 23-24, 84, 533grid-cathode, 18, 20, 39, 69, 70

Continuity,265-266

Continuity of electrodes, tests for, 73, 91-93, 123Continuous functions, 265-266Convergent infinite series, 268Conversion, English to metric units, 1329-1330Conversion factors applied to complete

r.c.c. stage, 512Conversion factors, valve, 36-40, 57, 493, 511,

568Conversion transconductance, definitions, 14,

109Converter, definition, 1399Converters, frequency—see under Fre-

quency converters.Coordinates, 279Coordinates, Cartesian, 279Coordinates, polar, 283Co-planar, definition, 1399Copper oxide rectifiers, 1169Copper, temperature coefficient of re-

sistivity, 237Core, definition, 1399Core materials for transformers, 206-209, 210,

214Cores, i-f and r-f—see under Inductors,

r-f; Iron cores.Cores, transformer—see under Trans-

formers, practical, a-f, output, power;also under Inductors, iron-cored.

Corner horns, 856Corrugations in loudspeaker cones, 835, 839Cosecant of an angle, 272Cosine of an angle, 272, 275Cosine wave, 278Cosmic rays, wavelength of, 404, 1363Cotangent of an angle, 272Coulomb, measure of charge, 1332, 1333Counter-modulation in receivers, 1264Coupling between oscillator and signal

circuits in converters, 973, 974-975, 980,988, 992, 994, 1000

Coupling between two coils, 142Coupling, coefficient of, 142Coupling condenser of r.c.c. amplifier, 483-484,

496Coupling factor (coefficient), 142

critical, 415, 426in aerial transformers, 918-920

Coupling factor (continued)in i-f transformers, 416, 1023-1024

calculation of, 414-416, 419-421,1023-1024. 1043-1048

measurement of, 1025, 1030-1031,1033-1034, 1102

in phase discriminator transformers, 1090in r-f transformers, 923of tuned circuits, 413-426transitional, 416, 1031

Coupling, mixed, in i-f transformers, 1025,1044-1048

Coupling of tuned circuits, 418-421Coupling, unity, 142Cracked carbon resistors, characteristics

of, 186, 190Creeping plate current in power amplifiers, 596Critical bandwidth of noise, 621Critical coupling factor, 415, 426Critical damping, conditions for, in feed-

back amplifiers, 385-388Critically coupled i-f transformers, 1026-1031Cross-coupled phase inverter, 527, 663-664Cross-coupling in push-pull amplifiers, 528Cross-modulation, definition, 1399Cross-modulation, external, 945, 1264Cross-modulation in r-f and i-f amplifiers,

927, 945, 1108, 1264, 1303Cross-over frequency in recording charac-

teristics, 728Cross-over frequency, loudspeaker, choice

of, 860-861Cross-over point, grid current, 19, 20Cross-over point, grid current, drift dur-

ing life, 23-24Cross-talk component in F-M receivers, 1317Cross-talk in A-M receivers. 1304 'Crystal constants, 1056-1057Crystal detectors, 1136-1139Crystal filter as whistle eliminator, 675Crystal filters, variable bandwidth, 1051-1061

behaviour of equivalent circuit, 1050-1051design of, 1053-1061

crystal constants, 1056-1057example, 1057-1061gain, 1053-1054gain variation with bandwidth, 1054position in receiver, 1057selectivity, 1055-1056types other than bridge, 1057

Crystal loudspeakers, 832Crystal microphones, 775, 778-779Crystal rectification, theory of, 1138Crystal triodes, 1138Cube, 275Cumulative grid detectors, 62, 1082-1084Current, alternating, 129-130Current and voltage, 128-130Current direct, 128-129Current, electric, as electron flow, 1, 2Current feedback—see under Feedback.Current flow, direction of, 128Current indicators, peak reading, 119Current leading voltage, 138Current regulators (barretters), 1213-1214, 1266Current sheet inductance, 429, 436-438,

441-442Current, units of, 1332Currents in windings of power trans-

formers, 236Curvature, radius of, in record, minimum 704Curve, average height of, 280Curve, finding equation to, 281Curve tracer methods, valve characteristics

by, 119-120Curves, typical tracking, 1003Cutler tone control, 664Cut-off frequency, definition, 1399Cycle, 129, 278, 403Cycle, definition, 1399Cylinder, solid or hollow, 275

INDEX 1435

DDamped oscillations, 408, 424Damping, acoustical, to eliminate standing

waves in loudspeaker cabinets, 843-845, 849Damping, compensated critical, in feed-

back amplifiers, 367Damping, critical, in feedback amplifiers, 365,

367, 378, 385-388Damping due to positive grid current,

r.c.c. amplifiers, 489Damping factor of oscillations, 408, 424Damping in loudspeakers, 833, 840-842,

844-845, 856Damping in loudspeakers, critical, 833, 840-841,

844-845Damping, input circuit, 20, 70, 489, 1036, 1074,

1077-1078, 1084Damping of circuits by valve admittances, 70Damping of feedback amplifier on tran-

sients, 365-367, 382, 386Damping of i-f amplifier due to diode

circuits, 1036, 1074, 1077-1078Damping of input circuits due to detec-

tors other than diodes, 1084Damping of resonances in pickups, 716Damping of tuned circuits in tone control, 639Data, sundry, with tables and charts, 1329-1423db per octave and db per decade, table, 368dbm, 808dbv, 776, 808dbvg, 810Dead spots, 959Decades, octaves and frequency ratio

(table), 368Decca ffrr type D pickup, 717-718Decibel expressed quantities, nomogram

for adding, 821-822Decibels and bels 806-823Decibels of voltage gain, 810Decibels per octave, calculations in-

volving, 637-638Decibels per octave, to convert to fre-

quency ratio, 637-638Decibels, tables and charts, 813-821Decibels, voltage expressed in (dbv), 776,Decimal equivalents of fractions, 1404Decoupling filter in diode detector cir-

cuit, 1073, 1080Decoupling in voltage amplifiers, 535-538Decrement, logarithmic, 408, 424De-emphasis characteristic in F-M re-

ceivers, 1315De-emphasis curve with time constant

75 microseconds, 638Definite integrals, 296-298Definitions, acoustical, 871-872Definitions, alphabetically arranged, 1398-1404

bibliography, 1403-1404special groups, 159-160, 1297-1298, 1314-

1315see also under individual subjects.

Deflector (diffuser) for loudspeakers, 839, 858,1260

Deformation, elastic, of record material, 706Degenerative coupling in a-f amplifiers, 535Degree, measure of angle, 1330Delay, definition, 1399Delayed a.v.c. 1106, 1111, 1113, 1114Demagnetizing of valves, 786Demodulation, 61Demodulation, definition, 1399De Moivre's theorem, 287-288Denominator, definition, 1399Derating curves of composition resis-

tors, 187, 1345, 1346Derivatives, 291Design-centre system of valve ratings, 9Detection, definition, 1399Detection, general, 61

see also under Detectors.Detectors, A-M 1072-1087

diodes, 1072-1082characteristic curves, 1075, 1076combined with i-f amplifier, 1081

Detectors, A-M (continued)compensated diode detector, 1074conduction resistance, diode, 1079contact potential, effects, of, 1079, 1080,

1082, 1106damping across i-f transformer, 1077-1078

relation between secondary damp-ing and detection efficiency, 1077

design, quantitative, 1075-1081detection efficiency, 1076, 1080-1081distortion, non-linear, 1072-1076, 1080-

1081, 1106, 1107differential, 1074, 1107due to a.c. shunting, 1072-1076, 1082,

1106-1107, 1133methods of overcoming, 1073-1074,

1082equivalent diode circuit, 1078equivalent resistance, internal, 1079filter, r-f (decoupling), 1073, 1080loadlines, 1075modulation percentage applied to de-

tector, 1078modulation ratio, critical, 1076-1077, 1081play-through, 1081, 1082regeneration or degeneration due to

coupling between diode detectorand i-f grid. 1081

residual volume effect, 1081, 1082response (frequency) characteristic,

1078-1080shunt capacitance, effect on detec-

tion efficiency, 1080suppressor grid as, 22, 1257time constant, 1080-1081

grid, leaky, 62, 1082-1084battery valves used as, 1083damping of input circuit, 1084distortion with, 1083

grid, power, 1084damping of input circuit, 1084distortion with, 1084

infinite impedance—see under Reflex.plate (anode bend), 57, 62, 508, 1084-1085

bottom bend rectification, 57, 1084-1085pentodes, choke coupling with, 1085top bend rectification, 508, 1084-1085

references, 1138reflex, 326, 1085-1086

distortion, 1086input impedance, 1085-1086use in high fidelity t.r.f. receivers 1086

regenerative, 1086-1087sinking diode circuit, 1108, 1117, 1257, 1295square law, 62super regenerative, 1087

amplitude limiting with, 1087distortion, 1087measuring selectivity of superregen-

erative receiver, 1087noise level, 1087radiation from, 1087separate quenching, 1087use in cheap F-M receivers, 1087

Detectors, crystal, 1136-1139fixed germanium, 1136-1137fixed silicon, 1137references, 1139theory of crystal rectification, 1138transistors (crystal triodes) 1138

Detectors, F-M, 1088-1105, 1292-1293amplitude discriminator, 1088Bradley detector, 108distortion, non-linear, 1088, 1104Fremodyne, 1088gated beam discriminator, 6BN6, 1293general principles, 1088limiting, amplitude—see under limiting,

amplitude.locked oscillator, 1088, 1292–1293measurement of amplitude rejection

properties of any type of detector,method for, 1104

phase discriminator, 1088-1095, 1292–1293alternative arrangement, 1095

1436 INDEX

Detectors, F-M (continued)basic circuit, 1089design data and example, 1090-1095

coefficient of coupling, transformer, 1090discriminator characteristic, 1092discriminator sensitivity, 1090generalised curves, 1091

limiter-discriminator combination,1292-1293, 1296

typical circuit arrangement, 1090voltage relationships, 1089

∅ detector, 1293ratio detector, 1088, 1095-1105, 1292-1293

a.f.c. voltage from, 1098amplitude rejection by, 1095-1096, 1103-1104a.v.c., use of, 1099, 1293a.v.c. voltage from, 1097balanced circuit, 1098circuit, types of, 1098-1099circuits, practical, 1101design considerations, 1099-1101, 1292-1293diodes for use with, 1099input/output curves, 1098, 1099measurements on, 1102-1105operation of, 1097output curve, typical, 1096unbalanced circuit, 1098-1099

references, 1138, 1296types of detectors in common use, 1088

Detuning due to a.v.c., 927, 928, 932-934,993, 1061-1064, 1112

Detuning of r-f and i-f amplifiers bya.v.c., 927, 928, 932-934

reduction of, by means of cathode re-sistance, 933-934

Deviation sensitivity in F-M receivers, 1317Deviation sensitivity, maximum, in F-M

receivers, 1317Diaphragm of horn loudspeaker, 854-855Dictaphone, 701Dielectric, 134Dielectric losses in coils, 465Dielectrics in oscillator circuit, require-

ments for, 957Differential and integral calculus, 289-299Differential coefficient, 291Differential coefficients, partial, 293Differential distortion, 1074,1107,1108, 1113Differential gain of push-pull amplifier, 528Differential unbalance in push-pull am-

plifier, 528Differential wear in records, 706Differentiating networks, 160Differentiation, 291-294Differentiation, partial, 293Differentiation, successive 292Differentiation, total, 294Digits, 256Diode bias, 1280, 1281Diode detectors—see under Detectors,

A-M.Diode line, definition, 591Diodes, general, 6-7

back emission test, 74, 100characteristics at low plate currents, 65characteristics, specific, tests for, 99-101contact potential, effects of, 1079, 1080,

1082, 1106, 1108, 1118high perveance; applications of, 1098noise diodes, 1308, 1309plate current commencement voltage of, 84power (rectification), 1161-1191

diode currents, determination of,1174-1176, 1183

power, rectification, test for, 74, 99-100ratio detectors, for use with, 1099see also under Detectors, A-M.shunt diode bias supplies, 1188-1191signal, rectification test for, 74, 100valves incorporating three, 1024, 1295zero signal plate current test, 101

Dipoles, 892-895, 898, 904-906, 908-911Dipping, flash, of coils, 477

Direct-coupled a-f amplifiers, 529-534Direct-coupled amplifiers—see under Am- .

plifiers, audio-frequency.Direct current, 128-129Direct current (zero frequency) ampli-

fiers, 529-534Direct current from rectified and filtered

a.c. supply, 129Direct current generator, 129Direct current, pure, 129Direct current with superimposed ripple

(or hum), 129Direct playback, 701, 766-768Direct radiator loudspeakers, 831-851, 860-864Direction of current flow, 128Direction of current flow, indications of, 130Directional characteristics of loudspeakers,

834, 839-840, 856Directional characteristics of micro-

phones, 779-780Directional pattern of microphones, stan-

dard for, 781Directivity index of loudspeaker, 875Directivity index, loudspeaker loudness, 875Disc recording—see under Records, re-

production from.Discharging characteristic of condenser, 137Discone aerials, 910Discontinuous functions, 265-266, 302Discriminator, amplitude, 1088Discriminator, phase—see under Phase

discriminator.Discriminators, frequency, 1151, 1152-1156Discs, characteristics of, 706-709Discs, materials for, 706, 766, 769Display of valve characteristics, 120Dissipation characteristic of valve heater

(filament), 10, 11Dissipation, definition, 1399Dissipation in distortionless Class Al

amplifier, 59-61Dissipation in reactive circuit, power,

140, 143-144Dissipation measurements in receivers, 1302Dissipation of composition resistors, 186-187Dissipation of electrodes, maximum, 75Dissipation of electrodes, tests for, 108Dissipation of resistance loaded triode, 26Dissipation, plate, and power output,

Class B2, 589Dissipation, plate, Class A triode, 559Dissipation, plate, max. signal, push-pull

Class A, AB, triodes, 578Dissipation, plate power, general theory, 63-64Dissipation, screen, Class A pentode, 562Dissonance, definition, 1399Distorted sine wave, 130Distortion and fidelity (Chapter 14), 603-634Distortion

amplitude, 604cross modulation, in r-f amplifiers, 927, 945distortion and power output

push-pull Class A, AB1 pentodesetc., 583-584

push-pull Class A, AB1, triodes, 577-579push-pull Class B2, 588-590

distortion and power output vs. loadresistance beam power amplifier, 570

type 45 triode, 558due to peak limiters or volume limiters, 681,

683due to tone control, 606, 636-637effect of sound level on audible, 631factor, 609factor meter, 1300factor, weighted, 610frequency, 604, 617-618, 626, 631frequency modulation, 604, 626frequency range and, 631harmonic, for type 2A3 triode, 607harmonic, for type 6F6 pentode, 608harmonics, 606-607, 608hum distortion, 1309, 1314, 1322-1323imagery for describing, 604-605

INDEX 1437

Distortion (continued)in A-M detectors (other than diodes),

1083, 1084, 1086, 1087in amplifiers, effect of feedback on,

308, 309, 313-316, 608in amplifiers, measurement of, 1321-1322in cathode follower, 319in Class A triode at high inputs cal-

culated from measurements of gmand gp at low inputs, 554, 555

in Class B amplifiers and drivers, 587in diode detectors, 1072-1076, 1080-1081,

1106, 1107differential, 1074, 1107due to a.c. shunting, 1072-1076, 1082,

1106, 1107, 1133methods of overcoming, 1073-1074, 1082

in F-M detectors, 1087, 1088, 1104in i-f A-M stages, 1063, 1067-1068in i-f F-M stages, 1038-1039, 1068-1069in loudspeakers, 600-601, 631, 632, 854-855,

868-871cross-over, 856, 860-861, 868frequency modulation, 855, 869horn loudspeakers, occurring in, 854-855inharmonic, 870intermodulation, 871non-linear, 836, 855, 868phase shift, 838, 870selective, below bass resonant fre-

quency, 600-601, 868sub-harmonics and sub-frequencies, 871transient, 618, 619, 833, 869-871

testing for, 870-871in particular amplifiers, 347, 353in power amplifiers, 546, 548-554, 557, 558,

563-565, 570, 577-579, 583-584, 587,588-590

in power amplifiers, rate of increase, 546in power valves with loudspeaker load,

general, 600-601single Class A triode, 558single pentodes, 566-567, 601

in r.c.c. amplifiers, comparison betweentriodes and pentodes, 511

in r.c.c. pentodes, vs. output voltage, 510-511in r.c.c. triode at mid-frequency, 490-491in r.c.c. triodes, vs. output voltage, 491-493in receivers, A-M, measurement of, 1306, 1314in receivers, due to a.v.c. design, 1314in receivers, F-M, measurement of, 1306, 1318in reflex receivers, 1140, 1141, 1145,1146in reproduction from records

due to imperfect tracking, 723-726due to stylus wear, 761other distortion effects, 760pickup, non-linear, 718, 719, 723,762recordings, non-linear, 756, 762, 766,769testing for non-linear distortion, 762testing, proposed standards for, 762tracing, (playback), 708, 757-760

effect of recording characteristicson, 759-760

in r-f amplifiers, 944-945in speech reproduction, 629in transformer cores—see under

Transformers, a-f.in transformer-coupled voltage am-

plifiers, 518in valves, relative positions of har-

monics, 303in valves, tests for, 106-107in valves, with resistive loads, graphical

harmonic analysis, 302-304, 305, 548-554, 557, 563-565, 578-579

pentodes and others, 563-565push-pull, third harmonic, 578-579triodes, second harmonic, 548-554triodes, third harmonic, 557in valves, with resistive loads, theo-

retical analysis, 61-62intermodulation, 604, 607, 610, 611-616

see also under Intermodulation dis-tortion.

minimum deviation, 1318

Distortion (continued).modulation envelope, in r-f amplifiers,

944-945, 1067-1068non-linear, 604, 605, 610-611, 617non-linear, criterion of, 610-611permissible total harmonic, 607-609, 630-631phase, 604, 618references, 632-634relationship between harmonic and

intermodulation distortion, 612-613, 615,758-759

rule, Espley and Farren, 550rule, 5%, 550scale, 604, 625-626sibilant speech sounds, with volume

compression, 683third and fifth harmonics, effect on

power output, 564, 565total harmonic, 608total harmonic, in high-fidelity ampli-

fiers, 630-631tracking, in record reproduction, 723-727transient, 604, 618, 619transient, in a-f amplifiers, 540-541transient, testing for, 619transient waveform, in volume limiting, 683types of, 604volume, 604, 620-625

see also under Volume range.weighted harmonic, 608-609

Divergent infinite series, 268Diversity reception, 1263-1264Dividend, definition, 1399Division, 260Divisor, definition, 1399Doppler effect, 869Double frequency changer superhetero-

dyne, 1253Double spotting in superhet. receivers,

1225, 1226Drain, definition, 1399Dram, 1329Drift of characteristics during life, 23-24, 70,

84, 533Drift of characteristics during life, com-

pensation for, 533Drift, oscillator frequency, 955-958Drill sizes for self-tapping screws, 1391Drill sizes, twist, 1392Driver, definition, 1399Driver for Class B stage, cathode follower

as, 591, 596Driver looking backwards impedance, 591Driver resistance and inductance, 591Driver stage, 547, 590-591Driver transformer design, 591Driver transformer, effect of leakage in-

ductance in Class B2, 590Driving conditions, grid, Class B2, 590-591Driving power, peak grid, Class B2, 590Driving units for loudspeakers, 855Dry batteries, characteristics of, 1272-1274Dry batteries, rechargeable, 1274Dry battery operation, valve ratings

for, 78, 79, 80Duerdoth's multiple feedback system,

365, 374-378Duerdoth's stability margin, 372Durchgriff, definition, 14Dual and triple system loudspeakers, 860-861Dual a.v.c. system, 1108

circuits to eliminate, 1108, 1113Dual system loudspeakers, integral, 860Dual wave receivers, design of, 1251-1252Dummy aerials (antennae), 906-907, 1299,

1315, 1316Dummy load, standard for receivers, 1299Dust on vinyl records, 706, 713Dynamic characteristics, comparison be-

tween r.c.c. pentodes and triodes 508-509Dynamic characteristic of pentode, 26-27, 72,

503-506Dynamic characteristic of pentode, slope

of, 506, 507-508Dynamic characteristic of triode, 25-26, 72, 491Dynamic, definition, 1399

1438 INDEX

Dynamic mass of pickup armature, 718, 719, 721, 722Dynamic microphones, 775, 779Dynamic range and its limitations, 620-625Dynamic range and surface noise in record

reproduction, 704-705, 763-765Dynamic range, peak, 620Dyne-five, measure of force, 1332Dyne, measure of force, 1330, 1332,1333Dyne per square centimetre, 1330

EEar as a judge of fidelity, 631Earth, attenuation of radio waves due

to, 896-900Earth, conductivity of, 896-900Earth connection in a.c./d.c. receivers, 1268Earth, effect on performance of aerials, 894-900Earth, resistivity of, 896Earthed-grid amplifiers, 529, 592, 914, 925Eccentric grooves in records, 705Economy switch in battery receivers, 1268Eddy currents in coils, 465Effective current, definition, 1400Effective voltage, current, power, 134Efficiency,definition, 1400

aerial radiation, 903amplifier, Class A1, 59-61detection (diode), 1076, 1080-1081loudspeaker, 839, 854-855, 860

in terms of acoustical power, 875-876loudness efficiency rating, 875pressure-efficiency rating, 812, 862, 874

plate, Class A pentode, 562plate, Class A triode, 559plate, Class B2, 589transformer, 205

audio-frequency, 228, 567condition for maximum, 205power, 233, 235

Electric and magnetic fields of wave, re-lation between, 897

Electric current as electron flow, 1, 2Electric field of radiated electromagnetic

energy, 404Electrical and magnetic units, 1331-1333Electricity and emission, 1-4Electrode continuity, tests for, 73, 91-93, 123Electrode potentials, datum point for, 2, 80Electrode supply voltages, valve, 6Electrode system, geometrical configura-

tion of, 69Electrode voltages, definition, 6Electrode voltages, supplied through series

resistors, 70Electrode voltages, uncontrolled changes

in, 70Electrode voltages, with respect to cathode, 5Electrodynamic loudspeakers, 831, 833-851,

860-864Electrolysis in battery receivers, 1269Electrolytic condensers, 192-194Electromagnetic energy, radiated, 404Electromagnetic field set up by inductor, 140Electromagnetic frequency spectrum,

wavelengths, 404Electromagnetic loudspeakers, 831-832Electromagnetic radiation, 403Electromagnetic radiations, wavelengths

of, 1363Electromagnetic system, c.g.s. 1331, 1332Electromagnetic waves, introduction to, 403-404Electromotive force, definition, 1400Electromotive force induced in inductor, 140Electromotive force, units of 1332Electron, 1

electric charge on, 1Electron-coupled oscillator, 953, 954, 958Electron ray tuning indicators, 1132-1136Electron velocity of emission, initial, 18Electronic attenuators, 797-798Electronic reactances, 1151, 1156-1160

Miller effect circuits, 1157quadrature circuits, 1157-1160

references, 1160resistance in series with capacitance, 1156-1157

Electrostatic system, c.g.s. 1331, 1332Elements, bilateral, 159Element of network, definition, 159Elements, unilateral, 159Ellipse, 274Ellipse, equation to, 280Elliptical loadlines, 30-34, 64, 213,576E.M.I. transcription pickup, 719Embossed groove recording, 768Emission, back, test for, 74, 100Emission-dependent dynamic test, 73, 91-93, 123Emission, grid, 3, 5, 20, 21, 51Emission, grid primary, tests for, 101-102Emission, grid secondary, tests for, 102Emission heater-cathode, hum due to,

1196, 1197Emission, photo, 2Emission, poisoning of, 2Emission, primary (other than cathode),

19, 20, 21, 69, 71Emission, secondary, 2, 7, 8, 21, 39, 69,71Emission, tests for, 73, 94-95, 123Emission, thermionic (cathode) 2, 3, 69Empirical, definition, 1400Enclosed cabinet loudspeaker, 843-845Enclosures, loudspeaker, 842-851Energy, 133Energy factor of tuned circuit, 409

see also under Q factor.Energy stored in charge on condenser, 135Energy stored in magnetic field, 141Energy, units of, 133, 1332ensi, 1307Envelope, definition, 1400Equalizers for record reproduction, 732-744

de-emphasis, high frequency, (N.A.B.), 770equalizer, high frequency (de-emphasis),

736-737, 739-740, 744-751, 770equalizer, position of, 636, 732, 743equalizers, low frequency, 732-736equalizers and equalizing amplifiers,

738-743equalizing, corrective, 728equalizing, definition, 727, 728equalizing to give standard playback

curve, 731-732Equalizing of headphones, 662Equalizing of microphones, 635, 636, 781Equalizing of pickups, 635, 636, 732-744Equalizing of sideband cutting in receiver, 654Equation, circle, 280Equation, ellipse, 280Equation, hyperbola, 280Equation, linear, 279Equation, parabola, 280Equation, straight line, 280Equation to a curve, finding the, 281Equations, definitions, 263, 1400Equations, solution of, 263-265Equivalent circuit, definition, 1400

aerial and input circuit of receiver, 904aerial-earth system, 903crystal filter, variable bandwidth, 1050-1051diode detector, 1078grid, 64loudspeaker, 838, 839, 844-845, 848-849push-pull amplifier, 577r.c.c. pentode, 512r.c.c. triode, 494rectifier, 1164transformer, 204, 205valve, 45-47, 53-55, 59, 63,512voltage feedback amplifier, 310

Equivalent electrode voltage, 71Equivalent noise resistance, 783, 937-938Equivalent noise sideband input, 1307Equivalent plate circuit theorem, 63Erg, measure of work 1332, 1333Erg per second, measure of power, 1332, 1333Esnault-Pelterie's formula for inductance

of solenoid, 432

INDEX 1439

Excitation, definition, 1400Expanders, volume—see under Volume

expansion.Expanding selectivity i-f transformers,

455-456, 1048-1050Exponential curve, definition, 1400Exponential form of vectors, 287Exponential functions, 268Exponential horns, 851-853, 854Exponential series, 269Exponents, 255Expression,definition, 1400Extended Class A operation (triode and

pentode in parallel on each side), 587Extension loudspeakers, 883-886Exterior of cabinet, design of, 850Eye, visibility curves of, 1396

FFactor, definition, 1400Factorial n, definition, 1400Factorials, 1407Factories, background music in, 867Factoring, 262Faders—see under Mixers and faders.Fading due to interference between re-

flected and ground waves, 901, 908Fading, selective, 1251Fahrenheit, 1334Fairchild transcription dynamic pickup, 720Farad, 1332, 1333Fatigue, listener, 626Feed, parallel (shunt) a.v.c., 1109,1110-1111Feed, series a.v.c., 1109-1110Feedback, general (Chapter 7) 306-402

acoustical, avoidance of, 866admittance neutralization, stable, 389admittance, short-circuit, 50-55admittance, short-circuit, test for, 117amplifier without phase distortion, 389balanced feedback amplifiers, 315bass boosting by feedback, 336, 347bridge feedback, 307, 313-314, 546bridge negative feedback at mid-fre-

quency, 313-314special applications to give positive,

zero or negative plate resistance, 314see also 354-355

cathode-coupled amplifiers, 348, 529, 531cathode-coupled phase inverters, 347-348,

526-527cathode-degenerative amplifier, 327-330

degenerative cathode impedance, 330effective plate resistance, 328-329gain, 327-328input resistance, 328other forms of cathode degenerative

amplifiers, 330unbypassed cathode resistor, 327-329valve characteristics, graphical treat-

ment, 397-399cathode-follower, 316-327

calculated operating conditions, 319-320capacitive load—gain, input resist-

ance and capacitance, plate re-sistance, 326-327

circuit to avoid screen currentthrough load, 325

circuit to make screen currentconstant, 326

cut-off effect, capacitive load, 327direct-coupled amplifier, 531distortion, 319effective plate resistance, 318effect of impedance of input source, 327electronic attenuator, use in, 797equivalent valve characteristics, 318gain, 317-318, 325inductive load—-input resistance and

reactance, 326infinite impedance (reflex) detector, 326input capacitance, 323, 325low noise, pre-amplifier input stage, 789-790noise in, 327

Feedback, general (continued)output capacitance, 323-324, 325output impedance, 320pentodes, special considerations with, 324resistance-capacitance coupled, 320--321screen-coupled, 326, 532transformer-coupled, 321valve characteristics, graphical treat-

ment, 390-394wide-band amplifiers, use in, 327

combined negative and positive, 314-315,352-355

comparison between different funda-mental types, 315

constancy of characteristics with feed-back, 388

current feedback, 307, 312-313, 315-316,327-330, 1236

degeneration or regeneration at anyfrequency, 342

effect on distortion, 308-309, 313, 314, 315,316

effect on gain, 308, 313, 315, 316effect on hum or noise, 309-310, 315, 316,

348-352effect on input resistance, 311-312, 313, 315,

316effect on output resistance, 310-311, 313, 314effective amplification factor and plate

resistance with feedback, 311, 313, 314,315, 316

electronic attenuators, 389feedback factor, 308feedback in volume expansion, etc. 685, 688feedback loop, 307, 336frequency range of amplifier before

feedback is applied, 369frequency response, 378-388, 1235-1239

flat frequency response, design ofamplifiers with, 379-388

Brockelsby's method, 382-385conditions for critical damping, 385-388Mayr's method, 379-382

maximal flatness, 367, 378, 382-385fundamental types of, 306--316in radio receivers, 1235-1239interconnected feedback loops, 343-344intermediate frequency, in receivers, 943loop amplification, 356multiple feedback, 343-344negative, 306-402negative current feedback at mid-fre-

quency, 312-313negative impedances, stabilized, 389negative voltage feedback at mid-

frequency, 307-312equivalent circuit of amplifier, 310feedback voltage applied in series

with input, 307, 312feedback voltage applied in shunt with

input, 308, 312feedback voltage applied to cathode, 308

optimum load resistance, 311peaks at high and low frequencies, 336, 359,

378peaks, high and low frequency, height

of, 359, 378, 379, 383phase inverter, choke coupled, 355phase shift at high and low frequencies,

316, 353, 355phase shift correction, 342, 343, 352phase shift, effect of negative feedback on, 389phase splitter, 329-330, 354, 522-524

with positive feedback, 354, 523pickup, applying negative feedback to, 743play-through, feedback to reduce, 1240-1241positive, 306-307, 354positive feedback at high and low fre-

quencies, 316, 338, 342, 378, 382positive feedback for eliminating by-

pass capacitors, 1284-1285practical feedback circuits, 316-355references to feedback, 399-402special applications of feedback, 389special features of feedback amplifiers, 352

1440 INDEX

Feedback, general (continued)stability factor (Becker), 388stability; phase shift, 356-378

attenuation characteristics, 360, 361cathode by-passing, slope and phase

angle, 360conditional stability, 358, 378conditions for stability, 356-359design of multi-stage amplifiers, 365-378

alternative methods of design, 366-367attenuation characteristics and sub-

sidiary voltages, summation of,372-375

Bode's method, 365-366, 367-369corrective networks, 371damping, compensated critical, 367damping, critical, 365, 367, 378, 385-388damping of amplifier on transients,

365, 366, 367, 382, 386Duerdoth's multiple feedback

system, 365, 374, 378Duerdoth's stability margin, 372Learned's method, 365, 369-371multiple loop amplifiers, 375parasitic oscillation, 316, 345, 365phase shifting network in feedback

line, 378step in attenuation characteristic,

368, 371subsidiary feedback, 375-378transient response, oscillatory, 365, 367,

382, 386transient response, testing amplifier

for, 366design of one and two stage

amplifiers, 364-365Nyquist criterion of stability, 356, 375Nyquist (polar) diagram, 338, 339, 356-359,

366, 375parallel-fed transformer, ultimate

slope of, 360phase angle and attenuation, relation-

ship between, 359-364phase angle, determination of, 362-365polar diagram for amplifiers with

feedback—see under Nyquist dia-gram.

Routh-Hurwitz criterion of stability, 356safety (stability) margin, 359, 367, 368, 372screen by-passing, slope and phase

angle, 360-361stability and instability, 344, 355, 356, 358,

359stability, effect of tolerances on com-

ponents, 359, 371staggering attenuation characteristics,

364-365, 367, 382-385step circuit, phase angle, 361testing amplifiers for stability, 1324total slope of attenuation characteris-

tics, 362subsidiary feedback, 343tabulated characteristics, voltage and

current feedback, 316tone control, feedback to provide,

330, 336, 347, 378-379, 645-647, 651, 655,667, 669-672, 741, 748-751, 757-758,

1234-1239transfer coefficient, 306use of symbols, 307valve characteristics and feedback, 390-399

cathode follower, pentode, 393-394cathode follower, triode 390cathode follower, triode, resistance

loaded, 390-391cathode follower, triode, transformer

coupled, 391-393feedback over two stages, 399pentode, cathode degenerative, 399pentode with voltage feedback, trans-

former coupled, 395-397triode, cathode-coupled, 399triode, cathode degenerative, 397-399triode with voltage feedback 394-395

voltage feedback, 307-312, 315-327, 330-347

Feedback, general (continued)voltage feedback from plate—r.c.c.

input, 332-334voltage feedback from plate—trans-

former input, 332voltage feedback from secondary of out-

put transformer, 330-332, 336-343voltage feedback over 2 stages, 334-344

from plate of V2 to cathode of V1, 334-336from secondary to grid circuit, com-

plete analysis of, 336-343voltage feedback over 3 stages, 344-347

bridge circuits, 347feedback from plate of V3 to screen

of V1, 344-345feedback from secondary, 345-347Williamson amplifier, 346-347, 745-751

voltage proportional to velocity ofloudspeaker cone, 841-842

Ferromagnetic materials, other 458-459Ferromagnetic spinels, 459Ferroxcube, 458-459Fibre needles, 710Fidelity and distortion (Chapter 14), 603-634

ear as judge of, 632fidelity, what it is, 603-604high fidelity receivers, t.r.f., use of

reflex detector in, 1086high fidelity reproduction, 630-632references, 632-634

Fidelity, electric, in phonograph com-binations, 1311-1312

Field intensity at receiver, charts, 897-900Field response, microphone, definition, 781Figure of merit for coil, 144Figure of merit for oscillator valves, 950Figure of merit for power triodes, 61Figure of merit for r-f amplifier valves, 927Figures in arithmetic, 255Filaments, general, 4-5

current, testing for, 93-94dissipation and temperature characteris-

tic, 10, 11filament type valves, ratings for, 77, 78, 79, 80on a.c. supply, 6, 80, 560oxide coated, 2

see also under Cathode.tungsten, 2voltage/current characteristics, 10voltage, recommended, published, 3

Film, sound on, 701Filter condenser, first, use of electrolytic

as, 193Filtering and hum (Chapter 31) 1192-1201

filter factor, 1192-1194hum—general, 1196-1200

due to circuit design and layout, 1198-1199due to conditions within valves,

540, 1196-1198hum levels in receivers and ampli-fiers, 1199-1200see also under Hum.

hum neutralizing, 539, 1200-1201inductance-capacitance filters, 1192-1194

avoiding resonance with, 1193parallel-T filter networks, 176, 1194-1196references, 1201resistance-capacitance filters, 172-176, 1194

Filters, 172-185attenuation band, 180band elimination, definition, 172band pass, definition, 172characteristic impedance, 179choke input, design of, 249-250constant k, 179-182, 652

half section, 180, 181mid-series image impedance, 180, 181mid-shunt image impedance, 180, 181, 182

section, 180-182T section, 180-182

crystal, variable bandwidth, 1051-1061decoupling, in .diode detector cir-

cuits, 1073, 1080filter factor, 1192, 1194

INDEX 1441Filters (continued)

frequency dividing networks, 184-185, 860, 887-889

half-section, "building out" trans-former to give, 214

high pass, definition, 172hum filters for rectifier systems, 1192-1201image impedances of four-terminal

networks, 177-179image attenuation constant, 178, 179image phase constant, 178, 179image transfer constant, 178-179, 180

impedance mismatching in, 184iterative impedances of four-terminal

networks, 176-177iterative transfer constant, 176-177low pass, definition, 172mains, for receivers, 475, 1279-1280M-derived filters, 182-184, 652

design of multiple section filters, 183-184half section, 182-184T section, 182-184

pass band, 180practical, 184references, 185reflection effects in, 178resistance capacitance, 172-176, 1194

attenuation characteristics, 173-176parallel-T network, 176, 647, 651, 657,

675-676, 737-738, 745-749, 1194-1196theoretical cut-off frequency, 172time constant, 172, 173

shunt across load of power pentodes, 567, 636stop band, 180symmetrical networks, 179, 180tone control, elements of, 639variable bandwidth crystal, 1051-1061

Fine groove recording, 701, 706-709First detector, definition, 1400Fixed bias in power amplifiers, 547, 597Fixed bias operation, determination of

maximum grid circuit resistance, 82-84Fixed bias, r.c.c. pentodes, 501-502, 506Fixed bias, r.c.c. triodes, 487-489Fixed bias, sources of, 597Flat baffles, 842Flare cut-off frequency, 852Flaring constant of horns, 851, 852Flash dipping of coils, 477Flat frequency response in feedback

amplifiers, 379-388Flicker effect, 783Fluctuations in line voltage for valves, 10Fluorescence, 4Flutter in receivers, 955, 958, 993, 998,

1244-1246Flutter in record reproduction, 761Flutter in record reproduction, tests for, 1312Flux density, 229Flux density in power transformers, 235Flux density, maximum, 243Flux density, remanent, 230Flux density, residual, 230Flux density, units of, 1332Flux leakage, 231Flux, lines of, 229Flux, luminous, unit of, 1334Flux produced by inductor, 140Flux, units of, 1332Flywheel tuning, 1252Folded horns, 856-859Footcandle, 1334Force, coercive, 230Force, stylus, vertical, 702, 708, 709, 712,

718-722, 768, 769Force, stylus, vertical, minimum for

tracking, 712, 715, 719, 720Force, units of, 1330, 1332Forecasting frequencies for long distance

short-wave communication, 404, 901Form factor, 134Form factor of coils, 414Formulae or laws (in Algebra), 265Forward admittance, short-circuit, 50-55Forward admittance, short-circuit, test for, 117

Fourier analysis, 130, 299-302Fourier analysis of some periodic waves,

301-302Fourier analysis, references, 305Fourier series, 299-302Fourier series, graphical harmonic an-

alysis, 302-304Fourier series, other applications of, 302, 964Freezing point of water, 1334Fremodyne F-M detector, 1088Frequencies and wavelengths—table, 1362Frequencies, high roll-off, in a-f ampli-

fiers, 631Frequencies, primary resonant, of aerial

and r-f coils, measurements of, 1325Frequencies, standard, 1361Frequencies, standard intermediate, 1361Frequencies, standard test, in F-M re-

ceivers, 1314Frequency, 129, 278, 403Frequency bands for broadcasting, 1361Frequency changer, definition, 1400Frequency characteristics, bass boosting,

641-643Frequency characteristic of ideal constant

velocity pickups, 724Frequency compensated volume control,

automatic, 672-674Frequency conversion, 62, 962-1001, 1017-1019Frequency converters and mixers, opera-

tion of, 962-986analysis of operation common to all

types, 964-968conversion transconductance, de-

finitions, 14, 109conversion transconductance of con-

verter valves, 966-967conversion transconductance of

modulator or mixer valves, 964-966detailed operation of modulator or

mixer section of converter, 968-984noise in, 967-968, 972-973, 978, 984oscillator section of converter valves, 968

coupling between oscillator and signalcircuits, 973, 974-975, 980, 988, 992,994,

1000harmonic operation of oscillator (har-

monic mixing), 62, 958, 964-966, 991,994-996, 1000, 1001

input admittance, signal grid, 970, 973,976-978, 980-981

negative, 977,985-986input conductance, signal grid, 976-978,

980-981, 982, 987-988negative, 976-978, 985-986

input susceptance, signal grid, 976-978negative, 976-978

loading of input circuit due to valveadmittance, 970, 973, 987-988

methods of frequency conversion, com-parison—table, 985

methods of operation of mixer or modu-lator valves, 969

oscillator and signal voltages appliedto same grid, 969-973

oscillator voltage on inner grid, signalvoltage on outer grid, 973-978

oscillator voltage on outer grid, signalvoltage on inner grid 978-984

negative admittance of current limitedgrids, (Appendix), 985-986

neutralization in converters, 959, 969, 970,975-977, 978, 992, 1000, 1001

noise in, 967-968, 972, 973, 978, 984oscillator frequency variation due to

a.v.c. 963oscillator transconductance, phase shift

at high frequencies, 968references, 1017-1019see also Oscillators.space-charge coupling in, 963, 975-977, 980

neutralization of, 975-977, 992Frequency converters, applications of,

987-1001, 1017-1019, 1244-1248alignment, short wave, 990-991

1442 INDEX

Frequency converters (continued)a.v.c. on short waves, limitations on

use of, 975, 997, 998, 1000, 1111-1112,1251broadcast frequencies, 987-990coupling between oscillator and signal

circuits, effects of, 992, 994flutter, 955, 958, 993, 998, 1244-1246frequency stability, 992-996, 1247, 1256

effect of a.v.c. 963, 993-994variations due to local oscillator, 992-993

improving stability, 993variations due to mixer, 993-996

harmonic mixing, 958, 964-966, 991, 994-996, 1000, 1001, 1247

images, 990-991procedure to distinguish image from

signal, 990-991magnetic field, effect of, 1248neutralization in converters, 959, 969, 970,

975-977,978, 992, 1000, 1001, 1248noise, 967-968, 972-973, 978, 984operating conditions, broadcast, 989-990,

1244-1248operating conditions, short-wave, 991-992,

1244-1248padder feedback, 1001, 1247pulling, 971, 990references, 1017-1019signal-circuit regeneration, controlled,

988-989signal-circuit regeneration from screen,

988-989signal grid loading, 970, 973, 987-988spurious responses, 62, 987, 995, 1247tuned plate operation, 994, 1248

Frequency converters, testing of, 108-113methods of operation, 108-109

oscillator driven, 109oscillator self-excited, 108-109static operation, 109

plate resistance, 111stage gain, 74transconductance, conversion, 74,109-111,

124Frequency converters, types of, 996-1001

inner-grid oscillator injection, 973-978,997-1001

1R5 pentagrid, 995, 996, 10016A8-G pentagrid, 8, 997-9986BE6, 6SA7, pentagrids, 998-10006K8-G triode-hexode, 998

mixers, types of,heptodes, 8, 9hexodes, 9

outer-grid oscillator injection, 978-984,996-997

6AE8, X61M, X79, triode-hexodes, 9976J8-G, triode-heptode, 996-997

Frequency, definition, 1400Frequency discriminators, 1151, 1152-1156

Foster-Seeley (Phase) 1153-1156references, 1160Round-Travis, 1153

Frequency, dividing networks, 184-185, 860,887-889

Frequency, effect on capacitance of elec-trolytic condensers, 192

Frequency, effect on resistance of com-position resistors, 189

Frequency range in a-f amplifier, 617minimum audible change in, 617-618

Frequency modulation, 405Frequency, natural resonant, 407, 408, 424Frequency of parallel resonance, 150-152Frequency, parallel resonant, 410Frequency range and sound intensity pre-

ferences, 627,633Frequency range and volume level, 621-623Frequency range in record reproduction,

desirable top limit to, 704Frequency range in recording, 704Frequency range notation, reproduced

sound, 604Frequency range of high fidelity a-f

amplifiers, 630-631

Frequency ranges for speech reproduction 630Frequency ranges, standard, 1361Frequency ratio, octaves and decades

(table), 368Frequency ratio, to convert to db/octave,

637-638Frequency, resonant, 408Frequency response, flat, in feedback

amplifiers, 379-388Frequency response in feedback ampli-

fiers, 378-388Frequency response of a-f amplifiers,

test for, 1323-1324Frequency response of amplifier, varia-

tion with output level, 626Frequency response of loudspeakers,

833, 838, 854-855, 860Frequency response of receivers, tests

for, 1305, 1318Frequency shift in receivers, tests for,

1310, 1319Frequency spectrum, electromagnetic, 404Frequency stability in converters, 992-996Frequency stabilization, oscillator, 957-958Frequency test records, 702-703, 716, 752-757Frequency variation, oscillator, causes

of, 950, 955-956Fringing, 231Full-wave rectification, 7, 1161-1169, 1173-

1185Function, definition, 1400Functional characteristics of valves, basic, 70-73Functions, 263Functions, continuous and discontinuous,

265-266Functions, inverse, 276-277Fundamental characteristic tests, 73-75Fundamental frequency, 130, 300Fundamental frequency, definition, 1400Fundamental physical properties of

valves, 69-70Fungus growth on materials, 475Fuses, 1281-1282, 1395

GG curves, 23, 554G.E. variable reluctance pickup, 718Gain, aerial coil, 916-917, 920Gain, amplifier, expressed in decibels, 810-811

in pre-amplifiers, standard, 793power, expressed in decibels, 810voltage, expressed in decibels, 810

Gain at any frequency, coupled circuits,416, 421-423

Gain at mid-frequency, r.c.c. pentodes, 506-508r.c.c. triode, 490-491transformer-coupled a-f, 517

Gain at resonant frequencyidentical stages in cascade, 421tuned primary, tuned secondary, 415, 426untuned primary, tuned secondary 425

Gain bridging, 811Gain control devices in volume expanders

and compressors, 684-686Gain/frequency characteristic, r.c.c. pen-

tode, 512incomplete cathode and screen by-

passing, 498-500incomplete cathode by-passing, 499-501incomplete screen by-passing, 496-497

Gain/frequency characteristic, r.c.c.triode, 494-495

incomplete cathode by-passing, 484-485Gain, maximum, of r.c.c. pentode, load

resistance to give, 507Gain, maximum stage, of i-f amplifier,

1028, 1032, 1036Gain, of a-f amplifiers, measurement of, 1323Gain of amplifier, effect of feedback on,

308, 313, 315, 316Gain of cathode degenerative amplifier, 327-328Gain of cathode follower, 317-318, 325

INDEX 1443

Gain of Class A power triode at high in-puts calculated from measurements ofg m and g p at low inputs, 554, 555

Gain of multistage voltage amplifier, 541Gain of stages in receiver, measurements

of, 1303Gain, power expressed in decibels, 806-807Gain, power, of aerials, 894Gain, radio frequency amplifiers, 923, 924Gain ratio/decibel gain, chart, 813Gain, stage, tests for, 74, 108Gain, units for measurement of, 806-823,

825-826bels and decibels, 806-823

absolute power expressed in, 807-808absolute voltage expressed in, 808amplifier gain expressed in, 810-811

bridging amplifier, gain of, 810-811in terms of power, 810in terms of voltage gain, 810

combined microphone and amplifiergain expressed in, 811-812

dbm, 808dbv, 808dbvg, 810decibels, slide rules and mental

arithmetic, 822-823loudspeaker output expressed in

decibels, 812microphone output expressed in, 808-810

in terms of effective output level, 809in terms of output power, 808-809in terms of output voltage, 808microphone system rating, R.M.A.,

809-810, 812minimum perceptible change of level, 807nomogram for adding decibel-ex-

pressed quantities, 821-822pickup output expressed in, 810power relationships expressed in, 806-807sound system rating, 812-813tables and charts, 813-821

decibels above and below 1mWinto 600 ohms, 820

decibels above and below 6 mWinto 500 ohms, 818

decibels above and below 6 mWinto 600 ohms, 819

decibels as power, voltage, currentratio—chart, 813

decibels expressed as power andvoltage ratios, 814-816

power and voltage or current ratiosexpressed in decibels, 817

watts, dbm and volts across 5000ohms, 821

voltage and current relationships ex-pressed in, 807

nepers, 825-826relationship between decibels and

nepers, 826references, 830transmission units, 826

Gain,voltage, of grounded grid stage, 925Gain,voltage, of power amplifier, 549Gamma rays, wavelengths of, 404, 1363Gang capacitor plates, vibration of, 958-959Gang capacitor, position of, 957Gang capacitor, tuning, difficulties with,

913, 958Gang condensers, 197, 1289Gas current, 3, 19, 51Gas current, tests for, 101, 102Gas pressure, 73Gas tube coupled direct-coupled amplifier, 532Gated beam discriminator 6BN6, 1293Gauss, 1332, 1333Gear ratios for universal coils, 456-457Generator, a.c., 129Generator, audio-frequency, 1299Generator, d.c., 129Generator, definition, 1400Geometrical mean frequency, 130Geometrical mean (mean geometrical

progression), 266-267, 272Geometrical progression, 266-267

Geometry, 272-275Germanium crystal detectors, 1136-1137Getter, 4, 69, 70Gilbert, 229, 1332, 1333Gilbert per maxwell, 1332, 1333Giorgi (m.k.s.) system, 1331, 1332Gliding tone frequency test records, 752, 753Glow, blue, 44Goldring Headmaster pickup, 718Gradient microphones, pressure, 775Grain, measure of mass, 1329Gram, unit of mass, 1329, 1331, 1332, 1333Gram weight, measure of force, 1330Gramophone, definition, 1400Graphical harmonic analysis, 302-304, 305

see also under Distortion.Graphical representation of relationships

between functions, 279-282Graphical representation with three vari-

ables, 281Graphical symbols, standard, 1370-1371Gravitational acceleration, 1330Greek alphabet, 1397Grid, anode, 9Grid bias, effect of change of, on charac-

teristics, 26Grid bias, effect of grid current on, 484, 488Grid bias for a.c. or d.c. filament ex-

citation, 2, 80Grid bias for Class A amplifiers, voltage

regulated, 1215Grid bias of Class A power triode cal-

culated optimum, 557Grid blocking, 21, 84, 1110

tests for, 107-108, 113Grid-cathode capacitances, values of, 56Grid circuit decoupling, 538Grid circuit resistance, maximum

determination of, 82-84general, 10, 70, 75in a-f power amplifiers, 566, 596-597in a-f voltage amplifiers,

pre-amplifiers, microphone, 788r.c.c. pentodes, 496, 501-503r.c.c. triodes, 482-483, 487, 488

in a.v.c. circuits, 1110-1111references, 543

Grid circuit resistance, r.c.c. pentode,maximum with cathode bias, 501maximum with fixed bias, 502-503

Grid coupling condenser—see underCoupling condenser.

Grid current characteristics, 18-21Grid current commencement point, 19, 84Grid current commencement voltage, test

for, 73, 102, 109Grid current cross-over point, 19, 20

drift during life, 23-24, 84Grid current, effect on bias, 484, 488Grid current, negative, 3, 19, 21, 51, 101-102,

484tests for, 73, 101-102, 109, 124typical maximum values in new valves,

101-102Grid current, noise caused by negative, 784Grid current, oscillator, test for, 111-112Grid current, positive, 18, 21, 51, 484, 489

in r.c.c. amplifiers, damping due to, 489tests for, 73, 102

Grid detector, leaky, 62, 1082-1084Grid detector, power, 1084Grid driving conditions, Class B2, 590-591Grid emission, 3, 5, 20, 21, 51, 71Grid input admittance, 49-53, 113-117,

493-494, 927-934, 970-988components of, 51-53due to electron transit time, 50, 51, 930-932,

971, 975, 980, 985-986due to grid-screen capacitance coupling, 53due to plate-grid and grid-cathode

capacitance coupling, 53due to plate-grid capacitance coupling,

51-53, 493-494effects of, 927-934

1444 INDEX

Grid input capacitance, 49-53components of, 51to prevent change in, 53

Grid input conductance, 49-53Grid input impedance, 49-53Grid input inductance, 49-53Grid input power, peak, Class B2, 590Grid input resistance, 49-53

increased by inductance between loadand plate, 53

inductance in screen circuit, 53minimum, Class B2, 590

Grid input reactance, 49-53Grid input susceptance, 49-53Grid leak bias, 489, 786, 1280-1281Grid leakage current, 19, 20, 51, 69, 70Grid leakage current, tests for, 101-102Grid load lines, 20Grid noise, induced, 939-940Grid-plate capacitance, 7

variation of, with plate current, 57Grid positive voltages, 21Grid primary emission current, 19, 20, 21, 69,

71Grid primary emission, tests for, 101-102Grid resistance, minimum variational, 590Grid resistor, effect on hum, 1197Grid, screen, 7Grid secondary emission, 2, 7, 8, 21, 39, 69, 71Grid secondary emission, tests for, 102Grid series compensation, 643Grid stopper, use of, 32, 61, 91, 560, 562, 958,

1000, 1283Grid, suppressor, 8Grid temperature, 5Grid variational conductance, 20Grid voltage limits, 79, 80Grids, 5Grids, aligned, 8Grids, numbering of, 1365Grilles, loudspeaker, 835Ground, definition, 1400Grounded-grid amplifiers, 529, 592, 914, 925

HHaas effect, 867Half-boost point, 641-642Half-wave dipole, folded, 910-911Half-wave rectification, 6, 1161, 1163, 1172,

1175, 1176, 1178Hangover, 619Hanna's method, design of iron-cored

inductors, 248-249Hard valve, definition, 1400Harmonic analyser, 106Harmonic analysis, graphical, 302-304, 305

see also under Distortion.Harmonic composition of some periodic

waves, 301-302Harmonic frequencies (harmonics), 62, 130, 300see also under Distortion, harmonicHarmonic frequency, definition, 1400Harmonic generation in A-M receivers,

tests for r-f, 1305Harmonic mean, 266-267Harmonic mixing, 958, 964-966, 991, 994-996,

1000, 1001Harmonic motion, simple, 278-279, 702Harmonic operation of oscillators, 958, 964-966,

991, 994-996, 1000, 1001Harmonic progression, 266-267Harmonics, effect of armature resonance

on, 716Harmonics, oscillator, 954, 955, 956Hartley oscillator, 112, 951-952, 967Hash elimination with vibrators, 1210-1211,

1270-1272, 1275-1276Headphones, 832-833Headphones, equalizing, 662Heater,

current, testing for, 93-94d.c. operation of, 744, 748, 785-786dissipation and temperature character-

istic, 10, 11forms of heaters, 5

Heater (continued)heater to cathode insulation

effect on design, 81maximum ratings, 75, 81

heater to cathode leakagehum due to, 81, 84, 540, 785, 1095, 1131,

1196, 1197tests for, 73, 94, 123

voltage/current characteristic, 10, 11voltage

characteristics with reduced, 3, 73effect of variation on characteristics, 24line fluctuations of, 10permissible variation, 10ratings, 77, 78, 79recommended, published, 3, 10reduced, dynamic tests at, 74-75

Heating of a resistor, 134Height above earth, aerial, effect of—

charts, 898-900Height above earth, desirable aerial, 895Height of curve, average, 280Henry, 1332, 1333Heptode as phase splitter, 524Heptodes, 8, 9Hertz, definition, 1400Hertzian waves, wavelengths of, 404Heterodyne oscillators, 960-961Hexodes, 9High fidelity amplifiers, filter required to

remove lower frequencies from out-put, 631

High fidelity, practicable, 630-631High fidelity reproduction, 630-632High fidelity reproduction, permissible

noise in, 630High fidelity, the target of, 630High frequency horns, 857-859High level, definition, 1400High pass filter, definition, 172, 1400High stability resistors (cracked carbon),

186, 190Hill and dale recording, 701Hinge frequency, 759Hinge point in recording characteristics,

737, 759Home recording, lacquer disc, 701, 766-768Honeycomb winding, definition, 1400Horizontal aerials, 895-896, 910Horizontal and vertical aerials, compari-

son between, 895, 896Horn loudspeakers, 831, 832, 851-861Horns, high-frequency, 857-859Hot stylus recording technique, 767Hum

acoustical measurement, 1310caused by electrostatic coupling, 539, 1198caused by inductive coupling, 539, 1197,

1198distortion, 1309, 1314, 1322-1323due to a-f transformers, 206, 207, 210-211,

540, 781, 785due to circuit design and layout, 1198-1199due to incomplete cathode by-passing, 786due to valves in magnetic field, 785, 786,

788, 1198effect of feedback on, 309-310, 315, 316,

348-352effect of grid resistor on, 1197heater induced, due to conditions within

valves, 81, 84, 540, 1196-1198capacitive coupling, 788, 1196-1197, 1198emission heater-cathode, 1196, 1197leakage heater-cathode, 81, 84, 540, 785,

1095, 1131, 1196, 1197methods for minimizing, 785, 786, 1197

leakage from any electrode with ripplevoltage to another electrode, 1196

modulation of electron stream bymagnetic field of filament, 1196, 1197

summary, 1197-1198heater induced hum, avoided by d.c.

operation, 744, 748, 785-786hum levels in receivers and amplifiers,

1199-1200in filtered rectifier output, 1192-1196

INDEX 1445

Hum (continued)in noise limiters, 1131in phase discriminators, 1095in phonograph combinations, 1309in power amplifiers, 573-574, 599, 1199in pre-amplifiers, 784-786in radio receivers, 1237, 1239-1241, 1309-

1310methods to reduce hum at minimum

setting of volume control, 1237, 1240testing, 1309-1310, 1319tracing, 1241

in ratio detectors, 1098in record reproduction, 705, 706, 719, 722, 763in rectified and filtered a.c. supply, 129in rectified and filtered plate supply,

effect of feedback on, 309-310, 316,348-352

power amplifiers, 573-574, 599, 1199voltage amplifiers, 538-540in unfiltered rectifier output, 1177

in voltage amplifiers, 483, 538-540effect of coupling condenser on, 483from grid bias supply, 539from parallel feed, 538from plate supply, 538from screens, 539from transformer-coupled amplifier, 538

level, pickup, 719, 722modulation hum, 1198, 1199, 1239-1241,

1267, 1268, 1290, 1309, 1314modulation of oscillator, 958, 993neutralization in reflex receivers, in-

herent, 1145neutralizing, 539, 785, 1200-1201, 1239references, 804-805screening, electrostatic, to reduce, 784, 1198shielding of microphone and a-f trans-

formers to reduce, 207, 210-211, 781, 784,1198

with pentode valves in pre-amplifiers, 786with type 12AY7 low noise type 787-788with type 5879 low noise type, 787, 1198

Hum bucking coil in loudspeakers, 840Humidity changes, oscillator frequency

variation due to, 955-956Humidity, effect on resistors, 188-189Hunting, definition, 1400Hyperbola, 274Hyperbola, equation to, 280Hyperbolic cosine horns, 854Hyperbolic exponential horns, 853-854Hyperbolic functions, 269-271Hyperbolic tables, 1421Hypex horns, 853-854Hypotenuse, 272Hysteresis loop, 230Hysteresis loss, 230

IIllumination, units of, 1334Image attenuation constant of 4-terminal

networks, 178, 179Image frequency, 987Image impedance, mid-series, 180, 181Image impedance, mid-shunt, 180-182Image impedances of 4-terminal net-

works, 177-179Image phase constant of 4-terminal net-

works, 178, 179Image ratio, 971, 978, 991, 1278, 1310Image rejection by r-f stage, 913, 925-927Image rejection circuit, 1256Image transfer constant of 4-terminal

networks, 177-179Imagery for describing reproduced sound,

604-605Images, procedure to distinguish from

signal, 990-991Imaginary axis, 285Imaginary part of complex quantity, 140, 285Impedance, general, 139, 143

a complex quantity, 144aerials, 901-906

Impedance (continued)and admittance, 144-158calculations, ideal transformers, 200-203characteristic, of 4-terminal network, 179conjugate, 165conversion from series to parallel, 157-158driver transformer looking backwards, 591grid input, 49-53image, of 4-terminal networks, 177-179iron-cored inductors, measurement

of, 250-251iterative, of 4-terminal networks, 176-177loudspeaker rating, 812, 874

blocked, 838electrical, 837-838, 847-849, 856free, 838measurement source, 812, 874motional, 838standard, 874

matching in pentodes, definition, 160maximum, determining parallel reson-

ance, 151-152microphone electrical, 781microphone nominal, 781, 782microphone rating, standard for, 781mismatching in filters, 186of parallel combinations of L, C and

R, 147-149of parallel tuned circuit, 149-152of power supply, effect on a-f amplifiers,

535, 537, 574of reactance and resistance in parallel,

graphical method, 149of series combinations of L, C and R, 144-147of series-parallel combinations of L, C

and R, 149-153of two-terminal network, general pro-

cedure, 153ratio of transformer, effect of losses on, 206reactance and resistance

in parallel (chart), 1380-1381in parallel (table), 1380in series (charts), 1384-1385in series (table), 1382, 1383in series or parallel, approximations

in, 1386total effective plate supply per plate,

1165-1167, 1180transmission lines, characteristic, 890-891transmission lines, impedance-trans-

former action, 891-892transmission lines, input, 892

Impedance, resonant, of parallel tunedcircuit, 411

Impedance, series, of tuned circuit, 409Impedances, negative stabilized, 389Impregnation of coils, 477Impulse, unit, as test for loudspeaker

transient response, 870Incremental change of voltage, 13Index (indices), 255Index of a logarithm, 256Indicating instruments, 825

decibel meters, 825noise meters, 827-829power-level indicators, 825power output meters, 825sound level meters, 828volume indicators, 823-824

Indoor aerials, 908Induced grid noise, 939-940Inductance, 140-144Inductance, calculation of (Chapter 10) 429-449

flat spirals, 445-446iron core, powdered, effect of, 1042multilayer solenoids, 441-444

approximate formulae, 442-443correction for insulation thickness, 442current-sheet inductance, 441-442design of multilayer coils, 443-444effect of concentric screen, 444universal coils, 444

mutual inductance, 446-448references, 448-449single layer coils or solenoids, 429-441

approximate formulae, 432

1446 INDEX

Inductance, calculation of (continued)current-sheet inductance, 429, 436-438

curves for, 436-438design of single layer solenoids, 433-435difference between Ls and Lo, 435-437effect of concentric screen, 438-441, 473solenoid wound with spaced round

wires, 430straight wire, 1287toroidal coils, 445

Inductance, critical value of, with chokeinput filter, 1182-1185

Inductance, grid input, 49-53Inductance, ideal, 144Inductance in a.c. circuits, 142-143Inductance, mutual, 142Inductance of composition resistors, 189Inductance of iron-cored inductors, 242

measurement of, 250-251Inductance of leads and electrodes, effect

of, 46, 50, 51, 53, 69, 930, 931, 932Inductance of transformer primary,

a-f, 204, 207, 209output, 212-214variation with signal, 547

Inductance ratio of iron-cored inductors, 242Inductance, units of, 1332Inductances in d.c. circuits, 141Inductances in series and parallel, 141Inductive circuits, impedance in, 143Inductive circuits, power factor in, 144Inductive circuits, power in, 143Inductive reactance, 142Inductive reactance, sign of, 50Inductive susceptance, sign of, 50Inductor, 140Inductor dynamic loudspeaker, 832Inductor, electromagnetic field due to, 140Inductor, electromotive force induced in, 140Inductor, figure of merit for, 144Inductor, flux produced by, 140Inductors, iron-cored, 242-253

design for choke-input filters, 249-250design of high Q inductors, 245-247design with d.c. flux, 247-249

Hanna's method, 248-249design with no d.c. flux, 243-245flux density, maximum, 243inductance, calculated, 242inductance ratio, 242length of magnetic path, 242-243measurement of inductance and im-

pedance, 250-251permeability, effective, 242-243, 244permeability, incremental, 230, 243, 248references, 253resonant circuits, in, 251see also under Magnetic circuit theory,

Transformers.swinging choke, 249, 250, 1182

Inductors, radio frequency, design of(Chapter 11), 450-480

intermediate-frequency windings, 453-459air-cored coils, 453-454, 1041-1043coupling, amount of, 458direction of windings, 458gear ratios for universal coils, 456-457, 1043iron-cored coils, 454-455, 1041-1043losses, 458other ferromagnetic materials, 458-459variable selectivity i-f transformers,

455-456, 1048-1050see also under Transformers, i-f.

medium wave-band coils, 459-463air-cored coils, 459-460iron-cored coils, 460-461matching, 462-463permeability tuning, 461-462, 912, 913,

953, 1002, 1289resonance solenoid design chart, 1386-1387

radio-frequency chokes, 474-475other types, 475pie-wound chokes, 474

references, 478-480self-capacitance of coils, 451-453

calculation for single layer solenoids,451-452

Inductors, radio frequency (continued)effects of self-capacitance, 451measurement of self-capacitance, 453

short-wave coils, 463-474aerial primary windings, 474design, 463-468design charts, 466-473, 1386-1387direction of windings, 474matching, 468-471resonance design chart, 1386-1387self-capacitance, 472-474

tropic proofing, 476-478baking, 476-477flash-dipping, 477general considerations, 476impregnation, 477materials, 477-478

Inequalities, 262Infinite impedance detector—see under

Detectors, A-M reflex.Infinite series, 268-269Infinity, definition, 261Inflection, point of, 293, 508Infrared rays, wavelengths of, 1363Inharmonic distortion in loudspeakers, 870Initial electron velocity of emission, 18In-phase a-f amplifiers, 529In-phase gain of push-pull amplifier, 528Input admittance, components of, 51-53Input admittance, converter signal grid,

970, 973, 976-978, 980-981Input admittance, grid, 49-53, 113-117,

493-494, 927-934, 970-988Input admittance, grid, due to

electron transit time, 50, 51, 930-932, 971,975, 980, 985-986

grid-screen capacitance coupling, 53plate-grid and grid-cathode capacitance

coupling, 53plate-grid capacitance coupling, 51-53,

493-494Input admittance, short-circuit, 50-55

tests for, 113-117Input admittance, valve, effects of, 927-934Input, antenna sensitivity test, definition,

1297-1298Input capacitance, change in, 927, 932-933Input capacitance change with bias change,

value of cathode resistor for com-pensation of, 56

Input capacitance, components of, 51Input capacitance, grid, 49-53Input capacitance of cathode follower, 323, 325Input capacitance of pentode with feed-

back to screen, 345Input capacitance, short-circuit, change

with transconductance, 55Input capacitances of pentodes, published

values, 56Input circuit damping, 20, 70, 489, 1036, 1074,

1077-1078, 1084Input circuit of network, definition, 160Input conductance

converter signal grid, 976-978, 980-981,982, 987-988

grid, 49-53short-circuit, typical values of, 55valve, at radio frequencies, 929-932

Input impedance of aerials, 904Input impedance of reflex detector, 1085-1086Input impedance, unloaded a-f trans-

former, 517Input inductance, grid, 49-53Input loading, valve, at radio frequencies,

928-934minimizing by tapping down, 921

Input measurements on F-M receivers, 1316Input power, peak grid, Class B2, 590Input reactance, grid, 49-53Input resistance

cathode degenerative amplifier, 328effect of feedback on, 311-316grid, 49-53grid, methods of increasing, 53minimum grid, Class B2, 590

INDEX 1447

Input resistance (continued)negative, instability due to, in Class B2

amplifier, 590Input signal for pre-amplifiers, standard, 793Input, standard mean signal, in F-M

receivers, 1314Input susceptance, converter signal

grid, 976-978Input susceptance, grid, 49-53Input voltage, standard, A-M, definition, 1297Input voltages and powers in F-M re-

ceivers, standard, 1314Insertion loss of frequency dividing net-

works, 887Insertion loss of mixers and faders, 799Instability due to negative input resistance

of Class B2 amplifier, 590Instability in A-M receivers, 1243-1244Instability in F-M receivers, 1288-1289Instability in r-f amplifiers, 942-944Instability, low frequency, in F-M re-

ceivers, tests for, 1319-1320Instability of valve electrical characteris-

tics, 70Insulating materials, properties of, 1372-1373Insulation between valve electrodes, 69, 70, 73Insulation heater to cathode, effect on

design, 81Insulation resistance, interelectrode, tests

for, 73, 94Integer, definition, 1400Integral, 256, 294-298Integral dual loudspeaker systems, 860Integral triple, loudspeaker systems, 860Integrals, definite, 296-298Integrals, definite, average (r.m.s.) value

of sine wave, 298Integrals, definite, average values by, 297-298Integrals, indefinite 296Integrating networks, 160Integration, 294-298Integration, areas by, 296Integration, limits of, 296Intensity, definition, 1400Intensity of pressure, units of, 1330Intensity, reference acoustical, 826Intercommunicating systems, 867Interference

co-channel, in F-M receivers, tests for,1317-1318

in A-M receivers, reduction of, 1279-1280masking, in F-M receivers, tests for, 1318tests in A-M receivers, 1313-1314

Intermediate frequency, 964Intermediate frequency, definition, 1400Intermediate frequency transformers-

see under Transformers, i-f.Intermediate frequency windings, design

of, 453-459Intermodulation, definition, 1400

difference frequency, 62distortion, 611-616

comparison between methods, 616difference frequency method, 613, 1322effect of high frequency pre-emphasis

and de-emphasis, 616equivalent single frequency power

output, 612in amplifiers, 353, 1322in loudspeakers, 871individual sideband method, 613-614Le Bel's oscillographic method, 614-616modulation method, peak sum, 614modulation method, r.m.s. sum, 612of r.c.c. triodes, 492-493permissible, 613, 630-631references, 633relation with harmonic distortion,

612-613, 615Williamson amplifier (A515 version), 347

production of spurious frequencies, 62r-f, in A-M receivers, tests for, 1305sum frequency, 62

Inter-station noise suppression, 1125-1130Inverse functions, 276-277

Inversion gain of push-pull amplifier, 528Inverted input a-f amplifiers, 325, 529Inverted L aerials, 901, 902, 903-904, 907Inverted T aerials, 907Ion bombardment of cathode, 3Ionic loudspeakers, 831Ionization, 3Ionization current 19Ionization noise, 783, 784Ionized layers in atmosphere, 404, 901Ionosphere, effect on reception, 901Ions, positive, 3, 71Iron-cored i-f coils, design of, 454-455,

1041-1043Iron-cored medium wave-band coils,

design of, 460-461Iron cores in r-f inductors, 450, 470, 475, 1023,

1025, 1041, 1042, 1101Iterative impedances of 4-terminal net-

works, 176-177Iterative transfer constants, 176-177

Jj as operator, 283j notation, 139, 283-284Johnson noise—see under Noise, thermal

agitation.Joule, 133, 1332, 1333

KKelvin temperature scale, 1334Kilogram, measure of mass, 1332, 1333Kilowatt hour, 133Kinkless tetrodes, 8Kirchhoff's laws, 159, 160-161Klipsch corner horn, 857-859

LLabyrinth, acoustical, 850Lacquer disc home recording, 701, 766-768Ladder type attenuators, 796-797Lamb noise silencer, 1130, 1131Laminations for power transformers, 234-235,

240Lamp characteristics, American panel, 1397Lamp, tungsten, spectral energy curves, 1396Lamps as control devices in volume ex-

panders, 685, 687-688carbon filament, characteristics of, 685tungsten filament, resistance charac-

teristic, 685Lamps, dial, in a.c./d.c. receivers, 1266-1267Lapel microphones, 780Lateral recording, 701-774Laws, in algebra, 265Layer, ionized, in atmosphere, 404, 901Layer winding, definition, 1401Lead, definition, 1401Leading voltage, current, 138Leak amplifier, 600Leakage current in valves, 19, 20, 51, 69, 70Leakage currents in valves, tests for, 101, 102Leakage currents of electrolytic con-

densers, 193Leakage flux, 231Leakage from any electrode with ripple

voltage to another electrode, humdue to, 1196

Leakage, heater-cathode, hum due to,81, 84, 540, 785, 1095, 1131, 1196, 1197

Leakage, heater-cathode, tests for, 73, 94, 123Leakage inductance, 204, 207, 209, 210, 212,

217-219, 233driver transformer, effect of, 590output transformer

pentodes, effects of, 566reduced by bifilar winding, 594triodes, effects of, 572-573

Leakage, valve, noise caused by, 784Leaky grid detectors, 62, 1082-1084Learned's method of design of feedback

amplifiers, 365, 369-371Length, units of, 1329, 1332

1448 INDEX

Level control, L type, 889Level, loudness, contours of, 826Level, loudness, unit of, 826Level, minimum perceptible change in, 807Level, recorded, 702-703Level, recorded, maximum instantaneous

programme peak, 702-703Level, recorded, normal maximum, 703Life, drift of characteristics during,

23-24, 70, 84, 530, 533Life of condensers, service, 192Life of valves, when to replace, 121Life test, valve, end points, 88-89Life tests, valve, 75, 85, 87-89Life, ultimate electrical, of valve, 70Life, working, of valves, 3, 70, 121Light intensity, measure of, 1334Light, spectral energy curves of sunlight

and tungsten lamp, 1396Light, velocity of, 1396Light, visibility curves of human eye, 1396Light, wavelengths of, 404, 1363Limen, 617-618Limiters, amplitude, 1023, 1040, 1088, 1090,

1095, 1098, 1099, 1147-1150, 1296A-M rejection by ratio detector, 1095-1096,

1103-1104applications of, 1023, 1040, 1088, 1090,

1095, 1098, 1099, 1151limiting by superregenerative detector, 1087references, 1160time constant of, 1148, 1149typical circuits for F-M receivers, 1149-1150

cascaded limiters, 1150single stage, 1149

Limiters, noise peak, 694-698, 1130-1132Limiters, output, 698-699Limiters, peak, 681, 682-683Limiters, volume, 681, 683Limiting Class A amplifier, definition, 545, 572Limiting ratings—see under Valve ratings.Limits in algebra, 265-266Limits of integration, 296Line, measure of flux, 1332, 1333Line per square inch, 1332Line voltage, definition, 1401Line voltage fluctuations, 10Line voltage operation, valve ratings for, 78, 79Linear, definition, 1401Linear elements in networks, 158, 948Linear equation, 279Linear reflex detectors, definition, 1401Linearity (transfer) characteristic of a-f

amplifiers, 587, 610, 611Link, 321Link coupling of tuned circuits, 418, 419Lip microphone, 780Listener fatigue, 626Listening levels, preferred, 623Listening tests of loudspeakers, 632, 834Listening tests of receivers, 1314Litre, measure of volume, 1329Litz wire in coils, 450, 456, 466, 1042Load, definition, 1401Load impedance for pre-amplifiers, stan-

dard, 793Load line, general, 24, 58

cathode, 29-30cathode bias, r.c.c. triodes, 29-30, 486-487composite, 576curved, driver valve, 591diode, 1075elliptical, 30-34, 64, 213, 576grid, 20maximum signal dynamic, 551screen, 513-514screen and cathode combined, 515-516shifted due to rectification, 551

Load, loudspeaker, maximum output with, 881Load, loudspeaker, on power amplifiers,

546, 558, 566-567, 600-601, 881-882Load, phase shift of, at low frequencies, 213Load resistance

effect of change of, 43matching of, with Class Al triodes, 61optimum with feedback, 311

Load resistance (continued)power amplifiers, critical value of, 546

Class A pentode, 561Class A triode, optimum, 557-558

r.c.c. pentode, 496to give maximum gain, 507

r.c.c. triode, 482Load, standard dummy, of receivers, 1299Loading of input circuit by converter valve

admittance, 970, 973, 987-988Loading of transformer-coupled a-f

amplifiers, 519Loading, valve, effect of a.v.c. on, 971Loading, valve, minimizing by tapping

down, 921Locked oscillator—F-M detector, 1088,

1292-1293Locus, definition, 1401Logarithm tables, 1418, 1419Logarithmic decrement, 268, 408, 424Logarithmic functions, 267-268Logarithmic graph paper, 280Log. scale interpolator, 1422-1423Log. scales, 1422Logarithmic series, 269Logarithms, 255-257Loop aerials, 901, 904, 908, 921-922Loop amplification, feedback, 356Loop, feedback, 307, 336Loss, copper, in power transformers, 235, 236Loss, iron, in power transformers, 235Loss, playback, 760Loss, translation, 759, 770Losses in transformers, relation between

copper and iron, 205Loudness, 826-827

contours of equal loudness level, 826definition, 1401loudness directivity index, loudspeaker, 875loudness efficiency rating, loudspeaker, 875loudness units, 827phon, unit of loudness level, 826reference intensity, 826reference pressure, 826, 828reference velocity, 826references, 830relation between loudness and loudness

level, 827Loudspeakers (Chapter 20), 831-879

acoustical data, summary of, 871-874definitions, 871-872electrical, mechanical and acoustical

equivalents, 872musical scales, 873-874pitch, international standard, 874velocity and wavelength of sound, 872

baffles and enclosures, 842-851acoustical labyrinth, 850acoustical phase inverter (vented

baffle), 845-850combination horn and phase in-

verter for personal radio re-ceivers, 859

matched vented baffles, 847-849equivalent electrical circuit, 848-849flat frequency response, design

for, 849impedance characteristic, elec-

trical, 847-849special types of, 1489

unmatched vented baffles, 849-850adjustable vent area, 849

enclosed cabinet, 843-845acoustical damping to eliminate

standing waves, 843-845, 849bass attenuation with, 844-845critical damping, effects, of, 844-845damping, 841, 844-845equivalent electrical circuit, 844-845standing waves, in, 843

exterior of cabinet, design of, 850flat baffles, 842

damping with, 833, 840-842dip in response with, 842impedance characteristic with 837-838,

848

INDEX 1449

Loudspeakers (continued)irregular shape, 842off-centre mounting, 842

open back cabinets, 842-843peak in response, 843

R-J loudspeaker, 850bass reflex—see under Acoustical

phase inverter.characteristics, 833-834colour codes for, 1343cone movement, amplitude of 834damping, 833, 840-842, 844-845, 856

critical, 833, 840-841, 844-845critical, definition, 840effect on transient response, 833electro-dynamic, enclosed cabinet,

841, 844-845electro-dynamic, flat baffle, 833, 840-842

electro-magnetic damping, 840Q of loudspeaker at bass resonance, 841

feedback of voltage, proportional tovelocity of cone, 841-842

source impedance, effect of zero ornegative, 841

deflectors, 839diffusing lenses, 839, 858direct radiator loudspeakers, 831-851,

860-864condenser, 832electro-dynamic (moving coil),

831, 833-851, 860-864electro-magnetic, 831-832

balanced armature, 831-832inductor dynamic, 832reed armature, 831-832

piezo-electric (crystal), 832direct radiators, definition, 831directional characteristics, 834, 839-840, 856directivity index, 875distortion, 854-855, 868-871

cross-over, 856, 860-861, 868frequency modulation, 855, 869horn loudspeakers, occurring in, 854-855inharmonic, 870intermodulation, 871non-linear, 836, 855, 868phase shift characteristics, 838, 870selective, below bass resonant fre-

quency, 600-601, 868sub-harmonics and sub-frequencies, 871transient, 833, 869-871

effect of other characteristics on, 869-870testing for, 870-871

decay characteristic (Shorter'smethod) 870-871

square wave, 870tone burst, 870unit impulse, 870

dual and triple system loudspeakers, 860-861choice of cross-over frequency, 860-861co-axial and co-planar mounting, 860compromise arrangements, 861frequency dividing networks, 860, 887-889integral dual systems, 860integral triple systems, 860overlap region, 856, 861

distortion in, 856, 860-861, 868effects of unequal acoustical paths, 861

phasing of, 860efficiency, 839, 854-855, 860efficiency in terms of acoustical power,

875-876electro-dynamic (moving coil), charac-

teristics of, 833-842cone movement, amplitude of, 834cones, practical, 834, 835-836, 839corrugations in cones, 835-839damping, 833, 840-842

critical, 833, 840-841effect on transient response, 833

deflector for, 839diffusing lens, 839directional characteristics, 834, 839-840duode, 837efficiency, 839

electro-acoustical, 839electro-mechanical, 839maximum, frequency of, 839

Loudspeakers (continued)equivalent electrical circuit, low fre-

quencies, 838equivalent electrical series circuit, 839frequency response, 833, 838

peaks in, 833, 834hum bucking coil, 840impedance, blocked, 838impedance characteristic, electrical,

837-838impedance, free, 838impedance, motional, 838magnetic flux, effect on damping,

831, 840, 841magnetic flux, effect on efficiency, 831, 840magnetic flux, optimum for frequency

response, 840magnets, types of, 831, 840phase characteristic, 838power output, maximum, 836radiation resistance of piston, 835resonant frequency, bass, 836, 837-841,

844-845, 848-849rigid (piston) cone in infinite baffle, 835source impedance, effect of, 833special constructions for wide fre-

quency range, 836-837double coil, double cone, 837double coil, single cone, 836-837multiple single coil, single cone, 836single coil, double cone, 836

suspension, cone, 835-836compliance, 836non-linear, 836resistance, mechanical, 836spider (centre mounting), 835stiffness, 836stiffness-control by, 836surround, annular, 835-836

equivalent circuits, 838, 839, 844-845,848-849

feedback of voltage proportional tovelocity of cone, circuit to give, 841-842

frequency response, 833, 838, 854-855, 860peaks in, 833, 834, 860-861

good qualities of, 834grilles (grille cloth), 835headphones (telephone receivers), 832-833

crystal, 833inductor, 833magnetic diaphragm, 832

correction, circuit for, 833moving armature, 833moving coil, 833ribbon, 833

horn, definition, 831horns, 831, 832, 851-861

catenoidal, 854combination horn and phase inverter

for personal radio receivers, 859conical, 851, 854corner, 856

Klipsch, 857-859damping and transients, 856diaphragm and throat, 854-855diffusing lenses, use of, 858directional characteristics, 856distortion due to

frequency modulation, 855sound chamber, 855suspension, non-linear, 855throat, 854-855

driving units, 855efficiency, 855, 860efficiency and frequency range, re-

lation between, 854-855exponential, 851-853, 854

dimensions of, 852, 853flare cut-off frequency, 852flaring constant, 851, 852minimum useful frequency, design

on basis of, 852-853folded, 856-859

concentric, 856-857low frequency, 856-858reflex, directional, 856-857, 867

1450 INDEX

Loudspeakers (continued)frequency limitations, 854high-frequency, 857-859hyperbolic cosine, 854hyperbolic exponential, 853-854hypex, 853-854impedance, electrical, 856multi-cellular construction, 858public-address, use in open air, 867rooms, use in, 856sound chamber, 854-855

impedance characteristics, electrical,837-838, 847-849, 856

impedance, standard for sound systems, 874in operation, 861-867

acoustical feedback, avoidance of, 866acoustics of rooms, 864-865background music in factories, 867

effect of noise level, 867extension loudspeakers, 883-886loudspeaker placement, 865-867multiple loudspeakers, 867, 882-883

Haas effect, 867time delay in, 866

operation at long distances fromamplifier, 886

power required, indoors, 863-864absorption coefficient, 863chart-acoustical power to produce

intensity 80 db v's room volume,863, 864

reverberation time, 863-864power required, outdoor, 861-863, 866, 867

chart—intensity v's watts output atspecified distances, 862

public address, open air, 867sound reinforcing systems, 866-867sound systems (constant line voltage),

874, 883stereophonic reproduction, 865-866

pseudo stereophonic effect, 866intercommunicating systems, 867ionic, 831line source, 866-867loudness directivity index, 875loudness efficiency rating, 875loudspeaker load with power amplifiers,

558, 566-567, 600-601, 881-882magnetic flux, effect on damping,

831, 840, 841magnetic flux, effect on efficiency, 831, 840magnetic flux, optimum for frequency

response, 840magnets, types of, 831, 840

elctromagnet, 831, 840permanent magnet, 831, 840

matching, 880-882matching Class A triodes, 881matching pentodes, 881-882metal cone, 836network between power valve and loud-

speaker, 880-889optimum plate resistance, 880-881output expressed in decibels, in terms

of acoustical pressure, 812power rating from standard distribu-

tion lines, 874pressure-frequency response (pressure

level), 875pressure rating, 812, 862, 874rating impedance, 812, 874references, 876-879references to matching, extension loud-

speakers and divider networks, 889reflections in rooms, effect of, 833, 841,

864-865room resonances, 841, 864-865sound system rating, 812-813sound impedance, effect of, 833, 840-841,

844-845, 848-849source impedance, effect of zero or

negative, 841source impedance, measurement, 812, 874standards for loudspeakers, 874-876

sound equipment, 874-876loudspeaker directivity index, 875loudspeaker efficiency in terms of

acoustical power, 875-876

Loudspeakers (continued)loudspeaker impedance, 874loudspeaker loudness directivity

index, 875loudspeaker loudness efficiency

rating, 875loudspeaker measurement source

impedance, 812, 874loudspeaker output expressed in

decibels, in terms of acousticalpressure, 812

loudspeaker power rating fromstandard distribution lines, 874

loudspeaker pressure-frequencyresponse (pressure level), 875

loudspeaker pressure rating (pres-sure efficiency), 812, 862, 874

loudspeaker rating impedance, 812, 874loudspeaker standard test signals,

874-875voice coil impedance for radio re-

ceivers, 874voice coil impedance for sound

equipment, 883tests, listening, 632, 834throttled air flow, 832tweeter, 832, 860-861types of, 831vented baffle—see under Baffles and

enclosures.vibration of walls etc., effects of, 864voice coil impedance for radio re- ,

ceivers, standard, 874Low level, definition, 1401Low-pass filter, definition, 172, 1401Lumen, 1334Luminous flux, unit of, 1334Lux (metre candle), 1334

MM.K.S. system, 1331, 1332Maclaurin's series, 299Magic eye tuning indicators, 1132-1136Magnetic and electric fields of wave,

relation between, 897Magnetic and electrical units, 1331-1333Magnetic circuit theory, 229-233

air loadline, 232BH characteristics, 230coercive force, 231flux density, 229flux, lines of, 229fringing, 231fundamental magnetic relationships, 229-231hysteresis loop, 230hysteresis loss, 230leakage flux, 231length of magnetic path, 242-243magnetic circuit, 231-232magnetic units and conversion factors,

232-233magnetization curve, normal, 231magnetomotive force, 229permeability, 230permeability, average, 231permeability, effective, 242-243, 244permeability, incremental, 230, 243, 248potential difference, magnetic, 231-232reluctance, 229remanence, 230remanent flux density, 230residual flux density, 230see also under Transformers; Inductors,

iron-cored.Magnetic field, energy stored in, 141Magnetic field of coil, kinetic energy of, 407Magnetic field of radiated electromagnetic

energy, 404Magnetic field set up by inductor, 140Magnetic field, valves used in, hum due

to, 785, 786, 788, 1198Magnetic recording, 701Magnetic units, 232-233Magnetization curve, normal, 231Magnetizing current in power trans-

formers, 235Magnetizing force, measure of, 1332

INDEX 1451

Magnetomotive force, 229Magnetomotive force, measure of, 1332Magnets, types of, in loudspeakers, 831-840Magnification factor, 144, 409, 424, 425

see also under Q factor.Magnitude of complex quantity, absolute, 140Mains filters, 475, 1279-1280Mains operation, valve ratings for, 78, 79Mains voltage fluctuations, 10Mantissa, 256Manual, definition, 1401Marconiphone Model 12A pickup, 719Masking effect of noise, 620-621, 625, 629, 679Masking interference in F-M receivers,

tests for, 1318Mass, units of, 1329, 1332Matching and effects of mismatching, push-

pullpentodes, 584triodes, 580-582

Matching generator to load, section oftransmission line for, 892

Matching, impedance, in networks,definition, 160

Matching loudspeakers, 880-882Matching of load with Class Al power

triode, 61Matching of medium wave-band coils, 462-463Matching of short-wave coils, 468-471Materials, ferromagnetic, 458-459Materials for tropic-proofing coils, 477-478Materials, properties of, 1372-1376Mathematical signs, 1366Mathematics (Chapter 6), 254-305Maximal flatness feedback amplifiers,

367, 378, 382-385Maximum grid circuit resistance—see

under Grid circuit resistance.Maximum negative grid currents of

valves, 101-102Maximum power output, distortionless

valve, 46, 60-61Maximum power transfer theorem, 165Maximum ratings, value 9, 75-80

absolute maximum system, 9, 77design-centre system, 9, 77-80see also Valve ratings.

Maximum signal, definition, 1401Maximum undistorted power output,

definition, 1298, 1315, 1401Maximum value of function, conditions

for, 292Maxwell, 229, 1332, 1333Mayr's method of designing feedback

amplifiers with flat frequency res-ponse, 379-382

McIntosh amplifier, 594-596McProud test of pickup and arm, 715Mean frequency, geometrical, 130Mean geometrical progression (geometrical

mean), 266-267, 272Mean proportional, 272Measurements—see under Tests and

measurements.Medium of transmission of a wave, 403Medium wave-band coils, design of, 459-463Medium wave-band coils, matching of, 462-463Mercury, pressure due to, 1330Mercury vapour rectifiers, 1161, 1164, 1165Mesh, definition, 159Metallized paper dielectric condensers, 195Meters for testing receivers, 1300Metre, measure of length, 1329, 1332, 1333Metric ton, 1329Mho, 1332, 1333Mho per centimetre cube, 1332Mica dielectric condensers, 196Mica, silvered, condensers, 196Microgroove recording, 701Micron, measure of length, 1329Microphones, 775-782

carbon, 775, 777-778ceramic piezo-electric, 779condenser, 778crystal, 775, 778-779crystal, optimum load for 788definition, 781

Microphones (continued)directional characteristics, 779-780

bi-directional, 779, 780cardioid, 780non-directional, 780poly-directional, 780uni-directional, 780

directional pattern, standard for, 781effective output level, 776equalization of, 781field response, definition, 781impedance, electrical, 781impedance, nominal, 781, 782lapel, 780lip, 780moving coil (dynamic), 775, 779output expressed in decibels, 808-810output voltage and sound pressure,

relation between, 775pre-amplifiers, for use with, 788-793pressure gradient, 775pressure operated types, 775pressure ribbon, 775, 779rating impedance, 781, 809ratings, 776-777

power, 776relationship between voltage and

power, 776-777system rating, R.M.A., 776, 809-810,

812-813typical, 777voltage, 776volume units, 776

references, 804sound pressure with conversational

speech, 775standards for, 781-782throat, 780transformers, 781velocity operated types, 775velocity ribbon, 775, 779

Microphonic, definition, 1401Microphony

in a-f amplifiers, tests for, 1311, 1324in receivers, tests for, 1311, 1312in valves, 73, 84, 786, 957-959, 1241-1242in valves, tests for, 74, 107, 113, 121other than valves, 1241-1243, 1250-1251,

1253, 1256, 1311Mil, measure of length, 1329Miller effect, 51, 52, 70, 493-494, 512, 598,

923, 1062, 1157Minimum value of function, conditions

for, 292Minimum volume effect in reflex re-

ceivers, 1141, 1142Mirror image, definition, 1401Mistuning in F-M receivers, tests for, 1320Mixed coupling in i-f transformers,

1025, 1044-1048Mixer, definition, 1401Mixers and faders, 798-805

constant impedance mixers 801-804bridge type, 802choice of mixer circuit, 803coil mixing, 802parallel type, 801-802precautions with studio type mixing

systems, 803-804series type, 802series-parallel type, 802

electronic fader mixer using 6BE6, 797-798fader, definition, 799insertion loss of, 799mixing, definition, 799non-constant impedance, 798-801

common plate load method, 799-800control of volume with, 800-801parallel network mixer, 799series network mixer, 799series network mixer, modified, 799

references, 805Mixers, operation of frequency converters

and, 962-1001, 1017-1019Modulation, anti-, bass frequency, 1116

1452 INDEX

Modulation, definition, 1401Modulation distortion, cross, 945, 1114Modulation, downward, in F-M receivers,

tests for, 1320Modulation envelope distortion, 944-945Modulation hum, 1198, 1199, 1239-1241, 1267,

1268, 1290, 1309, 1314Modulation of electron stream by magnetic

field of filament, hum due to, 1196, 1197Modulation of groove in recording, 702Modulation percentage applied to detector 1078Modulation ratio, critical, in diode de-

tectors, 1076-1077, 1081Modulation, reduction in percentage, in

reflex receivers, 1143Modulation rise in i-f amplifiers, 1112, 1114,

1117, 1118, 1232Modulation, standard test, in F-M re-

ceivers, 1314Modulation systems as d-c amplifiers, 532Modulation, systems of, 405-406Modulator valve (mixer), 962Modulus of complex quantity, 140, 285Molecules, 1Monaural, definition, 1401Monkey chatter, 1303-1304, 1305Motorboating, definition, 1401Motorboating in a-f amplifiers, 535, 537Mounting position for valves, 4, 80Moving coil (dynamic) microphones, 775, 779Moving coil loudspeakers, 831, 833-851,

860-864Mu-factor, definition, 14Mu-factor, plate to screen, 35-36Mu-factor, screen to control grid, 35Mu-factors, interelectrode, 73Multi-cellular horns, 858Multi-grid valves as r.c.c. amplifiers, 516Multi-grid valves in volume expanders,

685, 691-692Multi-grid valves, power, Class A, 560-570Multi-stage voltage amplifiers, 541Multiple channel amplifiers for tone

control, 673-674, 676Multiple feedback system, 365, 374-378Multiple loop feedback amplifiers, 375Multiple loudspeakers, 867, 882-883Multiples and sub-multiples, 1405Multiplication, 260Multipliers, 1363Music and acoustics, references, 634Music in factories, background, 867Musical scales, 873-874Muting (Q.A.V.C.), 1125-1130

biased diode systems, 1125-1126circuits used with F-M receivers, 1128-1130inoperative audio amplifier, 1126-1128references, 1139

Mutual characteristics, 17-18Mutual characteristics, shift during life, 23-24Mutual conductance, definition, 14

see also Transconductance grid-plate.Mutual conductance, graphical determina-

tion, 15, 16, 17Mutual conductance of r.c.c. pentodes,

506, 507-508, 511Mutual conductance of r.c.c. triodes, 493Mutual conductance, tests for, 74, 103-104,

113, 123, 124Mutual conductance, triode, of pentode, 34Mutual inductance, 142Mutual inductance, calculation of, 446-448Mutual inductance coupling in aerial

stages, 916-920Mutual inductance coupling in i-f trans-

formers, 1023, 1025-1041, 1046, 1048-1050Mutual inductance, coupling of tuned cir-

cuits by, 417Mutual inductive coupling in r-f ampli-

fiers, 922-923Mutual inductive coupling, tuned cir-

cuits, 418, 419

NNagaoka's constant, 430Naperian system of logarithms, 267Natural resonant frequency, 407, 408, 424Nautical mile, 1329Needle talk (chatter), 714, 718, 719, 760, 762Needles

fibre, 710semi-permanent, 709steel, 709, 711thorn, 710trailing, 711, 726see also under Stylus.

Negative feedback—see under Feedback.Negative grid current—see under Grid

current, negative.Negative impedances, stabilized, 389Negative transconductance oscillator, 953-954Negative transconductance to provide bass

boosting, 648Nepers, 825-826Network, definition, 1401Network, resistive, procedure with, 133Networks (Chapter 4), 128-198Networks, theory of, 158-171

active, definition, 160between power valve and loudspeaker,

880-889characteristic impedance of, 179 corrective, in feedback amplifiers, 371definitions, 159differentiating and integrating, 160four terminal, 166-167

bridged T section, 166-167definition, 159equivalent T and

sections, 167image attenuation constant, 178, 179image impedances, 177-179image phase constant, 178, 179image transfer constant, 177-179iterative impedances, 176-177iterative transfer constant, 176-177lattice section, 166, 167

section, 166, 167T section, 166, 167

frequency dividing, 184-185, 860, 887-889impedance matching, definition, 160input circuit, definition, 160input impedance of passive network, 169Kirchhoff's laws, 159, 160-161minimum phase shift, 359, 374multi-mesh, 167-170

flat, 167mesh equations, 167-169mutual impedances, 167, 168mutual inductance, 168, 169self-impedance, 168

non-linear components in, 158, 170non-linear elements in, 158, 170Norton's theorem, 165Ohm's law, 130, 131, 158output circuit, definition, 160parallel combinations of L, C and R, 147-149parallel T, 176, 647, 651, 657, 675-676,

737-738, 745-749passive, definition, 160phase shift, 170phase-shifting, in feedback line, 378potential dividers, 161-164problems, hints on solution, 159references to, 171series combinations of L, C and R, 144-147series-parallel combinations of L, C and

R, 149-153symmetrical, 179Thevenin's theorem, 164transfer impedance of 4-terminal net-

work, 169transients in, 171two-terminal, definition, 159two-terminal, general procedure to de-

termine impedance, 153valve, general case, 64

1452 INDEXWheeler, 368, 377

INDEX 1453

Neutralization, definition, 1401Neutralizing,

effect on input capacitance, 1063hum neutralizing, 539, 785, 1200-1201, 1239in converters, 959, 969, 970, 975-977, 978,

992, 1000, 1001in i-f amplifiers, 1065-1067, 1291in reflex receivers, 1145

Neutron, 2Newton, measure of force, 1332, 1333Node, definition, 1401Noise

audibility tests of receivers, 1310-1311, 1319background, effect of volume expansion

on, 679, 763circuit, 782-783current noise, 783current, of resistors, 190diode, 1308, 1309effect of feedback on, 309-310, 315, 316effect on sound reproduction, 624-625equivalent noise resistance of valves,

783-784, 937-938, 967-968, 972-973,978, 984, 1230

equivalent noise sideband input, 1307factor, 1262, 1307-1309factor of grounded-grid stage, 925flicker effect, 783impulse, effect on F-M receivers, 1148in cathode followers, 327in converters, 967-968, 972-973, 978, 984in high fidelity reproduction, per-

missible, 630in pre-amplifiers, 782-784in receivers, 694-699, 1108, 1114, 1118,

1119, 1130-1132, 1229-1234, 1262, 1307-1309,

a.v.c. and noise, 1108, 1114, 1118, 11191229-1234

measurement of, 1262, 1307-1309noise limiting, 694-699, 1130-1132tests for, 1307-1309see also under individual stages

(amplifier, r-f, etc.).in superregenerative detectors, 1087induced grid, 939-940inter-station noise suppression, 1125-1130ionization, 783, 784level, definition, 829level in amplifier output, permissible, 625level in amplifiers, measurement of, 1324level in factories, effect on music, 867level, weighted, standard, 829low noise input stage, cathode follower

as, 789-790low noise valve types, 786-788man-made, reduction of, 1279-1280masking, effect of, 620, 621, 625, 679masking of speech by, 629measurement of sound level and noise,

827-830, 1324acoustical noise, 827electrical noise, 827noise in amplifiers, measurement of,

829-830, 1324broadcast systems, 829sound equipment, 829, 1324

noise in receivers, measurement of,1262, 1307-1309

objective noise meter, 828radio noise, measurement of, 829-830

radio noise meter, 829-830references, 830sound level meter, American stan-

dard, 828sound levels, typical—table, 828-829weighting network, 827-828

noise audibility, test for, 1310-1311, 1319noise bandwidth, 936noise current, 935noise factor, 925, 1262, 1307-1309noise-power output, average, 935noise voltage, r.m.s., 935-942of resistors, 189-190, 783, 1345, 1356partition, in converters, 972, 984partition, in pentodes, 783

Noise (continued)peak limiters, 694-699

see also under Noise limiting in re-ceivers.

random, 704, 782, 935-942reduction in A-M receivers, 1279-1280reduction in record reproduction, 763-765references, 634, 804-805, 945-946resistance fluctuation noise of resistors, 190room, 620-621, 625shot effect, 783, 787, 936-938, 1230signal to noise ratio,

definition, for audio facilities forbroadcasting systems, 829

in receivers, tests for input to givespecified signal to noise ratio, 1302, 1303

in record reproduction, 704-705, 766, 770in reflex receivers, 1146maximum possible in microphone

pre-amplifiers, 788standard, in pre-amplifiers, for

broadcasting, 793with crystal microphones, 788

suppressor, Olson, 763suppressor, Price balanced clipper, 765suppressor, Scott dynamic, 764surface (needle scratch) and dynamic

range in record reproduction, 704-705763-765

thermal agitation, 4, 189-190, 782, 788,935-936

total noise calculations, 940-942valve, 4, 70, 73, 81, 782, 783, 784, 788,

935-942, 967-968tests for, 74, 107, 113, 124

valve leakage, 784white, 619

Noise limiting in receivers, 694-699, 1130-1132Lamb silencer, 1130, 1131noise limiter, automatic threshold con-

trol, 695, 1131-1132noise limiter, degenerative, 698noise limiter, other types, 694-697noise limiter, series diode, 694-696, 1131noise limiter, shunt diode, 697, 1131output limiters, 694, 698-699references, 699-700, 1139

Non-linear, definition, 1401Non-linear elements in networks, 158, 170, 948Non-linearity in valves, 61, 948, 1164Non-synchronous vibrators, 1202-1203Norton's theorem, 165Nucleus of atom, 1Null point indicator using electron ray

tuning indicator, 1134-1135Numbering systems for valves, 10-12Numerator, definition, 1401Numerical values, 1406Nyquist criterion of stability, 356, 375Nyquist diagram, 338, 339, 356-359, 366, 375

OOctal sockets, use of pin No. 1, 81Octaves and decibels, calculations in-

volving, 637-638Octaves, decades and frequency ratio

(table) 368Octode, 92Oersted, 1332, 1333Ohm, 1332, 1333Ohm-centimetre, 1332Ohm's law, 130, 131Ohm's law in network analysis, 158Olson noise suppressor, 763On (and off) contact time in vibrators, 1205Open back cabinet, 842-843Open-circuit, definition, 1401Open-circuited electrodes, tests for,

73, 91-93, 123Operating conditions, effect of change in, 42-44Operating conditions for valves, typical, 80Operation of valves, recommended, 80-84Operator, j as, 283Operator, trigonometrical, 286, 287

1454 INDEX

Operators, symbols, 1364Optical methods of testing frequency test

records, 752-753Orchestra level, maximum, 623Orchestra, peak acoustical power of, 623Order, definition, 1401Ordinate, 279Orienting a-f transformers to give least

hum pickup, 785Orthacoustic recording characteristic, 730-731Oscillation, conditions for maintenance

of, 949-954Oscillation due to instability, 943-944Oscillation, parasitic, 316, 345, 365, 547, 562,

572, 582, 585, 587-588, 590, 952-953,959, 1283

Oscillation, unstable, 958-959Oscillations, damped, 408, 424Oscillators, general (Chapter 24) 947-961

beat frequency oscillators, 954, 960-961, 1263Class A, B and C, 954Colpitts, 952-953, 1290conditions for maintenance of oscilla-

tion, 949-954electron-coupled, 953, 954, 958factor of merit for oscillator valve, 950feedback winding for good tracking, 1004flutter, 955, 958frequency stabilization, 957-958, 1289frequency variation, causes of, 950,955-956

at high frequencies, 968due to changes in supply voltage,

949, 953, 955due to oscillator harmonics, 956due to temperature and humidity

changes, 955-956frequency variation in converter os-

cillators due to a.v.c. 963, 993-994grid current, test for, 74, 111-112harmonic operation of (harmonic mix-

ing), 958, 964-966, 991, 994-996, 1000,1001, 1289

Hartley, 112, 951-952, 967, 1290in superhet. receivers, comments on,

1244-1248in superhet, receivers, requirements for, 954introduction, 947-948L/C ratio of, 957locked oscillator F-M detector, 1088,

1292-1293negative transconductance, 953-954oscillator section of converter valves, 968

driven, 109self-excited, 108-109

parasitic oscillations, 952, 953, 959, 1290performance, tests for, 111-112practical design, methods used in, 959-960Q of circuit, 957radiation from, in F-M receivers,

measurement of, 1311, 1320references, 961squegging, 958tapping down on coil for stability, 957temperature compensation, 196, 956, 957,

1041test circuit, Boonton, 112tests for oscillator characteristics, 111-113transconductance, phase shift of, 968transconductance, test for, 74tuned-grid, 950-951, 952tuned-plate, 949-950, 951, 952, 994tuned-plate operation of frequency con-

verters, 994, 1248tuning capacitor plates, vibration of, 958-959types of circuits, 947, 949-954unstable oscillation, 958-959

Oscillatory transient response in feedbackamplifiers, 365, 367, 382, 386

Output admittance, short-circuit, 50-55Output admittance, short circuit, test for, 117Output capacitance of cathode follower,

323-324, 325Output circuit of network, definition, 160Output circuit of push-pull a-f voltage

amplifiers, 527-528Output impedance of cathode follower, 320

Output level for pre-amplifiers, standard, 793Output limiters, 698-699Output, maximum, in receivers, defini-

tion, 1482Output, normal (standard) test, defini-

tion, 1298, 1315Output power,

graphical determination of, 549maximum undistorted, definitions,

1298, 1315, 1482maximum undistorted, tests for, 1306, 1318of a-f amplifiers, tests for, 74, 105-106, 124,

1323of distortionless valve, 46, 59, 60-61of receivers, tests for, 1300, 1316power-measuring device, 1299

Output power and distortionpentode, single, 561, 563-565push-pull pentodes, 583-584push-pull triodes, 577-579

Class B2, 588-590triode, single, 548-554vs. load resistance, triode, 558

beam power amplifier, 570Output power and plate dissipation,

Class B2, 589Output resistance, effect of zero or ne-

gative, on loudspeakers, 841Output resistance of amplifier with feed-

back, 310-311, 313, 314Output stage, definition, 1401Output transformers—see under Trans-

formers, a-f.Output voltage and distortion

r.c.c. pentode, 510-511r.c.c. triode, 491-493transformer coupled a-f amplifiers, 518-519

Over-coupled i-f transformers, 1031-1034Overlap region with dual system loud-

speakers, 856, 861Overloading characteristics

power amplifiers, 560, 563reflex receivers, 1141, 1142, 1146

Overloading, effect of bass boosting on, 640Overmodulation in recording, 729Overtones, 92

PPad, 794, 888Padded signal circuits, 1013-1017Padder condenser, 1003-1004, 1010-1017Padder feedback, 1001, 1247Paper dielectric condensers, 194-195Paper dielectric condensers, metallized, 195Parabola, 274Parabola, equation to, 280Parallel Class A amplifiers, 570-571Parallel combinations of L, C and R, 147-149Parallel, condensers in, 135Parallel connection of batteries (cells), 129Parallel, definition, 1401Parallel-feed in transformer-coupled a-f

amplifiers, 519, 520, 645, 650Parallel impedance, conversion from

series to, 157-158Parallel, inductances in, 141Parallelogram, 273Parallel operation of rectifiers, 1165Parallel, reactance and resistance in, 1380-1381Parallel, resistances in, 132-133

graphical method, 132Parallel resonance, 150-153, 410-411, 424-425

determined by maximum impedance, 151-152determined by unity power factor, 150

Parallel resonant frequency, 410Parallel-T network, 176, 647, 651, 657,

675-676, 737-738, 745-749Parallel tuned circuit, impedance of, 149-152Parameter, 281Parameter, definition, 1401Paraphase bass-treble tone control, 665Paraphase, floating, 524-525, 534Paraphase inverter, 524-526Parasitic oscillation, 316, 345, 365, 547, 562,

572, 582, 585, 587-588, 590, 952, 953, 959,1283

INDEX 1455

Parry cathamplifier, 586Partial differentials, 293-294Partial differentials, valve coefficients as, 64-65Partial triode operation of pentodes, 570, 587Partition noise in converters, 972, 984Partition noise in pentodes, 783Pass band of filter, 180Patchett tone control, 667-668Peak acoustical power of orchestra, 623Peak cathode current, maximum, 75Peak clipping, effect on intelligibility of

speech, 629Peak inverse voltage, maximum, 75Peak inverse voltage of rectifiers, curves, 1177Peak limiters, 681, 682-683Peak limiters, noise, 694-698Peak-reading voltage and current indicators, 119Peak response of transformer-coupled a-f

amplifier at high frequencies, 209, 518Peaks at high and low frequencies in feed-

back amplifiers, 336, 359, 378-379, 383Pentagrid converters, 8, 961-1001Pentagrids in volume expanders etc.,

685, 688-689Pentodes, general, 7-8

amplification factor,plate to screen, 35-36screen to control grid, 35triode, 35-36

capacitances, input,published values, 56with feedback to screen, 345

cathode follower, use as, 324characteristics at low plate currents, 65characteristics, cathode current, 16-17characteristics, specific tests for, 101-108mutual conductance, triode, 34operation at low screen voltage, 84partition noise, 783phase splitter, use as, 524plate detectors, 508, 1084-1085plate resistance, triode, 36power, general, 8

ideal,561load resistance, 561matching to loudspeaker, 881-882operating conditions, 561-563partial triode operation of, 570, 587push-pull, Class A, AB1, 583-587quiescent push-pull, 592-593ratio plate/screen currents, 562shunt filter across load, 567, 636single Class A, 560-570triode operation of, 547

pre-amplifiers, use in, 783-786hum with, 786low noise types, 786-787noise resistance values, r.c.c. 783-784triode operation with screen as

anode, 785, 787remote cut-off, 8, 516, 945remote cut-off, in volume expanders,

684, 688-689resistance-capacitance coupled, 496-517

attenuation and phase shift character-istics with incomplete by-passing,

496-500dynamic characteristics, 26-27, 503-506equivalent circuit, 512gain at mid-frequency, 506-508output voltage and distortion, 510-511phase shift/frequency characteristics 512plate resistance, 507-508, 511-512ratio of plate/screen currents, 514, 515remote cut-off valves, use of, 516screen supply from voltage divider, 506tabulated characteristics, comments on, 517triode operation with screen as

anode, 785, 787sharp cut-off, 8, 496-517sharp cut-off, use as limiters, 1147-1150suppressor-grid controlled, in volume

expanders, 686, 689-690triode operation of, 34-36, 785, 787

connection of suppressor grid, 36Penultimate, definition, 1401

Period, definition, 1402Periodic phenomena, 278-279Periodicals, titles of, 1367-1369Permanent magnet loudspeakers, 831, 840Permeability, 230, 231Permeability, effective, 242-243, 244Permeability, incremental, 230, 243, 248Permeability of free space, 1332Permeability tuning, 461-462, 912, 913, 953,

1002, 1289Perveance, definition, 14, 71Perveance of diode, test for, 117-118Perveance of triode, test for, 118Phase angle, 139, 140Phase angle of load at low frequencies, 213Phase angle, tuned circuits, 412, 413, 417, 422,

425Phase compressor, 527, 528Phase discriminator, 1088-1095, 1153-1156,

1292-1293alternative arrangement, 1095basic circuit, 1089design data and example, 1090-1095

coefficient of coupling, 1090discriminator characteristic, 1092discriminator sensitivity, 1090generalised curves, 1091

limiter discriminator combination, 1292-1293typical circuit arrangement, 1090voltage relationships, 1089

Phase distortion, amplifier without, 389Phase inverter, normal, 524

cathode-coupled, 347-348, 532choke-coupled, 355cross-coupled, 527, 663-664phase inversion in power stage, 585-586Schmitt, 526, 670

Phase modulation, 405-406Phase shift

and attenuation, relation between, 359-364anode to grid voltage, 50at high and low frequencies, 316, 353, 355coupled tuned circuits, curves for, 422of attenuation characteristic, deter-

mination of, 362-365of loudspeakers, 838, 870of r.c.c. pentode, 512

incomplete cathode and screen by-passing, 498-500

incomplete screen by-passing, 498-499of r.c.c. triode, 494-495

incomplete cathode by-passing, 485-486of transformer-coupled a-f amplifiers,

206, 207, 214, 518with feedback, 342, 343, 352, 389

Phase splitter, 329-330, 522-524with positive feedback, 354, 523

Phasing of loudspeakers, 860∅ detector, 1293Philips-Miller engraved film system, 701Phon, 826Phonograph, definition, 1402Phot (centimetre-candle), 1334Photo emission, 2Photometric units, 1334Physical and chemical constants, 1376Physical properties of valves, funda-

mental, 69-70Physical units, general, 1329-1334Pickering cartridges, 718Pickering turnover pickup, 718Pickups, general, 714-723

arm resonance, 712, 714, 716, 719, 720, 722armature of, 702armature resonance, 712, 714, 716, 719, 720,

722armature resonance, effect on har-

monics, 716capacitance, 722damping of arm resonance in, 716damping of armature resonance in, 716distortion in, 718, 719, 723, 762dynamic mass, 718, 719, 721, 722dynamic (moving coil), 715, 719-720

1456 INDEX

Pickups (continued)eddy current, 723effective vertical pressure of, 702, 708, 709,

712, 718-722, 768-769electromagnetic, 715, 717-719

effect of shunt capacitance, 738-739frequency of armature resonance af-

fected by record material, 716hum level, 719, 722ideal constant velocity, frequency

characteristic of, 724lacquer discs, for use on, 768magnetostriction, 721needle armature, 717offset angle, optimum, 726offset-arm, 725-726piezo-electric (crystal), 715, 716, 717,

720-721, 752piezo-electric, response curves, 742pressure, effective vertical, 702ribbon, 716, 722straight-arm, 725-726strain sensitive, 721-722testing of, 715, 716-717, 762tracking capability, checking, 762underhang, optimum, 725-726

Picofarad, 1363Pie-wound r-f chokes, 474Piezo-electric loudspeakers, 832Pin straightener, valve, 80Pinch effect, 711, 712, 720, 757, 760Piston cones in infinite baffle, ideal, 835Pitch, definition, 1402Pitch, international standard, 874Placement, loudspeaker, 865-867Plane figures, 272Plastics, composition of, 1375Plate and screen currents, average, push-

pull pentodes, 584Plate characteristics, general, 15-17Plate circuit decoupling in a-f amplifiers,

535-537Plate circuit decoupling without de-

coupling condensers, 537Plate circuit efficiency, maximum with

loudspeaker load, 880-881Plate conductance, definition, 14Plate conductance testing, 124Plate current, 2, 6Plate current, average, push-pull triodes,

Class A, AB1, 579-580Plate current commencement, test for, 74Plate current in power amplifiers, creeping 596Plate current near cut-off, effect of rate of

change in, in Class AB1, ampli-fiers, 572-573

Plate current of Class A triode, calculatedoptimum, 557

Plate current, peak hot-switching tran-sient, 1163, 1180-1181

Plate current test, triodes and multi-grid, 103, 109, 113

Plate current test, zero signal diode, 101Plate currents, low, valve characteristics at, 65Plate decoupling circuit gives bass boost-

ing, 643-644Plate detector (anode bend), 57, 62, 508,

1084-1085Plate dissipation

theory, general, 63-64triode, Class A, 559triode, Class B2, relation between power

output and plate dissipation, 589triode, push pull, at max. signal, 578triode, resistance loaded, 26

Plate efficiency, Class A pentode, 562Plate efficiency, Class A triode, 559Plate efficiency, Class B2, 589Plate efficiency in power amplifiers, de-

finition, 545Plate reflex superhet. receivers, design

of, 1143-1145Plate resistance, d.c., 14Plate resistance (variational) 13, 14, 72

control in volume expanders, 685, 692-693definition 14, 72

Plate resistance (variational) (continued)effective, feedback circuit to give

positive, zero or negative values, 314effective, of cathode follower, 318effective, with feedback, 311. 313, 314,

315, 316graphical detcrmination of, 15, 18of cathode degenerative amplifier, 328-329of power amplifiers, optimum, 546, 880-881of r.c.c pentodes, 507-508, 511-512of r.c.c. triodes, 493tests for, 74, 104-105, 111, 113triode plate resistance of pentode, 36

Plate series compensation, 536, 643-644Plate shunt compensation, 640-643, 660-661,

733-734Plate supply by-passing in a-f amplifiers, 535Plate supply impedance per plate, trans-

former, 99Plate supply voltage of r.c.c. amplifier, 482, 496Plate-to-screen amplification factor, 35-36Plate voltage, effect of change of, on

characteristics, 42-43Plates, 5Playback characteristics, 728, 731-732Playback curve, AES standard, 731-732Playback, direct 701, 766-768Playback loss, 760Playthrough in A-M receivers, 1081,1082, 1237

circuit to reduce, 1235, 1237, 1240Playthrough in reflex receivers, 1140-1143,

1145-1146Poisoning of emission, 2Polar coordinates, 283Polarity, definition, 1402Polarity, indications of 130Polish of jewel stylus tip, 712Polydirectional microphones, 780Polyethylene discs, 705Polygon, 273Positive feedback—see under Feedback.Positive grid current—see under Grid

current, positive.Positive ions, 3, 71Potential, definition, 1402Potential difference, definition, 1402Potential difference, magnetic, 231-232Potential dividers, 161-164Potentiometers, 161-164, 1356Pound weight, measure of force, 1330, 1332Poundal, measure of force, 1330Power, absolute, expressed in decibels, 807-808Power amplifier valves

beam power valves, 8, 569pentones, 8triodes, 7

Power available at receiver from aerial, 893Power, average (effective), 134Power factor, 144Power factor of condenser, 140Power factor of electrolytic condenser, 193Power factor of tuned circuit, relationship

with Q, 144, 409Power factor, unity, determining parallel

resonance, 150, 410Power-flux per unit area at receiver 896-897Power gain, expressed in decibels, 810Power gain of aerials, 894Power grid detector, 1084Power in d.c. circuits, 133Power in reactive circuit, 140, 143-144Power in resistive a.c. circuits, 133-134Power level indicators, 825Power line operation, valve ratings for, 78, 79Power output—see under Output powerPower output meters, 825Power pack, definition, 1402Power, peak acoustical, of orchestra, 623Power rating of loudspeakers on standard

distribution lines, 874Power reactive, 144Power required, loudspeakers, indoors, 863-864Power required, loudspeakers, outdoors,

861-863, 866, 867Power supply, effect of impedance in,

on a-f amplifiers, 535, 537 574

INDEX 1457

Power supply regulation, effect on poweramplifiers, 547-548, 551, 562, 568-569,

572, 582, 584Power transfer between two dipole

aerials, 892-893Power transfer theorem, maximum, 165Power, units of, 1332Power, wattless, 144Powers in algebra, 260-261Powers of numbers, 255, 257Practical systems of units, 1331, 1332Pragilbert, 1332, 1333Pragilbert per weber, 1332, 1333Praoersted, 1332, 1333Pre-amplifiers, 782-793, 804-805

gain-controlled, 693hum in, 784-786introduction, 782microphone, 788-793

cathode follower as low noise inputstage, 789-790

crystal microphones, for use with, 788-790general, 788grid resistor, limitations on, 788

see also under Grid circuit resist-ance, maximum.

incorporating mixing, 799-801load resistance for crystal micro-

phones, optimum, 788low impedance microphones, for use

with, 790-793signal to noise ratio, maximum

possible, 788signal to noise ratio with crystal

microphones, 788microphony in, 786

see also under Microphony.noise in, 782-784pickup, 732, 733-736, 737-741, 744-749power gain ratings of, 809references, 804-805standard, for broadcasting, 793

input signal, 793output level, 793signal to noise ratio, 793source and load impedances, 793

standard, for sound equipment, 793amplifier gain, definition, 793source impedance, 793

valves for use in, 786-788selection and treatment of, 787special low noise types, 786-788type 6AU6, operation with screen as

anode, 785, 787types 6AU6, 12AY7, 1620, 5879, 786-788

Pre-emphasis and de-emphasis, high fre-quency, effect of, 763

Pre-emphasis characteristic in F-M re-ceivers, 1315

Pre-emphasis, high frequency, in record-ing characteristics, 717, 727, 728-729

in terms of time constant, 728Pre-emphasis with volume compression,

effect of, 683Preferred listening levels, 623Pre-heating before testing valves, 91, 101, 125Pressure, effective vertical, on records,

702, 708, 709, 712, 718-722, 768, 769Pressure efficiency, loudspeaker, 812, 862, 874Pressure-frequency response, loudspeaker, 875Pressure gradient microphones, 775Pressure, intensity of, units of, 1330Pressure level, loudspeaker, 875Pressure microphones, 775Pressure rating, loudspeaker, 812, 862, 874Pressure, reference acoustical, 826, 828Pressure ribbon microphones, 775, 779Pre-tuned r-f stages, 924-925Price balanced clipper noise suppressor, 765Primary windings, short-wave, aerial, 474Printed circuits, 1283-1285Prism, rectangular, 275Processing of records, 705Progression, arithmetical, 266-267Progression, geometrical, 266-267

Progression, harmonic, 266-267Progressions and Series, 266-267Proofing, tropic, of coils, 476-478Properties of materials, 1372-1376

conducting materials, 1374insulating materials, 1372-1373plastics, composition of, 1375references, 1376resistance of a conductor at any tem-

perature, 1376weights of common materials, 1375

Properties of valves, fundamental phy-sical, 69-70

Proportion, 262Protons, 2Pseudo-stereophonic effect, 866Public address audio a.v.c., 693Public address, open air, 867Public address, use of horn loudspeakers

in open air, 867Pulling (pull-in) in converters, 971, 990Pulse generators for valve characteristics, 119Pulse methods, valve characteristics by, 118-119Pulse modulation, 406Pulse waveform, 130Pulses, distortion by a-f amplifiers, 540-541Pumping in peak and volume limiters, 682Push-pull

equivalent circuit of, 576-577fundamental principles of, 571-573methods of exciting, 521-527pentodes, Class A, AB1, 583-587theory of, based on infinite series, 572-577triodes, Class A, AB1, 571, 582voltage amplifiers, 527-528

impedance-coupled, mathematicaltreatment, 528

Pyramid, 275Pyramid windings of coils, 475

Q

Q factor, definition, 1402Q factor of condenser, 140Q factor of tuned circuit, 145, 409-426Q factor, relationship with power factor,

144, 409Q of loudspeaker at bass resonance, 841Q of oscillator circuit, 957Q of short-wave coils, design for opti-

mum, 463-472Quadrant (of circle), 276, 1330Quadrature electronic reactances, 1157-1160Quadrilateral, 273Quality control of valves, 85Quality factor of coil, 409

see also Q factor of tuned circuit.Quality switch (tone control), 659Quarter-wave aerial, 909-910Quenching oscillator in superregenerative

detectors, 1087, 1224Quiescent, definition, 1402Quiescent push-pull pentodes, 592-593Quieting-signal sensitivity, tests for 1317

RR.C.A. light-weight pickup, 719R-J loudspeaker, 850Radial lead, definition, 1402Radian, 1330Radians, 272Radiated electromagnetic energy, 404Radiation efficiency of aerial, 903Radiation from local oscillator in F-M

receiver, tests for, 1311, 1320Radiation from superregenerative de-

tector, 1087Radiation resistance of aerial, 902, 905, 906Radiation resistance of piston, 835Radio-frequency amplifiers—see under

Amplifiers, radio-frequency.Radio-frequency chokes, design of, 474-475Radio-frequency chokes, self resonant, 475Radio-frequency, definition, 1402Radio telegraphy, 405

1458 INDEX

Radio telephony, modulation systems, 405Radius compensation, 711, 770Radius of curvature, minimum, in re-

cord, 703-704Random noise (fluctuations), 704, 782, 935-942Rate of change of function with its in-

dependent variable, 289-291Rate of change of plate current near

cut-off, effect of, in Class AB1 am-plifiers, 572-573

Rating impedance, loudspeaker, 812, 874Rating impedance of microphone, stan-

dard for, 781Rating, loudspeaker pressure, 812, 862, 874Rating systems—see under Valve ratings.Ratings, microphone, 776-777Ratings, voltage, of composition re-

sistors, 187Ratio detectors, 1088, 1095-1105

a.f.c. voltage from, 1098a.v.c., use of, 1099a.v.c. voltages from, 1097balanced circuit, 1098circuit, types of, 1098-1099circuits, practical, 1101design considerations, 1099-1101diodes for use with, 1099input/output curves, 1098, 1099measurements on, 1102-1105operation of, 1097receivers incorporating some features

of, 1022, 1024references, 1138typical output curve, 1096unbalanced circuit, 1098-1099

Rationalized systems of units, 1331, 1332Reactance, capacitive, 138Reactance chart (reference only), 1387Reactance, grid input, 49-53Reactance, inductive, 142Reactances, capacitive—table, 1378-1379Reactances, electronic, 1151, 1156-1160Reactances, inductive—table, 1377Reactances, signs of, 50Reactive component of impedance of

aerial, 903Reactive loads, 30-34Reactive power, 144Real axis, 285Real part of complex quantity, 140, 285Receivers, a.c./d.c.

barretters for, 1213-1214, 1266design of, 1264-1268dial lamps, 1266-1267earth connection, 1268modulation hum in, 1240rectifier, 1267rectifiers for, 1165

series resistor to limit current, 1165series resistor operation, 1264-1266valve order, 1198, 1267-1268

Receivers, A-M superheterodyne, designof (Chapter 35), 1228-1286

a.c./d.c. receivers, 1264-1268see also under Receivers a.c./d.c.

a.c. operated receivers, 1256-12644-valve receivers, 1256-1259

superhet. with a-f amplifier, 1256superhet. with i-f amplifier, 1257-1258superhet. with reflexing, 1258-1259t-r-f receivers, 1256

5-valve receivers, 1259larger receivers, 1260receivers, communication, 1260-1264

see also under Receivers, com-munication.

battery receivers, 1268-1274see also under Receivers, battery.

car radio, 1275-1278see also under Receivers, car.

contact potential biasing, 1280-1281frequency ranges, 1250-1256

band-spread receivers, 1253-1256circuit to give linear scale, 1255-1256

dual wave receivers, 1251-1252checking resonance in unused coils, 1252

Receivers, A-M superhet. (continued)drive ratios, 1252flywheel tuning, 1252

medium frequency receivers, 1250-1251multi-band receivers, 1252-1253

fuses, 1281-1282, 1395general design, 1229-1250

a-f response, 1234-1239a.v.c. and noise, 1229-1234

see also under Automatic volumecontrol.

cabinet design, 1248-1249converters, frequency, operation

of, 1244-1248see also under Frequency converters.feedback in, 1235-1239, 1241

compensated negative feedback andfeedback tone control, 1235, 1237

negative current feedback, 1236see also under Feedback.

field testing, 1250frequency-compensated tone con-

trol, 1234-1239hum in, 1239-1241

see also under Hum.instability in, 1243-1244microphony in, 1241-1243

see also under Microphony.oscillator, local, 1244-1248

see also under Oscillators.ratings, checking, 1249-1250ventilation, 1249

interference, reduction of, 1279-1280introduction, 1228parasitic oscillations, 1283

see also under Parasitic oscillation.printed circuits, 1283-1285references, 1285-1286specifications and requirements, 1229spurious responses, 1278-1279

see also under Spurious responses.tests and measurements—see belowtropic proofing, 476-478, 1282-1283

commercial tropic proofing, 1282-1283vibrator-powered receivers, 1270-1272

dry batteries, characteristics of, 1272-1274Receivers, A-M, tests and measurements,

1297-1314acoustical tests, 1314antenna sensitivity-test input, defini-

tion, 1297-1298automatic volume control characteristic, 1307bandwidth, definition, 1298battery receiver tests, dry, 1301, 1313

battery end-of-life tests, 1313lowest filament voltages used for

testing battery valves, 1313definitions, 1297, 1298distortion, 1314distortion, harmonic, 1306equipment required, 1298-1300

audio-frequency attenuator, 1299audio-frequency generator, 1299distortion factor meter, 1300equipment for acoustical tests, 1300meters, 1300output power-measuring device, 1299standard dummy antenna, 1299standard signal generator, 1298-1299wave analyser, 1299

frequency response, 1305frequency shift, 1310harmonic generation, r-f, 1305hum, 1309-1310

acoustical measurement, 1310hum distortion, 1309hum modulation, 1309

image ratio, 1310image sensitivity test input, 1310interference tests, 1313-1314intermediate-frequency-response ratio, 1310intermediate-frequency-response sensi-

tivity, 1310intermodulation, r-f, 1305maximum undistorted output, 1306maximum undistorted output, definition, 1298

INDEX 1459

Receivers, A-M, tests and measurements(continued)

measurements only requiring simpleinstruments, 1301-1302

dissipation measurements, 1302measurements on many valves, 1302power transformers, temperature rise, 1302voltage and current measurements,

1301-1302microphony, 1311, 1312noise, 1307-1309

effects on sensitivity measurements, 1302ensi, 1307noise factor, 1307-1309

noise audibility (listening test), 1310-1311normal test output, definition, 1298operating conditions, 1300-1301

operating voltages, 1300-1301output measurements, 1300

phonograph combinations, 1311-1312fidelity, electric, 1311-1312output, maximum, 1312rumble, 1312wow or flutter, 1312

radiation from local oscillator, 1311references, 1327signal to noise ratio, tests for input to

give specified, 1302, 1303spurious responses, 1310

image response, 1310spurious response ratio, 1310

standard antenna, definition, 1298standard dummy antenna, 1299standard dummy load, 1299standard input voltage, definition, 1297tests, performance, 1302-1314

blocking interference, 1304cross-talk, 1304gain of individual stages, 1303regenerative effects, 1303selectivity, 1303-1305sensitivity, 1302-1303two-signal, 1304-1305whistle interference, 1304-1305

tuning tests, 1312Receivers, A-M, types of (Chapter 34)

1223-1227crystal, 1223references, 1227regenerative, 1223see also under individual stages (R-F

amplifiers, etc.).superheterodyne, 1225-1226

communication—see under Receivers,communication.

double frequency changer, 1253reflex, 1140-1146

superregenerative, 1087, 1224synchrodyne, 1226-1227tuned radio frequency, 912-915, 1224, 1256

reflex, 1146use of reflex detector in high fidelity, 1086volume control circuit, 1257

tuning methods, 913Receivers, battery

a-f response, 1236converter problems, 1246-1248design of, 1268-1274end-of-battery-life tests, 1313feedback, negative current, 1236instability in, 1243-1244loudspeaker, combination horn and

phase inverter, for personal portables, 859operation with reduced battery voltages, 1247portable, 1021, 1115series filament operation, 1115, 1250tests, 1301, 1313

Receivers, car (automobile)battery voltage variations, 1206, 1277chassis pickup of vehicular receivers,

1313-1314design of, 1275-1278elimination of hash, 1210-1211, 1270-1272,

1275-1276interference tests, 1313-1314

Receivers, car (continued)valve operating conditions, 1277-1278vibrator power supply for, 1202-1212

Receivers, communicationaerial input, 912-921, 1263A-M, design of, 1260-1264a.v.c. circuit design in, 1108, 1116band changing, 1261bass attenuation in, 649beat frequency oscillator, 954, 960-961, 1263cross-modulation, 1264diversity reception, 1263-1264frequency coverage and calibration,

1260-1261mobile F-M, limiters for, 1149-1150muting (q.a.v.c.) for, 1125noise limiting in, 1130, 1131selectivity, 1262sensitivity and noise, methods of

measuring, 1262signal strength meter (S meter), 1263stability, frequency, 1262variable bandwidth crystal filters for,

1051-1061, 1262volume control and a.v.c., 1262-1263

Receivers, F-Maerial and r-f design, 1287-1289, 1294a.v.c., use in, 1097, 1099, 1112, 1288,

1291-1296composite F-M/A-M i-f trans-

formers, 1024-1025, 1294-1295converter circuit, 1290de-emphasis curve, 75 microseconds, 638de-emphasis time constant, 1092, 1093, 1293design of (Chapter 36), 1287-1296

comparison with A-M, 1287detectors in, 1088-1105, 1295F-M/A-M receivers, design of, 1294-1296

aerial input circuit, 1294general considerations, 1295-1296i-f amplifier, 1294-1295r-f section, 1294

F-M detection and A-M rejection,1088-1105, 1292-1293

i-f amplifiers in, 1022, 1024-1025, 1290-1292,1294-1295

tracing regeneration in, 1290-1291i-f transformers in, 1024-1025, 1037-1041limiters, amplitude, 1147-1150

applications of, 1023, 1040, 1088, 1090,1095, 1098, 1099

muting in, 1128-1130oscillator design, 947-961, 1289-1290phase discriminator in, 1088-1095references, 1296r-f amplifiers in, 915-946, 1287-1289superregenerative detectors in, 1087tests and measurements—see below.tuning indicators for, 1135-1136

Receivers, F-M, tests and measure-ments, 1314-1320

a.v.c. characteristic, 1307, 1318definitions, 1314-1315distortion, harmonic, 1306, 1318

maximum-deviation distortion, 1318downward modulation, 1320frequency drift, 1310, 1319hum, 1309-1310, 1319low frequency instability, 1319-1320maximum undistorted output, 1306, 1318mistuning, 1320noise audibility, 1310-1311, 1319operating conditions, 1300-1301, 1316

input measurements, 1316output measurements, 1300, 1316

radiation from local oscillator, 1311, 1320receiver adjustments, 1316-1317references, 1327spurious radiation, open field method

of measurement of, 1320spurious responses, 1310, 1319standard de-emphasis characteristic, 1315standard input values (powers, volt-

ages), 1314standard mean-signal input, 1314standard pre-emphasis characteristic, 1315

1460 INDEX

Receivers, F-M, tests and measurements(continued)

standard test frequencies, 1314standard test modulation, 1314standard test output, 1298, 1315standard v-h-f dummy antennae, 1315, 1316standard 300-ohm antenna, 1315testing apparatus, 1315-1316

standard signal generator, F-M, 1315-1316standard signal generator for ampli-

tude-suppression testing, 1316two-signal tests, 1316

tests, 1317-1320amplitude-modulation suppression, 1318frequency response, 1305, 1318interference, co-channel, 1317-1318

beat-note component, 1317cross-talk component, 1317

interference, masking, 1318selectivity, 1318sensitivity, 1317

deviation sensitivity, 1317maximum-deviation sensitivity, 1317maximum sensitivity, 1317quieting-signal sensitivity, 1317

tuning characteristic test, 1319undistorted output, maximum, 1298, 1315

Receivers, radio, pickups for connectionto, 751, 752

Receivers, reflex (Chapter 28), 1140-1146advantages and disadvantages of, 1140-1141a.v.c. design, 1142bass boosting in, 1141, 1146bubbling in, 1141, 1142comparison between plate and screen

reflexing, 1146description of reflex amplifiers, 1140design of plate reflex superhet. re-

ceivers, 1143-1145design of screen reflex superhet. re-

ceivers, 1145-1146design of t.r.f. reflex receivers, 1146distortion in, 1140, 1141, 1145, 1146four valve receivers, design of, 1258-1259hum neutralization, inherent, 1145minimum volume effect, 1141, 1142modulation, reduction in percentage, 1143negative feedback in, 1141, 1143, 1145neutralization in reflex stage, 1145operating conditions of reflex stage, 1143overloading characteristics, 1141, 1142, 1146play-through, 1140-1143, 1145-1146, 1240

circuit for reducing, 1240references, 1146regeneration in, 1143sensitivity, receiver, 1144, 1146signal to noise ratio, 1146some characteristics of reflex re-

ceivers, 1142-1143Receivers, telephone (headphones), 832-833Reciprocal, definition, 1402Reciprocity theorem, 165Recording characteristics, 727-732, 766, 770Records, reproduction from (Chapter

17), 701-774acoustical radiation (needle talk), 714, 718,

719, 760, 762American recording standards, 702amplitude, critical, 704, 708amplitude, peak, 702-703, 709automatic record changers, 705-706, 727bibliography of disc recording, 702buzz, 715, 722, 759complete amplifiers for reproduction of

sound from records, 744-751compliance at stylus tip, lateral, 712, 717-722compliance at stylus tip, vertical, 712, 718-722constant amplitude recording, 703-704, 727constant velocity recording, 703-704, 727discs, characteristics of, 706-709discs, materials for, 706, 766, 769distortion and undesirable effects, 757-762

due to stylus wear, 761non-linear, in pickups, 718, 719, 723, 762non-linear, in recordings, 756, 762, 766,

769

Records, reproduction from (continued)playback distortion, 708, 757-760tracing distortion, 708, 757-760

effect of recording characteristicson tracing distortion, 759-760

harmonic, 757-758intermodulation, 758-759other distortion effects, 760ratio of intermodulation to har-

monic, 758-759dust on vinyl records, 706, 713equalizers for record reproduction, 732-744

applying negative feedback to pickup, 743equalizer, position of, 732, 743equalizers and equalizing amplifiers,

738-743for crystal pickups, 741-743for electromagnetic pickups, 738-741

equalizers, high frequency (de-emphasis), 736-737, 739-740, 744-751,

770equalizers, low frequency, 732-736equalizing, corrective, 728equalizing, definition, 727, 728equalizing to give standard playback

curve, 731-732high-frequency attenuation (scratch

filter), 214, 737-738, 746-751input transformers, 743-744rumble filter, 744-749

fine groove (microgroove) recording,701, 706-709

flutter, 761flutter, tests for, 1312frequency characteristic of ideal con-

stant velocity pickup, 724frequency range, desirable top limit to, 704frequency range, filters to limit high,

214, 636, 655-658, 737-738, 746-751, 763frequency range of recording, 704frequency test records, 702-703, 716,

752-757banded tone, 752, 753-756gliding tone, 752, 753optical method of testing, 752-753special test records, 756-757

glossary of disc recording terms, 702groove diameter for reasonable fidelity,

minimum, 759hinge frequency, 759hum in record reproduction, 705, 706, 719,

722, 763introduction to disc recording 701-706lacquer disc home recording (direct

playback), 701, 766-768amplifier, 767-768cutter head, 767cutting stylus, 767distortion, 766embossed groove recording, 768equalization of cutter, 767hot stylus recording technique, 767materials for discs, 766motor and turntable, 767pickups for lacquer discs, 768recording characteristics, 766signal to noise ratio, 766, 770standards for disc home recording, 766

lateral recording, 701-774lateral recording, principles of, 702-706McProud test of pickup and arm, 715magnetic recording, 701mechanical groove recording, 701methods used in sound recording, 701-702needle scratch, 704-705, 763-765needle talk (chatter), 714, 718, 719, 760, 762needles, fibre, 710needles, semi-permanent, 709needles, steel, 709, 711needles, thorn, 710needles, trailing, 711, 726

see also Styli.noise reduction, 763-765

analysis of noise, 763high frequency pre-emphasis and de-

emphasis, effect of, 763

INDEX 1461

Records, reproduction from (continued)Olson noise suppressor, 763Price balanced clipper noise suppressor, 765Scott dynamic noise suppressor, 764volume expansion, effect on noise, 763

pickup arm resonance, 712, 714, 716, 719,720, 722

pickup, armature of, 702pickup armature resonance, 712, 714, 716,

719, 720, 722pickup distortion, 718, 719, 723, 762pickup dynamic mass, 718, 719, 721, 722pickup, electromagnetic, effect of shunt

capacitance, 738-739pickup, hum level, 719, 722pickup needle armature type, 717pickup output expressed in db, 810pickups, 714-723pickups, armature resonance, effect on

harmonics, 716pickups, capacitance, 722pickups, damping of arm resonance in, 716pickups, damping of armature resonance

in, 716pickups, dynamic (moving coil), 715, 719-720

Fairchild transcription, 720Lexington moving coil, 720

pickups, eddy current, 723pickups, electro-magnetic (moving

iron), 715, 717-719Audak polyphase, 719Connoisseur, 718Decca ffrr type D, 717-718E.M.I. and Marconiphone Model

12A, 719G.E. variable reluctance, 719Goldring Headmaster, 718Pickering home phonograph cart-

ridge, 718Pickering transcription Model 161L, 718R.C.A. light-weight, 719W.R.N. standard transcription, 718

pickups for connection to radio re-ceivers, 751-752

pickups for fine groove, 715, 717-723pickups for 78 r.p.m. 715, 717-723pickups, frequency of armature reson-

ance affected by record material, 716pickups, magnetostriction, 721pickups, piezo-electric (crystal), 715, 716,

717, 720-721ceramic (barium titanate) 720-721other materials, 720response curves of typical crystal

pickup, 742Rochelle salt, 720-721use of, in record players, 752

pickups, ribbon, 716, 722Brierley pickup, 722

pickups, strain gauge, 721-722pickups, testing of, 715, 716-717, 762pickups, types of, 715pinch effect, 711, 712, 720, 757, 760playback loss, 760pre-amplifiers for use with pickups,

732, 733-736, 737-741, 744-749pre-emphasis, high frequency, difficul-

ties with large degree of, 729pressure, effective vertical, 702, 708, 709,

712, 718-722, 768-769processing of records, 705radius compensation, 711, 770radius of curvature, minimum, 704record players, 751-752references, 771-774recorded level, 702-703recorded level, maximum instantaneous

programme peak, 702-703, 708, 709recorded level, normal maximum, 703recording characteristics, 727-732, 766, 770

constant amplitude, 727constant velocity, 727cross-over frequency, 728high-frequency pre-emphasis, 727,

728-729

Records, reproduction from (continued)ideal theoretical, 727measurement of recorded velocities, 729playback curve, A.E.S. standard, 731-732practical recording characteristics, 730-731pre-emphasis in terms of time con-

stant, 728rumble, 705, 706, 744, 1312scratch filters, 214, 636, 655-658, 737-738,

746-751, 763shellac pressings, 701, 704-708side-thrust on grooves, 723, 726-727signal to noise ratio, maximum, 704-705,

766, 770single point contact, 710skating, groove, 710, 713sound on film, 701specification for motor and turntable

unit, 705speed of rotation for recording, 701speed of rotation, tolerance in, 701stroboscope, use of, 702styli, 702, 704, 706, 708, 709-714styli, colour codes for, 711styli, diamond, 710, 711, 714, 717, 718,

719, 720styli, osmium, 711, 714styli, oval, 710styli, permanent, 710-714styli, sapphire, 710-714, 717, 718, 719, 720,

722styli, tungsten carbide, 710, 711, 717, 722

see also Needles.stylus force, vertical, 702, 708, 709, 712,

718-722, 768, 769stylus force, vertical, minimum for

tracking, 712, 715, 719, 720stylus, N.A.B. secondary standard, 711stylus tip, jewel, polish of, 712stylus tip, shape of, 710stylus wear, method for giving positive

indication of, 714surface noise and dynamic range,

704-705, 763-765testing distortion in sound recording,

proposed standards, 762testing phonograph combinations, 1311-1312testing pickups for harmonic distortion, 762testing pickups for intermodulation dis-

tortion, 762tracking, 723-727

distortion due to imperfect tracking,723-726

general survey, 723-725minimum distortion, how to design

for, 725-726other effects of imperfect tracking, 723-725pickup, offset arm, 725-726pickup, optimum offset angle, 726pickup, optimum underhang, 725-726pickup, straight arm, 725-726stylus friction, influence of, 726-727

tracking capability of pickup, checking, 762tracking efficiency of pickup and arm,

test for, 715tracking error, 712, 723-727transcription records, reproduction

from, 701, 731, 769-771distortion, 769equalization, high frequency de-em-

phasis (N.A.B.), 770materials for records, 769N.A.B. and B.B.C. characteristics, 769radius compensation, 711, 770recording characteristics, 730, 770signal to noise ratio, 770sound track, 770translation loss, 759, 770wear, record, 769

translation loss, 759, 770turntable, effect of wobbling or eccen-

tric, 761turntables and driving mechanism, 705types of discs, 701, 766, 769ultrasonic frequencies, 704

1462 INDEX

Records, reproduction from (continued)velocity, critical, 704, 708velocity of stylus tip, transverse, 702-703vertical recording, 701warping, effect of record, 760-761wavelength vs. frequency, 708wear, records, 706, 712-713, 723, 769wear, stylus, sapphire, 713-714wow, 626, 705, 760, 1312

Recovery time of peak limiters, 682-683Rectangle, 273Rectification (Chapter 30), 1161-1191

biphase half-wave, 7, 1161conduction period, 1164copper oxide rectifiers, 1169curves, constant current, 1165, 1167-1169curves, constant voltage, 1165-1169curves, published, use of, 1165-1169definition, 1402effects in power amplifiers, 551-552, 553-554,

561, 565, 566, 568-569equivalent circuit, 1164filtering—see under Filtering and hum.full-wave, 7, 1161-1169, 1173-1185half-wave, 6, 1161, 1163, 1172, 1175,

1176, 1178impedance per plate, total effective plate

supply, 1165-1167, 1180parallel operation of rectifiers, 1165power supply regulation, 1164, 1182principles of, 1161-1164references, 1191ripple, 1161, 1173ripple current through filter con-

densers, 1181-1182ripple factor (percentage), 1176, 1177selenium rectifiers, 1169series resistors to limit current, 1165, 1173shunt diode bias supplies, 1188-1191symmetry, lack of, 1161test, power diodes, 74, 99-100test, signal diodes, 74, 100transformer heating, 236-237, 1185-1186valve ratings, maximum, 1163-1164valve rectifiers, high vacuum, 1161-1191valve rectifiers, mercury vapour, 1161, 1164,

1165valves and types of service, 1164-1165voltage and current waveforms, 1161-1162voltage doubler, 1174, 1175, 1178,

1186-1187voltage multiplying rectifiers, 1186-1188voltage quadrupler, 1187-1188voltage tripler, 1187with choke-input filter, 1162-1164,

1167-1169, 1182-1185design curves, 1184diode current, peak, 1183inductance, critical value of, 1182-1185swinging choke, 249-250, 1182transient current, initial, 1185

with condenser-input filter, 1161-1163,1165-1167, 1169, 1170-1182

analysis and design curves, 1170-1181aproximations when capacitance is

large, 1178, 1180diode currents, determination of

peak and average, 1174-1176peak inverse voltage, curves, 1177procedure when complete data not

available, 1177-1179symbols, 1170transformer secondary r.m.s. current,

1177, 1178transient plate current, peak hot-

switching, 1163, 1180-1181Rectified and filtered a.c. supply, 129

see also under Rectification.Rectified sine wave, 130, 302Rectifier, equivalent circuit for, 1164Rectifier in a.c./d.c. receivers, 1267Reed armature loudspeakers, 831-832Reference acoustical intensity, 826Reference acoustical pressure, 826, 828

Reference acoustical velocity, 826Reference frequency in tone control, 636References to periodicals, abbreviations

and form of, 1367-1369Reflected load impedance in transformers,

200-203Reflection coefficient of transmission lines, 891Reflection effects in filters, 178Reflections in rooms, effects of, 833, 841,

864-865Reflex detector, 326, 1085-1086Reflex horn loudspeakers, 856-857, 867Reflex receivers—see under Receivers,

reflex.Regeneration in converters, controlled, 988-989Regeneration in i-f amplifiers due to

coupling between diode detectorand signal grid, 1081

Regeneration in reflex receivers, 1143Regenerative coupling in a-f amplifiers, 535Regenerative detector, 1086-1087Regenerative effects in receivers, tests for, 1303Regulation of power supply, effect on

power amplifiers, 547-548, 551, 562,568-569, 572, 582, 584

Regulation of transformers, 205-206Regulation, power supply, 1164, 1182Regulators, current and voltage (Chapter

33), 1213-1222barretters, 1213-1214, 1266current regulators, 1213-1214, 1266references, 1222voltage regulators, 1214-1222

gaseous tube types, 1214-1215valve types, 1215-1222

screen used to correct for inputvoltage changes, 1219-1220

simplest series form, 1218-1219valves suitable for use, 1218with controllable output voltage,

1220-1221with extremely good regulation,

1221-1222wet electrolytic condenser, use as, 193

Reluctance, 229Reluctance, units of, 1332Remanence, 230Remanent flux density, 230Replacement of valve, when to effect, 121Reproduction, high fidelity, 630-632Residual flux density, 230Residual volume effect—see under Play-

through.Resistance, 130-133Resistance-capacitance coupled pentodes,

496-517Resistance-capacitance coupled triodes,

482-495Resistance-capacitance filters, 172-176Resistance, equivalent noise, of valves,

783-784, 937-938, 967-968, 972-973, 978,984, 1230

Resistance, equivalent series loss, of aerial, 902Resistance, grid input, 49-53Resistance, interelectrode, tests for, 73, 94Resistance-loaded amplifiers, 24-27, 58-59,

482-517Resistance, loudspeaker suspension, mech-

anical, 836Resistance of a conductor at any tem-

perature, 1376Resistance of any valve electrode, de-

finition, 14Resistance of grid circuit, maximum—

see under Grid circuit resistance.Resistance of space, intrinsic, 897Resistance, output, effect on loudspeakers,

833, 840-841, 844-845, 848-849Resistance, series, of electrolytic con-

denser, 192Resistance, units of, 1332Resistances in parallel, 132-133Resistances in parallel, graphical method, 132Resistances in series, 131-132Resistances, interelectrode variational, 73Resistive component of impedance of

aerial, 902

INDEX 1463

Resistivity of earth, 896Resistivity, units of, 1332Resistor, heating of, 134Resistors, characteristics of, 186-191, 1344-1347

ambient temperatures, 187, 1345-1346capacitance of, 189carbon, 186, 1344-1346

composition, 186standard composition, 1344-1346

cracked carbon (high stability), 186, 190,1345-1346

colour codes for, 1335-1336de-rating characteristic (dissipation),

187, 1345, 1346de-rating characteristic (voltage),

187, 1345, 1346dissipation, 186-187effect of frequency on resistance, 189effect of humidity on resistance,

188-189, 1345, 1346effect of soldering, 188, 1345, 1346effect of temperature on resistance,

188, 1345-1347effect of voltage on resistance, 188, 1345inductance of, 189negative temperature coefficient, 158, 190,

1267noise of, 189-190, 783, 1345potentiometers, 191, 1356preferred values, table of, 1337-1339references, 198, 1358-1360stability, 186standard resistors, 1344-1360temperature coefficient, 190, 1346temperature rise, 187, 1394thermistors, 158, 190, 1267tolerances in resistance, 186, 1344-1347variable composition, 191, 1356voltage coefficient, 1345, 1346voltage ratings, 187, 1345wire-wound, 186, 1346-1347

non-inductive, 186standard, 1346-1347

Resonance/frequency table, a-f, 1386Resonance, parallel, 150-153, 410-411,

424-425determined by maximum impedance, 151-152determined by unity power factor, 150

Resonance, r-f solenoid design chart, 1386, 1387Resonance, series, 145, 409, 412, 424Resonance with LC hum filters, avoiding, 1193Resonances in unused coils, checking, 1252Resonances, room, 841, 864-865Resonant circuits, iron-cored inductors

in, 251Resonant circuits to provide bass boost-

ing, 644-645, 666-667, 736Resonant frequency, 408,409Resonant frequency, loudspeaker bass,

836, 837-841, 844-845, 848-849Resonant frequency, natural, 407, 408, 424, 948Resonant frequency of Colpitts oscillator, 952Resonant frequency of Hartley oscillator, 951Resonant frequency of negative transcon-

ductance oscillator, 954Resonant frequency of tuned-grid os-

cillator, 950, 951Resonant frequency of tuned-plate os-

cillator, 949, 951Resonant frequency, parallel, 410Resonant frequencies, primary, of aerial

and r-f coils, measurements of, 1325Resonant impedance of parallel tuned

circuit, 411Reverberation time, 863-864Reversible self-rectifying vibrators, 1203-1204Revolution (angular measure), 1330Ribbon microphone, pressure, 775, 779Ribbon microphone, velocity, 775, 779Ripple, 1161, 1173Ripple current ratings of electrolytic

condensers, 193-194, 1358Ripple current through filter condensers,

1181-1182Ripple factor (percentage), 1176, 1177Ripple frequency, definition, 1402Ripple in rectified and filtered a.c. supply, 129

Rocking tuning control, 990Roll-off, definition, 1402Roll-off frequencies in a-f amplifiers, high, 631Room noise, 620-621, 625Room resonances, 841, 864-865Rooms, acoustics of, 864-865Root mean square, 134, 1298Roots, 255, 261Routh-Hurwitz criterion of stability, 356Rumble filters, 744-749Rumble in phonograph combinations,

tests for, 1312Rumble in record reproduction, 705, 706, 744,

1312

SS-meter, 1263Sabin, definition, 863Safety margin in feedback amplifiers,

359, 367, 368, 372Saw-tooth waves, 130, 301Scalar, definition, 1402Scales, musical, 873-874Schmitt phase inverter, 526, 670Scientific notation in arithmetic, 255Scott dynamic noise suppressor, 764Scratch filters for record reproduction,

214, 636, 655-658, 737-738, 746-751, 763Scratch, needle, 704-705, 763-765Screen and bias stabilized amplifier, 593-594Screen and cathode by-passing of r.c.c.

pentode, incomplete, attenuation andphase shift characteristics, 498-500

Screen by-pass r.c.c. pentode, 496-499Screen by-pass, r-f, series resonant,

944, 1289, 1291Screen by-passing, attenuation slope and

phase angle, 360-361Screen by-passing of r.c.c. pentode, in-

complete, attenuation characteristics,496-497

Screen by-passing of r.c.c. pentode, in-complete, phase shift/frequency char-acteristics, 489-499

Screen characteristics of pentode, 16-17Screen circuit decoupling, 537Screen, concentric, effect on inductance

of coils, 438-441, 444, 473Screen-coupled cathode follower, 326, 532Screen-coupled direct-coupled amplifier, 532Screen current, average, push-pull Class

A, AB1, pentodes, 584Screen current, Class A pentode, 562Screen current test; 103, 109, 113Screen dissipation, Class A pentode, 562Screen grid of tetrode or pentode, 7Screen loadlines, 513-514Screen regeneration in converters, 988-989Screen reflex superhet. receivers, design

of, 1145-1146Screen series resistor, r.c.c. pentode, de-

termination of, 505-506Screen source regulation, effect on power

amplifiers, 562Screen stopper, type 807, 563Screen stoppers, general, 91, 1283Screen supply from voltage divider, r.c.c.

pentode, 506Screen supply, r.c.c. pentode, 496Screen to control grid amplification factor, 35Screen transconductance, 34Screen voltage, low, operation at, 84Screen voltage supply, valve ratings for, 79Screening, electrostatic, in power trans-

formers, 233, 786, 1198, 1279Screening, electrostatic, to reduce hum, 784Screens around coils, design of, 466, 473Screw threads, 1388-1391

American screw threads, 1388B.A. screw threads, 1389self-tapping screws, drill sizes for, 1391unified screw threads, 1390

1464 INDEX

Screw threads (continued)Whitworth screw threads, 1389wood screws, 1391

Scroggie's method for a.v.c. characteris-tics, 1114, 1232

Secant of an angle, 272Second, measure of time, 1332Secondary emission, 2, 7, 8, 21, 39, 69, 71Sectionalized windings in transformers, 221-223Sector of circle, 273-274Selectivity, 412-417, 425-426, 917-918, 920

adjacent channel, F-M, 1040curves, universal, 421-422curves, universal, applications of, 1027,

1031, 1035, 1055expanding, 455-456, 1048-1050, 1260, 1262graphical methods, 416-417

single tuned circuit, 416-417two identical coupled tuned circuits, 417

of aerial stages, 917-918, 920of A-M receivers, adequate, 1040-1041of coupled circuits of equal Q, 415-416, 426of coupled circuits of unequal Q, 416, 426of coupled circuits—tuned primary,

tuned secondary, 414-415, 426of coupled circuits—tuned secondary,

413-414, 425of identical tuned circuits in cascade, 421of i-f amplifiers, 1026-1028, 1031-1033,

1035-1037of single tuned circuit (series and

parallel), 412-413, 425of superregenerative receiver, measur-

ing, 1087of variable bandwidth crystal filters,

1055-1056tests in receivers, 1303-1305, 1318variable, i-f, 455-456, 1048-1050, 1260, 1262

Selenium rectifiers, 1169Self-bias operation—see under Cathode

bias.Self-rectifying vibrators, 1203, 1204Semi-infinite straight line, definition, 362Sensitivity, deviation, tests for, 1317Sensitivity, maximum-deviation, tests for, 1317Sensitivity of power amplifiers, definition, 545Sensitivity, power, Class A triode, 559Sensitivity, quieting-signal, test for, 1317Sensitivity tests on A-M receivers, 1302-1303Sensitivity tests on F-M receivers, 1317Series arm of network, definition, 159Series combinations of L, C and R, 144-147Series, condensers in, 135Series connection of batteries (cells), 129Series, definition, 1402Series expansion: general case, 63Series expansion: valve with resistance

load, 61-62Series, Fourier, 299-302Series impedance of tuned circuit, 409Series in algebra, 266-267Series, inductances in, 141Series, infinite, 268-269Series, Maclaurin's, 299Series-parallel combinations of L, C and

R, 149-153Series, reactance and resistance in, im-

pedance of—tables and charts, 1382-1385Series, resistances in, 131-132Series resistors, electrode voltages sup-

plied through, 70Series resistors to limit rectifier current,

1165, 1173Series resonance, 145, 409, 412, 424Series, Taylor's, 298Series to parallel impedance, conversion

from, 157-158Service tester practice, 121-125Service testers

a.c. versus d.c. test voltages, 124characteristics which should be tested, 122methods of testing in, 123-125types of commercial, 122-123

Service testing of valves, 121-125Sheet metal gauges, 1393Shellac pressings, 701, 704-708

Shielding a-f transformers to reduce hum,207, 210-211, 781, 784, 1198

Shielding of leads, magnetic, in pre-ampli-fiers, 786

Short-circuit, definition, 1402Short-circuit feedback admittance, 50-55

tests for, 117Short-circuit feedback admittance,

methods of increasing in i-f amplifiers, 1064Short-circuit forward admittance, 50-55

tests for, 117Short-circuit interlectrode admittances, 69Short-circuit input admittance, 50-55

tests for, 113-117Short-circuit input capacitance, change of,

with transconductance, 55Short-circuit input conductance, typical

values of, 55Short-circuit output admittance, 50-55

tests for, 117Short-circuits, interelectrode, tests for,

73, 91-93, 123Short-wave coils, design of, 463-468

charts, 466-473Short-wave communication, long dis-

tance, 404, 901forecasting frequencies for, 404, 901

Shorter's method of testing for loud-speaker transients, 870-871

Shot effect noise, 783, 787, 936 -938, 1230Shunt arm of network, definition, 159Shunt capacitance coupling in i-f trans-

formers, 1023-1024Shunt, definition, 1402Shunt diode bias supplies, 1188-1191Sibilant speech sounds, distortion of,

with volume compression, 683Sideband cutting in receiver, equalization

of, 654Sideband, definition, 1402Side-chain amplifier in volume expansion, 686Side frequency, definition, 1402Side-thrust on grooves of record, 723, 726-727Siemens, 1332Signal circuits, padded, 1013-1017Signal generator, standard, 1298-1299,

1315-1316Signal strength meter, 1263Signal to noise ratio in microphone pre-

amplifiers, 788, 793maximum possible, 788standard, in pre-amplifiers for broad-

casting, 793with crystal microphones, 788

Signal to noise ratio in record reproduc-tion, maximum, 704-705, 766, 770

Signal voltage, definition, 1402Silicon crystal detectors, 1137Silvered mica dielectric condensers, 196Simple harmonic motion, 278-279, 702Sine of an angle, 272, 275Sine wave alternating current, 129, 130, 278Sine wave, average (r.m.s.) by definite

integrals, 298Sine wave, derivative and integral of, 130Sine wave, distorted, 130Sine wave, fundamental, 130, 299-300Sine wave, harmonic frequency, 130, 300Sine wave, rectified, 130, 302Single channel sound system vs. dual .

channel, 627Single time constant circuit, 359Sinking diode circuit, 1108, 1117, 1257, 1295Sinusoidal, definition, 1402Skating, groove, 710, 713Sky (space) wave, 404, 896, 897Slide rule, 257-258Slide rule, special calculations on, 258, 822-823Sliding screen, effect on gain, 28-29Slope, negative, 25, 289Slope of bass boosting frequency charac-

teristics, maximum, 642Slope of curve, 280, 289-291Slope of dynamic characteristic, r.c.c.

pentode, 506, 507-508

INDEX 1465

Slope of mutual characteristic, 17Slope, rate of change of, 289-291Small compared with, definition, 1402Sockets, octal, use of pin No. 1, 81Sockets, valve, connections to, 80, 81Soft valve, definition, 1402Soldering, effect on composition resistors, 188, 1345, 1346Soldering valves into wiring, 81Solenoids, multilayer, design of, 443-444Solenoids, multilayer, inductance of, 441-444Solenoids, single layer, calculation of

self-capacitance, 451-452Solenoids, single layer, design of, 443-445Solenoids, single layer, inductance of, 429-441Solids, surfaces and volumes of, 275Sound chamber in horn loudspeakers, 854-855Sound, critical frequency bands, 621-622Sound equipment, loudspeakers, standards

for, 874-876Sound level and noise, measurement of, 827-880

acoustical noise measurement, 827electrical noise measurement, 827noise in amplifiers, measurement of, 829-830

broadcast systems, 829sound equipment, 829

noise level, definition, 829noise level, weighted, standard, 829objective noise meter, 828radio noise, measurement of, 829-830

radio noise meter, 829-830references, 830sound level meter, American standard, 828sound levels, typical—table, 828-829weighting network for measurements,

827-828Sound level and peak acoustical power,

difference between, 623Sound level—see also under Volume level.Sound levels, nomogram for adding two

component, 821-822Sound levels, preferred listening, 623Sound or film, 701Sound pressure with conversational

speech, 775Sound reinforcing system, 866-867Sound, reproduced, imagery for describ-

ing, 604-605Sound system, complete, 810, 812-813Sound system rating, 812-813Sound system, single channel vs. dual

channel or stereophonic, 627Sound systems, constant line voltage, 874, 883Sound, velocity and wavelength of, 872Sound waves, 403Source impedance, effect of zero or nega-

tive, on loudspeakers, 841Source impedance for pre-amplifiers,

standard, 793Source impedance, loudspeaker measure-

ment, 812, 874Space charge, 3, 71Space charge, coupling in converters,

963, 975-977, 980Space charge, effect on input capacitance, 51Space charge tetrodes as power amplifiers, 569Space current, 70

see also Cathode current.Space current, definition, 1402Space, intrinsic resistance of, 897Space (sky) wave, 404, 896, 897Spark plates in car radio, 1277Specification for power transformers, 241Specifications for a-f transformers, 228Specifications for motor and turntable

unit, 705Speech and noise, references, 634Speech articulation, 628-629, 630Speech clippers, 693-694Speech, compression of, 684Speech, conversational, sound pressure

with, 775Speech, declamatory, 629Speech, masking by noise, 629Speech peak dynamic range, 628Speech power, 628

Speech reproduction, 628-630Speech reproduction, distortion in, 629Speech reproduction, frequency ranges

for, 630Sphere, 275Spider cone suspension, 835Spirals, flat, inductance of, 445-446Split-reed synchronous vibrators, 1204Spurious frequencies

formed by intermodulation distortion, 62from converters, 62, 987, 995, 1247in A-M receivers, 1116, 1278-1279

tests for, 1310spurious response ratio, 1310image response, tests for, 1310image ratio, tests for, 1310

in F-M receivers, 1112, 1294, 1295, 1310,1319

Spurious radiation in F-M receivers, openfield method of measurement of, 1320

Spurious-response ratio, 1310Spurious responses—see under Spurious

frequencies.Sputter in rectifier valves, 100Sputtering, 3Square wave testing for loudspeaker

transients, 870Square wave testing of a-f amplifiers, 1324Square waves, 130, 301, 870, 1324Squeals (squeaks) in A-M receivers, 1246, 1312Squegging, 958, 992, 1001, 1244, 1246Squelch systems, 1125-1130Stability factor (Becker), 388Stability in a-f amplifiers, tests for, 1324Stability in feedback amplifiers, 356-378 see also under Feedback.Stability in i-f amplifiers, 1065-1067Stability in r-f amplifiers, 942-944Stability in voltage amplifiers, 535-538Stability margin in feedback amplifiers,

359, 367, 368, 372Stability of composition resistors, 186Stability of electrical characteristics of

valves, 69, 70Stabilization, frequency, 957-958, 992-996Stabilized amplifier, bias and screen, 593-594Stacking factor in power transformers, 235Stage gain, test for, 74, 108Stagger tuning of i-f transformers, 1026Staggering attenuation characteristics of

feedback amplifiers, 364-365, 367, 382-385Stand-by operation of valves, 84Standard a.c. waveform, 130Standard distribution lines, loudspeaker

power rating, 874Standard test signals, loudspeaker, 874-875Standards, American recording, 702Standards for loudspeakers, 874-876Standards for microphones, 781-782Standards for pre-amplifiers, 793Standards for vibrator power transformers, 1207Standards for vibrators for auto-radio, 1205Standing-wave ratio of transmission lines, 891Standing waves in enclosed cabinets, 843Statampere, 1332, 1333Statcoulomb, measure of charge, 1332, 1333Statfarad, 1332, 1333Stathenry, 1332, 1333Static characteristics, 71, 72Statmho, 1332, 1333Statohm, 1332, 1333Statvolt, 1332, 1333Step circuit in feedback amplifiers, phase

angle, 361Step in attenuation characteristic, 368, 371Stephan's formulae for inductance of

coils, 442, 443-444Steradian, definition, 1402Stereophonic reproduction, 627, 865-866Stiffness of cone suspension, 836Stop band of filter, 180Stopper resistors, 91, 326, 560, 562, 563, 958,

959, 1000, 1283Storage battery operation, valve ratings

for, 78, 79

1466 INDEX

Straight line, equation to, 280Strain, definition, 1403Stress, definition, 1403Striking voltage of gaseous voltage regu-

lator, 1214Stroboscope, use of, in recording, 702Styli (needles), 702, 704, 706, 708, 709-714Styli, colour codes for, 711

see also under Needles.Styli, diamond, 710, 711, 714, 717, 718, 719, 720Styli, osmium, 711, 714Styli, oval, 710Styli, permanent, 710-714Styli, sapphire, 710-714, 717, 718, 719, 720,

722Styli, tungsten carbide, 710, 711, 717, 722Stylus force, vertical, 702, 708, 709, 712,

718-722, 768, 769minimum, for tracking, 712, 715, 719, 720

Stylus friction, influence of, 726-727Stylus, N.A.B. secondary standard, 711Stylus tip, jewel, polish of, 712Stylus tip, shape of, 710Stylus wear, method for giving positive

indication of, 714Sub-frequencies in loudspeakers, 871Sub-harmonic, definition, 1403Sub-harmonics in loudspeakers, 871Sub-multiples and multiples, 1405Subscript, definition, 1403Subscripts for magnitude letter symbols,

1364-1365Subsidiary feedback, 375-378Subsidiary voltages and attenuation char-

acteristics in feedback amplifiers,summation of, 372-375

Subtraction, 260Sunlight, spectral energy curves of, 1396Superheterodyne tracking, 1002-1019Superposition theorem, 165Superregenerative detector, 1087Superscript, definition, 1403Supersonic, definition, 1403Supplementary angles, 272Supply impedance per plate, plate, 99Supply voltage, oscillator frequency varia-

tion due to changes in, 949, 953, 955Suppressor characteristics, 21-22Suppressor grid as detector, 22, 1257Suppressor grid, connection of, with

triode operation, 36Suppressor grid controlled pentodes in

volume expanders, 686, 689-690Suppressor grid of pentode, 8Suppressor, noise—see under Noise.Surface noise and dynamic range, 704-705,

763-765Surface wave, 896, 897Surgeproof electrolytic condensers, 193Surround, annular cone, 835-836Susceptance and conductance from re-

actance and resistance, chart for de-termining, 155, 156

Susceptance, grid input, 49-53Susceptance of arms and networks, 153-154Susceptance, sign of, 50, 153Susceptance, signal grid input, in con-

verters, 976-978Suspension, cone, 835-836Swarf in recording, 766Swinging choke, 249-250, 1182Symbols, standard, and abbreviations,

1363-1371abbreviations, 1366-1367

titles of periodicals, 1367-1369graphical, standard, 1370-1371magnitude letter symbols, 1364

subscripts for, 1364-1365with subscripts, 1365-1366

mathematical signs, 1366multipliers, 1363references to periodicals, form of, 1369references to symbols and abbrevia-

tions, 1369Symmetrical, definition, 1403

Symmetrical networks, 179Synchrodyne receiver, 1226-1227Synchronous vibrators, 1203, 1204Synthetic bass, 616, 676System rating, R.M.A. microphone, 776,

809-810, 812-813

TTables, charts and sundry data (Chapter 38) 1329-1423

(for details see Contents).decibel tables, 813-821

Tangent of an angle, 272, 275Tangent to a curve, 280, 291Tap, definition, 1403Tapping down on oscillator coil for

stability, 957Taylor's series, 298Telephone receivers (headphones), 832-833Temperature changes, oscillator frequency

variation due to, 955-956Temperature characteristic of valve heater,

10, 11Temperature coefficient of composition

resistors, 190, 1346Temperature coefficient of resistivity of

copper, 237Temperature compensation of tuned cir-

cuits, 196, 956, 957, 1041Temperature, effect of, on capacitance of

electrolytic condensers, 192, 193Temperature, measurement of, 1334Temperature rise of composition re-

sistors, 187, 1394Temperature rise of power transformers,

236-237tests for, 1302

Temperature rise of wire-wound re-sistors, 1394

Term, definition, 1403Terminal, definition, 1403Tertiary, coils in i-f transformers, 1048-1049Tertiary, definition, 1403Test records, frequency, 702-703, 716, 752-757Testing apparatus for receivers, 1298-1300, 1315-1316Testing of a-f amplifiers for frequency

response at different levels, 626, 1323Testing of a-f power amplifiers, 548, 1321-1325Tests and measurements

amplifiers, a-f, 548, 626, 1321-1325amplitude of frequency test records,

optical methods, 752-753coils, 453, 1325-1326coils, self-capacitance of, 453distortion in sound recording, proposed

standards for, 762inductance and impedance of iron-cored

inductors, 250-251phonograph combinations, 1309, 1311-1312pickups, 715, 716-717, 762ratio detectors, 1102-1105receivers, A-M, 1297-1314receivers, F-M, 1314-1320recorded velocities, 729references, 1327transformers, a-f, 207, 227-228, 626transformers, power, 236-237, 1302valves, 68-127

Tetrodes, 7kinkless, output, 8, 569space charge, as power amplifiers, 569

Thermal agitation noise, 4, 189-190, 782,788, 935-936

Thermionic emission, 2, 3, 69Thermistors, 158, 190, 1267Thevenin's theorem, 164Thorn needles, 710Threshold howl with regenerative de-

tectors, 1087Throat microphones, 780Throat of horn loudspeakers, 854-855Throttled air-flow loudspeakers, 832Throw-in (and out) frequency (a.f.c.), 1154

INDEX 1467

Thump in volume limiters and ex-panders, 683, 688

Thyrite, 158Time constant, 137, 141, 172, 173, 536

de-emphasis curve with time constant75 microseconds, 638

of a.v.c. filter circuits, 1105-1106, 1109,1115-1117, 1233

of diode detector circuits, 1080-1081of r.c. filters, 172, 173, 638recording pre-emphasis in terms of, 728single time constant circuit, 359

Time delay in loudspeaker installations, 866Time-efficiency of vibrator, 1205Time, units cf, 1332Titles of periodicals, abbreviations of, 1366-1369Tolerance, definition, 1403Tolerances in components, effect of, on

stability in feedback amplifiers, 359, 371Tolerances in composition resistors,

186, 1344-1347Tolerances in electrolytic condensers, 192Tolerances in elements in tone control

networks, 639Tolerances in screen series resistors and

cathode bias resistors, effect on r.c.c.pentodes, 515-516

Tolerances in valve characteristics, 9, 15, 88screen currents, 9

Tonal balance, 617, 632Tone burst for testing loudpeaker tran-

sients, 870Tone compensation and tone control

(Chapter 15), 635-678attenuation expressed as time con-

stant, 638automatic frequency-compensated volume

control, 672-674, 1234-1239method incorporating inverse volume

expansion with multi-channel am-plifier, 673-674

bass attenuation, 649-652see also under Bass attenuation.

bass boosting, 640-648see also under Bass boosting.

calculations involving decibels peroctave, 637-638

combined bass and treble controls,658-669, 739-740, 746-751

continuously variable controls, gen-eral, 662

dual controls, 664-668ganged controls, 664single control, 662-664

fixed bass and treble boosting, 662quality switch, 659step-type using feedback, 669-670stepped controls, general, 658universal step-type, not using in-

ductors, 660-661universal step-type using inductors,

661-662combined bass controls, 653

stepped controls, 653combined treble controls, 658damping of tuned circuits, 639distortion due to tone control, 606, 636-637elements of tone control filters, 639feedback to provide special attenuation

characteristics at low or high fre-quencies, 671-672

feedback to provide tone control,330, 336, 347, 378-379, 645-647, 651, 655,

667, 669-672, 741, 748-751, 757-758fundamental circuit with R and C for

constant input voltage, 639general considerations, 636limitation of frequency range by filters,

214, 636, 655-658, 737-738, 746-751, 763see also Bass attenuation.

listener and tone control, 677multiple channel amplifiers, 673-674, 676position of equalizer and tone control, 636purpose of tone compensation, 635-636references to tone control and tone

compensation, 677-678see also under Equalizing.

Tone compensation and tone control(continued)

synthetic bass, 616, 676tolerances of elements, 639tone control, definition, 636tone control in volume expanders,

position of, 686treble boosting, 653-655

see also under Treble boosting.whistle filters, 673-676

crystal filters, 675narrow band rejection filter, 675parallel-T network, 675-676resonant circuit filters, 673-675

Tone control—see under Tone compensa-tion and tone control.

Top bend of dynamic characteristic, 508Top bend rectification, 508, 1084-1085Toroidal coils, inductance of, 445Torque of turntable unit, 705Tracking capability of pickup, checking, 762Tracking error in record reproduction,

712, 723-727Tracking in record reproduction, 723-727, 729Tracking, superheterodyne, 1002-1019

arithmetical-mean tracking, charts for, 1014arithmetical-mean tracking, formulae

for, 1010, 1015-1017centre tracking frequency, 1004charts for geometrical-mean tracking,

1005-1009circuits used for tracking analysis, 1002feedback winding for good tracking, 1004formulae and charts for design, 1005-1011

worked examples, 1011-1013general treatment, 1002-1004geometrical-mean tracking, charts for,

1005-1009high impedance primaries, effect on

tracking, 1003minimizing tracking error, 1233padded signal circuits, 1013-1015

worked example, 1015-1017padder, 1003-1004, 1010-1017padder, possible arrangements of, 1003permeability circuits, 1002references, 1017-1019three point tracking, 1002-1019tracking curves, typical, 1003two point tracking, 1002

Transconductance, conversion, defini-tions, 14, 109, 964-967

Transconductance, conversion, tests for,74, 109-111, 124

Transconductance, definition, 14Transconductance, grid-plate, 14, 72

see also Mutual conductance.tests for, 74, 103-104, 113, 123, 124

Transconductance, mixer, test for, 111Transconductance, screen, 34Transconductances, interelectrode, 73Transcription records, reproduction from,

701, 731, 769-771Transducer, definition, 1403Transfer characteristics, 17Transfer coefficient, 306Transfer (linearity) characteristics of a-f

amplifiers, 587, 610, 611Transformer-coupled amplifiers, 27-34Transformer plate supply impedance per

plate, 99Transformers, aerial coupling, 912, 916-921

capacitance coupling, 921coefficient of coupling, 918-920fixed tuned, 912, 921gang capacitor tuned, 912-922

difficulties with, 913inductance tuned, 912mutual inductance coupling, 912, 916-920

high-impedance primary, 918top capacitance coupling, 918

tapped inductance, 912, 920-921Transformers and iron-cored inductors

(Chapter 5), 199-253

1468 INDEX

Transformers, audio-frequency, 206-228amplification at mid-frequency, 209" building out " into half section filter, 214capacitance due to layer winding, chart 224capacitance due to random winding,

chart, 225colour code, 1342core materials, 206-209, 210, 214

high permeability alloys, 206-209silicon steels, 206-207

core, weight of steel in, 208d.c. polarization, effect of, 207device to give improved high frequency

characteristics, 214distortion due to core, 206, 207, 210, 211,

212, 213, 214-217, 227distortion in cores, method of measur-

ing, 207driver transformer design, 591

driver inductance, 591driver resistance, 591looking backwards impedance, 591McIntosh amplifier, 595-596

driver transformer leakage inductance,effects of, 590

efficiency, 228, 567frequency response, 206, 207, 209, 227, 518frequency response and distortion, 209, 217

interstage transformers, Class A andB, 209-210

low-level transformers, 210-211output transformers, 211-217

hum in, 206, 207, 210-211, 540, 781, 785insertion copper loss, 214leakage inductance, 207, 209, 210, 212leakage inductance chart, 219leakage inductance, designing for low,

217-219loss, 228microphone, 781mixing windings, 221-223operating level, 206-207orienting to reduce hum, 785output, effect on frequency response

variation with output level, 626, 1323output, matching with, 880, 881-882output primary resistance, effects of, 566output transformer leakage inductance,

effects of, 566, 572-573output transformer, power handling

capacity, 227, 631output transformers for special ampli-

fiers,McIntosh, 594-595Williamson, 346-347

output transformers, tests for charac-teristics, 227-228

phase shift in, 206, 207, 214, 518primary inductance, effect on frequency

response, 207, 209, 212-214primary inductance, output trans-

formers, , 212-214random winding, 223-227references, 252sectionalizing windings, 221-223shielding to give hum reduction,

207, 210-211, 781, 784, 1198specifications for, 228spiral cores of grain-oriented silicon

steel, 208winding capacitances, 207, 209, 210, 212winding resistances, 214see also Amplifiers, a-f transformer

coupled.Transformers, ideal, 199-203

auto-transformers, 200double-wound, 199impedance calculations—multiple loads,

201-203impedance calculations—single load, 200-201transformed (reflected) load imped-

ance, 200-203Transformers, input, for record pre-

amplifiers, 743-744

Transformers, intermediate frequencycans for, 1043capacitance, values of, for tuning,

1021, 1024, 1062colour code, 1342commonly used circuits, 1022-1025composite F-M/A-M, 1024-1025construction, 1041-1043coupling factors, 1023-1024coupling factors, calculation of, 414-416,

419-421, 1023-1024, 1043-1048coupling factors, measurement of,

1025, 1030-1031, 1033-1034, 1102coupling, mixed, 1025, 1044-1048design of coils, 454-455, 1041,enclosed in powdered iron pots, 1042F-M i-f transformers, 1037-1041

bandwidth requirements, 1037-1038distortion in, 1038-1039, 1068-1069example, 1039-1041frequency deviation, method for

measuring, 1039introduced amplitude modulation,

1038-1039L/C ratios in, 1024mixed coupling, 1025, 1044-1048mutual inductance coupling, 1023, 1025-1041,

1046, 1048-1050design methods, 1025-1048

critically-coupled, 1026-1031k measurement, 1025, 1030-1031

over-coupled, 1031-1034k measurement, 1033-1034, 1102

under-coupled, 1035-1037selectivity of, 1026-1028, 1031-1033,

1035-1037shunt capacitance coupling, 1023-1024stagger tuning of, 1026tapping down in, 1024, 1040television receivers, for, 1026tertiary coils, 1048-1049triple tuned, 1026variable (expanding) selectivity, 455-456,

1048-1050windings, design of, 453-459

Transformers, parallel-fed, ultimate slopeof attenuation characteristic, 360

Transformers, power, 233-241area, cooling, 237build of winding, 236coil data, table, 240colour code, 1342-1343copper loss, 235, 236core losses, 234core material, 234-235core size, 235currents in windings, 236-237, 1177, 1188,

1185-1186efficiency, 233, 235electrostatic screening, 233, 786, 1198, 1279flux density, 235iron loss, 235laminations, 234-235leakage inductance, 233magnetizing current, 235mean length of turn, computing, 241primary turns, 235references, 252-253secondaries, turns for, 235specifications for, 241stacking factor, 235temperature rise, 236-237

standard tests for, 237, 1302typical design, 237-241vibrator transformer design, 1205-1207wire gauges choice of, 236see also under Inductors, iron-cored.

Transformers, practical, 204-206capacitances, 204, 207, 209, 219-227core loss, 204effects of losses, 205-206efficiency, 205equivalent circuit, 204, 205impedance ratio, effect of losses on, 206inductances of windings 204

INDEX 1469

Transformers, practical (continued)leakage inductances, 204, 207, 209, 210,

212, 217-219maximum efficiency, condition for, 205regulation, 205-206regulation, effect of copper loss on, 206relation between copper and iron losses, 205resistances of windings, 204see also Magnetic circuit theory.

Transformers, quarter wave, 892Transformers, radio frequency, 922-925

choke-capacitance coupling, 924grounded-grid stages, 925high-impedance primary, effect on

tracking, 1003mutual inductance coupled, 922-923

coefficient of coupling, 923high-impedance primary, 923low-impedance primary, 922top-capacitance coupling, 923

parallel-tuned circuit, 923-924untuned and pre-tuned, 924-925

Transient current with choke inputfilters, initial, 1185

Transient, definition, 540Transient distortion in a-f amplifiers, 540, 582Transient plate current, peak hot-switch-

ing, 1163, 1180-1181Transient response, effect of damping on

loudspeaker, 833Transient response, oscillatory, in feed-

back amplifiers, 365, 367, 382, 386Transient response, testing feedback am-

plifier for, 366Transient waveform distortion in volume

limiters, 683Transients, 137, 141, 483, 540, 582, 683Transistors, 1138Transit time effects in valves, 47, 50, 51, 69,

930-932, 968, 971, 975, 980, 983, 985, 986Transitional coupling factor, 416, 1031Translation loss, 759, 770Transmission lines, 890-892

characteristic impedance of, 890-891correct termination for, 890-891impedance-transforming action of, 891-892input impedance, 892matching generator to load, section of

line for, 892quarter-wave transformer, 892reflection coefficient, 891standing-wave ratio, 891standing-waves on, 891velocity of propagation along, 891wavelength in cables, 891

Transmission of intelligence, 405-406Transmission units, 826Trapezoid, 273Traps (band elimination filters), de-

finition, 172Treble attenuation, 655-658

by constant k filter, 657by M-derived filter, 657by multiple channels, 739-740by negative feedback, 657-658, 746-751,

1235, 1237, 1238by parallel-T network, 176, 657, 675-676,

737, 738, 746-751by RC network, 660-661by shunt capacitance, 174-176, 655-656,

660, 661-662by step-type control, 660-661de-emphasis for record reproduction,

736-737, 744-751distortion with, 636-637scratch filter for record reproduction,

214, 636, 655-658, 737-738, 746-751, 763whistle filters, 673-676

Treble boosting, general, 653-655automatic frequency-compensated tone

control—see under Tone compensa-tion.

by feedback, 379, 655, 667, 669-670, 672,1235-1237

by inductance in grid circuit, 654by multiple channels, 739-740

Treble boosting (continued)by network incorporating inductors, 661-662by RC network, 660-661, 664by resonant circuits, 654, 666-667by step-type control, 660-661distortion with, 606, 637equalization of side-band cutting, 654methods not involving resonance or

feedback. 653-654, 660-661, 664conventional (RC) circuit, 653-654

Treble, definition, 1403Triangle, angles of, 272Triangles, 272-273Trigometrical operator, 286, 287Trigometrical relationships, 271-272, 275-278

angles of any magnitude, 276approximations in, 271-272, 278

Trigometrical series, 269Trigometrical tables, 1420

hyperbolic tables, 1421Trimmer condensers, 197, 1356Triode amplification factor of pentodes, 35-36Triode characteristics, specific, tests for, 101-108Triode, dissipation of resistance-loaded, 26Triode, dynamic characteristics of,

25-26, 72, 491Triode gm of pentode, 34Triode-heptode, 8, 963Triode-hexode, 8, 963Triode operation, connection of sup-

pressor grid, 36Triode operation of pentodes, 34-36, 547,

785, 7876AU6 pentode with screen as anode, 785, 787

Triode operation of power pentodes, 547Triode operation of power pentodes,

partial, 570Triode-pentode, 8Triode plate resistance of pentode, 36Triodes, 7Triodes, characteristics at low plate

currents, 65Triodes, crystal, 1138Triodes, general purpose, 482Triodes, high mu, 482Triodes, matching of load resistance with, 61Triodes, matching to loudspeaker, 881Triodes, power amplifier, 7Triodes, power, figure of merit for, 61Triodes, push-pull, Class A, AB1, 571-582Triodes, remote cut-off, in volume ex-

panders, 689Triodes, r.c. coupled, 482-495

comments on tabulated characteristics, 495equivalent circuit, exact, 494gain/frequency characteristic, 494-495maximum output voltage and distortion,

491-493phase shift/frequency characteristic,

494-495Triodes, single, Class A, 548-560

optimum operating conditions, 555-558Triodes, twin, 8Trip mechanisms in record changers, 705-706Triple system loudspeakers, 860-861

integral, 860Tropic proofing, commercial, 1282-1283Tropic proofing of coils, 476-478Tuned circuit, parallel, impedance of, 149-152Tuned circuit, parallel resonance de-

termined by maximum impedance, 151-152Tuned circuit, parallel resonance de-

termined by unity power factor, 150Tuned circuit, series (series resonance),

145, 409, 412, 424Tuned circuits, 407-428, 947-948, 1034-1035

coupling of, 418-421, 1022-1050complex (mixed) coupling, 420-421high impedance (top) coupling, 418i-f transformers, 1022-1050link coupling, 418, 419low impedance (bottom) coupling,

418, 419mutual inductive coupling, 418, 419

1470 INDEX

Tuned circuits (continued)in cascade, identical, gain and selec-

tivity of, 421in tone control, damping of, 639references, 427-428single, 407-413, 416-417, 421-428, 947-948,

1034-1035summary of formulae, 423-426

Tuned grid oscillator, 950-951, 952Tuned plate oscillator, 949-950, 951, 952, 994Tuning indicators, 1132-1136, 1139

electron ray type (" Magic Eye ") 1132-1136for F-M receivers, 1135-1136miscellaneous methods, 1132null pint indicator using, 1134-1135references, 1139shunting of detector diode by, 1074wide angle tuning with, 1134

Tuning methods in radio receivers, 913gang capacitor tuned, 912-925

difficulties with, 913inductance (permeability) tuned, 461-462,

912, 913, 953, 1002, 1289push-button, 1151, 1260

Tuning test of receivers, 1312, 1319Tuning, permeability, 461-462, 912, 913, 953,

1002, 1289Turnover voltage in germanium detectors,

1136, 1137Turntable and driving mechanism, 705Turntable unit, specification for, 705Tweeters, 832, 860-861Twist drill sizes, 1392Typical operating conditions for valves, 80

UUltimate attenuation, 174, 359-364, 637"Ultra-linear" operation of pentodes, 570, 587Ultrasonic, definition, 1403Ultrasonic frequencies, recording of, 704Ultraviolet light, wavelengths of, 404, 1363Under-coupled i-f transformers, 1035-1037Undistorted output, maximum, 1298, 1306,

1315, 1318Unidirectional current, definition, 1403Unidirectional microphones, 780Unilateral elements, 159Unit impulse for testing loudspeaker

transients, 870Units, 1329-1334

electrical and magnetic units, 1331-1333absolute c.g.s. electrostatic system, 1331,

1332absolute c.g.s. electromagnetic

system, 1331, 1332absolute m.k.s. (Giorgi) system, 1331, 1332absolute system, definition, 1331practical systems, 1331, 1332rationalized systems, 1331, 1332relationships between, 1333unrationalized systems, 1331, 1332

photometric units, 1334physical units, general, 1329-1330temperature, 1334

Unity, definition, 1403Universal coils, gear ratios for, 456-457Universal coils, inductance of, 444Unrationalized systems of units, 1331, 1332Unstable oscillation, 958-959Untuned r-f stages, 924-925

VVacuum, 69, 70Valve, amplification by, 13Valve basing and electrode connections, 69Valve characteristic curves, 15-24

cathode current characteristics of pen-tode, 16-17

cathode loadlines, 29-30characteristics by curve tracer methods,

119-120characteristics by pulse methods, 118-119characteristics, display of, 120

Valve characteristic curves (continued)composite characteristics for push-pull

amplifiers, 574-577, 581constant current curves, 22-23diode curves (detection and a.v.c.), 1075, 1076dynamic characteristic of r.c. pentode,

26-27, 72, 503-506dynamic characteristic of r.c. triode,

25-26, 72, 491elliptical loadlines, 30-34, 64, 213G curves, 23grid current characteristics, 18-21grid loadlines, 20load line, 24, 58maximum plate dissipation curve, 550mutual characteristics, 17-18plate characteristics, pentode, tetrode, 15-17plate characteristics, triode, 15-17plate characteristics, triode connection,

type 807, 1217rectifier, constant current, 1165, 1167-1169rectifier, constant voltage, 1165-1169rectifier, published, use of, 1165-1169screen characteristics, pentode, tetrode, 16-17static characteristics, 71, 72suppressor characteristics, 21-22transfer characteristics, 17with feedback, 390-399

Valve characteristics (Chapter 2), 8, 13-67activation of cathode, 69amplification factor, 13, 72

effective, with feedback, 311, 313, 314,315, 316

graphical determination, 15, 16, 18arcing in rectifier valves, 100calculation of, other than published, 40-42capacitance grid-plate, 7capacitances, interelectrode, 73cathode current, total available average, 73cathode current, total available peak, 73cathode current—see also under Space

current.cathode follower, equivalent charac-

teristics, 318change in operating conditions, effect

of, 42-44characteristic parameters, derived, 72conductance, definition, 14contact potential, general—see under

Contact potential.contact potential (grid-cathode), 18, 20, 39,

69, 70control during manufacture, 85-89conversion factors, 36-40, 57, 493, 511, 568conversion transconductance, defini-

tions and basis of, 14, 109, 964-967distortion in—see under Distortion.drift of characteristics during life,

23-24, 70, 84, 530, 533durchgriff, definition, 14dynamic characteristics of pentode,

26-27, 72, 503-506dynamic characteristics of triode,

25-26, 72, 491effect of heater voltage on characteris-

tics, 24emission, thermionic, 2, 3, 69equivalent electrode voltage, 71figure of merit for r-f amplifier valves, 927filament dissipation and temperature

characteristic, 10, 11filament voltage/current characteristic, 10, 11filaments on a.c. supply, 6functional characteristics, basic, 70-73fundamental physical properties, 69-70gas current, 3, 19, 51gas pressure, 73grid blocking, 21, 84grid circuit resistance, maximum—

see under Grid circuit resistance,maximum.

grid current characteristics, 18-21grid current cross-over point, 19, 20grid current commencement point, 19, 84grid current, maximum negative, typical

values, 101-102

INDEX 1471

Valve characteristics (continued)grid current, negative, 3, 19, 21, 51,

101-102, 484, 488grid current, positive, 18, 21, 51, 484, 489grid current, positive, damping due to, 489grid emission, 3, 5, 20, 21, 51grid input admittance, 49-53

see also Signal grid input admittance.grid input admittance, components of, 51-53grid input admittance, effects of, 917, 927-934grid input capacitance, 49-53grid input capacitance, components of, 51grid input conductance, 49-53, 929-932grid input circuit damping, 20grid input impedance, 49-53, 929grid input inductance, 49-53grid input loading at radio frequencies,

928-934grid input reactance, 49-53grid input resistance, 49-53, 939-940grid input susceptance, 49-53grid temperature, 5grid variational conductance, 20heater dissipation and temperature

characteristic, 10, 11heater/filament voltage, with reduced, 3, 73heater voltage, 3, 10heater voltage/current characteristic, 10, 11inductance of leads and electrodes,

effects of, 46, 50, 51, 53, 930, 931, 932initial electron velocity of emission, 18input capacitance, change in, 927, 928,

932-934input capacitance, effect of space charge

on, 51input capacitances of pentodes, pub-

lished values, 56instability of electrical characteristics, 70insulation between valve electrodes,

69, 70, 73interelectrode admittances, 49-57, 69, 70interelectrode capacitances, effect of,

7, 46, 51, 53, 69interelectrode resistances, 69ionization current, 19leakage current, 19, 20, 51, 69, 70life, ultimate electrical, 70life, working, 3, 70, 121low plate currents, at, 65mathematical relationships, concern-

ing, 57-65maximum negative grid current, typical

values, 101-102, 788microphony, 73, 84, 786, 957-959, 1241-1242mu factor, definition, 14mu factors, interelectrode, 73mutual conductance, definition, 14mutual conductance, graphical deter-

mination, 15, 16, 17noise, 4, 70, 73, 81, 782, 783, 784, 787, 788,

935-942, 967-968, 972-973, 984perveance, definition, 14, 71photo emission, 2plate d.c. resistance, 14plate conductance, definition, 14plate current, 6plate resistance, effective, with feed-

back, 311, 313, 314, 315, 316plate resistance, variational, 13, 14plate resistance, variational, definition, 14, 72plate to screen amplification factor, 35-36poisoning of emission, 2primary emission (other than cathode),

19, 20, 21, 69, 71reduced heater/filament voltage, with, 3, 73references, 66, 125-127resistance of any electrode, definition, 14reverse grid current—see under Negative

grid current.screen to control grid, amplification

factor, 35secondary emission, 2, 7, 8, 21, 39, 69, 71series expansion: valve with resistance

load, 61-62short-circuit admittances, 69short-circuit feedback admittance, 50-55

Valve characteristics (continued)short-circuit forward admittance, 50-55short-circuit input admittance, 50-55short-circuit input capacitance, change

with transconductance, 55short-circuit input conductance, typical

values of, 55short-circuit output admittance, 50-55signal grid input admittance, con-

verter, 970, 973, 976-978, 980-981negative, 977, 985-986

signal grid input conductance, con-verter, 976-978, 980-981, 982, 987-988

negative, 976-978, 985-986signal grid input susceptance, con-

verter, 976-978negative, 976-978

space current, 70sputter in rectifier valves, 100stability of electrical characteristics, 69-70stability of mechanical construction, 69-70static characteristics, 71, 72suppressor characteristics, 21-22transadmittance, oscillator, 968transconductance, definition, 14transconductance, grid-plate, 14, 72

see also Mutual conductance.transconductance, screen, 34transconductance, suppressor-screen,

953-954transit time effects, 47, 50, 51, 69, 930-932,

968, 971, 975, 980, 983, 985, 986triode amplification factor of pentodes, 35-36triode gm of pentodes, 34triode plate resistance of pentode, 36variational resistances, interelectrode, 73voltages, with respect to cathode, 5

Valve coefficients, 13-14, 64-65Valve coefficients as partial differentials, 64-65Valve constants, 13-14Valve electrode supply voltages, 6Valve electrode voltages, datum point

for, 2, 5, 80Valve electrode voltages, definition, 6Valve electrodes supplied through series

resistance, 70Valve equivalent circuits, 45-47, 53-55, 59,

63, 512Valve factors, 13-14Valve gettering, 4, 69, 70Valve networks, general case, 64Valve numbering systems, 10-12Valve pin straightener, 80Valve ratings and limiting effect on

operation, 75-80, 85capacitances, interelectrode, 75characteristics usually rated, 75-77electrode potentials, datum point for, 2, 80general electrical ratings, 75general mechanical ratings, 75grid bias for a.c. or d.c. filament ex-

citation, 6, 80grid voltage limits, 79-80heater or filament voltage, 77, 78, 79heater to cathode voltage, maximum, 75, 81limiting ratings, 75maximum average cathode current, 75maximum electrode dissipations, 75, 1249maximum grid circuit resistance—see

under Grid circuit resistance, maxi-mum.

maximum peak cathode current, 75maximum peak inverse voltage, 75maximum ratings, 9, 75, 77-80maximum ratings, interpretation of, 77-80rating systems, 77-80

absolute maximum system, 9, 77design-centre system, 9, 77-80

ratings for a.c. or d.c. power line opera-tion, 78, 79

ratings for battery filament types, 79-80ratings for dry-cell battery operation, 78, 79ratings for indirectly-heated types, 78-80ratings for rectifiers, 1163-1164ratings for storage battery operation, 78, 79

1472 INDEX

Valve ratings and limiting effect onoperation (continued)

screen voltage supply, 79specific additional electrical ratings

applied to particular types, 76-77tolerances in characteristics, 9, 15, 88typical operating conditions, 80

Valve sockets, connections to, 80, 81Valve test specifications

basic manufacturing test specification, 85characteristics, 75-77, 85, 86

see also under Valve ratings.grid current, negative, typical values, 101-102life test, 75, 85mechanical and electrical tests, 85quality control, 85ratings—see under Valve ratings.

Valve vectors, 47-49Valve wiring jig, 80Valves for use in pre-amplifiers, 786-788Valves, fundamental physical properties

of, 69-70Valves, glass-based, sockets and connec-

tions for, 80, 81Valves, hum due to conditions within,

81, 84, 540, 1196-1198Valves, in magnetic field, hum with,

785, 786, 788, 1198Valves in receiver, position of, 957Valves, low noise types, 786-788Valves, mounting position for, 4, 80Valves, recommended practice and opera-

tion, 80-84Valves, soldering into wiring, 81Valves, stand-by operation of, 84Valves, testing of (Chapter 3), 68-127

acceptance testing, 120admittance, short-circuit feedback, 117admittance, short-circuit forward, 117admittance, short-circuit input, 113-117admittance, short-circuit output, 117amplification, a.c., 74, 105, 124amplification factor, 74, 104, 113back emission, 74, 100basis of testing practice, 68, 84beam tetrode characteristics, specific, 101-108blocking, 107-108, 113capacitances, interelectrode, tests for,

73, 95-99characteristics by curve tracer methods,

119-120characteristics by display, 120characteristics by pulse methods, 118-119control of characteristics during manu-

facture, 85-89conversion stage gain, 74conversion transconductance (mixer),

74, 109-111, 124converter characteristics, specific, 108-113

methods of operation, 108-109oscillator driven, 109oscillator self-excited, 108-109static operation, 109

dimensions, physical, 91diode characteristics, specific, 99-101diode plate current, zero signal, 100display of valve characteristics, 120dissipation of electrodes, 108distortion in power amplifier valve, 106-107electrode continuity, 73, 91-93, 123emission, 73, 94-95, 123emission-dependent dynamic test, 73filament voltages, lowest used for testing

battery valves, 1313fundamental characteristic tests, 73-75fundamental physical properties, 69-70gas current, 101, 102grid current, commencement voltage,

test for, 73, 102, 109grid current, negative (reverse)

tests for, 73, 101-102, 109, 124typical maximum values in new

valves, 101-102grid current, positive, tests for, 73, 102grid emission (primary), 101, 102grid emission (secondary), 102

Valves, testing of (continued)grid leakage current, hot and cold, 101, 102heater or filament current, 93-94heater to cathode leakage, 73, 94, 123hexaphase shorts and continuity test, 91-93interelectrode insulation resistance,

73, 94, 102life test end points, 88-89life tests, 75, 85, 87-88methods of testing characteristics, 89-120

general conventions, 90-91microphony, 74, 107, 113, 121mixers (frequency changers), 109-113

mixer conversion transconductance,74, 109-111, 124

mixer plate resistance, 111mixer transconductance, 111

mutual conductance (transconductancegrid-plate), 74, 103-104, 113, 123, 124

noise, valve, 74, 107, 113, 124open-circuited electrodes, 73, 91-93, 123oscillator characteristics, 113oscillator grid current, 74, 111-112oscillator performance, 111-112oscillator transconductance, 74pentode characteristics, specific, 101-108perveance of diode, 117-118perveance of triode, 118physical dimensions, 91plate conductance, 124plate current commencement, 74plate resistance, 74, 104-105, 111, 113positive voltage electrode currents,

103, 109, 113power output, 74, 105-106, 124power output, Class B amplifier 106preheating before testing, 91, 101, 125rectification (operation) power diodes,

74, 99-100rectification, signal diodes, 100reduced heater voltage, dynamic tests

at, 74-75references, 125-127service testers, a.c. versus d.c. test

voltages, 124service testers, characteristics which

should be tested, 122service testers, methods of testing in, 123-125service testers, types of commercial 122-123service testing and service tester prac-

tice, 121-125short-circuits, interelectrode, 73, 91-93, 123special characteristics, 113-118stage gain, 74, 108statistical sampling, 86systematic testing, 86-88

design tests, 87life tests, 87-88, 88-89production tests, 86-88recorded readings, 87warehouse tests, 88

transconductance, grid-plate (mutualconductance), 74, 103-104, 113, 123, 124

triode, pentode and beam tetrodecharacteristics, specific, 101-108

Valves, types ofbeam power valves, 8combined valves, 8component parts of, 4-6diodes, 6-7heptodes, 8-9hexodes, 9introduction to, references, 12kinkless tetrodes, 8low noise, 786-788pentagrid converters, 8, 963pentodes, 7-8tetrodes, 7triode-heptode, 8, 963triode-hexode, 8, 963triode-pentode, 8triodes, 7twin triodes, 8vacuum, types of, 4, 6-9

Valves, when to replace, 121

INDEX 1473

Variable composition resistors, character-istics of, 191, 1356

Variable, definition, 1403Variable, dependent, 279Variable, independent, 279Variable-mu pentodes—see under Pen-

todes, remote cut-off.Variable selectivity i-f amplifiers, 1048-1050Variables in algebra, 265Variables, three, graphical representation, 281Variation (in algebra), 262Variation, oscillator frequency, causes of,

950, 955-956due to supply voltage changes, 949, 953, 955

Variational, definition, 1403Variational grid resistance, minimum,

Class B2, 590Vector, definition, 1403Vector diagram, 138, 143Vector quantities, 139, 140, 285-287Vectors, addition and subtraction, 282Vectors and j notation, 282-284Vectors, complex algebra with polar co-

ordinates, 286-287Vectors, complex algebra with rectangular

coordinates, 285-286Vectors, components of, polar, 283Vectors, components of, rectangular, 283Vectors, conversion from complex to polar,

283, 287Vectors, exponential form, 287Vectors, multiplication of, 282Vectors, negative, 282Vectors, radius, 283Vectors, rotating (j notation), 283-284Vectors, scalar product of two, 282Vectors, valve, 47-49Velocities, recorded, measurement of, 729Velocity, angular, 278Velocity, critical, in recording, 704, 708Velocity of electromagnetic radiation,

424, 1376, 1396Velocity of emission, initial electron, 18Velocity of propagation along transmission

lines, 891Velocity of propagation of a wave, 403Velocity of sound, 872Velocity of stylus tip, transverge, 702-703Velocity operated microphones, 775Velocity recording, constant, 703-704, 727Velocity, reference acoustical, 826Velocity ribbon microphones, 775, 779Velocity trip in record changers, 705-706Vented baffle loudspeaker, 845-850, 1489Ventilation of equipment, 81, 1249Versine of an angle, 278Vertical aerials, 892, 893, 895, 896, 901, 904,

907, 909-910Vertical and horizontal aerials, com-

parison between, 895, 896Vertical, recording, 701Very small compared with, definition, 1403Vibration of valves, 70, 81Vibration of walls, effects of, 864Vibrator power supplies (Chapter 32),

1202-1212basic types, 1202-1203

interrupter (non-synchronous), 1202-1203reversible self rectifying, 1203-1204self-rectifying (synchronous), 1203, 1204split-reed synchronous, 1204

choice of vibrator, 1203-1204coil energizing, 1204

separate driver system, 1204shunt coil energizing, 1204

general principles, 1202-1205hash elimination, 1210-1211, 1270-1272,

1275-1276on (and off) contact time, 1205operation, 1202references, 1212standards for vibrators for auto radio, 1205standards for vibrator power trans-

formers, 1207time efficiency, 1205

Vibrator power supplies (continued)timing capacitance, 1207-1209

calculation of timing capacitance,1207-1208

effect of flux density on capacitance,1208-1209

percentage closure, 1208typical vibrator power supply circuit, 1211vibrator interference, elimination of,

1210-1211vibrator-powered receivers, design of,

1270-1272vibrator transformer design, 1205-1207waveform and time efficiency, 120512, 24 and 32 volt vibrator supplies,

1211-1212Vinyl discs, characteristics of, 705, 706-709,

769-771Virtual cathode, 3, 70, 71, 973, 978, 986Voice coil, definition, 1403Voice coil impedance for radio receivers,

loudspeaker standard, 874Voice coil impedance for sound equip-

ment, loudspeaker standard, 883Volt, 1332, 1333Volt-amperes, reactive, 144Voltage, absolute, expressed in decibels, 808Voltage amplifiers, a-f (Chapter 12), 481-543

see also under Amplifiers, a-f, voltage.Voltage and current, 128-130Voltage divider, screen supply of r.c.c.

pentode from, 506Voltage dividers—see under Potential

dividers.Voltage doubler, 1174, 1175, 1178, 1186-1187Voltage, effect on resistance of composi-

tion resistor, 188, 1345Voltage expressed in decibels (dbv), 776, 808Voltage feedbacks—see under Feedback.Voltage indicators, peak reading, 119Voltage multplying rectifiers, 1186-1188Voltage quadrupler, 1187-1188Voltage regulator valve to give good

oscillator frequency stability, 955Voltage regulators, 1214-1222

gaseous tube types, 1214-1215valve types, 1215-1222

as plate supplies for a-f amplifiers, 537Voltage tripler, 1187Voltmeters, method of determining no

load voltage, 163-164Volume compression and limiting,

679-681, 681-684compression characteristics, 682, 684compression of commercial speech, 684distortion caused by peak limiters or

volume limiters, 681, 683introduction, 679-681noise peak and output limiters, 694-699

instantaneous noise peak limiters, 694-698output limiters, 698-699

peak limiters, 679, 682-683peak limiters, definition, 681public address audio a.v.c., 693references, 699-700speech clippers, 693-694volume compression, 679, 683-684volume compression plus limiting, 684volume compressors, definition, 681volume limiters, 683volume limiters, definition, 681

Volume controls, 794characteristics of potentiometers, 191, 1356

Volume effect, minimum, in reflex re-ceivers, 1141, 1142

Volume expansion, compression and limit-ing (Chapter 16), 679-700

compression, 679-681, 681-684see also under Volume compression.

distortion in, 681, 683effect on noise, 679, 763gain control devices, 684-686

lamps, 685negative feedback, 685pentagrids and triode hexodes, 685pentodes, remote cut-off, 684plate resistance control, 685suppressor-grid control, 686

1474 INDEX

Volume expansion, compression andlimiting (continued)

general principles, 679-681ideal system, 680limitations of, 679-680references, 699-700volume expanders, 686-692

desirable characteristics, 686electronic methods, two groups of, 686incorporating feedback, 688incorporating lamps, 687-688

lamp-controlled feedback, 688incorporating plate resistance control,

692-693incorporating remote cut-off pen-

todes, 688-689incorporating remote cut-off triodes, 689incorporating suppressor-grid con-

trolled pentodes, 689-690incorporating valves with five grids,

691-692tone control, relative position of, 686

volume expansion, 679effect on background noise, 679practical problems, 680-681

Volume indicators, 823-824see also under Volume units.

Volume level and peak acoustical power,difference between, 623

Volume levels, preferred listening, 623Volume range and hearing, 620-621

see also Dynamic range.Volume range broadcast or recorded, 624Volume range in musical reproduction, 623-624Volume range of sound reproducer, maxi-

mum, 679Volume units, 776, 824

reference volume, 824see also under Volume indicators.vu, 823, 824

Volume, units of, 1329vu, 823, 824

W

Warping, effect of record, 760-761Watt, measure of power, 1332, 1333Watt-second, 133Wattless power, 144Wave analyser, 1299Wave antenna, 908Wave motion, 403-404Wave propagation, electromagnetic, 404, 901Wave, sky (space), 404, 896, 897Wave, surface, 896, 897Wave tilt, 908Waveform, cosine, 278Waveform of vibrator, 1205Waveform, pulse, 130, 302Waveform, rectified sine, 130, 302Waveform, saw-tooth, 130, 301Waveform, sine, 129, 130, 278Waveform, sine, distorted, 130Waveform, square, 130, 301, 870, 1324Waveform, standard a.c., 130Wavelength, 403Wavelength-frequency conversion table, 1362Wavelength in cables. 891

Wavelength vs. frequency for recordmodulation, 708

Wavelength vs. frequency on records, 708Wavelengths of electromagnetic radia-

tion, 404, 424, 1363Waves, cosmic radiation, wavelengths of

404, 1363Waves, electromagnetic, introduction to,

403-404Waves, gamma rays, wavelengths of, 404, 1363Waves, Hertzian, wavelengths of, 404Waves, light, wavelengths of, 404, 1363Waves, longitudinal, 403Waves, sound, 403Waves, transverse, 403, 404Waves, water, 403Waves, X rays, wavelengths of, 404, 1363Wear, record, 706, 712-713, 723, 769Wear, stylus, method for giving positive

indication of, 714Wear, stylus, sapphire, 713-714Weber, 1332, 1333Weber per square metre, 1332, 1333Weights of common materials, 1375Wheeler networks, 368, 377Wheeler's formula for inductance of short

coils, 443Wheeler's formula for inductance of

solenoid, 432Whistle filters, 673-676Whistle, heterodyne, 1303Whistle interference, 954Whistle interference in A-M receivers,

tests for, 1304-1305Whistles, tests for, 1304, 1305White noise, 619Whitworth screw threads, 1389Wide angle tuning with electron ray

tuning indicator, 1134Williamson amplifier, new, 745-751

A515 version, 346-347output transformer specifications, new, 748output transformer specifications, ori-

ginal 346-347Windings of a-f transformers, mixing, 221-223Windings of a-f transformers, random, 223-227Windings of i-f transformers, direction of, 458Wire tables, 1408-1417

bare copper, 1408-1411insulated copper, 1410-1413, 1416, 1417resistance wire, 1414-1415

Wirewound resistors, characteristics of,186, 1346-1347

Wiring, chassis, colour code, 1343-1344Wiring jig, valve, 80Wood screws, 1391Work function, definition, 1403Work, units of, 1332Wow, 626, 705, 760, 1312

XX rays, wavelengths of, 404, 1363

ZZero signal, definition, 1403Zero temperature, absolute, 1334

Radiotron Designer's Handbook

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