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This Volume is for REFERENCE USE ONLY

2529(1 1

RADIO BROADCAST

VOLUME XIV

NOVEMBER, 1928, to APRIL, 1929

GARDEN CITY NEW YORK

DOUBLEDAY, DORAN & COMPANY, INC.

1929

V3.&$@i 1 f?i ^-:>:

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INDEX

(*Illustrated Articles. Editorials in Italics)

PAGE

* A AND B Power from the D. C. Lines

r\. (William B. Dall) 34

*A-Power Unit, The Improved Knapp. 43

Aircraft Radio 18, 234

Aircraft Radio, Progress in the Field of. 93 *A11 About the Dynamic Loud Speaker

(Joseph Morgan) 159

Allocation Plan, WGY's Attack on the. . . 163 Allocation Plan, WGY Protests New. ... 92 Allocation Repairs the Broadcast Struc- ture, New 16

Allocations Attempted, Regulation of. . . . 373 Allocations, Fitting Receivers to the New. 234 "A. C. Band-Pass Screen-Grid Receiver, An— The Master "Hi-Q 29" (William

E. Barton) 117

*A. C. Operated Tube Tester, A Simple

(The Laboratory Staff) 173

*A. C. Screen-Grid Browning-Drake Re- ceiver, The New (Glenn H. Browning) 115 *A. C. Tubes. The "Chronophase" for

(Bert E. Smith) 126

Amateur and Commercial Radio 374

*Amplifier and Power Supply for the

"Vivetone 29," An (R. F. Goodwin). 45 Amusement Industries, Radio May Yet

Become the Cornerstone of 91

*Apparatus, New 52

* Apparatus and Its Applications, New

127, 194

*Are Filters Needed in A. F. Amplifiers? (Keith Henney) 250

*Armchair Chats on Short- Wave Sub- jects (Robert S. Kruse) 189

*As the Broadcaster Sees It (Carl Dreher) 32, 102, 185

*Audio Oscillator, An Inexpensive . (Edward Stanko) 186

*Audio System of Dynamic Speaker Reproduction, A New (Frank C. Jones) 29

*Automatic Volume Control System. New (Charles Williamson) 299

Aviation, A New Radio Service to 297

*TD POWER from the D. C. Lines, A

JD and (William B. Dall)

'Band-Pass Filters, Some Experiments

with (Kendall Clough) 104

*Band-Pass Screen-Grid Receiver, An A. C.— The Master "Hi-Q 29" (Wil- liam E. Barton) 117

'Battery-Operated Receiver, An Eco- nomical (Howard E. Rhodes) 257

Book Reviews:

Advertising by Radio, by Orrin E. Dunlap, Jr. (Edgar H.

Felix) ... 388

B. B. C. Handbook, The 1929, by The British Broadcasting Corporation (Carl Dreher).. 252 Laboratory Treatise on B Bat- tery Eliminator Design and Construction, A (Howard E.

Rhodes) 125

Practical Radio, by James A. Moyer and John F. Wostrel

(Carl Dreher) 162

Practical Television, by E. T. Larner (Carl Dreln 354

34

PAGE

Radio, by Elmer E. Burns

(Carl Dreher) 252

Treatise on 25 Testing Units for Service Men, A (Howard

E.Rhodes) 116

*Broadcast Engineering (Carl Dreher)

246, 311, 402

Broadcasting, In the World of 297, 373

Broadcasting Increases, Commercial .... 18

Broadcasting Stations, Mexican 358

Broadcasting Stations, With the. .93, 164, 235 "Browning-Drake Receiver, A Loop- Operated (J. H. Gockel) 171

*Browning-Drake Receiver, The New A. C. Screen-Grid (Glenn H. Brown- ing) 115

*Building Receivers for Television (Zeh

Bouck and James Millen) 35

*Business Side of Radio Servicing, The (John S. Dunham) 236

CHARACTERISTICS of Power

V^ Rectifiers (Roger Wise) 393

"Chart for Making DX Measurements,

A (James B. Friauf) 188

*"Chronophase" for A. C. Tubes, The

(Bert E. Smith) 126

*" Chronophase" Screen-Grid Receiver,

The (Bert E. Smith) 49

Commercial Broadcasting Increases 18

Commerical Radio Telegraphy and Tele- phony 165

Commissioner Robinson Stands Firm . . 163 "Condenser Type Loud Speaker, The

(Joseph Morgan) 369

Congress Considers the Commission's

Record 372

"Crystals, Quartz (R. C. Hitchcock) ... 85 "Cuban Short- Wave Receiver, A (Frank

H. Jones) 313

"TAX Measurements, A Chart for

LJ Making (James B. Friauf) .... 188 Davis-Dill Publicity Barrage Begins, The 233

Decisions of the Courts 236

"Double-Detection Short-Wave Set, A

(Robert S. Kruse) 309

"Dynamic Loud Speaker, All About the

(Joseph Morgan) 159

"Dynamic Speaker Reproduction, A

New Audio System for (Frank C.

Jones) 29

"Dynamic Speakers, Measurements on

(Frank C. Jones) 316

* T? CONOMICAL Battery-Operated •L-' Receiver, An (Howard E.

Rhodes) 257

"Efficient Push-Pull A. F. System, An

(Kendall Clough) 241

"Examination for Radio Servicemen, An

(J. B. V. Meacham) 405

"Experimenter's Armchair, The (Robert

S. Kruse) 380

LTEDERAL Radio Commission, A

r Well-Balanced .. 372

"Fellows of the Institufcou^he (Carl

Dreherj *»*uj^uj 51

"Few Radio Questions yfrSWreH, A .... 166

PAGE

Fight for Short- Wave Allocations, The ... 92 "Figure in Radio Progress, A (Edgar H.

Felix) 227

"Filters Needed in A. F. Amplifier? Are

(Keith Henney) 250

Fitting Receivers to the New Allocations . . 234

Frequency Control, More Discussion on. 373

"f^RID-LEAK, Grid-Condenser De- VJ tection (Frederick EmmonsTer- 303

man)

"Grid-Leak Power Detection (Frederick Emmons Terman) 382

I-fERE and There 18

-f 1 High-Frequency Allocations 297

"High-Power Output Tube, A (K. S.

Weaver) 329

"High-Voltage Metallic Rectifiers for B-Power Units, New (J. George

Uzmann) 120

"Home Study Sheets, "Radio Broad- cast's":

Alternating Current, Pt. Ill 28 Calibrating a Radio Wave- meter 183

Effects of an Electric Current,

The 27

Experiments with a Wave- meter 254

Fundamental Radio Theory . . 397

Inductance Standards 398

Plotting Curves 307

Plotting Power Tube Charac- teristics 184

Resonance in Radio Circuits.

Pt. 1 107

Resonance in Radio Circuits,

Pt. II 108

Transmission Unit, The 253

"IMPORTANCE of Impedance Rela-

1 tions (C. T. Burke) 322

"Improved Knapp A-Power Unit, The. 43 *In the Radio Marketplace ....267, 331, 406

In the Visual Broadcasting Field 94

In the World of Broadcasting 298, 373

"Inexpensive Audio " Oscillator, An

(Edward Stanko) 186

"Isotone Screen-Grid "Super," The

(Dudley Walford) 174

*T7"NAPP A-Power Unit, The Im-

43

proved

*T ABORATORY Information Sheets, t-^ "Radio Broadcast's":

Advantages of Dual Push Pull 276

Alternating-Current Ratings. . 132

A. C. Tubes 206

Analysis of Filter Circuits, An 274

Audio Amplifiers 204

Audio Transformer, The 56

Balancing Radio Receivers ... 56

Band-Pass Circuits 206

Bucking Coils in Dynamic

Loud Speakers 112

Circuit for Short-Wave and

Broadcast Reception 60

Effect of Room Acoustics. . 346

634466

1 '2i

INDEX— Continued

PAGE

Electrifying Battery-Operated

Sets 346

Filter Circuit Characteristics. 274 Formulas for Power Output . . 352 Frequency Characteristics of Television Amplifier Devel- oped by. the Bell Telephone

Laboratories 134

Heater Connections for A. C.

Tubes 272

Hook-Up for Short-Wave and

Broadcast Receivers, A .... 60 Importance of Bass Notes .... 348 Importance of Correct Fila- ment Voltages 354

Mathematics of the Tuned

Circuit 348

Moving-Coil Loud Speakers . 58, 204 Neutralizing and C^u Bat- ing R. F. Circuits . . ." 412

Obtaining Grid Bias frqm B-

Power Units 414

Power in Broadcasting Har- monics 348

Power Output 58, 132. 206

Power Output Characteristics

of Vacuum Tubes 132

Resistance-Coupled Amplifiers

130, 132, 202

Shielding 204

Simple Two-Way Telephone

Set 414

Supplying Power Devices from

220 Volts A. C 130

Television 58, 60, 134

Test for a Faulty Push-Pull

Amplifier 352

Three Types of Graphs 272

Voltage Gain in Resistance- Coupled Amplifiers 274

Wavelength-Kilocycle Chart . . 276 Where A. C. Hum Originates. . 276 'Laboratory, "Strays" from the (Keith Henney):

Accuracy of the "Slide-Back"

Voltmeter 97

Accuracy of Variable Con- densers 240, 301

Approved Amateur Intermedi- ates 378

Cause of Winter Static 377

Correction, A 378

Dynamic Vs Magnetic Speak- ers 23

Empirical Rules and Formulas 170 Experiments With the Pentode 377 "Gyps" Are Still At It, The. . 24 How Long Will the Engineers'

Job Last? 240

How Much Output Power Is

Needed? 169

How to Stabilize Rice Ampli- fiers 24

How Useful Is a Tube? 240

Hum in the "Lab" Circuit

Receiver 97

Impedance of Standard Loud

Speakers 240

Importance of Reducing A. C.

Hum 301

Is a 112 Tube Needed in the

First Stage? 98

League of Nations to Broad- cast 301

Life of A. C. Radio Tubes .... 378 More Data on Underground

Aerials 98

New High Voltage Rectifier

Tube 240

New Precision in Quartz Plates 24 New Radio Tubes in England 301 New Radio Tubes Needed. ... 24 New Regulations of Radio

Commission 240

New Trends in Radio Design 300

Novel Dynamic Baffle 378

Obtaining C Bias for A. F.

Amplifiers 169

Output Vs Voltage Amplifica- tion . . 377

PAGE 1 ' Phantom ' ' Power Tubes .... 378

Portable Radio Sets 24

Power of Station Harmonics. . 239 Present Designs Do Not Con- sider Economy 23

Rated Voltages Should Be Ap- plied to Tubes 239

Receiving on 600 Meters with

Lab. Set 301

Regarding Power, Efficiency

and Energy 239

Regarding Series-Filament

Operation 23

Removing Noise in Shielded

Receher 301

Selectivity in the Browning- Drake Set 301

Seven New Radio Booklets. . . 24 Some Interesting Formulas . . . 169 Task of Editing Radio Copy,

The 170

Test for Screen-Grid R. F.

Tubes, A 240

Three New Pamphlets Availa- ble 239

Two New A. C. Tubes on the

Way 300

Underground Aerials 24

Vacuum Tubes as Fuses 377

What Is a Dynamic Speaker? 169

Letters from Readers 137, 354

""Loop-Operated Browning-Drake Re- ceiver. A (J. H. Gockel) 171

*Loud Speaker, The Condenser Type

(Joseph Morgan) 369

*Loud Speakers— A JDebate 109

*]\ /TANUFACTURED Receivers, 1VJ. "Radio Broadcast's" Service

Data Sheets on (See Set Data Sheets)

41, 121, 177, 265, 327, 304 Manufacturers' Booklets

56, 128, 199, 270, 334 *March of Radio, The (E. H. F.)

16, 91. 163, 233, 296, 372 Market, The Real Size of the Radio ... 379 *Marketplace, In the Radio. . . .267, 331, 406 *Measurements on Broadcast Receivers

(L. M. Hull) 230

*Measurements on Dynamic Speakers

(Frank C. Jones) 316

*Measuring a Receiver's Performance

(Kenneth W. Jaryis) 167

Mexican Broadcasting Stations 358

Milestone in Television, A 17

*Modulator for the 1929 Short-Wave

Transmitter, A (Robert S. Kruse) ... 38 *More Data on the Sargent-Rayment

(Howard Barclay; 197

More Discussion on Frequency Control. 373 *Multiple-Receiver Antenna System, A

(V. D. Landon) 291

ATEED for Defining Television Prac-

1\ tices 18

New Allocation Repairs the Broadcast

Structure 16

*New A. C. Screen-Grid, Browning- Drake Receiver, The (Glenn H. Browning) 115

*New Apparatus 52

*New Apparatus and Its Applications

127, 194

*New Audio System for Dynamic Speaker Reproduction, A (Frank C. Jones; 29

*New Automatic Volume Control Sys- tem (Charles Williamson) 299

*New High- Voltage Metallic Rectifiers for B-Power Units (J. George Uz- mann) 120

New Nation-wide Picture Transmission Service 18

New Radio Service to Aviation, A 297

*New Trends in Radio Designs for 1929- 30 (Keith Henney) 14

*New Uses for Power Amplifiers (Fred H. Canfield) 367

News of the Radio Industry 94, 236

Newspaper Has Radio Picture Transmitter 18

PAGE

* /^ORGANIZATION, An Unusual W (Robert S. Kruse) 302

*"Our Readers Suggest ..."

47, 114, 192, 260, 324

*Phonograph-Radio Amplifiers (How- ard E. Rhodes) 88

Picture Transmission Service. l\eiv Na- tion-wide 18

Picture Transmitter, Neuispjpzr Has Radio 18

*Power Amplifiers, New Uses for (Fred H. Canfield) 367

*Power Rectifiers, Characteristics of (Roger Wise) 393

*Power Supply for the "Vivetone 29," An Amplifier and (R. F. Goodwin) . . 45

*Practical Radio Service Records (John S. Dunham) 392

*Problems in Synchronizing Television Receiving Discs (Boyd Phelps> 123

*Production Testing with Oscillators (Richard F. Shea) 387

Program Possibilities May Open New Radio Market, A Study of 296

Progress in Short and Long Wave Radio 235

Progress in the Field of Aircraft Radio . . 93

*Push-Pull A. F. System, An Efficient (Kendall Clough) 241

VARTZ Crystals (R. C. Hitch-

cock) 85

*Questions Answered, A Few Radio. . . . 166

J~>ACE for Television Publicity, The 17

-A. Radio Abroad 94

*" Radio Broadcast's" Home Study Sheets (Keith Henney) (See Home)

27, 107, 183. 253, 307, 397 ""Radio Broadcast's" Laboratory In- formation Sheets (Howard E. Rhodes) (See Laboratory)

56, 130, 202, 272, 346, 412 ""Radio Broadcast's" Service Data Sheets on Manufactured Receivers

(See Sets) 41, 121, 177, 265

*" Radio Broadcast's" Set Data Sheets

(See Sets) 327,403

*Radio Design for 1929-30. New Trends

in (Keith Henney) 14

Radio in Foreign Countries 19

Radio Industry, News of the 94

Radio Manufacturers, With the 165

Radio May Become the Cornerstone of the

Amusement Industries 91

Radio Picture Transmitter, Newspaper

Has .... 18

*Radio Service Records, Practical (John

S. Dunham) 375

Radio Service to Aviation, A New 297

*Radio Servicing, The Business Side of

(John S. Dunham) 236

Real Size of the Radio Market. The ... 379 *Real Versus Apparent Selectivity

(Kenneth W. Jarvis) 399

Reasons for the 300-Mile Chain Regu- lation 92

Regenerative Decision, The 164

Regulation of Allocations Attempted .... 373 *Removing Nonsense from Short-Wave

Transmission (Robert S. Kruse) Ill

*Routine of Testing Receivers, The (John S. Dunham) 375

•OARGENT-RAYMENT, More Data O on the (Howard Barclay) 197

Schedule of the Best Short- Wave Programs 298

Schedule of Broadcast Television Trans- missions 234

*Screen-Grid Browning-Drake, The New A. C. (Glenn H. Browning) 115

*Screen-Grid Receiver, An A. C. Band- Pass— The Master "Hi-Q 29" (Wil- liam E. Barton) 117

*Screen-Grid Receiver, The "Chron- ophase" (Bert E. Smith) 49

*Selectivity, Real Versus Apparent (Kenneth W. Jarvis) 399

*Service Data Sheets on Manufactured Receivers, "Radio Broadcast's" (See Set Data Sheets) 41, 121, 177, 265

INDEX— Continued

PAGE

*Service Man Should Study, What the

(John S. Dunham) . . . . , 294

*Serviceman's Comer. The

101, 181, 255, 319, 389 *Servicing Home-Made Radio Receivers

(B. B. Alcom 179

'Servicing. The Business Side of Radio

(John S. Dunham i 236

Set Data Sheets. " Radio Broadcast's": A. C.-66 Dayton Receiver.

The 121

Bosch Model 28 Receiver, The 404 Bremer-Tully 8-20 Receiver,

The 177

Browning-Drake Receiver.

The 266

Croslev Model 704-B Receiver,

The" 328

Crosley Model 705 Receiver,

The 328

Day-Fan 8-AC Power Set, The 403 Fada 50. 70, 71, 72 A. C. Elec- tric Radio Receivers, The . . 122 Federal Type D (60 Cycle) Re- ceiver 327

Freed-Eisemann Model NR-80 42 Freshman Model "G" Re- ceivers 41

Freshman Model Q Receiver. 178 Freshman Model 2N-12 Re- ceiver, The 403

King Model H. Receiver, The 404 Majestic Model 70-B Receiver,

The 328

Philco Electric Receiver. The. 265 Short-Wave Allocations, The Fight for . . 92

Short- Wave List 358

*Short-\Vave Receiver, A Two-Tube T. R. F. (William Bostwick and W. T.

Thomas) 20

Short-Wave Stations 141

'Short-Wave Subjects, Armchair Chats

(Robert S. Krusei 188

'Short-Wave Superheterodyne, A

(Robert S. Kruse) 262

Short-Wave Transmission. Removing

Nonsense from i Robert S. Kruse) . . . Ill 'Short-Wave Transmitter, A Modulator

for the 1929 < Robert S. Kruse) 38

'Simple A. C. Operated Tube Tester, A

(The Laboratory Staff) 173

'"Skyscraper" Screen-Grid Receiver,

The (Clifford Dentoni 95

'Some Experiments with Band-Pass

Filters (Kendall Clough) 104

'Sound Motion Pictures (Carl Dreher)

32, 102, 182, 244, 314, 385 '"Strays" from the Laboratory (See

Laboratory) 23, 97, 169, 239, 300, 377

Study of Program Possibilities May

Open New Radio Markets, A 296

'Synchronizing Television Receiving Discs, Problems in (Boyd Phelps) ... 123

T*ABLE of Wavelength Allocations . . 323

J. Television. A Milestone in 17

'Television Abroad? What Prospects of

(Lawrence W. Corbett) 11

'Television, Building Receivers for (Zeh

Bouck and James Millen) 35

Television Practices, Need for Defining . . 18

Television Publicity, The Race for 17

'Television Receiving Discs, Problems

in Synchronizing (Boyd Phelps) 123

PAGE

Telecision Transmissions 17

Television Transmissions, Schedule of

Broadcast 234

*Television. Unscrambling (Boyd

Phelps) 157

Test Set for the Radio Service Man. A

(B. B. Alcom i 99

'Testing Receivers, The Routine of

(John S. Dunham) 375

'Thermionic Milliammeter, A (G. F.

Lampkin) 325

300-Mile Chain Regulation, Reasons for

the 92

'Transmitting Amateur Television

(Boyd Phelps) 247

'Trouble Shooting in the Power Unit

(B. B. Alcorn) 264

'Tube-Tester, A Simple A. C. Operated

(The Laboratory Staff) 173

'Two-Tube T. R. F. Short-Wave Re- ceiver, A (William Bostwick and W.

T. Thomas) 20

*T TNSCRAMBLING Television (Boyd

U Phelps) 157

'Unusual Organization, An (Robert S. Kruse) 309

T/rISUAL Broadcasting Field, In the. 94 r ""Vivetone 29," An Amplifier and

Power Supply for the (R. F. Goodwin) 45 'Volume Control System, New Auto- matic (Charles Williamson) 299

'Volume Control Systems 259

JI/G Y'S Attack on the Allocation Plan 163

rr WGY Protests New Allocation Plan 92

WRNY Television Transmissions 17

Wavelength Allocations, Table of 323

Well-Balanced Federal Radio Commis- sion, A 372

'What is a Good Tube? 335

What is Public Interest? 17

'What Prospects of Television Abroad?

(Lawrence W. Corbett) 11

'What the Serviceman Should Study

(John S. Dunham) 294

'When the Set Stops Working (B. B.

Alcorn) 25

With the Broadcasting Stations. . .93, 164, 235

With the Radio Manufacturers 165

AUTHORS Alcorn, B. B 25, 99. 179, 264

Barclay, Howard. . 197

Barton, William E 117

Bostwick, William 20

Bouck, Zeh 35

Browning, Glenn H.. . 115

Burke, C. T 322

Canfield, Fred H. . . 367

Clough, Kendall 104, 241

Corbett, Lawrence W 11

PAGE Felix, Edgar H.

16, 91, 163, 227. 233, 296, 372, 388 Friauf, James B 188

Dall, William B 34

Denton, Clifford 95

Dreher, Carl. .32, 51, 102, 162, 182, 185, 244,

246, 252, 311, 314. 354, 385, 402

Dunham, John S 236, 294. 375, 392

Gockel, J. H

Goodwin, R. F. . .

171 45

Henney, Keith

14. 23, 97, 169. 239. 250, 300, 377

Hitchcock, R. C 85

Hull, L. M 230

Jarvis, Kenneth . . . . 167, 399

Jones, Frank C 29, 316

Jones, Frank H ... 313

Kruse, Robert S.

38, 111, 189, 262, 302, 309, 380

Laboratory Staff, The 173

Lampkin, G. F 325

Landon, V. D 291

Meacham, J. B. V 405

Millen. James 35

Morgan, Joseph 159, 369

Phelps, Boyd 123, 157, 250

Rhodes. Howard E 88. 116, 125, 257, 412

Shea, Richard F... 387

Smith, Bert E 49, 126

Stanko, Edward 186

Terman, Frederick Emmons. . . .303, 382 Thomas W. T. . . 20

Uzmann, J. George

120

Walford, Dudley 174

Weaver, K. S 329

Williamson, Charles 299

Wise, Roger 393

PORTRAITS

('Portraits in "The March of Radio")

'Aird, John

'Bowman, Charles A. .

'Cady, Walter G. 'Christiansen, Kay Clark, Clarence R.

'Frigon, Augustin . . . .

296

296

235 164 402

296

'Gilmour, Hugh 93

Goldsmith. Alfred N. 51, 228

'Horton, J. W..

163

Kemp, G. S 156

Kyle, Colin 369

"Linden, Adolph F 372

'Manson, Donald 296

Raycroft, Louis B. F. 366

Copyright, 1929, by DOUBLEDAY, DORAN & COMPANY, INC.

RADIO BROADCAST ADVERTISER

Hammarlund Hi-Q 29

Authorized Official Distributors

Silver-Marshall Kit Headquarters

National Short Wave Aero Products

WE are ready to ship all parts specified in this publication, as well as those parts called for in other leading radio papers. Tie up with a house that is amply financed to carry a complete and varied stock of merchandise. Royal-Eastern has been in business since 1897' 31 years and we are known to have the fastest snipping facilities in New York. Send for our new 1919 trade catalog. There is a copy for you. It is chock full of all the latest radio and television developments, as well as kindred electrical lines. We feature only nationally advertised merchandise. All kits are in stock Send your order today Prompt shipment is assured. We know you will like our service!

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ROYAL-EASTERN ELECTRICAL SUPPLY COMPANY

16 West 22nd St. New York City

ROBERT s. KRUSE

Consultant and Technical Writer

103 Meadowbrook Road, West Hartford, Conn. Telephone Hartford

ArelfourTubes Jus Limping Along /

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SELF-ADJUSTING''/^^/

30 FRANKLIN ST., NEW YORK

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Sargent-Rayment Screen Grid Seven

Designed by the

Inventors of the

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Manufactured by Silver-Marshall, Inc.

A Station for Every Dial Degree

That is the average performance of the Sargent-Rayment Seven over the entire dial. Under average conditions 100 stations per night can be heard with it.

The Sargent-Rayment Seven has an amplifier composed of four screen-grid tubes. There is no regeneration. No "grid suppressors" or other counteracting devices are used to stop oscillation, the oscillation is fundamentally eliminated in the circuit design thus allowing every bit of tube amplification to be retained for useful work. Under these conditions are we unreasonable when we claim that this receiver has more power, more sensitivity and more selectivity than any- thing else ever offered for sale? Watch the DX records go to smash this winter!

WRITE FOR FREE BOOKLET

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If you send this by AIR MAIL we will answer same way.

RADIO BROADCAST

NOVEMBER, 1928

WILLIS KINGSLEY WING, Editor

KEITH HENNEY EDGAR H. FELIX

Director of the Laboratory Contributing Editor

Vol.4X. No. i

Cover Design - - - From a Design by Haney Hoptyns Dunn Frontispiece

Pictures Transmitted in One Minute at Radio World's Fair What Prospects of Television Abroad? - Lawrence W. Corbett New Trends in Radio Design for 1929-30 - - - Keith Henney The March of Radio - An Editorial Interpretation

New Wavelength Allocation Plan Need for Defining Television Practice

Newspaper Has Radio Picture Transmitter Commercial Broadcasting Increases Here and There Aircraft Radio Radio in Foreign Countries

A Two-Tube T.R.F. Short- Wave Receiver

William BostwicJ{ and W. T. Thomas "Strays" From the Laboratorv

Dynamic vs. Magnetic Speakers Regarding Series- Filament Operation Present Designs Do Not Consider Economy

What is Public Interest? The Race for Television Publicity WRNY Television Broadcast* A Milestone in Television New Nationwide Picture Service

How to Stabilize Rice Amplifiers New Radio Tubes Needed

Keith Henney

The "Gyps" Are Still at It New Precision in Quartz Plates Seven New Radio Booklets Portable Radio Sets Underground Aerials

B. B. Akorn

When the Set Stops Working

"Radio Broadcast's" Home Study Sheets - -

No. 9. The Effect of an Electric Current No. 10. Alternating Current Part HI

A New Audio System for Dynamic Speaker Reproduction

Franl( C. Jones As the Broadcaster Sees It Carl Dreher

Sound Motion Pictures Part II Commercial Publications

A and B Power from the D.C. Lines -William B. Doll

Building Receivers for Television Zeh Bouci( and James Millen A Modulator for the 1929 Short- Wave Transmitter

Robert S. Kru.se "Radio Broadcast's" Service Data Sheet on Manufactured Re-

ceivers

No. ii. Freshman Model "G" Receivers

No. 11. Freed Eisemann Model NR-8o

The Improved Knapp A-Power Unit

An Amplifier and Power Supply for the "Vivetone 29"

R. F. Goodwin "Our Readers Suggest

Short-Wave Plug-in Coils Improving Capacity Feed-Back Circuits

Receiving Without an Aerial Tuning-m With a Distant Loud Speaker

Polarity Indicators Home-made I. F. Transformers

Reducing Hum in the Detector Prolonging the Life of the 171 A

Reducing Hum in A.C. Sets Special Soldering Irons for Difficult Jobs

The "Chronophase" Screen-Grid Receiver - Bert E. Smith

The Fellows of the Institute - Carl Dreher

New Apparatus - - - Useful Information on New Products Manufacturers' Booklets "Radio Broadcast's" Laboratory Information Sheets - -

No. ijj. Balancing Radio Receivers No. 158. Hook-up for Short-Wave and

No. 134. The Audio Transformer Broadcast Receivers

No. 135. Television No. ajo. Circuit for Short-wave and Broad

No. 336. Moving-Coil Loud Speaker* cast Reception

No. »j7. Power Output No. 340. Television

The contents of this magazine is indexed in The Readers' Guide to Periodical Literature, which is on file at all public libraries.

IO II 14

16

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AMONG OTHER THINGS. . .

A FUNDAMENTAL part of the policy of this magazine is the careful scrutiny of everything appearing in its pages, from the smallest advertisement to the most intricate of technical articles. We have always felt that our first duty to the reader was to protect him from misleading statements and in- accuracies of whatever sort. This rr.agaiine is not, however, the expression of one man's opinion, ncr even of the group respon- sible for editing and publishing it. We have frequently given space to articles on technical subjects in which the authors came to conclusions at variance with our own opinions. Almost in- variably after the appearance of the magazine we would be del- uged with letters and telephone calls demanding to know why we "said" this or that. The editorial expressions of this maga- zine, whether general or technical are always definitely identi- fied. Articles from other sources are also indentified, and for the opinions expressed, the author is alone responsible. We wel- come the opportunity of printing controversial articles.

'"PO JUDGE from reports which reach us, the motion-picture JL industry is in nearly as complete a turmoil as that in which radio found itself some years ago. The cause of the trouble is, of course, the application of synchronized and non-synchronized sound accompaniment to the "feature picture." This develop- ment is bringing into play practically all of the experience that broadcasters have so laboriously accumulated in the past few years, and is drawing into the movie field many broadcasters and other engineers who have developed apparatus and its uses for this work. In this connection, the pages of Carl Dreher's department, "As the Broadcaster Sees It," are well worth watching, for Mr. Dreher is including much first-hand and practical information on sound motion picture work. Much of this work is being done by expert radio service men.

ANEW ZEALAND radio distributor writes us he is in- terested in communicating with American radio manu- facturers who wish New Zealand distribution for kits or com- plete sets, either a.c. or d.c. operated. Manufacturers who are interested may communicate with the editor.

"pOR those to whom the news has not yet traveled, we J- repeat the announcement made in this column last month : the bound volume of RADIO BROADCAST Laboratory Information Sheets Nos. 1-190 is now available at $i. Order from your newsdealer or directly from the Circulation Department of Doubleday, Doran.

'"HO JUDGE from the comments in many letters, the Home JL Study Sheets are increasing in popularity. It may have escaped the attention of many who are following these Sheets that we are quite willing to examine the answers to the problems in each Study Sheet. These answers will be promptly examined and returned with our comments.

THE December issue will contain an interesting article on band-pass filters, an interesting and practical article on television, more good data for the service man and professional set builder, instructions on how to grind quartz crystals, a number- of important constructional articles and our regular departments.

WILLIS KINGSLEY WING.

DOUBLEDAT, DORA7\[ ^ COMPACT, IXC., Garden Qity9

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Copyright, 1928, in the United State** Newfoundland, Great Britain, Canada, and other counties by Doubleday, Doron

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Pictures Transmitted in One Minute at Radio World's Fair

This radio-photo receiver was demonstrated by the Westinghouse Electric and Manufacturing Company for the first time in the New Madison Square Garden, New York, during the week of the radio show. The apparatus is capable of converting electrical impulses into a complete photograph in less than one minute. Because of the difficulty in securing a wavelength assignment Lie demonstration was carried on with the use of wires. However, the engineers state that the equipment functions equally well by radio within the limits of fading and static. The chief advantage of this new apparatus is that it reduces the time required for the transmission of a photograph from five minutes to one minute. The size of the repro- duced photograph is five by eight inches

10

DEVICE PUTS MOVIES ON THE AIR This apparatus is the heart of the television motion picture transmitter developed by West- inghouse. It is used at KDKA for the broadcasting of radio motion- picture programs

By LAWRENCE W. CORBETT

IN DISCUSSING the progress of television the technical press of the United States and Great Britain appears to take turn in de- ploring the lack of initiative of its own countrymen and in praising that of its rivals across the Atlantic. Yet, if we take the opinion of no less an authority than Sir Oliver Lodge, we must admit that the eading exponents of the art in both countries are equally up against a stone wail and that the limitation of the apparatus they are using at

present will not permit further improvement.

But Sir Oliver Lodge, and other equally famous scientists whose opinions incline in his direction, are by no means pessimistic of the ultimate success of television. His criticism applies only to that apparatus now commonly used by many of those who claim recog- nition in the art. Mechanical con- trivances, Sir Oliver believes, are limited by certain physical restric- tions which it will be inordinately impossible to surmount. To use his own words:

Cathode rays or moving elec- trons are the only things likely to be sufficiently docile and con- trollable to be used as the agents for television. No material things are likely to be able to move quickly enough, but electrons re- spond so instantaneously that, if devices can be invented for utiliz- ing them, the theoretical difficul- ties with the required rapidity of motion would begin to disappear both from the sender and the re- ceiver, especially as photoelectric response is almost infinitely rapid.

A. Campbell Swinton, whose early apparatus was described in an article on television which appeared in RADIO BROADCAST for July, 1928, by R. P. Clarkson, appears to have realized the limita- tions that mechanical equipment would impose upon television, as

The British Situation

BY NORMAN EDWARDS Managing Editor, Popular Wirekss and Modern Wireless

FOR months past the question of television has been agitating the minds of the British public, and day by day the Press in all parts of Great Britain has been persisting in dinning into the public ear that "television is here."

The Baird International Television Development Co., backed by British capital, invested for the development of television in England, now definitely has promised a television service by the end of the current year, despite the fact that the British Broadcasting Corporation, uhich has a monopoly on broad- casting in England, has refused to cooperate with Baird and bis associates be- cause, in the opinion of the Chief Engineer of the B. B. C., and his advisers, the Baird system is not developed sufficiently to warrant it being utilised as a public service: and the Chief Engineer and bis associates in the British Post Office having investigated the Baird system believe it to be in a state of experi- mental infancy and unfitted for offering a means of service to the public.

Furthermore, the Wireless Telegraphy Act, which governs the use of radio in England, legally has been interpreted to cover television, and as the British Post Office refused to licence the Baird system as a public utility service, the question now arises in the public mind as to what Baird