RCA INSTITUTESR E C E I V I N G S E T DIAGRAMS . PART 1 SHEET AERO SEVEN . : . . . . . . . . . . . . . . 2AERO SHORT WAVE ADAPTER FOR A.C. RECEIVERS . . . . . . . . . . . . 2 AMRAD A.C. 7 . . . . . . . . . . . . . . 3 APEX 36 ALL-ELECTRIC ...... 3 ATWATER KENT 20 . . . . . . . . . . . 4 ATWATER KENT 30 . . . . . . . . . . . 5 ATWATER KENT 32 . . . . . . . . . . .5 ATWATER KENT 35 . . . . . . . . . . . 6 ATWATER KENT 40 . . . . . . . . . . . 6 BALKITE . MODEL A . . . . . . . . . 6 BOSCH 28 . . . . . . . . . . . . . . . . . . 5 BREMER TULLY 7-70 . . . . . . . . .8 BROWNING DRAKE-34. 36. COLONIAL 31 A.C&

38 . . . 8

. . . . . . . . . . .9

CROSLEY 608 . . . . . . . . . . . . . . . 9 CROSLEY 704-A . . . . . . . . . . . . . 10 DAVEN BASS NOTE . . . . . . . . . . .10 DAY FAN A.C. POWER SET . . . . 11 DAY FAN 35 D.C . . . . . . . . . . . . 11 FADA -MODELS 10.11. 306

31 (60 CYCLES). . 12&

FADA-MODELS 102.112. 302

312 (25 CYCLES). . . 12

FEDERAL ORTHO-SONIC A.C ... 12 FREED EISMAN NR 5 . . . . . . . . . 13 FREED EISMAN NR 80 . . . . . . . .13 FRESHMAN EQUAPHASE . . . . . . . . 24 FRESHMAN-MODEL G . . . . . . . . . 24 GILFILLAN GN 6 . . . . . . . . . . . 14

RCA INSTITUTESGREBE SYNCHROPHASE. . . . . . . 14 HAMMERLUND ROBERTS H. 1Q

. . 15

KING-MODEL FF. . . . . . . . . . . . 15 KING-MODEL H

. . . . . . . . . . . . 15

KING-62 TRF . . . . . . . . . . . . . . 16 KOLSTER 6K . . . . . . . . . . . . . . . 1 7 MAJESTIC A.C . . . . . . . . . . . . . 17 MOHAWK ALL-AMERICAN LYRIC MODELS 60.61. 62.65. & 66 . . . . . . . . . 18 MOHAWK ALL-AMERICAN LYRIC MODELS 80.83.84. 85 & 88 . . . . . . . . . 18 PFANSTEIHL 34&

50 A.C. . . 19

PHILCO ELCTRIC- SERIES 5.19 RCA- RADIOLA 16 . . . . . . . . . . 20 RCA- RADIOLA 17 . . . . . . . . . . 20 RCA- RADIOLA 18 A.C . . . . . . 21 RCA- RADIOLA 18 D.C. . . . . . 21 RCA RADIOLA 60. . . . . . . . . . . 22 RCA RADIOLA 62 . . . . . . . . . . . 22 ROBERTS AC . . . . . . . . . . . . . . . 23 SILVER MARSHALL-MODEL 630 . . . . . . 23 SPARTON EQUASONNE-MODEL 89 . . . . . 25 SPLITDORF INHERENTLY ELECTRIC .. 25 STEINITE 261 . . . . . . . . . . . . . . . . . . . 26 STEWART WARNER-MODELS 801. 801A 811. AND 811A SERIES B . . . . . . . 26 STROMBERG CARLSON-MODELS 635.636 .. 27 ZENITH-MODELS 11.12. AND 14 . . . . . . . 27 CHARACTERISTICS OF RECEIVING VACUUM TUBES. . . 29

RCA INSTITUTESPART 2

ATWATER KENT MODEL 55 . . . . . . . . . . . 29 BRANDES MODEL B-15&

16 ......... 29

CROSELEY R.F.L. 90 . . . . . . . . . . . . . . 30 CROSELEY MODEL 804 . . . . . . . . . . . . . . 30 FADA MODELS 50.71.71.&

72 . . . . . . 31

FREED-EISMAN NR 55 A.C . . . . . . . . . . 31 FREED-EISMAN NR 78 . . . . . . . . . . . . . . 32 GREBE SYNCHROPHASE BATTERY . . . . . .32 GREBE A.C. SIX . . . . . . . . . . . . . . . . . . 33 MAJESTIC MODEL 90 . . . . . . . . . . . . . . . 33 RCA-RADIOLA 28- A.C . . . . . . . . . . . . . 34 RCA-RADIOLA 25 . . . . . . . . . . . . . . . . . . 36 RCA-RADIOLA 20 . . . . . . . . . . . . . . . . . . 36 RCA-RADIOLA 44 .................. 37 RCA-RADIOLA 66 . . . . . . . . . . . . . . . . . . 38 STROMBERG-CARLSON NO . 641 . . . . . . . 38 STROMBERG-CARLSON NO . 846 . . . . . . . 39 ZENITH 17 . . . . . . . . . . . . . . . . . . . . . . . 39FOREWORD . INTRODUCTION TO RADIO

TECHNICAL LESSON 1 . MATHEMATICS LESSON 2 . UNITS OF ELECTRICAL MEASUREMENTS AND SYMBOLS LESSON 3 . THE ELECTRON THEORY-SUBSTANCE AND MATTER-STATIC ELCTRICITY LESSON 4 . MAGNETISM LESSON 5 . ELECTROMAGNETISM-ELECTROMAGNETIC INDUCTION LESSON 6 . PRIMARY CELLS LESSON 7 . RESISTANCE AND CONDUCTION LESSON 8 . ELECTRICAL CIRCUITS

RCA INSTITUTESLESSON 9 - D.C. MOTORS LESSON 10 - D.C. GENERATORS LESSON 11 - A.C. CURRENT LESSON 12 - THE MOTOR-GENERATOR LESSON 13 - POWER TRANSFORMERS LESSON 14 - INDUCTANCE LESSON 15 - CAPACITY LESSON 16 - THE STORAGE OR SECONDARY BATTERY LESSON 17 - THE USE OF STORAGE BATTERIES ON SHIPBOARD LESSON 18 - METERS LESSON 19

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GRAPHS

LESSON 20 - SOUND LESSON 21 - ELECTROMAGNETIC WAVES LESSON 22 - FUNDAMENTALS OF RADIO RECEPTION LESSON 23 - VACUUM TUBES LESSON 24 - CHARACTERISTIC CURVES LESSON 25 - THE OSCILLATORY CIRCUITS LESSON 26

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MID-TERM EXAMINATION

LESSON 27 - PRACTICAL RADIO CONSTRUCTION LESSON 28 - PRACTICAL RADIO CONSTRUCTION LESSON 29 - AUDIO AMPLIFIER CIRCUITS LESSON 30 - PRACTICAL RADIO CONSTRUCTION LESSON 31 - REGENERATIVE DETECTOR WITH CAPACITIVE CONTROL OF FEED-BACK LESSON 32 - PRACTICAL CONSIDERATIONS FOR THE DESIGN OF SCREEN-GRID RECEIVERS LESSON 33 - CONSTRUCTIONAL DETAILS OF THE RCA INSTITUTES A.C. SCREEN-GRID RECEIVER

LESSON 33-A - BUILDING THE BATTERY-OPERATED SCREEN-GRID RECEIVER LESSON 34 - PRACTICAL RADIO CONSTRUCTION

RCA INSTITUTESLESSON 35 - COMMON FAULTS AND TROUBLES LESSON 36 - PRACTICAL RADIO CONSTRUCTION LESSON 37 -THE DEVELOPMENT OF THE SUPER-HETERODYNE LESSON 38-PRINCIPLES AND USE OF TEST EQUIPMENT FOR SERVICING RADIO RECEIVERS LESSON 39 - INSTRUMENTS USED IN SERVICING RADIO RECEIVERS LESSON 40 - INSTRUMENTS USED IN RADIO SERVICING AND PRINCIPLES OF SET TESTING LESSON 41 - BALANCED ARMATURE LOUD SPEAKERS LESSON 43 - RADIOLA 28 A.C. OPERATED LESSON 44 - VICTOR MICRO-SYNCHRONOUS RADIO R-32, R-52, RE-45, RE-75 LESSON 45 - GENERAL ELECTRIC MODEL H-31 MODEL 80 - GRAYBAR MODEL 700

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WESTINGHOUSE MODEL WR-5, RADIOLA

LESSON 46 - GENERAL ELECTRIC MODELS H-51 & H-71 - WESTINGHOUSE MODELS WR-6 WR-7- REDIOLA MODELS 82 & 86 - GRAYBAR MODELS 770 & 900 LESSON 47 - CROSELEY R.F.L. 90 -- ZENTIH 17 LESSON 48 - PRACTICAL RADIO CONSTRUCTION LESSON 42 - THE ELCTRO-DYNAMIC SPEAKER LESSON 49 - RADIO RETAILING - SALESMANSHIP LESSON 50 - GREBE - BATTERY AND A.C. RECEIVERS LESSON 51 - BATTERY ELIMINATORS LESSON 52 - PRACTICAL RADIO CIRCUITS - PART 1 LESSON 53 - PRINCIPLES OF ELECTRICALLY OPERATED TUNES R-F CIRCUITS LESSON 54 - ELECTRICALLY OPERATED TUNED R-F AND SUPER-HETERODYNE RECEIVERS LESSON 55 - INTERFERENCE ELIMINATORS LESSON 56 - COMMERCIAL LONG AND SHORT WAVE RECEIVERS LESSON 57 - SPARK TRANSMISSION LESSON 58 - ARC TRANSMITTERS LESSON 59 - RADIO AVIATION EQUIPMENT LESSON 59-A - AVIATION RADIO EQUIPMENT FOR TWO WAY COMMUNICATION LESSON 60 - VACUUM TUBES USED IN TANSMITTING LESSON 61 - COMMERCIAL TUBE TRANSMITTERS

&

RCA INSTITUTESLESSON 62 - VACUUM TUBE TRANSMITTERS LESSON 63 - SHORT WAVE TRANSMITTERS LESSON 64 - SHORT WAVE (HIGH FREQUENCY) RECEIVERS LESSON 65 - TELEVISION - PART 1 LESSON 66 - TELEVISION - PART 2 LESSON 67 - PHOTORADIOGRAMS - BEAM TRANSMISSION LESSON 68

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BROADCAST TRANSMITTERS

LESSON 69 - RADIO DIRECTION FINDER OR RADIO COMPASS LESSON 70 - SOUND MOTION PICTURES LESSON 71 - SOUND MOTION PICTURES AND SOUND REPRODUCING EQUIPMENT SUPPLEMENTARY INTRODUCTION

R. C . A. INSTITUTES, 1N.C.75 VARICK STREET

NEW YORK, N. Y.

Please Read These Instructions CarefullyThis binder is for keeping your lessons in good condition and it should be used for that purpose only. When you submit your answers to the lessons, and whenever you write to us, write your name, address and student number plainly so that we will not be delayed in giving you prompt attention. After you have answered the examinations on the exadnation paper which we furnish you, file the lessons in this binder. Do not return the lessons, themselves, to us all we want-qre your answers. Use only one side of the examination paper and write your answers with pen and ink, or typewriter. In answering the examina6ons it is not necessary for you to copy the questions write or type just the answers.

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The examination will be found at the end of each 1ess::n. With the exception of standard diagrams, symbols, characters and formulas, your answers must not be copied from the lessons, nor should they be copied from a text. Instead, use the instruction in constructing a line of reasoning of your own and build your reply upon such parallel lines of reasoning. The passing mark for each lesson is 75 per cent. and if your gradeis less than 75 per cent. you will be required to re-submit it entirely.

In grading the examinaiions of o m students we give each answer the proper credit. We take into consideration such factors as neatness, general preparation end manner of expression. Always send in two examinations at one time and keep your mailings at least five days apart. You will at all times be supplied with sufficient study material with which to keep busy. Your exanination papers should be sent to us FIRST CLASS mail. The mailing rate is 2 cents for each ounce or fraction of an ounce. If your examination papers consist of five sheets, or less, the postage required is 2 cents. If from six to eleven sheets are mailed the postage.required is 4 cents; if twelve to seventeen sheets, 6 cents, and so on, addmg two cents for each additional six sheets. Always advise us of any change in your address. Write plainly and d o not abbreviate the name of your town, state and street.

R. L. DUNCAN PresidentM

P. S. Remember to send in two examinations at one time no more.

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DEFINITIONS AND SYMBOLST h i s lesson c o n t a i n s standardized r a d i o d e f i n i t i o n s and symbols only and does not r e q u i r e a n examination, However, it should be always a v a i l a b l e

t o t h e student as a ready reference when studying t h e l e s s o n s of t h e course. It i s not expected t h a t t h e student w i l l understand the e n t i r e contents of t h i s l e s s o n u n t i l he w i l l have completed t h e course,

W express our thanks t o t h e I n s t i t u t e of Radio Engineers f o r permission e t o make use of t h e i r d e f i n i t i o n s and symbols,

"A" POWER SUPPLY:the cat'node ofACLTPTGK:B

A power s u p p l y ' d e v i c e which provides h e a t i n g c u r r e n t fop

vacuum t u b e .

A c i r c u i t of inductance and c a p a c i t y which i s s o arranged and tuned a s t o o f f e r low impedance t o c u r r e n t s of a given frequency, and hlgh impedance t o c u r r e n t s of any o t h e r fiequencg.

ACOUSTIC

INiPEDANCEz The a c o u s t i c impedance of a sound medium on a g i v e n surface i s the complex q u o t i e n t of t h e p r e s s u r e ( f o r m p e r wit a r e a ) on t h a t surface by the f l u x (volume v e l o c i t y , ox- I f n e a r v e l o c i t y multip l i e d by the a p e a ) t w o u g h t h a t s u r f a e e , The a c o u s t i c impeaance way be expressed i n terms of mechanical impedance, acoust f c impedance being e q u a l t o mechanical impedance d i v i d e d by t h e square of khe a r e a of t h e s u r f a c e considered,

ACOUSTIC RADIATOR:

An a c o u s t i c r a d i a t o r i s t h a t p o r t i o n of a transducer which f a c i l i t a t e s t h e r a d i a t i o n of sound v i b r a t i o n s ,

ACOUSTIC REACTANCE: The a c o u s t i c reactance of a sound medium i s t h e imagin a r y p a r t of t h e a c o u s t i c Lmpedance, It i s the'component of the a c o u s t i c impedance r e s u l t i n g from t h e e f f e c t i v e mass o r compliance of the medium,ACOUSTIC RESISTANCE " e h a c o u s t i c r e s i s t a n c e of a sound medium i s t h e r e a l component of t h e a c o q s t i c impedance, T h i s i s the component of t h e

a c o u s t i c impedance a s s o c i a t e d w i t h t h e d l s s i p a t i o n of energy,

ACTIVE TRANSDUCER : A n a c t i v e t r a l a s d u c e ~is one in which t h e psvier supplied t o t h e second system i s obtained from a l o c a l source and is c o n t r o l l e d by t h e power from the f i x s t system.AERIAL:

An e l e v a t e d con8.uctor p o r t i o n of a condenser antenna.

AERIAL C I R C U I T :

The components between t h e f r e e o r i n s u l a t e d end of t h e a e r i a l and t h e connection w i t h t h e e a r t h ,

Printed in U.S A. .

..

i

AIR CONDENSER:

A condenser having a i r a s i t s d i e l e c t r i c

ALTERNATIW CURRENT: A c u r r e n t , the d i r e c t i o n of which r e v e r s e s a t regul a r l y r e c u r r i n g i n t e r v a l s , the algeb7aic average value being zero.ALTERNATION:A LT E RNATOR :

A a l t e r n a t i o n i s one-half cycle of e.m.f. n r i s e and f a l l i n one d i r e c t i o n .

or c u r r e n t , o r t h e

A e l e c t r i c a l machine f o r g e n e r a t i n g a l t e r n a t i n g e .m.f n

.

ALTERNATOR TRANSMTl'TER:

A r a d i o t r a n s m i t t e r which u t i l i z e s radio- frequency power generated by a r a d f o-frequency a l t e r n a t o r .

AMMETER: A instrument connected i n s e r i e s i n a c i r c u i t t o measure t h e n c u r r e n t flowing.

AMPERE: The standard e l e c t r i c a l u n i t of c u r r e n t i s t h e ampere, and i t i s the current e s t a b l i s h e d i n a c i r c u i t of 1 ohm r e s i s t a n c e by an e l e c t r o motive force of 1 v o l t . AMPEREHOUR: The ampere-hour i s t h e u n i t f o r e x p r e s s i n g t k e q u a n t i t y of e l e c t r i c i t y passing through a c i r c u i t under t e s t , when a c u r r e n t of 1 ampere i s e s t a b l i s h e d i n a c i r c u i t f o r a period of one hour. AMPLIFIER: A device f o r i n c w a s i n g the amplitude of e l e c t r i c c u r r e n t , voltage or power, t h r o u g h t h e c o n t r o l by t h e input power of a l a r g e r amount of power supplied by a l o c a l source t o t h e output c i r c u i t .AMPLIFICATION F C O " ATX

m a s u r e of t h e e f f e c t i v e n e s s of t h e g r i d voltage r e l a t i v e t o t h a t of t h e p l a t e voltage i n a f f e c t i n g ths p l a t e c u r r e n t ; it i s the r a t i o of t h e change i n p l a t e v o l t a g e t o a change i n g r i d v o l t age i n the opposite d i r e c t i o n , under the c o n d i t i o n t h a t t h e p l a t e curr e n t remains unchanged.

AMPLITUDE: The amplitude of a wave i s a measure of th maximum d e v i a t i o n from i t s zero or normal a x i s .ANODE:

The e l e c t r o d e t o which t h e e l e c t r o n stream flows.A device f o r r a d i a t i n g o r absorbing r a d i o waves.

ANTENNA:

ANTENNA F R FACTORdhe r a t i o of t h e e f f e c t i v e h e i g h t of an antenna t o OM

i t s a c t u a l physical h e i g h t .ANTENNA RESISTANCE :

A e f f e c t i v e r e s i s t a n c e which i s numerically e q u a l t o n t h e quotient of t h e average power i n the e n t i r e antenna c i r c u i t by t h e square of the e f f e c t i v e c u r r e n t a t the p o i n t of maximum c u r r e n t . Note: Antenna r e s i s t a n c e includes: R a d i a t i o n r e s i s t a n c e , ground r e s i s t a n c e , radio- frequency r e s i s t a n c e of conductors i n antenna c i r c u i t , e q u i v a l e n t r e s i s t a n c e due t o corona, eddy c u r r e n t s , i n s u l a t o r leakage, d i e l e c t r i c loss, etc.

Definitions

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APERIODIC :

That which has no d e f i n i t e i n d i v i d u a l period.

A P E R I O D I C CIRCUIT:ARC:

A a p e r i o d i c c i r c u i t is a c i r c u i t which n e l e c t r i c a l p r o p e r t i e s which prevent it from o s c i l l a t i n g . An a r c i s formed by the passage of an e l e c t r i c c u r r e n t thr or vapor, t h e c o n d u c t i v i t y of which is mainly due t o t h e i o n i z t h e gas or vapor.

AFfC

CONVERTER: An e l e c t r i c a r c used f o r t h e g e n e r a t i o n of a l t e r n a t i n g or pulsating current.A device f o r changing a-c. t o d-c,

ARC RECTIFIM:A RT IC U L A TION:

A r t i c u l a t i o n of an e l e c t r o - a c o u s t i c t r a n s d u c e r i s a measure of i t s a b i l i t y t o t r a n s m i t detached speech s y l l a b l e s and i s expressed a s a percentage of t h e t o t a l s y l l a b l e s spoken which a r e c o r r e c t l y understood by t h e l i s t e n e r a t t h e output of a t r a n s m i s s i o n system including the transducer a s t h e o n l y source of d i s t o r t i o n of d e t e c t a b l e magnitude.

ARRESTER Apparatus w i t h s u i t a b l y arranged e l e c t r o d e s and s h o r t air- gap, : placed i n s e r i e s w i t h t h e ground lead of a t r a n s m i t t e r o r r e c e i v e r ; a lead i s t a k e n t o t h e r e c e i v i n g apparatus from t h e s i d e of t h e sparkgap remote from t h e ground; used f o r c o n t r o l l i n g s i g n a l s on c i r c u i t , and f o r keeping t h e antenna grouxled i n thunder storms and other e l e c t r i c a l disturbances. ATMOSPHERIC ABSORPTION: A l o s s of power i n t s a n s m i s s i o n of r a d i o waves due t o a d i s s i p a t i o n i n t h e atmosphere, ATMOSPHERICS: S t r a y s produced by atmospheric condit t o n s ,

(See STATIC )

ATTENUATION: The r e d u c t i o n i n power of a wave or a c u r r e n t with i n c r e a s i n g d i s t a n c e Prom t h e source of transmission, ATTENUATION EQUALIZER"device f o r a l t e r i n g the t o t a l transmis s ion l o s s of a c i r c u i t f o r v a r i o u s f r e q u e n c i e s i n order t o make s u b s t a n t i a l l y equal t h e t o t a l t r a n s m i s s i o n l o s s f o r a l l f r e q u e n c i e s w i t h i n a c e r t a i n range.AUDIO FREQUENCY: A frequency corresponding t o a normally audible sound wave. The u p p r l i m i t o r d i n a r i l y l i e s between 10,000 and 20,000 cycles. A transformer f o r use w i t h audio-f requency

AUD10-FREQUENCY TRANSFORMER: ourrent s,AUDION:

~ i Vacuum Tube. e

AUTODYNE RECEPTION: A system of heterodyne r e c e p t i o n through t h e use of a device which i s both an o s c i l l a t o r and a d e t e c t o r ."BW POImR SUPPLY:

A power supply device connected i n t h e p l a t e c i r c u i t of

a vacuum tube. BAFFLE: A b a f f l e is a p a r t i t i o n which may be used w i t h a f r e e r a d i a t o r t o impede c i r c u l a t i o n from f r o n t t o back. Definitions

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FREQLJENCES: A continuous range e f l n i t e frequencies.

Of

frequencies e

E

A WINDING: ~ A form of c o i l winding i n which s i n g l e t u r n s a r c e s s i v e l y i n each of two o r more l a y e r s , t h e windi ng proceedi end of t h e c o i l t o t h e o t h e r , without r e t u r n .

BAND-PASS FILTER: A f i l t e r designed t o pass c u r r e n t s of frequencies w i t h i n a continuous band l i m i t e d by an upper and a lower c r i t i c a l or cut- off

frequency and s u b s t a n t i a l l y reduce the amplitude of c u r r e n t s of a l l frequencies out s i d e of t h a t band.BAR:

A pressure of one dyne per square centimeter i s c a l l e d a bar,A b a t t e r y f s a combination of two ol- more c e l l s .

BATTERY:

BEAM ANTENNA: A u n i l a t e r a l d i P e C t i w antenna such t h a t i t s r a d i a t i o n i s subs t a n t i a l l y confined t o a narrow beama

BEAT:

A complete cycle of such p u l s a t i o n s .

BEAT FREQUENCY: BEATING:

The number of b e a t s per second. This frequency i s e q u a l t o t h e d S f f e r e m e between t h e frequencies of t h e combining waves,

A phenomenon i n whioh two o r more periodic q u a n t i t i e s o f , n o t g r e a t l g d i f f e r e n t f r e q u e n c i e s r e a c t w i t h each o t h e r t o produce a r e s u l t a n t havfng p u l s a t i o n s of amplitude.

BEAT RECEET I O N :

See Heterodyne Reception c

BI~LATERAL ANTENNAAn antenna having t h e p r o p e r t y of r a d i a t i n g o r r e c e i v i n g s a d i o waves f n l a r g e p r o p o r t i o n i n angular r e g i o n s 180 degrees a p a r t t h a n i n a l l other d i r e c t i o n s ,BREATHING: Breathing f s a slow and f o r t h e most p a r t p e r i o d i c v a r i a t i o n i n t h e r e s i s t a n c e (and microphonicness ) of a carbon microphone. It may be of r e l a t i v e l y l a r g e magnitude and is not i n g e n e r a l audible.

BROADCASTING: Radio t r a n m i s s i o n intended f o r g e n e r a l r e c e p t i o n . B U H DISCHARGE: A dkschtlrge occurring on t h e s u r f a c e of conductors charged RS t o high potential.BURNING: Burning i s a r a p i d , t r a n a i t o r y and f o r t h e most p a r t nonperkodic r e s i s t a n c e f l u c t u a t i o n i n a carbon microphone, It i s evidenced by a f r y i n g o r s p u t t e r i n g nofse sometimes heard from a connected r e c e i v e r .

B S BAR: A broad l e a d t o which s m a l l e r leads from t h e u n i t s of a power l i n e , U condenser, b a t t e r y bank, or switchboard, a r e joined,BUZZER, TUNED: A eommon buzzer w i t h t h e c o i l s of a n electromagnet shunted by a non-induct i v e r e s i s t a n c e,

BYPASS CONDNESXi : A condenser used t o provide an a l t e r n a t i n g c u r r e n t p a t h of comparatively low impedance around some c i r c u i t element. . Definitions

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A T : An a n t e n n a h a v i n g c o n d u c t o r s which c o n s i s t of g r o u a r e l l e l w i r e s a r r a n g e d a s the e l e m e n t s of a c y l i n d e r .C A P A C I T I V E COUPLING:

The a s s o c i a t i o n of one c i r c u i t w i t h a n o t h e r by means of c a p a c i t y common o r mutual t o b o t h .

CAPACITOR: (same a s c o n d e n s e r ) A d e v i c e employed i n r a d i o c i r c u i t s t o i n t r o d u c e t h e e l e m e n t s of c a p a c i t a n c e . CAPACITY: The c a p a c i t y o f a c o n d e n s e r , o r b e t t e r , i t s c a p a c i t a n c e , i s a measure of t h e amount of e l e c t r i c a l e n e r g y which t h e condenser c a n s t o r e UP CARBON CONTACT PICKUP: A c a r b o n c o n t a c t pickup i s a phonogpaph p i c k u p which depends f o r i t s o p e r a t i o n upon t h e v a r i a t i o n i n r e s i s t a n c e of one o r more carbon contacts.C A RB O N MIGROPHOITZ:A c a r b o n microphone i s one u s i n g one o r more c a r b o n

contacts, Burning i s a r a p i d , t r a n s i t o r y and f o r t h e most p a r t n o n p e r i o d i c r e s i s t ance f l u c t u a t i o n i n a c a r b o n microphone. I t i s e v i d e n c e d b y a f r y i n g or s p u t t e r i n g n o i s e sometimes h e a r d from a c o n n e c t e d r e c e i v e r , B r e a t h i n g i s a slow and f o r t h e most p a r t p e r i o d i c v a r i a t i o n i n t h e It may be of r e s i s t a n c e (and microplionicness ) of a carbon microphone, r e l a t i v e l y l a r g e magnitude and i s n o t i n g e n e r a l e u d i b 1 e . Packing i n a c a r b o n microphone i s a c o n d i t i o n c a u s e d b y excesp mechanEcal p r e s s u r e between p o i n t s o f c o n t a c t oP b g a d h e r e n c e between p o i n t s of cont a c t r e s u l t i n g from e x c e s s i v e v o l t a g e s , It i s e v i d e n c e by d e c r e a s e d r e s i s t a n c e and s e n s i t i v i t y of t h e a l c r o p h o n e , CARRIER CUR?.F;NT: An a l t e r n a t i n g , e ~ r r e n t lnihlch i s modulated by a s i g n a l . O r d i n a r i : r e f e r s t o w i r e t r a n s i n i s s i c n of h i g h - f r e q u e n c y cu.rrents g

.

CARRIER FREQXZNCY I Frequency of a c a r r i e r wave o r a c a r r i e r c u r r e n t . CARRIER SUPPRESSION: That method of o p e r a t i o n i n which t h e c a r r i e r wave o r c a r r i e r c u r r e n t i s not t r a n s m i t t e d , CARRIER W m The component of a modulated wave which has t h e same f r e q u e n c y A: a s t h e o r i g i n a l unmodulsted wave. CASCADE:CATHODE: A s e r i e s of c o n d e n s e r s o r s t a g e s of a m p l i f i c a t i o n .

The e l e c t r o d e from which t h e e l e c t r o n s t r e a m f l o w s .

CATIIODE, INDI!:ECTLY HEATED: A c a t h o d e i n which t h e h e a t i s s u p p l i e d from a separste heater element. CAT WHISKER: A f i n e w i r e used t o make c o n t a c t w i t h t h e s u r f a c e of a crystal detector. sheet 5 Definitions

-

C

E

7 . S T : A s p c i a l s w i t c h arranged t o s h i f t the antenna c m e e t i c n from t h e sending t o t h e r e c e i v i n g apparatus and vice v e r s a .

C H O K E COIL:

A inductance c o i l i n s e r t e d i n a c i r c u i t t o o f f e r reactance n t o t h e flow of a l t e r n a t i n g - c u r r e n t components while allowing d i r e c t c u r r e n t t o pass.A chopper i s a device f o r r a p i d l y opening and c l o s i n g a c i r c u i t .

CBOFFER:

CIRCITIT-PJtEAKER: A c i r c u i t - b r e a k e r i s a s p e c i a l type of switch s o arranged a s t o open a c i r c u i t r a p i d l y and without i n j u r y t o i t s e l f . GOHERFIR: A device used i n t h e e a r l y days of r a d i o c o m n i c a t i o n f o r det e c t i n g t h e presence of electromagnetic waves; u s u a l l y c o n s i s t e d of a g l a s s tube c o n t a i n i n g m e t a l l i c f i l i n g s making connection between two electrodes,COMAIUTATOR:

c ir c u i t

.

A device f o r r e v e r s i n g the d i r e c t i o n of e l e c t r i c c u r r e n t i n a

COMPLIANCE: The compliance of a mechanical e l e m n t i s i t s d e f l e c t i o n per u n i t of f o r c e . This i s t h e r e c i p r o c a l of i t s s t i f - f n e s s . Compliance i n system a mechanical syseem is analogous t o c a p a c i t a n c e i n a n e l e c t ~ f c a l and i s expmssed i n c e n t i m e t e r s p r dyne, Negative compliance ( r e c i p r o c a l of negative s t i f f n e s s ) occurs f n a case of u n s t a b l e e q u i l i b r i u m where a small displacemex-it r e s u l t s i n a f o r c e t e n d i n g t o give a f u ~ t h e r displacement i n t h e same d i r e c t i o n .

CONDENSER: A condenser fs a device f o r s t o r i n g up e l e c t r i c a l energy, It u s u a l l y c o n s i s t s of two o r more conducting s u r f a c e s s e p a r a t e d by an i n s u l a t i n g meat u c a l l e d the d i e l e c t r i c , m@ONl)ENSETt AmENlQA:

An antenna consi s t i n g of two c a p a c i t y a r e a s .

COWIIEN5ER LOUDSPEAKEX: A condenser loudspeaker i s one f n which t h e mechanics f o r c e s a r e o b t a i n e d by var3ying t h e voltage between 'two e l e c t r o a e s of a condenser forming a. p a r t of an e l e c t r i c a l c i r c u i t .

C P D N E MPCROFEOIQT ; A. condenser microphone i s one t h e o p e r a t i on of which OT E S R fnvolves a v a r l . n t i a n i n t h e e l e e t r o s t a t f c capacltg' produced by a sound wave.CONDENSER PICKUP: A condenser pickup is a phonograph pickup whose e1ectrfcs.f. output i s generated by a mechanical v a r i a t % o n of i t s charged c a p a c f t y . CONDUCTIVITY; The c o n d u c t i v i t y of a substance i s a measure of i t s a b i l i t y t o carry e l e e t r f e current,C O N I C A L HORN"

coolaical horn i s a horn whose e q u i v a l e n t s e c t i o n a l r e d i u s has a constant r a t e of i n c r e a s e ,

A constrained r a d i a t o r i s an acoustic r a d i a t o r , t h e CONSTRAINED RADIATOR: sound from which i s o r i g i n a t e d i n a c o n s t r a i n e d p o r t i o n of t h e medium,Definitions

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6

CCYLJXTEKPOISE:

A system of wires or other conductors, f omin& i;he lower c a p a c i t y a r e a of a condenser antenna e l e v a t e d above and i ~ s u l a t e ?f r ~ z t h e ground.

CONTROL ELECTRODE:

The e l e c t r o d e , the voltage between which and the cathode c o n t r o l s t h c u r r e n t flowing between t h e anode and t h e cathoee.

CONVERTER:

A machine employing mechanical r o t a t i o n in changing e l e c t r i c a l energy f rom one form t o another.

CORRECTED R A D I O B E A R I N G : has been applied,COULOMB:

A r a d i o bearing t o which t h e c a l i b r a t i o n c o r r e c t i o n

The coulomb f s t h e q u a n t i t y of e l e c t r i c i t y or t h e charge t r a n s mitted i n 1 second by a c u r r e n t of 1 ampere.

COUPLER: A device employed t o t r a n s f e r radio- frequency power from one c i r e u i t t o another by a s s o c i a t i n g t o g e t h e r p o r t i o n s of these c i r c u i t s Couplers a r e of t b same types a s the types Of coupling; namely, i n d u c t i v e : c a p a c i t i v e and r e s i s t a n c e .COUPLING: The a s s o c l a t f o n of two c i r c u i t s i n such a way t h a t energy mag- be t r a n s f e r r e d from one "c th.e o t h e r ,COUPLI~VGCOEFFICIENT:

.

The r a t i o of t h e mutual or common impedance component of two c f r c u i t s t o t h e square r o o t of t h e product of the t o t a l impedance components of the same kind i n two c i r c u i t s , (Impedance components may c o n s l s t of inductance, c a p a c i t y or r e s i s t a n c e . )

C R E T AMPLIFICATION (OF A N AMPLIFIER jr "h UKN Te r a t i o of the a l t e r n a t i n g curr e n t produce& i n t h e output c i r c u i t t o the a l t e r n a t i n g c u r r e n t supplied t o t h e input c i r c u i 6 ,CYCLE:pl id

One compl-ete s e t of t h e r e c u r r e n t values of a p e r i o d i c phenomenon,

@

DAMPED ALTERNATING CURRENT:

$j

A a l t e r n a t fng c u r r e n t pas s i n g through succe s sive n c y c l e s with p r o g r e s s i v e l y diminishing amplftude.

,# FB!,f.,~,,

1 1

,

DAMPED IXPLQANCE : The damped impedance of" an e l e c t r o - a c o u s t i c transducer i s t h e impedance measured a t t h e t e r m i n a l s of i t s e l e c t r i c a l system when t h e impedance of t b a t t a c h e d m c h a n i c a l system is S n f i n i t e or vice versa.DAMPED W V S A E : Electromagnetic waves proceeding i n wave t r a i n s i n each o f which t h e amplitude of successive cycles p r o g r e s s i v e l y diminishes.DAMPING CONSTANT:

The Napierian l ~ g a f f t h mof the r a t i o of two values of an e x p o n e n t i a l l y d e c r e a s i n g q u a n t i t y s e p a r a t e d by u n i t time.

DECREKWER: A instrument f o r measuring t h e l o g a r i t h m i c decrement of a n t r a i n of waves.

DECREMENT:

Percentage of decrease of amplitude i n o s c i l l a t i o n . Definitions

-

sheet 7

:

"at :ortion of t h e r e c e i v i n g apparatus which, connected t o e c i r w i t c a r r j i i l g c u r r e n t s of radio- frequency, and i n conjunction w i t h a s e l f - c m t a i n e d or s e p a r a t e i n d i c a t o r , t r a n s l a t e s t h e r a d i o - f r e w e n c y power i n t o a form s u i t a b l e f o r o p e r a t i o n of t h e i n d i c a t o r , This t r a n s l a t i o n may be e f f e c t e d e i t h e r by t h e conversion of t h e radio- frequency power, or by means of the c o n t r o l of l o c a l power, The i n d i c a t o r may be a telephone r e c e i v e r , r e l a y i n g device, tape r e c o r d e r , e t c .

The most common t y p e of d e t e c t o r i s a vacuum tube operated on a nonl i n e a r p o r t i o n of i t s c h a r a c t e r i s t f c curve, t h e r e b y converting a modul a t e d radio-frequency c u r r e n t i n t o a modulated d i r e c t c u r r e n t ,A tube which o p e r a t e s s i m i l a r l y t o a d e t e c t o r t u b e , but t h e output of which does not o p e r a t e an i n d i c a t o r , may p r o p e r l y be c a l l e d a frequency converting tube.

DIAPHRAGM:tions,

A diaphragm i s a v i b r a t i n g s u r f a c e which produces sound v i b r a -

DIELECTRIC: D i e l e c t r i c i s an i n s u l a t i n g substance t h a t a l l o e s e l e c t r o s t a t f c i n d u c t i o n t o a c t a c r o s s i t , as t h e i n s u l a t i n g medium between t h e p l a t e s of a condenser. DIODE: A type of vacuum tube c o n t a i n i n g two e l e c t r o d e s which passes c u r r e n t wholly ay8 predominantly i n one d i r e c t i o n ,

Note:: A vacuum tube having a s i n g l e cathode and two modes which o p e r a t e a l t e r n a t e l y may p r o p e r l y be c a l l e d a double diode,DIFlECT CAPACITANCE (C ) BETWEEN TWO CONDUCTORS: The r a t i o of the charge produced on one coneuctor t o t h e voltage between it and t h e o t h e r cond u c t o r divided by t h i s v o l t a g e , a l l . o t h e r conductors i n t h e neighborhood being a t t h e p o t e n t i a l of e i t h e r conductor, DIRECT CCUPLING: A s s o c i a t i o n of two r a d i o c i r c u i t s by having an i n d u c t o r , a condenser, or a r e s i s t o r cormon t o both c i r c u i t s , DIRECT CUIIREKT: A unidiapectional e m r e a t . A s o r d i n a r i l y u s e d , t h e term designates s p r a c t i c a l l y non-pulsatim current, DIRECTIONAL ANTENIJA: An antenna having t h e p r o p e r t y of r a d l a t f n g or r e c e i v i n g r a d i o waves i n l a r g e r p r o p o r t i o n along some d i r e c t i o n s t h a n o t h e r s , An antenna o r t h i s type used f o r t r a n s m i t t i n g iis o f t e n c a l l e d a d i r e c t i v e antenna. DIRECTION-FINDER CALIERATION: The d e t e r m i n a t i o n of t h e d i r e c t ion and amount of f i x e d l o c a l wave f r o n t d i s t o r t i o n t o the end t h a t the c o r r e c t bearing may be obtained, DIRECTION FINDER (GONIOIVETER): A r a d f o r e c e i v i n g d e v i c e which permits detela mination of the l i n e of t r a v e l of waves a s r e c e i v e d . DISCHARGER: A device i n an O s c i l l a t i n g c i r c u i t by which t h e spark or a r c discharge i s c o n t r o l l e d . ( A l s o c a l l e d s p a r k d i s c h a r g e r ).

-

Definitions

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8

,~ " ..~- ., ,,.!: ,

. .mTqT.-,-c

- - ..a.

A c h c r G e i n wave f o r m o c c w i n g i n a t r a n s d u c e r or t r a n s ~ i s s i o n

n r e ? l w . whec t h e output wave f o r i l i s not a f a i t h f u l r e p r o d u c t i o n of t h e i w u t wave f o r m . The principal sources of d i s t o r t i o n a r e r

b, c.

Non-linear r e l a t i o n between input and output a t a g i v e n f'requency, Non-unif orm t r a n s m i s s i o n a t v a r i o u s f r e q u e n c i e s . Phase s h i f t not proporltional t o frequency.

DOUBLE MODULATION: The process of modulation i n which a c a r r i e r wave of one frequency i s f i r s t moduleted by t h e s i g n a l wave and i s then made t o modulate a second c a r r i e r wave of another frequency.

DRIVER ELEMENT: The d r i v e r element of a telephone r e c e i v e r i s t h a t p o r t i o n of t h e r e c e i v e r rrhich r e c e i v e s power from t h e e l e c t r i c a l system and conv e r t s i t i n t o mechanical power,

DRY CELL: A d r y c e l l . i s a type of primary c e l l i n which t h e e l e c t r o l y t e i s i n t h e form of a p a s t e , DUPLRX DI'ERATION T 1 o p e r a t i o n of a s s o c i a t e d t r a n s s x i t t i n g and r e c e i v i n g 1e channels i n which t h e processes of t r a n s m i s s i o n and r e c e p t i o n a r e concurrent.EARTH: That connection of t h e lower e x t r e m f t i e s of an antenna system f o r completing an e l e c t r f c c i r c u i t t o t h e ground,EDDY CUKRFNTSAnduced. e l e c t r i c e m r e n t s occurring when a m e t a l l i c mass i s a c t e d upon by a changing magnetic f i e l d , or th.e mass r o t a t e d i n a magnetic f i e l d , which consume a c o n s i d e r a b l e amount of e n e r g y ,E ~ C T ~ V E Hl3IGlE AS o r d i n a r i l y ing a unfforrn i n the actual

O AN ANTEIQiAflThe h e i g h t of an e q u i v a l e n t i d e a l antenna. F d e f f n e d , t h i s i d e a l antenna i s a v e r t i c a l conductor c a r r y c u r r e n t e q u a l t o t h e maximum c u r r e n t e x i s t f n g a t any p o i n t antenna.

Note: T h i s a p p l i e s m o s t s t r i c t l y t o a r t e n n a systems producing o r a f f e c t e d by a s u b s t a n t i a l l y v e r t i c a l electric field, ELFCTRO-ACOUSTIC TRARSDUCER: An e l e c t r o - a c o u s t i c t r a n s d u c e r i s a t r a n s d u c e r which i s a c t u a t e d by power Prom an e l e c t r i c a l . system ancl s u p p l i e s power t o an a c o u s t i c system o r v i c e v e r s a . ELECTRICAL OSCILLATION: An e l e c t r i c a l o s c f l l a t % o n i s a complete c y c l e of h i g h or audf o-frequency c u r r e n t , ELECTRICAL PHONOGRAPH RECORDER : A n e l e c t r i c a l phonograph r e c o r d e r i s a n electromechanical t r a n s d u c e r a c t u a t e d by power i n an e l e c t r i c a l system and supplying power t o a r e c o r d i n g mechanical system, t h e recorded wave form produced by t h e mechanical system c o r ~ e s p o n d i n gt o t h e wave form i n the e l e c t r i c a l system,ELECTROMAGNETIC LINES O FORCE: F Eleotromagnetic l f n e s of f o r c e a r e t h e l i n e s of f o r c e s e t up by a l l . c u r r e n t - c a r r y i n g conductars.

Definitions

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9

A s e n s i t i v e form of d e t e c t o r (now o b s o l e t e ) co e l e c t r o l y t i c c e l l , u s u a l l y w i t h a very small anode of insoluble m a t e r i a l , such as platinum, and a l a r g e r cathode immersed i n an e l e c t r o l y t e of 10 per c e n t s u l p h u r i c aciZ s o l u t i o n . O s c i l l a t i o n s from an outside source d e p o l e r i e e the anode and changes occur i n t h e l o c a l c u r r e n t which a c t s upon t h e telephone r e c e i v e r .

I G DETECTOR:

I

I

I

EmCTROMAGNETIC WAVE:

The propagation Of e l e c t r i c a l energy through space s e t i n t o motion by t h e displacement c u r r e n t about a r a d i o t r a n s m i t t i n g antenna.

EIXCTROMOTIVE FORCE: Electromotive f o r c e i s t h e voltage or e l e c t r i c a l pressure t h a t causes e l e c t r i c i t y t o flow i n a c i r c u i t . ELECTRON: A e l e c t r o n i s assumed t o be t h e s m a l l e s t known p a r t i c l e of matter n and i s an a c t i v e charge of negative e l e c t r i c i t y . ELECTRON EMISSION: The phenomenon of t h e l i b e r a t i o n of e l e c t r o n s from t h e s u r f a c e of a body i n t o t h e surrounding space, u s u a l l y under t h e influence of h e a t , i l l u m i n a t i o n , x- rays, impact e x c i t a t i o n , or chemical d i s i n t e gration. ELECTRON TUBE: An e l e c t r o n t u b e i s one whose o p e r a t i o n depends p r i m a r i l y upon a flow of e l e c t r o n s from one element t o another, ELECTROSCOPE: An i n s t r m n t f o r d e t e c t i n g small s t a t f c charges.

E .M . . : Abbreviation f o r Electromotive FOrCr3. F

EMISSION CHARACTERISTIC: The graph p l o t t e d between a f a c t o r c o n t r o l l i n g e l e c t r o n emission (such a s t h e temperature, voltage o r c u r r e n t of t h e cathode o r filament) a s a b s c i s s a s and t h e t o t a l emission from t h e cathode o r filament a s o r d i n a t e s . (See Grid C h a r a c t e r i s t i c ; P l a t e C h a r a c t e l ~ i s t i e ; and Mutual C h a r a c t e r i s t i c . ) EQUISIGNAL RADIO RANGE: A r a d io range which t r a n s m i t s two d i s t i n c t i v e s i g n a l s which may be r e c e i v e d w i t h e q u a l i n t e n s i t y only i n c e e t a i n directions, EQUISIGNAL ZONE: A r e g i o n i n which two d i s t i n c t i v e s i g n a l s from an e q u i s i g n a l r a d i o mnge a r e r e c e i v e d w i t h e q u a l i n t e n s f t ye EXPONENTIAL HORN: A e x p o n e n t i a l horn (sometimes c a l l e d logarithmic horn) n i s a horn whose s e c t i o n a l a r e a v a r i e s e x p o n e n t i a l l y with i t s length. FACSIMILE TRANSMISSION: The e l e c t r i c a l transmission of a copy o r reproduct i o n of a p i c t u r e , drawing, or document, ( T h i s i s also called picture transmission). FADING: The v a r i a t i o n of the s i g n a l i n t e n s i t y received a t a given l o c a t i o n from a r a d i o t r a n s m i t t i n g s t a t i o n a s a r e s u l t of changes occurring i n t h e transmission path. FARAD: The f a r a d is t h e u n i t of c a p a c i t y and r e p r e s e n t s t h e charge i n a condenser when an e l e c t r o m o t i v e f o r c e of 1 v o l t w i l l place i n t o it an e l e c t r i c charge of 1 coulomb. Definitions s h e e t 10

iii!

i -

,:,j

-

he sum of the c u r r e n t s a t a11 tb a n t i eeding the antenna.FIDELITY: FIU&~NT:

RATIO ( O F A M U L T I P L E TUNED ANPENNA):

The degree t o which a system, o r a p o r t i o n of a system, accur a t e l y reproduces a t i t s output t h e s i g n a l which i s imp-essed upon i t .

A cathode i n which t h e heat i s supplied by c u r r e n t passing through t h e cathode.

FILAMENT CAPACITANCE ( C f ) : The sum of t h e d i r e c t capacitances between t h e

filament and a l l o t h e r conductors of a vacuum t u b e ,FII,A&~ENT CURRENT: FI~.&~J?,NT FILTER:

The c u r r e n t supplied t o t h e f i l a m e n t t o heat it.

VOLTAGE : The voltage between t h e terminals of t h e filament

.

A s e l e c t i v e c i r c u i t network, designed t o pass c u r r e n t s within a continuous band o r bands of frequencies o r d i r e c t c u r r e n t , and s u b s t a n t i a n y reduce the amplitude of c u r r e n t s of undesired frequencies.

FIXED

CONDENSER: A f i x e d condenser i s one whose p l a t e s a r e s t a t i o n a r y and whose c a p a c i t y cannot be changed, ANTENNA: A n antenna having approximately h o r i z o n t a l conductors a t

FMT-TOP FLUX:

the top. By t h e f l u x of a c o i l i s meant the electromagnetic l i n e s of f o r c e produced by a c u r r e n t i n t h a t coP1.

FORCE FACTOR:

The f o r c e f a c t o r of an e l e c t r o - a c o u s t i c transducer i s a meas u r e of t h e coupling between i t s e l e c t r i c a l and mechanical systems. ~t i s t h e r a t i o of t h e open c l r c u i t f o r c e or v o l t a g e i n t h e secondary system t o the c u r r e n t o r v e l o c i t y i n t h e primary system.

FORCED ALTERNATING CURRENT:

The a l t e r n a t i n g c u r r e n t which flows i n a c i r c u i t a s t h e r e s u l t of an impressed a l t e r n a t i n g voltage and which has t h e same frequency.

FREE ALTERNATING CURRENT: The damped a l t e r n a t i n g c u r r e n t which flows i n a c i r c u i t following t h e c e s s a t i o n of an impressed voltage.F R E E RADIATOR: A f r e e r a d i a t o r i s an a c o u s t i c r a d i a t o r , t h e sound fram which i s o r i g i n a t e d i n an unconstrained medium.

FREQUENCY:

The number of c y c l e s per second.

FREQUENCY CHANGER: FREQUENCY METER:

A device d e l i v e r i n g a l t e r n a t i n g c u r r e n t a t a frequency which d i f f e r s from t h e frequency of the supply c u r r e n t .

A instrument f o r measuring frequency. n used i n r a d i o work a r e sometimes c a l l e d wavemeters.

Frequency meters

FREQUENCY MULTIPLER:

A frequency changer used t o m u l t i p l y by a n i n t e g e r the

frequency of an a l t e r n a t i n g c u r r e n t , Definitions

-

sheet 1 1

h a l f cycle of the a l t e r n a t i n g c u r r e n t supply, one element f u n c t i o n i n g d u r i n g one-half cycle and t h e o t h e r during t h e next h a l f c y c l e , and so on.FUNDAMENTAL FREQUENCY: T h a t frequency a r e integral multiples.Of

which a l l component f r e q u e n c i e s

PUNDANENTAL OR NATURAL FREQUENCY (OF AN A T N A ) : The lowest' resonant f r e NE N quency of a n antenna, without added inductance o r c a p a c i t y .

-

A EE F N A E T L W V I NGTH : The wavelength corresponding t o fundamental f reguency. U D MNA G L A O E W : A s e n s i t i w e instrument f o r i n d i c a t i n g t h e presence of an AV N MT e l e c t r i c current i n a c i r c u i t , and determining i t s d i r e c t i o n . GENERATOR: A e l e c t r i c generator i s a device or machine f o r converting n mechanical energy i n t o e l e c t r i c a l energy.

I1

I

GONION1ETER:

Same a s D i r e c t i o n Finder.

GRID: A e l e c t r o d e having openings through which t h e e l e c t r o n stream n between cathode and anode may pass.

GRID BIAS:

The d i r e c t eomponent of t h e g r i d voltage.

G R I D CAPACITANCE ( C g ) : The sum of t h e d i r e c t capacitances b8 tween t h e g r f d and a l l o t h e r conductors of a vacuum tube.G R I D CHARACTERISTIC: T h e graph p l o t t e d between g r i d voltage a s a b s c i s s a s (See P l a t e C h a r a c t e r i s t i c ; Mutual Charand g r i d current a s o r d i n a t e s . a c t e r i s t i c and Emission C h a r a c t e r i s t i c ),

I I

GRID CONDENSER:

A s e r i e s condenser i n t h e g r i d or c o n t r o l c i r c u i t of a

vacuum tube.G R I D CONDUCTANCE:

The r a t i o of t h e change i n g r i d c u r r e n t t o the change i n g r i d voltage producing i t , under the condition of constant p l a t e p o t e n t i a l . The d i r e c t c u r r e n t passing from t h e g r i d through t h e vacuous The d i r e c t capacitance between the g r i d

GRID CURRENT: space.

FILAMENT CAPACITANCE ( C g f ) z GRIDand the filament.

GRID LEAK.' A r e s i s t o r used t o a f f e c t or determine t h e g r f d b i a s .GRID-PLATE CAPACITANCE ( C g p ) : the plate.G R I D VOLTAGE:

The d i r e c t capacitance between t h e g r i d and

The v o l t a g e between t h e g r i d and a s p e c i f i e d p o i n t of the

cathode.

h 'i I* 4?1

GROUND:

Same a s Earth. Definitions

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sheet 12

GROUND EQUALIZIER INDUCTORS:

C o i l s of r e l a t i v e l y low inductance placed. i n the c i r c u i t connected t o one or more of the grounding p o i n t s of an antenna ground system, t o d l H d e t h e c u r r e n t between t h e v a r i o u s p o i n t s i n any d e s i r e d way.

GROUND S S E Y T M (OF AN ANTENNA) :

That p o r t i o n of t h e antenna system below t h e antenna l o a d i n g devices or generating apparatus most c l o s e l y a s s o c i a t e d w i t h t h e ground and including t h e ground i t s e l f .A conductive connection t o t h e e a r t h .

GROUND \nllRE:

GROUP FREQUENCY:

The number of t r a i n s of damped waves or c u r r e n t per second.

H L - A E RECTIFIER: A r e c t i f i e r which changes a l t e r n a t i n g c u r r e n t i n t o p u l A FW V s a t i n g c u r r e n t , u t i l i z i n g only one-half of each cycle.HARMONIC : A component of a p e r i o d i c q u a n t i t y having a frequency which i s an i n t e g r a l multiple of t h e findamental frequency. For example, a component

t h e frequency of which i s twice t h e fundamental frequency i s c a l l e d the second harmonic.HARP ANTENNA: A antenna composed of v e r t i c a l , or approximately v e r t i c a l n conductors, a l l i n one plane.HELIX:

A hollow conducting c o i l o r solenoid.

HEWRY:

A henry i s t h e u n i t of inductance, and a c i r c u i t has an inductance of 1 henry when a c u r r e n t changing a t t h e r a t e of 1 a m p r e p e r second

produces an induced e.m.f.KERTZIAN WAVES:

of 1 v o l t .

Electromagnetic waves f i r s t observed by Hertz, which o r i g i n a t e i n a r a p i d l y v i b r a t i n g o r a l t e r r a t i n g c u r r e n t and a r e p r o j e c t e d f a r i n t o surrounding space. Radio communication i s a p r a c t i c a l a p p l i c a t i o n of t h i s discovery.

H T R D N RECEETION: The process of r e c e i v i n g r a d i o waves by combining t h e EEO Y E received voltage w i t h l o c a l l y generated a l t e r n a t i n g voltage. The l o c a l l y generated frequency i s ~ommonlyd i f f e r e n t from t h e r e c e i v e d frequency, t h u s producing beats. ? h i s i s c a l l e d beat r e c e p t i o n .HIGH-FREQUENCY CURRENT: A c u r r e n t where s e v e r a l thousand or more o s c i l l a t i o n s take place i n a second of time.

HIGH-PASS FILTER: A f i l t e r designed t o pass c u r r e n t s of a l l frequencies above a c r i t i c a l or cut - off frequency and s u b s t a n t i a l l y reduce t h e amplitude of c u r r e n t s of a l l f r e q u e n c i e s below t h i s c r i t i c a l frequency.HOMODYNE RECEPTION: The process of d e t e c t i n g a wave by t h e a i d of a l o c a l l y generated wave of c a r r i e r frequency. (Some times c a l l e d zero-beat reception). HONEYCOMB COIL: mation.HORN:

A m u l t i p l e l a y e r c o i l wound a i a g o n a l l y i n l a t t i c e l i k e f o r -

A horn i s a constrained r a d i a t o r c o n s i s t i n g of a tube of varying s e c t i o n a l area f o r determining the shape of t h e c o n s t r a i n e d p o r t i o n of t h e medium. Definitions sheet 13

-

HOT-WIRE

AMMETER : (Expansion type ) : An ammeter dependent f o r i t s i n d i c a t i o n s on a change i n dimensions of an element which i s heated by a current through i t ,

HYDROMETER:

An instrument f o r measuring the s p e c i f i c g r a v i t y of t h e e l e c t r o l y t e i n a s t o r a g e c e l l t o give a n i n d i c a t i o n of the s t a t e of charge of the c e l l .

HYSTERESIS: Expenditure and l o s s O f energy i n t h e form of h e a t due t o the work r e q u i r e d t o change t h e molecules; takes place i n process of magnetizing and de -magnet i e ing

.

IDFAL TRANSDUCER:

An i d e a l t r a n s d u c e r f o r connecting two s p e c i f i c systems i s a passive t r a n s d u c e r which converts the maximum p o s s i b l e power from t h e e l e c t r i c a l system t o t h e a c o u s t i c system or vice versa.

IMPEDANCE:

The impedance i s t h e t o t a l opposition of a c f r m i t t o the passage of a n a l t e r n a t i n g c u r r e n t .

IMPULSE EXCITATION: A method of producing damped o s c i l l a t o r y c u r r e n t i n a - c i r c u i t i n which t h e d u r a t i o n of t h e impressed voltage is s h o r t compared w i t h t h e d u r a t i o n of t h e c u r r e n t produced,INDUCTANCE:

The inductance of a c i r c u i t is i t s p r o w r t y t h a t allows it t o s t o r e up e l e c t r i c a l energy i n electromagnetic f o m .

INDUCTION: The inPluence e x e r t e d by the i n t e r f e r e n c e or influence of f i e l d s upon f i e l d s o r f i e l d s upon conductors o

MDUCTION MUDSPEAKER: An Induction loudspeaker i s a moving c o i l loudspeaker i n which t h e c u r r e n t which r e a c t s w i t h t h e p o l a r i z i n g f i e l d i s induced i n t h e mov3.ng member e INDUCTIVE COUPLINQ: The a s s o c i a t i o n of one c i r c u i t w i t h another by means of ( T h i s term when used without modiinductance common or mutual t o both. f ying words i s commonly used f u r coupling by means of mutual inductance whereas coupling by means of self- inductance common t o both c i r c u i t s i s c a l l e d " d i r e c t i n d u c t i v e coupling".

,

INDUCTOR: A device used i n r a d i o c i r c u i t s t o introduce t h e element o f InductanceINPUT ADMITTANCE : The r e c i p r o c a lOf

input impedance.

INPUT IMPEDANCE:

The r a t i o of the a l t e r n a t i n g voltage impressed on t h e input t e r m i n a l s of t h e device t o t h e a l t e r n a t i n g . c u r r e n t t h e r e b y produced a t t h e s e t e r m i n a l s , i n t h e absence of impressed a l t e r n a t i n g voltages a t o t h e r points.

I NS UL AT OR: An i n s u l a t o r i s a m a t e r i a l t h a t p r e s e n t s such a high opposition t o a flow of e l e c t r i c i t y t h a t t h e r e i s n o t a p e r c e p t i b l e flow through t h a t material.

INTERFEREXICE: Confusion of r e c e p t i o n due t o s t r a y s , undesired s i g n a l s or o t h e r causes; a l s o t h a t which produces t h e confusion. Definitions

- s h e e t 14

!< .. . ,,:.,

~ ? 6 ! Z D I A T EFREQUENCY: A frequency between t h a t O f t h e c a r r i e r employed i n r a d i o transmission and the frequency of modulation, and t o which t h e

c a r r i e r i s converted i n super-heterodyne r e c e p t i o n .INTERNAL OUTPUT ADMITTANCE:

The r e c i p r o c a l of i n t e r n a l output impedance.

INTERNAL OUTPUT IMPEDANCE: The r a t i o of t h e a l t e r n a t i n g voltage impressed on t h e output terminals of a vacuum tube t o t h e a l t e r n a t i n g c u r r e n t t h e r e b y produced h t t h e s e t e r m i n a l s , i n t h e absence of impressed a l t e r n a t i n g voltages a t o t h e r p o i n t s . Note: T h i s i s sometimes c a l l e d simply "output impedance" but t h e p r e f i x " i n t e r n a l n i s p r e f e r r e d i n order more s u r e l y t o d i s t i n q u i s h it from t h e impedance of t h e e x t e r n a l output c i r c u i t . INTERRUPTED CONTINUOUS W V S Waves obtained by i n t e r r u p t i o n a t audioA E: frequency i n a p e r i o d i c manner of an otherwise continuous wave. INTERRUPTER: Apparatus f o r breaking up a continuous c u r r e n t i n t o a success i o n of pulses. INVERTED '$L" ANTENNA: A f l a t t o p antenna the l e a a d i n of which i s taken from one end of t h e h o r i z o n t a l portfon.IONIZATION:JAMMING:

The breaking up of a compound i n t o p o s i t i v e and negative ions.

I n t e r f e r e n c e , malicious or otherwise, from u n d e s b e d s t a t i o n s .

JOULF:

The p r a c t i c a l u n i t of e l e c t r i c a l energy; denotes work done by one coulomb under one v o l t pressure.

m:

A key i s a s p e c i a l form of switch arranged f o r r a p i d operation t o form d o t s and dashes of t h e t e l e g r a p h codes.

KEIY-MODULATED W V S : Continuous waves of which t h e amplftude o r frequency AE i s va'rfed by t h e o p e r a t i o n of a t r a n s m i t t i n g key i n accordance w i t h t h e c h a r a c t e r s of a communicating code.KILOCYCLE (STRICTLY KILOCYCLE P R SECOND ) : A thousand cycles per second. E

KILOWATT:

One thousand w a t t s .

LEAD-IN That p o r t i o n of an antenna system which completes t h e e l e c t r i c a l connection between t h e e l e v a t e d outdoor p o r t i o n a d t h e instruments o r disconnecting switches i n s i d e the building.-ENJ AR: A condenser composed of a g l a s s j a r w i t h i n n e r and outer surf a c e s coated w i t h copper.

LIGHTNING ARRESTER: A l i g h t n i n g a r r e s t e r i s a d e v i c e f o r p r o t e c t i n g a c i r c u i t or apparatus from l i g h t n i n g or o t h e r e x c e s s i v e l y h i g h voltages.LOADIRTG COIL:

An i n d u c t o r i n s e r t e d i n a C i r c u i t t o i n c r e a s e i t s inductance but not t o provide coupling with any other c i r c n i t . Definitions sheet 1 5

-

L OD E S T ONE :

A n a t u r a l o r e possessing inherent q u a l i t i e s of magnet i s m .

LOGARITHMIC DECRENENT:

The Napierian logarithm of t g e r a t i o of t h e f i r s t t o t h e second of two s u c c e s s i v e amplitudes i n t h e same d i r e c t i o n , f o r an exp o n e n t i a l l y damped a l t e r n a t i n g c u r r e n t . The l o g a r i t h m i c decrement can a l s o be considered a s a constant of a simple r a d i o c i r c u i t , being f l times the product of t h e r e s i s t a n c e and the square r o o t of t h e r a t i o of t h e c a p a c i t y t o t h e inductance of t h e c i r c u i t .

L O A T N A An antenna c o n s i s t i n g of one o r more complete t u r n s of wire. O P NE N : This i s a l s o c a l l e d a c o i l antenna. LW FREQUENCY CURRENT: A c u r r e n t where a l i m i t e d number of o s c i l l a t i o n s , O about 60 t o 500 c y c l e s , t a k e place i n a second of time. LOUDSPEAKER: A loudspeaker i s a telephone r e c e i v e r designed t o r a d i a t e a c o u s t i c power i n t o a room or open a i r . PASS FILTER: A f i l t e r designed t o pass c u r m n t s of a l l f r e q u e n c i e s beLOWlow a c r i t i c a l or c u t - o f f frequency and s u b s t a n t i a l l y r e a c e t h e amplitude of c u r r e n t s of a l l f r e q u e n c i e s above t h i s c r i t i c a l frequency.MAGNETIC FIELD:

The r e g i o n surrounding a magnet L h r ough which magnetic

forces act.MAGNETIC LOUDSPEAKER:M A GNETIC MICROPHONE:A magnetic loudspeaker i s one i n which t h e mechanfcal f o r c e s r e s u l t from magnetic r e a c t i o n s ,

A magnetic microphone i s one whose e l e c t r i c a l output i s generated i n a c o i l o r conductor i n a magnetic c i r c u i t o r f i e l d . A magnetic device employed a s a modulator a d f u n c t i o n ing by v i r t u e of i t s non- linear magnetization c h a r a c t e r i s t i c ,

MAGNETIC MODULATOR: MAGHETIC PI CKUP :

A magnetic pickup i s a phonograph pfckup whose e l e c t r f l c a l output i s generated i n a c o i l o r conductor i n a magnetic c i r c u i t or f i e l d ,

MAGNETOSTRICTION LOUDSPEAKER: A magnetostriction kouilspeaker i s a magnetic loudspeaker i n which t h e mechanical f o r c e s a r e obtained by magnetostriction.MASTER 0SCILLATOR"n

o s c i l l a t o r of comparatively low power s o arranged a s t o c o n t r o l the frequency of the output of an amplif 5.e~.

ME C H A N I C A L DdPEDANCE:

The mechanical impedance of a mechanical system i s t h e complex q u o t i e n t of t h e a l t e r n a t i n g f o r c e a p p l i e d t o t h e system by t h e r e s u l t i n g a l t e r n a t i n g l i n e a r v e l o c i t y i n t h e d i r e c t i o n of t h e f o r c e a t i t s p o i n t of a p p l i c a t i o n .

ME C H A N ICAL REACTANCE:

The mechanical reactance of a mechanical system i s t h e magnitude of t h e imaginary component of t h e mechanical impedance. It may a l s o be expressed a s t h e component of the mechanical impedance of t h e system r e s u l t i n g from i t s e f f e c t i v e mass or compliance.

rn

Definitions

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sheet 16

I

I I

MECHANICAL RESISTANCE:

!I

The mechanical r e s i s t a n c e of a p e c h a n i c a l system i s t h e r e a l component of t h e mechanical impedance. It may a l s o be expressed a s the quotient of the power absorbed by t h e system by the square of the a l t e r n a t i n g v e l o c i t y a t t h e point o f a p p l i c a t i o n of t h e force.A m i l l i o n Cycles per second.

d

,I

MEGACYCLE (STRICTLY MEGACYCLE PERSECOND ) :

iI

MEGOHM:

A megohm i s a r e s i s t a n c e of 1,000,000 ohms.

i

METER: ( a ) The meter i s t h e u n i t of l e n g t h i n t h e m e t r i c system, l a r g e l y used i n European c o u n t r i e s , and corresponds t o a l e n g t h of 39.37 inches. ( b ) A meter i s an instrument f o r measuring some q u a n t i t y , as a voltmeter.

M T R AMPERES: The product of t h e antenna c u r r e n t i n amperes a t t h e point EE of maximum currellt and the antenna e f f e c t i v e height i n rreters f o r any r a d i o t r a n s m i t t i n g s t a t ion.MICA:

A mineral i n s u l a t o r . A microfarad i s a c a p a c i t y of l/l,000,000

MICROFARAD:MICROPHONE:

of a f a r a d .

A microphone i s an e l e c t r o - a c o u s t i c t r a n s d u c e r a c t u a t e d by power i n a n a c o u s t i c system and d e l i v e r i n g power t o an e l e c t r i c system, t h e wave form i n t h e e l e c t r i c system corresponding t o t h e wave form i n t h e a c o u s t i c system. T h i s i s a l s o c a l l e d a telephone t r a n s m i t t e r .

MILLIAMPERE: . A milliampere i s a c u r r e n t of t h e s t r e n g t h of 1/1,000 of an ampere.

MOBILE STATION:

A s t a t i o n capable of moving and which o r d i n a r i l y does move.

MODULATED W V S Continuous waves Of which t h e amplitude or frequency i s A E: r e p e a t e d l y varied i n accordance w i t h a s i g n a l wave. MODULATION: The process whereby t h e frequency or amplitude of a wave i s varfed i n accordance w i t h a s i g n a l wave,MOD U LA T OR :' A device t o e f f e c t t h e process of modulation. It may be operated by v i r t u e of some non- linear c h a r a c t e r i s t i c or by a c o n t r o l l e d v a r i a t i o n of some c i r c u i t q u a n t i t y .

K O N I T O R I N G RADIO RECEIVER: A r a d i o r e c e i v e r arranged t o enable an operator t o check t h e operation of a t r a n s m f t t i n & s e t .blOTIONAL IMPEDANCE:

The motional impedance of an e l e c t r o - a c o u s t i c t r a n s ducer i s t h e vector d i f f e r e n c e between the normal and t h e damped i m pedance.

MOUTH O A HORN: F The mouth of a horn i s t h e end w i t h the l a r g e r c r o s s s e c t i o n a l area.M O V I N G I R O N LOUDSPEAKER:

A moving i r o n l o u d s p a k e r i s a magnetic loudspeaker whose operation involves t h e v i b r a t i o n of a p o r t i o n of t h e ferro- magnetic circuit.

V

Definitions

- sheet

17

* MOVING C O I L LOUDSPEAKER: A moving c o i l loudspeaker i s a magnetic loudspeaker i n which the mechanical f o r c e s a r e developed by t h e i n t e r a c t i o n of curr e n t s i n a conductor and t h e p o l a r i z i n g f i e l d i n which it i s located. T h i s i s sometimes c a l l e d an Electro-Dynamic o r a Dynamic Loudspeaker.MULTIPIBTUNED ANTENNA: A antenna w i t h connections t o ground or countern poise through inductances a t more than one p o i n t , the inductances being s o determined t h a t t h e i r r e a c t a n c e s i n p a r a l l e l present a t o t a l reactance equal t o t h a t necessary t o g i v e t h e anteqna t h e d e s i r e d n a t u r a l frequency.MUTUAL CHARACTERISTIC (GRID-PLATE CHARACTERISTIC ) :

V

The graph p l o t t e d between g r i d voltage a s a b s c i s s a s and p l a t e current a s o r d i n a t e s . (See G r i d C h a r a c t e r i s t i c ; Mutual Conductance ; P l a t e C h a r a c t e r i s t i c ; and Emission characteristic.) The r a t i o of t h e change i n p l a t e c u r r e n t t o the change i n g r i d p o t e n t i a l producing i t , under the condition of constant p l a t e voltage. (The u n i t o r d i n a r i l y used i s t h e micromho).

MUTUAL CONDUCTANCE:

NUTUAL 1ADUCTANCEAut.ual inductance i s the term a p p l i e d t o d e s i g n a t e tne inductance produced by a c u r r e n t change i n one of two independent c i r c u i t s which r e a c t upon e a c h other.

NORMAL IMPEDANCE : The normal impedance of a n e l e c t r o - a c o u s t i c transducer i s the impedance measured a t t h e terminals of t h e e l e c t r i c a l system when the mechanical system i s connected t o i t s load o r vice v e r s a .OHM: An ohm i s the u n i t of r e s i s t a n c e , and may be defined a s the r e s i s t a n c e t h a t w i l l allow 1 ampere of c u r r e n t t o pass under the pressure due t o an electromotive f o r c e of 1 v o l t .

OSCILLATIONS: Electromagnetic waves s e t up i n space by t r a n s m i t t i n g instruments. OSCILLATION CONSTANT: The o s c i l l a t i o n constant of an o s c i l l a t i n g c i r c u i t i s t h e numerical f i g u r e obtained from the square r o o t of i t s inductance multi p l i e d by i t s capacity. OSCILLATION TRANSFORMER: An o s c i l l a t i o n transformer i s a s p e c i a l open type of transformer p r i m a r i l y used f o r t r a n s f e r r i n g l a r g e amounts of o s c i l l a t ing energy from one c i r c u i t t o another. CSCILLATOR: A non - rotating device f o r producil3g a l t e r n a t i n g power, the out put frequency of which i s determined by t h e c h a r a c t e r i s t i c s of the device. OSCILLATORY CIRCUIT: A r e l a t i v e l y low r e s i s t a n c e c i r c u i t containing both inductance and c a p a c i t y , such t h a t a voltage impulse w i l l produce a curr e n t which p e r i o d i c a l l y r e v e r s e s .PACKING:

-

Packing i n a carbon microphone i s a c o n d i t i o n caused by excess mechanical p r e s s u r e between pofnt s of contact or by adherence betrzeen It i s evidenced by p o i n t s of contact r e s u l t i n g from excessive voltages. decreased r e s i s t a n c e and s e n s i t i v i t y of the microphone.

Definitions

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sheet 18

i

PARALLFL C O N N E C T I O N :

A p a r a l l e l connection of e l e c t r i c a l devices o r c i r c u i t s

i s one i n which t h e c u r r e n t d i v i d e s , only a p a r t of t h e t o t a l c u r r e n t passing through e a c h d e v i c e or c i r c u i t .PARALLEL RESONANCE: A c o n d i t i o n which e x i s t s i n a c i r c u i t having inductance and c a p a c i t y connected i n p a r a l l e l , when t h e supply c u r r e n t and supply v o l t a g e a r e i n phase.PASSIVE TRANSDUCER:

A p a s s i v e t r a n s d u c e r i s one i n which t h e power supplied t o t h e second system i s obteined e n t i r e l y from t h e power a v a i l a b l e frorn t h e f i r s t system.

PERCENTAGE MODULATION: The r a t i o of h a l f t h e d i f f e r e n c e between t h e maximum and minimum amplitudes of a modulated wave t o t h e average amplitude, expressed i n per c e n t . PERIOD: The period of a n a l t e r n a t i n g Current i s t h e time r e q u i r e d f o r one cycle t o pass through a complete s e t of p o s i t i v e and negative values. PERIODIC CURRFNT: P e r i o d i c a l l y r e v e r s i n g c u r r e n t the frequency of which i s determined by t h e e l e c t r i c a l c o n s t a n t s of t h e c i r c u i t s i n which i t flows. It may be e i t h e r damped or continuous.PERIODIC TIME:

The time of a completed p e r i o d .

PHONOGRAPH PICKUP: A phonograph pickup i s a n e l e c t r o m e c h a n i c a l t r a n s d u c e r a c t u a t e d by a phonograph r e c o r d and d e l i v e r i n g power t o an e l e c t r i c a l system, t h e wave form i n t h e e l e c t r i c a l system corresponding t o t h e wave form i n t h e phonograph r e c o r d .

PHOTOEIECTKIC T B " UE . form Of vacuum tube i n which the e l e c t r o n emission i s produced by t h e i l l u m i n a t i o n of t h e cathode. (Also c a l l e d t h e photoelectric cell. ) PIEzO-ELECTRIC LOUDSPEAKZR: A p i e z o - e l e c t r i c loudspeaker is one i n which t h e mechanical f o r c e s a r e obtained by use of a p i e z e - e l e c t r i c element. PIEZO-ELECTRIC PICKUP: A p i e z o - e l e c t r i c pickup i s a phonograph pickup whose e l e c t r i c a l output i s g e n e r a t e d by varying mechanical s t r e s s e s i n t h e piezo- electric c r y s t a l .PLATE:

The common name f o r t h e anode i n a vacuum t u b e .

The sum of t h e d i r e c t c a p a c i t a n c e s between the PLATE CAPACITANCE ( C p ) : p l a t e and a l l o t h e r conductors of a vacuum tube.PLATE CHARACTERISTIC : The g r a p h p l o t t e d between p l a t e volt age a s a b s c i s s a (See Grid C h a r a c t e r i s t i c ; Mutual C and p l a t e c u r r e n t a s o r d i n a t e s . a c t e r i s t i c : and Emission C h a r a c t e r i s t i c . )

PLATE C m C U I T :

The p l a t e c i r c u i t of a n e l e c t r o n t u b e include connected d i r e c t l y i n t h e e x t e r n a l c i r c u i t between t h e c a t p l a t e elements.

P

ate p o t e n t i a l producing it , under t h e cotial.

GOhWCTANCE:

The r a t i o of t h e change i n

PLATE CURRENT: space

.

The d i r e c t c u r r e n t passing from t h e p l a t e through t h e vacuous

PLATE-FILAhBNT CAPACITANCE ( C p f ) : and t h e filamentPLATE RESISTANCE:

.

The d i r e c t capacitance between t h e p l a t e

The r e c i p r o c a l of t h e p l a t e conquctame.

PLATE VOLTAGE: cathode.

The voltage between t h e p l a t e and a s p e c i f i e d point of t h e

POLARITY:POTENTIAL:

The p r o p e r t y of having opposite poles o r e l e c t r i c signs (

+ and

- ).

The degree of pressure of a n e l e c t r i c a l charge.

POTENTIOMETER: The potentiometer i s an arrangement f o r o b t a i n i n g any d e s i r e d voltage by u t i l i z i n g t h e voltage drop across t h e r e q u i r e d p o r t i o n of a current- carrying r e s i s t a n c e .

P W R AAIPLIFICATION (OF AN AMPLIFIER ): The r a t i o o f t h e a l t e r n a t ing- current O E power produced i n t h e output c i r c u i t t o t h e a l t e r n a t i n g - c u r r e n t power supplied t o the input c i r c u i t . POWERAMPLIFIER: A a m p l i f i e r t h a t i s capable of producing r e l a t i v e l y l a r g e n power i n an putput c i r c u i t .POWER LFVEL: The power l e v e l a t any point i n a system i s an expression of the power being t r a n s m i t t e d p a s t t h i s point.

PRIMARY CELL: A primary c e l l i s a type of c e l l whose voltage i s d i r e c t l y due t o t h e chemical decomposition of matter. (See d r y c e l l ) .

PRIKARY C O I L :

A primary c o i l i s t h e input winding of a transformer.

PROTECTDE DEVICE: A device f a r keeping c u r r e n t s or v o l t a g e s of undesirably l a r g e magnitude out of a given p a r t of an e l e c t r i c a l c i r c u i t . For example, f u s e ; l i g h t n i n g a r r e s t e r . PULSATING CURRENT: A p e r i o d i c c u r r e n t , t h a t i s , c u r r e n t passing through successive c y c l e s , t h e a l g e b r a i c average v a l u e of which is not zero. A p u l s a t i n g current i s e q u i v a l e n t t o t h e sum of a n a l t e r n a t i n g and a d i r e c t current. PUSH-PULL MICROPHONE: A push- pull microphone i s one which makes use of t w o functioninq elements 180 degrees out of phase.RADIATE:RADIATION:

To emit e l e c t r o m a g n e t i c waves i n t o space. The process of e m i t t i n g electromagnetic waves i n t o space.

RADIATION EFFICIENCY:

The r a d i a t i o n e f f i c i e n c y of a n antenna i s t h e r a of power r a d i a t e d t o t h e t o t a l power d e l i v e r e d t o the antenna, a t given frequency

.

RADLATION RESISTANCE:

The r a t i o of t h e t o t a l power r a d i a t e d b t h e square of the e f f e c t i v e current a t the point of maximum Definitions

RADIO- BEACON:

A r a d i o t r a n s m i t t i n g s t a t i o n i n a f i x e d geographic l o c a t i o n which e m i t s a d i s t i n c t i v e or c h a r a c t e r i s t i c s i g n a l f o r e n a b l i n g mobile r e c e i v i n g s t a t i o n s t o determine bearings or courses.

R A D I O BEARING:

The angle between t h e d i r e c t i o n of t h e advance of t h e i n coming r a d i o wave and an a r b i t r a r i l y f i x e d l i n e (such a s t h e c e n t e r l i n e of a s h i p ).

RADIO CHANIEL:

A band of f r e q u e n c i e s or wavelengths of a width s u f f i c i e n t t o permit of i t s use f o r r a d i o communicotion. The width of a channel depends upon t h e t y p e of t r a n s m i s s i o n ./

R A D I O COMMUNICATION: Applies t o the t r a n s m i s s i o n by r a d i o of w r i t i n g , s i g n s , s i g n a l s , p i c t u r e s , and sounds of a l l kinds.RADIO CONIMUNICATION STATION (OR RADIO STATION): c a r r y on r a d i o communications.

Any s t a t i o n equipped t o

RADIO C M A S O PS

A d i r e c t i o n f i n d e r used f o r navig?.tional purposes.

R A D I O FIELD INTENSITY: The Toot -mean-square value of t h e e l e c t r i c or magnetic f i e l d i n t e n s i t y a t a p o i n t due t o t h e passage of r a d i o waves. It i s u s u a l l y expressed tn terms of t h e e l e c t r i c f i e l d i n t e n s i t y , i n microvolts p e r meter or m i l l i v o l t s per meter.RADIO FREQUENG! : A frequency h i g h e r than those corresponding t o normally a u d i b l e sound waves,

Note:

It i s not implied t h a t r a d i a t i o n cannot be secured a t lower f r e q u e n c i e s , nor t h a t r a d i o - f r e q u e n c i e s a r e n e c e s s a r i l y above the l i m i t of a u d i b i l i t y .

RADIO-FREQUEBCY ALTERNATOR : A r o t a t i n g - t y p e a l t e r n a t i n g c u r r e n t generator which g e n e r a t e s radio- frequency power.RADIO-FREQUENCY TRANSFORMER: cur r e n t s

.

A transformer f o r use w i t h radio- frequency

RADIO NOISE FIELD INTENSITY: A measure of the f i e l d i n t e n s i t y , a t a point ( a s a r a d i o r e c e i v i n g s t a t i o n ) of e l e c t r o m a g n e t i c waves of an i n t e r f e r ing character. I n p r a c t i c e t h e q u a n t i t y measured i s not the f i e l d i n t e n s i t y of t h e i n t e r f e r i n g waves, b u t some q u a n t i t y which i s p r o p o r t i o n a l t o o r bears a known r e l a t i o n t o t h e f i e l d i n t e n s i t y .R A D I O RANGE: A r a d i o beacon which t r a n s m i t d i r e c t e d waves by means of which d e p a r t u r e s from a given course may be observed.R A D I O RECEIVER:

A device f o r c o n v e r t i n g r a d i o waves i n t o p e r c e p t i b l e s i g n a l s .

R A D I O TRANSWITTEE:

A d e v i c e f o r producing radio- frequency power and modifyi n g i t i n accordance w i t h a s i g n a l .

R A D I O TRANSMISSION:

The t r a n s m i s s i o n of s i g n a l s by means of r a d i a t e d e l e c t r o mag~etic waves o r i g i n a t i n g i n a c o n s t r u c t e d c i r c u i t . Definitions

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sheet 21

R A D I O IIIrAVE-FRONT DISTORTION:

waves.

A change i n the d i r e c t i o n of advance of r a d i o

REACTANCE:

Reactance i s t h e term applied t o express t h e opposition of a wire t o changes of , c u r r e n t e s t a b l i s h e d i n i t .

RECTIFIER: A device having a n asyrumetricay conduction c h a r a c t e r i s t i c which i s used f o r t h e conversion of an a l t e r n a t i n g c u r r e n t i n t o a p u l s a t i n g c u r r e n t . Such devices include vacuum-tube r e c t i f i e r s , g a s r e c t i f i e r s , oxide r e c t i f i e r s , e l e c t r o l y t i c r e c t i f i e r s , e t c . Note: In d e a l i n g w i t h r e c t i f i c a t i o n i n t h e r e c e p t i o n of r a d i o s i g n a l s t h e term " d e t e c t o r " i s p r e f e r red t o " r e c t i f i e r " . REFLEX C I R C U I T : A c i r c u i t arrangement i n which one o r more a m p l i f i e r tubes amplify the s i g n a l both before and a f t e r d e t e c t i o n . REFRACTION: The change i n d i r e c t i o n of the flow of a n e l e c t r i c c u r r e n t when i t passes from one medium t o another of d i f f e r e n t c o n d u c t i v i t y or of o t h e r differing electric qualities.REGENERATION: The process by which a p a r t of t h e output power of an amplif y i n g device r e a c t s upon the input c i r c u i t i n such a manner a s t o r e i n f o r c e t h e i n i t i a l power t h e r e b y i n c r e a s i n g the a m p l i f i c a t i o n . (Sometimes c a l l e d "feed back' or " r e a c t i o n " . )

REJECTOR: . c i r c u i t of inductance and c a p a c i t y which i s so arranged and P tuned a s t o o f f e r h i g h impedance t o t h e flow of c u r r e n t s of a given f r e quency and low impedance t o c u r r e n t s of a l l other frequencies.I

RELAY: A device by means of which c o n t a c t s i n one c i r c u i t a r e operated by a 'change i n conditions i n t h e same c i r c u i t o r i n one o r more a s s o c i a t e d circuit s

.

RESIDUAL MAGNETISM: The magnetism which remains i n t h e core of a n e l e c t r o magnet a f t e r t h e c i r c u i t has been broken, RESISTANCE: Resistance i s t h e opposition t o t h e passage of a d i r e c t c u r r e n t or low-frequency a l t e r n a t i n g c u r r e n t by any substance o r m a t e r i a l . RESISTANCE COUPLING: The a s s o c i a t i o n of one c i r c u i t w i t h another by means of r e s i s t a n c e common t o both.RESISTIVITY:

The r e s i s t i v i t y of any m a t e r i a l i s a measure of i t s r e s i s t a n c e or opposition t o t h e flow of e l e c t r i c i t y .

RESISTOR: ance

.

A device used i n r a d i o c i r c u i t s t o introduce t h e element o f r e s i s

RESONANCE: Two c i r c u i t s a r e i n resonance i f they are i n tune w i t h ea t h a t I s , i f t h e products oP t h e inductance and c a p a c i t y of each ar RESOHANCE FREQUENCY ( O F A REACTIVE CIRCUIT ): The frequency a t whi c u r r e n t and supply voltage of t h e c i r c u i t are i n phase. Def i n i t

R S N N E T A S O M R : A transformer h t h condenser load, whose c i r c u i t s EO A C R NF R E a r e adjusted a s a whole t o have t h e same frequency a s t h a t of the a l t e r n a t i n g c u r r e n t s u p p l i e d t o t h e primary, t h e r e b y c a u s i n g the secondary v o l t a g e t o b u i l d up t o h i g h e r v a l u e s than would otherwise be a t t a i n e d . RHEOSTAT: A r e s i s t o r which is provided with means f o r r e a d i l y a d j u s t i n g i t s resistance. REVERSED G R I D CURRENT: vacuous space. The d i r e c t c u r r e n t passing t o t h e g r i d through t h e

~1ppI.E FILTER: A low-pass f i l t e r designed t o reduce the r i p p l e c u r r e n t while f r e e l y passing t h e d i r e c t c u r r e n t from a r e c t i f i e r or g e n e r a t o r .

RIPPLE V L A E : The a1 t e r n a t i n g component of u n i d i r e c t i o n a l voltage from a OT G r e c t i f i e r or g e n e r a t o r . Per c e n t r i p p l e is t h e r a t i o of t h e r . m . 8 . value of the r i p p l e v o l t a g e t o t h e a l g e b r a i c average v a l u e of the t o t a l (R . .S. i s t h e a b b r e v i a t i o n f o r r o o t M voltage expressed i n percentage. mean square. )SCREEN G R I D : A e l e c t r o d e of s u i t a b l e p o t e n t i a l i n t e r p o s e d between c e r t a i n n of t h e other e l e c t r o d e s of a vacuum tube t o s u b s t a n t i a l l y e l i m i n a t e t h e e f f e c t of t h e capacitance between them. SCREEN4RID VACUUM TUBE: A type of vacuum tube i n which t h e capacitance between c e r t a i n e l e c t r o d e s ( o r d i n a r i l y the c o n t r o l g r i d and t h e p l a t e ) i s s u b s t a n t i a l l y e l i m i n a t e d by t h e i n t e r p o s i t i o n of an a d d i t i o n a l e l e c t r o d e of s u i t a b l e p o t e n t i a l

.

S C N A Y CELL: EO D R

Same a s Storage Cell.

SELECTIVITY: The degree t o which a r a d i o r e c e i v e r i s capable of d i f f e r e n t i a t i n g between s i g n a l s of d i f f e r e n t c a r r i e r f r e q u e n c i e s , This c h o r a c t e r i s t i c i s not e x p r e s s i b l e by a s i n g l e numerical value, but r e q u i r e s one o r more graphs f o r i t s e x p r e s s i o n .SELF-INDUCTANCE: Self- inductance i s t h e property of e l e c t r i c a l c i r c u i t s which t e n d s t o prevent any change i n t h e c u r r e n t e s t a b l i s h e d i n t h e c i r cuit s

.

SENSE FTXDER: An a d d i t i o n t o a d i r e c t i o n f i n d e r which permits determination of tlie d i r e c t i o n without 180 degrees ambiguity.

SELF-HETERODYNE RECEPTION: A system of heterodyne r e c e p t i o n by u t i l i z i n g a device which i s b o t h an o s c i l l a t o r and a d e t e c t o r . SENSITIVITY: The degree t o which a r a d i o r e c e i v e r responds t o s i g n a l s of It i s measured q u a n t i t a t i v e l y by t h e f r e q ~ e n c y o which i t i s tuned. t t h e r e c i . r o c a l of t h e Nomal Radio F i e l d I n t e n s i t y . p SERIES OR F E E D RESISTANCE (OF A MULTIPLE TUNED ANTENNA ) : The q u o t i e n t t h e power d e l i v e r e d t o the antenna by t h e square of t h e c u r r e n t i n l i n e f e e d i n g t h e antenna.

Definition

SERIES RESONANCE: A c o n d i t i o n which e x i s t s i n a c i r c u i t h a v i n g i n d u c t a n c e and c a p a c i t y connected i n s e r i e s , when t h e s u p p l y c u r r e n t and s u p p l y v o l t a g e a r e i n phase. SIDE BANDS: The bands of f r e q u e n c i e s , one on e i t h e r s i d e of t h e c a r r i e r f r e q u e n c y , proeuced by t h e p r o c e s s of m o d u l a t i o n . SIDE FREQUENCY: The f r e q u e n c y on e i t h e r s i d e of t h e c a r r i e r f r e q u e n c y p r o duced by t h e p r o c e s s o f s i n g l e - f r e q u e n c y m o d u l a t i o n . SIGNAL-NOISE R A T I O : The r a t i o a t a p o i n t of t h e f i e l d i n t e n s i t y of t h e r a d i o wave t o t h e r a d i o n o i s e f i e l d i n t e n s i t y .

I

SIGNAL WAVE:

A wave, t h e form of which conveys a s i g n a l .

SINE CURVE: A wave- like curve drawn t o r e p r e s e n t t h e changes i n s t r e n g t h and d i r e c t i o n of an a l t e r n a t i n g c u r r e n t or v o l t a g e . SINGLE-SIDE-BAND TRANSMISSION: That method of o p e r a t i o n i n which one s i d e band i s t r a n s m i t t e d , and t h e o t h e r s i d e band Is s u p p r e s s e d . The c a r r i e r wave may be e i t h e r t r a n s m i t t e d or s u p p r e s s e d . SOLENOID: An e l e c t r o n a g n e t i c c o i l w i t h o u t t h e i r o n c o r e . Same a s Group Frequency.

SPARK FREQUENCY:

SPARK GAP: An arrangement of e l e c t r o d e s used for c l o s i n g a c i r c u i t ( u s u a l l y o s c i l l a t o r y ) a t a p r e d e t e r m i n e d v o l t a g e . Among t h e t y p e s of s p a r k g a p s a r e p l a i n g a p , r o t a r y gap, synchronous gap, and quenched g a p . SPARK TRANSMITTER: A r a d i o t r a n s m i t t e r which u t i l i z e s t h e o s c i l l a t o r y d i s charge o f a condenser t h r o u g h a n i n d u c t a n c e a d a s p a r k gap a s t h e s o u r c e of i t s r a d i o - f r e q u e n c y power. SPECIFIC GRAVITY: The s p e c i f i c g r a v i t y o f a n y s u b s t a n c e i s i t s weight i n p r o p o r t i o n t o t h a t o f a n e q u a l volume o f w a t e r . SPECIFIC INDUCTIVE CAPACITY: The s p e c i f i c i n d u c t i v e c a p a c i t y of a s u b s t a n c e i s a d i r e c t measure o f i t s a b i l i t y t o s t o r e up e l e c t r i c a l e n e r g y when used as a d i e l e c t r i c m a t e r i a l i n a condenser. STATIC : C ond.uction o r c h a r g i n g c u r r e n t i n a n a n t e n n a r e s u l t i n g from p h y s i c a l c o n t a c t between t h e a n t e n n a and charged b o d i e s o r masses of g a s . Note: I n t h e U n i t e d S t a t e s t h i s term h a s come. t o be used q u i t e g e n e r a l l y a s a synonym f o r a t m o s p h e r i c s . STOPPING CONDENSER: A c o n d e n s e r u s e d t o i n t r o d u c e a c o m p a r a t i v e l y h i g h pedance i n some b r a n c h o f a c i r c u i t f o r t h e purpose of l i m i t i n g t h e of low- frequency a l t e r n a t i n g c u r r e n t o r d i r e c t c u r r e n t w i t h o u t m a t e r a f f e c t i n g the flow of high- frequency a l t e r n a t i n g c u r r e n t .STaRAGE CELLS:

A s t o r a g e c e l l i s a t y p e of c e l l i n which t h e che of d i s c h a r g e may be r e v e r s e d by a n e l e c t r i c c u r r e n t t o c h a r t o i t s o r i g i n a l condition.

Def i n i t i

STRAYS: E l e c t r o m a g n e t i c d i s t u r b a n c e s i n r a d i o r e c e p t i o n o t h e r t h a n t h o s e produced by r a d i o t r a n s m i t t i n g s y s t e m s . SUPW-YETERODYNE RECEPTION: A method of r e c e p t i o n i n which t h e r e c e i v e d v o l t a g e i s combined w i t h t h e v o l t a g e f r o m a l o c a l o s c i l l a t o r and c o n v e r t e d i n t o v o l t a g e of an i n t e r m e d i a t e f r e q u e n c y which i s t h e n a m p l i f i e d and d e t e c t e d t o r e p r o d u c e t h e o r i g i n a l s i g n a l wave. (Sometimes c a l l e d " s u p e r s o n i c r e c e p t i o n " and "double d e t e c t i o n " ) . SWINGING: The v a r i a t i o n i n f r e q u e n c y of a t r a n s m i t t e d wave r e s u l t i n g from momentary changes i n t h e t r a n s m i t t e r c i r c u i t s . T h i s may be evidenced by1.2. A v a r i a t i o n i n t h e b e a t n o t e when a l o c a l o s c i l l a t o r is adjusted t o t h e c a r r i e r frequency, o r A v a r i a t i o n i n i n t e n s i t y of t h e r e c e i v e d s i g n a l .

SYNCHRONY: The a d j u s t m e n t o f one c i r c u i t t o a n o t h e r , o r o f a t r a n s m i t t e r t o a r e c e i v e r , so t h a t t h e i r time p e r i o d s a r e t h e same.

SYNTONIC CIRCUITS: S y n t o n i c c i r c u i t s a r e two o r more o s c i l l a t i n g c i r c u i t s h a v i n g s i m i l a r t i m e p e r i o d s o r n a t u r a l f r e q u e n c y of o s c i l l a t i o n ."T" ANTENNA: ' A f l a t t o p a n t e n n a t h e l e a d - i n of which i s t a k e n from about t h e c e n t e r of t h e h o r i z o n t a l p o r t i o n .

TAhrK C I R C U I T : An i n t e r m e d i a t e o s c i l l a t o r y c i r c u i t a s s o c i a t e d w i t h t h e o u t p u t c i r c u i t o f a vacuum t u b e t r a n s m i t t e r which a b s o r b s t h e o u t p u t of the vacuum t u b e t r a n s m i t t e r i n t h e form o f e n e r g y i m p u l s e s o f h i g h v a l u e and s h o r t d u r a t i o n and d e l i v e r s the po-qer t o t h e l o a d i n s u b s t a n t i a l l y s i n u s o i d a l form, TELEPHONE RECEIVER: A t e l e p h o n e r e c e i v e r i s a n e l e c t r o - a c o u s t i c t r a n s d u c e r a c t u a t e d b y power from a n e l e c t r i c a l system and s u p p l y i n g power t o a n a c o u s t i c system, t h e wave f o r m i n t h e a c o u s t i c system c o r r e s p o n d i n g t o t h e wave form i n t h e e l e c t r i c a l system. TELEVISION: The e l e c t r i c a l t r a n s m i s s i o n of a s u c c e s s i o n o f images and t h e i r r e c e p t i o n i n such a way a s t o g i v e a s u b s t a n t i a l l y c o n t i n u o u s r e p r o d u c t i o n of t h e o b j e c t o r s c e n e b e f o r e t h e eye o f a d i s t a n t o b s e r v e r . TETRODE: A t y p e of vacuum t u b e c o n t a i n i n g a n anode, a c a t h o d e , and two a d d i t i o n a l e l e c t r o d e s ( o r d i n a r f l y t h e two a d d i t i o n a l e l e c t r o d e s a r e of t h e n a t u r e of g r i d s ) .TICKLER: A t i c k l e r i s t h e name sometimes a p p l i e d t o the c o i l i n t h e p l a t e c i r c u i t used t o f e e d some o f t h e e n e r g y back i n t o t h e g r i d c i r c u i t .

TREEMhL RECEIVER: A t h e r m a l r e c e i v e r i s a t e l e p h o n e r e c e i v e r i n which t e m p e r a t u r e of a c o n d u c t o r i s caused t o v a r y i n r e s p o n s e t o t h e c u r r i n p u t , t h e r e b y p r o d u c i n g sound waves a s a r e s u l t o f t h e e x p a n s i o n c o n t r a c t i o n of t h e a d j a c e n t a i r . TRER?dIONIC : R e l a t i n g t o e l e c t r o n e m i s s i o n under t h e i n f l u e n c e of

Def i n i t i o

THERMOCOUPLE AMMETER:

A ammeter dependent f o r i t s i n d i c a t i o n s on the n change i n therno electromotive f o r c e s e t up i n a thermo e l e c t r i c couple which i s heated by the c u r r e n t t o be measured. The t h r o a t of a horn i s t h e end w i t h t h e s m a l l e r crossOf

THROAT O A HORN: F

s e c t i o n a l area.TIME PERIOD:TORQUE:

Ascertained by t h e amount i n the c i r c u i t .

inductance, c a p a c i t y and r e s i s t a n c e

The value of f o r c e s t e n d i n g t o produce r o t a t i o n .

TOTAL EMISSION:

The value of t h e c u r r e n t c a r r i e d by e l e c t r o n s emitted from a cathode under t h e i n f l u e n c e of a v o l t a g e such a s w i l l draw away a l l t h e e l e c t r o n s emitted,

TRANSFORMER: A transformer i s a device f o r t r a n s f e r r i n g energy from one c i r c u i t t o another. TRANSDUCER: A transducer i s a device a c t u a t e d by power from one system and supplying power t o another system. These systems may be e l e c t r i c a l , mechanical, or a c o u s t i c . TRANSNISSION-FREQUENCY CHARACTERISTIC : A graph showing the transmission e f f i c i ency of a c i r c u i t o r t r a n s m i s s i o n path a s o r d i n a t e s and t h e frequency a s abscissas. TRANSMISSION LEVEL: The r a d i o f i e l d i n t e n s i t y o r t h e s i g n a l i n g power amplitude a t any point i n a communication system, expressed e i t h e r i n some absolute u n i t or w i t h r e f e r e n c e t o an a r b i t r a r y base value. TRANSMISSION LOSS: The l o s s