ND1E-TALKIE FOR INDUS IAL USE NOV
1 9 4 8
30
U. S. and LATEST IN RADIO:,- ELECTRONICS - TELEVISION CANADA MAN . 5E o\\`r9 N rst '"Gos ;dec P P `° och `ca\ 4 /:(tNE . ors R r e/4 Ill' the \t s ate s44 ot9 or`1otstems' the\P what tr `d,, r`I 010 ?r. \,e°er Moroo\ be 5a se °\ ' ßßd CM" M VOLUME 1
". e . of course we have all 17 RIDER MANUALS." RIDER pp MANUAL .. and attribute a good bit of our success in producing a quantity of work in a minimum of time to their always dependable, complete, mut factory information. We will have Volume XVIII as soon as it Is published." Covers 145 Manufacturers' Amplifiers, from 1938 to Date Bigger and better than even we had antici- pated, the scope and thoroughness of this first industry -wide PA service manual makes it an \opts. essential piece of equipment for any shop doing PA work. It covers public address systems, outdoor announcing, musical instruments and phonographs, theatre and church hearing aids, electronic mega- phones, intercommunications systems, theatre and home motion pictures, school, hotel and hospital sound systems, mobile and portable sound systems. ' oc.e, TOO -NEED ALL 17 RIDER MANUALS It provides schematics, voltage and resistance Volume XVII $16.50 Abridged Manuals I to V tables, tube and chassis layouts, Installation notes, Volume XVI 8.40 (one volume) . . . $19.80 instructions, impedance matching. Volume XV 19.80 Record Changers and operational Volume XIV to VII Recorders 9.00 Separate "HOW IT WORKS" book explains the (each volume) . . . 16.50 theory of various designs employed in different Master Index, covering 2030 Pages in this new Volume VI 14.50 Manuals, Vols. Ito XV 1.50 the PA types of amplifier systems, servicing of RICER FIRST plusseparate systems, using the sine wave and square wave "HOW IT WORKS" and voL.1 RIDER '7el ec«e c.t MANUAL means of checking, methods of rapidly locating INDEX $18.00 faults. Everything you need. 1400Pages, PLUS separate "HOW IT WORKS" and Index, $18.00. ORDER YOURS TODAY! Everything that most be known about the 1946 -47 television receivers (completo and kit) of 34 manufacturers. Separate "How It Works" covers theory of television; trans- mission and reception, frequency standards, antennas, various RIDER MANUALS portions of receivers. MEAN SUCCESSFUL SERVICING Television "HOW IT WORKS" Available Separately If television is not yet in your area, it will be soon. Hero is JOHN F. RIDER, PUBLISHER, Inc., 404 Fourth Avenue, N. Y. 16 theory 208 you want. pages S4 70 Export Agent: Rocke International Corp., 13 E. 40th St., N.Y.C. Cable ARAB NOTE: The Mallory Radio Service Encyclopedia, 6th edition, makes reference to only one source of radio receiver schematics -Rider Manuals. ANOTHER NOTE. The C -D Capacitor Manual for Rodio Servicing, 1948 edition No. 4, makes reference to only one source of receiver schematics -Rider Manuals HaveYou Met the Little Fellow with the
Advantages MalloeThe A// New
Offers These BIG Ad vantages .
The small size of the Mallory Midgetrol lets you service portables, auto MARK radios and small AC -DC receivers which require 15/ts" controls.
- SIMPL The unique shaft design of the Alallory Midgetrol saves installation time INSTALL with all types of knobs.
Electrical characteristics let you use the M \Iidgetrol to replace SIMPLER 11/8" as As ell as 15/16" controls. Stocks reduced because STOCKIN are further no special shafts are needed.
'l'Ire Mallory Midgetrol is unusual'. quiet, both me- NEW SIZE NEW ELEMENT chanically and electrically NEW DESIGN NEW CONTACT -and tests prove it stays NEW SHAFT NEW TERMINAL quiet. In addition, the Mal- NEW EXTENSION NEW TWO -POINT has nine y lory Midgetrol all NEW SWITCH SUSPENSION nere features.
It's the NEW Standard in Carbon Controls. See your Alallory distributor.
P. R. MALLORY . CQtnc. CAPACITORS ... CONTROLS ... VIBRATORS ... SWITCHES ... RESISTORS ... RECTIFIERS... MALLORY VIBRAPACK* POWER SUPPLIES... FILTERS Rp. u. s. Pot. Off. APPROVED PRECISION PRODUCTS
0 . R. MALLORY & CO., Inc., INDIANAPOLIS 6, INDIANA ...the - automatically ra Cates one of 18 separate scales into position as you select the range. SIMPSON MODEL 221 ROTO- RANGER Ranges HIGH- SENSITIVITY A.C. -D.C. VOLT- OHM -MILLIAMMETER 20,000 Ohms per Volt D.C., 1,000 Ohms per Volt Here is the only multiple scale test instrument of its kind in the world. A.C. Volts, A.C.: 2 5, 10, 50, 250, 1000, 5000 It reduces definitely the possibility of errors by providing a single scale Volts, D.C.: 2 5, 10, 50, 300, 1000, 5000 for each range of this finest of voltohm- milliammeters. As the selector Milliamperes, D.C.: 10, 100, 500 switch is moved to the range desired, an ingenious gearing mechanism Microamperes. D.C.: 100 Amperes, D.C.: 10 rotates a drum, bringing into place behind the meter window the proper Output: 2.5, 10, 50, 250, 1000 scale for that range. Here is the 25 separate equivalent of instru- Ohms: 0.2000 (12 ohms center), 0- 200,000 (1200 ments combined in one sturdy and compact unit. (18 scales; 7 additional ohms center), 0 -20 megohms (120,000 ohms center). direct reading ranges through use of high voltage and jack output Size: 123.4" > 101/4" x 5311" The patented Roto- Ranger principle eliminates the confusion of nu Weight: 8 lbs. 9 oz. erous readings on one scale, and the multiplying factors common t Price, complete with test leads and 28 -Page Operator's Manual $69.85 ordinary multi -range testers, by providing a separate scale for each range. There are no cramped calibrations in these full sized Roto- High voltage probe (25,000 volts) for TV, radar, x -ray and other high Ranger scales. Each is designed as it would be for a separate instrument. voltage tests, also available. SIMPSON ELECTRIC COMPANY Ask your Jobber, or write for 5200 -5218 W. Kinzie St., Chicago 44, III. complete descriptive literature In Canada: Bach -Simpson, Ltd., L London, Ontario
IP °CMAMPS to MA- 2000 OMMS 100 M.A - p0cio0O5 A separate scale SOO M.A for every range - t pMi,S automatically! IO AMPS SVAC LSV.O.C ipVAC
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SO Y D.C 750 YA C po YD.C. !00°YA[.
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Large 5' r" meter, with 18 separate,
full length scales) COMMON OUTPUT A.c. . D,C. 98 Whether you require large quantities of relays for production runs or single units for laboratory or amateur work, Wells can make immediate delivery RELAYS and save you a substantial part of the cost. Our capable engineering staff is prepared to offer assistance in the selection of correct types to suit FOR EVERY PURPOSE your exact requirements. Each relay is brand new, standard make, inspected, Over a Million in Stock! individually boxed and fully guaranteed. The following list represents only a tiny portion of J our relay stock. Write or wire us for information on STANDARD DC TELEPHONE RELAYS types not shown. senmel Stock Operating Coll Net AD No. Voltage Resistance Contacts Manufacturer Each R -101 24V 1500. DPST (NO) Auto. Elec. $1.35 R -102 24V 400. SPOT Auto. Elec. 1.10 RM1-T31 R -103 24V DUAL -1000 3PST (NO) Auto. Elec. 1.35 CUTLER HAMMER RIOS 24V 600. 3PST (NO) Clore 1.20 HEAVY DUTY CONTACTORS R.106 24V 1300. 3PST (NC) Clare 1.25 R -152 12V 50 DPDT -SPST (NO) Guardian 1.10 R 153 12V 200. SPDT SPST (NO) Stromberg 1.25 8.154 12V 200. SPST (NO) are 1.20 SENSITIVE Stock Operating Coil Net 0.155 I2V 100. SPST (4N04NC) Auto Elec. 1.15 DC RELAYS No. Voltage Resistance Contacts Manufacturer Each R -158 6V 50 4PST (NO) Stromberg 1.10 R-178 24V DC 100 SPST (NO) 100A. 6141H34A $3.85 R -159 6V 50 DPST !NO) Stromberg 1.10 R.179 6V DC 6.5 SPSTIND) 50A. 60411183A 3.00 R-160 6V 12 3PDT -3PST !NO) Auto. Elec. 1.05 R-180 12V DC 25 SPST NO) 50A. 60411308 3.25 R -161 6V 10 3PST(2NC -INO) Auto Elec .90 R-181 24V DC 65 SPSTINO)100A. 6041H8B 3.85 R -121 150V 5000 2PST (NO) SPDT Clore 1.65 Stack Operating Coil Net H-232 24V 55 SPST(NO) 50A. Metal Cased 3.25 R -12" 150V 6300 SPST (NO) Clare 1.75 No. Voltage Resnbnce Contacts Manufacturer Each H-233 6V 15 SPST(NO) 50A. Metal Cased 3.15 R -6) 150V 6500 3PST (NO) Clare 1.75 R.211 4.6V 18000 SPDT Kaltman 220C $1.95 H-235 24V 70. SPSTiN01100A. Type 616 3 85 R -51: 24V 750 SPST (NO) Clare 1.25 R -220 8- 5000 SPDT Allied Cont. 1.2) R -521 12V 250 DPST (NO) Clare 1.20 R -221 16. 24V 5000 SPST (NO) Allied Cont. 1.1. DIRECT CURRENT AIRCRAFT CONTACTORS R -519 I 250V 14000. SPDT Auto. Elec. 1.95 R -174 256: 5000 DPST NO) G.M. 1.8 Slack Operating Cail Net R -520 DPDT R.B.M. R 250V 14000 2.10 -175 358V 11000 DPDT -DPST (NO) G M 295 co. Voilage Resistance Contacts Manufacturer Each R -521 32V 1000. DPDT Kellogg 1.20 R -176 2CV 250 DPST (NO) G.M. 1.50 1 182 28V 80 SPST NO) 25 A Guardian $1.85 R.166 24V DUAL -200 DPOT-SPST (NO) Stromberg 1.59 R -177 4PD1 G.M. 1.65 24V 300 0 183 24V 60 SPST NO) 50 A. Allen Bradley 2.75 R -168 /PST rNO( R 24V DUAL-200 Auto. Elec. 1.20 -600 8.12V 5000 SPDT S- DunnKS 2.10 Type BOA H.240 250.350V 40000 DPST IRO) Auto. Elec. 2.95 R -507 24.48V 1000 SPDT -DPST (NC) Guardian 1.15 R.184 28V 50 SPST NO) 100A. General Elec. 2.95 H -241 48V 650 SPDT (NO) SPST Clare 1.25 R-185 24V 100 SPST NO) 50 A. Leach5055ECR 2.75 TYPE 18 DC TELEPHONE 'R -186 24V 132 SPST .rio, 50 A. Leac.(722n-3- 243.51 Stock Operating Coil Net TYPE BO DC i R.187 24V 100 SPST 'NM 50 A. Allen Bradley 2.95 No Vollage Resistance Contacts Manufacturer Each Stock Operating Coil ,, ,R -188 24V 200 SPST :N(7) 75 A. Allied Cool. 2:95 N -234 45 ,NO) A. 1.65 R -109 24.48V 4000. SPDT Auto. Elec. $1.50 No. Voltage Resistance Contacts Manufacturer Each 14V SPST 30 - R -110 i 24.32V 3500 SPDT Auto. Elec 1.50 R -169 241 250 SPST (NO) Allied Cant $195 R -112 90.120V 6500 SPST (NC) Auto. Elec. 1.75 R -171 24V 230 DPOT Allied Conl. 2.15 CHANGEOVER RELAYS R -114 24V 500 4PST (NO) Auto. Elec 1.30 R -172 5 -8V 30 DPDT -SPST (NO) Allied Conl. 1.70 Stock Operating Coil Net R -603 24V 400 DPST (NQ) Auto. Elea 1.25 R -113 7.6V 5 SPST (NO) Allied Cont. 1.25 No. Voltage Resistance Contacts Manufacturer Each H -238 241/ 150 DPDT -SPST (NC) R.B.M.' 1.25 R -529 24.48V 1000 DPDT Allied Cool. 2.50 1R-192 6á2V DC 44 2PD710 AMP Allied -CBS $1.35 14-239 24V DPST Auto 180 (NO) Elea 1.25 R.231 12VDC 100. DPDT 6 AMP G. E. 1.95 R -256 24á2V DC - SPDT -DPST(NC) Guardian 1.45 TYPE 1113 DC RELAYS 1KW R 501 110 AC 4 ()PDT '10W) G. E. 2.45 Stock Operating Coil Net 1503 12á2V DC 100 SPDT5PST G E. -500 W 1.95 No Voltage Resistance Contacts Manufacturer Each R -204 12V 65 DPST X01 Allied Cont. $1.15 COMBINATION PUSH BUTTON AND R -205 24V 260 DPDT Allied Cont 1.25 REMOTE RELAY R -224 12V 75 SPST (NO) Allied Cool 1.15 H -237 27V 230 DPDT Allied Coot 1.25 Stock Operating Coil Net SEALED DC TELEPHONE RELAYS No Voltage Resislance Contacts Manufacturer Each Stock Operating Coil Net N -244 12 -24 V DC Dual -60 SPOT CR2791-R106C8 $1.65 No " 'Nag, Resistance Contacts Manufacturer Each HEAVY DUTY KEYING RELAYS R -125 24V 300. DPDT Clare $2.75 ADJUSTABLE TIME R 126 90-120V 2000 Stock Operating Coil Nal OPDT Clare 3.00 Stock Operating Coil Net R -504 24 -70V 2800 SPOT No. Voltage Resistance Contacts Manulaemrer Each GE- C103C25 3.00 No. Voltage Resistance Manufacturer Tee R -248 28V DC 150 SPST (NO) 10A Guard. 36471 $1.05 Contacts V DC R AC R W. TYPE TELEPHONE RELAYS R -244 75V AC 265 SPST (NO) 20A Leach 1327 1.75 -246 115 SPST .90) or Cramer Stock Operating Coil Net R 206 24V DC 150 SPDT -3 AMP PLO-KL 1.20 (NC) 10 AMPS 1.120 Sec $6.5: No Voltage Resistance Contacts Manufactures Each R -207 24V DC 210 4PD7.3 AMP. PIB -OL 1.10 R -164 24 -32V 1000. SPST (NO) W E $1.20 R -219 50V DC 1500 DPST NO) 15A PIB -SP 1.25 DC MECHANICAL ACTION RELAYS R -512 24.48V 3500 DPDT W E. 1.30 R -217 115 AC 600 SPDT -10 AMP St. Cunn IXAX2.25 Stock Operating Coil Ner R -513 12 -24V 300 DPDT-DPST (NC) W E 1.20 R -525 24V DC 200 DPDT -10 AMP Guard 34464 1.25 No. Vollege Resistance Contacts Manufacturer Ear R -514 4-6V 60 SPOT W E 1.05 R -508 AC 600 SPDT -6 AMP Guard 37189 1.95 110 R -245 12V 25 4' Lever G.M. $09. .1.526 6V 35 DPDT SPST (INC R -506 24 V DC 300 DPST !NO, 6A - .95 R -527 6.12V 200. 2' Lever .95 1140) W. E. 1.05 R -510 24 V DC 200 3PDT -10 AMP Guard. 516983 1.05 AC- TELEPHONE RELAYS R -604 24 V DC 200 SPST (NO 30A. SI. Dunn-B2A 1.25 (NO( Dunn- TYPE C.M.S. Stock Operating Coil Net H -608 115 AC SPST 20A St. IHX)(225 R -620 DC 35 3PST (NO) 10A Guard B1(2 1.05 Stock Operating Coil No. Voltage Resistance Contacts Manufacturer Each 12V R -223 28V DC ISO SPST ( NO) 40A. Price Bros. 1.35 No. Voltage Resistance Contacts Manulaclure( Ear' R -212 90.135V - NONE Clare $0.95 H -230 12.24V DC 80. DPST (NO) 10A. 1.20 R -S11 24V DC 200 MICRO-SW Clare $2.4( 8.213 5.8V - DPST (NO) Clue 1.50 - N -231 24V 230. DPST (NO) SA. R.B.M 1.15 SPST :NO) R -605 24V - 3PST (NO) Auto Elec .95 R -606 24V - DPST (INO.INC) Auto. Elec. .95 R -607 24V - SPST (NO) Auto. Elec. .95 DC CURRENT REGULATOR DC -TYPE 76 Slack Operating Coil Net Stock Operating Coil NN No. Voltage Resistance Contacts Manufactwer Each No. Voltare Resistance Contacts Manufacturer Each R -509 6.12V DC 40 SPST ANC) G. E. 30.85 R -197 9 -16V 70 DPDT Price Bros. 31.65 DIRECT CURRENT R -198 9.16V 125 6PST (3N0) LATCH AND RESET RELAY MIDGET RELAYS (3NC) SPOT Price Bros. 1.65 Stock Operating Coil Net R-199 24-32V 250 SPDT -DPST (NC) Price Bros. 1.65 No Voltage Resistance Contacts Manufacturer Each Price R200 24-32V 275 3PDT -SPST (NCI Bros. 1.65 R.500 12V DC 10. DPDT 10 AMP St. Ounn- Stock 0 ing Coil Net R-201 24-32V 250 DPST (NO) SPOT CX-3190B $2.85 No Voltage Resistance Contacts Manufacturer Each (NC) DPDT Price Bros 1.65 R -601 9 -14V 60. (NO) Price Bros. 1.65 It 132 24V 300 DPDT Clare $1.70 DC- ROTARY STEP R-133 24V 300 NONE Clare .60 Net R-134 24V 250 4PDT Clare 1.20 Slack Operating Coil Each R-135 24V 300 SPST (NC) Clare 1.1$ No. Voltage Resistance Contacts Manufactura R -621 POLO R-137 24V 300 SPDT Clare 1.15 6.12V 30 3 POSITION W. E. 110.95 0-138 24V 300 ¿PST (NO) Clare 1.15 23 ß139 24V 200 4PD1 Clare 1.15 R 140 24V 280 SPOT R.B.M. 1.15 DIRECT CURRENT DC- RACHET RELAY R 141 24V 280 3PST (NO) R.B.M. 1.15 KEYING RELAYS Lock Operating Coil Nel R-142 24V 400 DPDT Allied Cool. 1.20 No. Voltage Resistance Contacts Manufacturer Each R-143 24V 280 SPST (NO) R.B.M. 1.15 (R -230 5.8V SPOT- DPS71NO) Guardian $2.15 R-144 24V 250 SPST (NO) Allied Cont. 1.15 Stock Operating Coil Net R-145 24V 300 Allied Cont. 1.15 No. Voltage Resistance Conlacls Manufacturer Each R-146 12V 126 DPST (INO) (INC) Clare 1.10 R -190 12V 65 DPDT 10 AMP Advance Elec. R 147 9.14V 75 SPDT Guardian 1.05 TYpe2000-A $1.15 R148 12V 100 DPDT -SPST (NC) Price Bros. 1.10 8.191 28V 125 DPDT 10 AMP Guardian 1.20 Special Sample Engineering Offer R -192 R149 6-IV 45 SPST (NC) Clare 1.00 12V 44 3PDT 10 AMP Allied Cont. (one of type) R150 6V 3 SPST (NO) E -Z Elec. 95 Type NB5 1.35 Any ten relays listed each R -193 5 -11V R 522 2.6V SPST (NO) R.B.M. .6S II OPDT 10 AMP Leach with the exception of Stock Nos. R -621 R 523 90 -125V 6500 DPDT Clare 1.90 SPST (NO) Type 1027 1.05 A 222 12V loo DPST (NO) P I B 95 R -194 74V 265 DPST (NO) 10 AMP Leach and R -246 -only $10.00. N 242 24.32V 300 DPDT R.B.M. 1.20 Type 10S4SNW1.25 H443 24.32V 300 4PDT R.B.M. 1.20 R.195 6V 32 DPDT 3 AMP G.E.Co. 1 15 0.196 12V 50 DPDT 10 AMP SPST (NC) Guardian 1.15 ORDER DIRECTLY FROM THIS AD OR THROUGH YOUR 1242 24V 170 SPOT 2 AMP Leach Type 12530EW 1.25 LOCAL PARTS JOBBER H- 236 9-8V 16.5 SPDT 10 AMP Leach-HEM 1.05 Manufacturers: Write For Quantity Prices. /WELLS Distributors: Write For The New Wells Jobber Manual. aS.4LES, INC. / 320 N. LA SALLE ST., DEPT. -Y, CHICAGO 10, ILL. RADIO -ELECTRONICS for NOVEMBER, 194E Nook Reviews 97 INDUSTRIAL ELECTRONICS REFERENCE those interested in the principles of Earn the big BOOK. by Electronics Engineers of the West- an PaY inghouse Electric Corp. Published by John Wiley microwave transmission, for whom it of expert & Sons. 9 x 12 inches. 6NO pages. Price $7.50. will provide a complete theoretical back- radioman This is a large book, physically, and ground. It is not intended to be an engi- it covers a large subject. The coverage neering guide.- R.H.D. This self -study is thorough, beginning with the physical background of electronics -the atomic RCA Triple l'index. Base diagrams of 475 tube BASIC theory. Much of the material is on sub- types. Price 75c. FREE TRIAL! The book is composed of three sepa- RADIO jects of interest to the communication EASY TERMS! engineer as well as the industrial de- rate base- diagram booklets, each with COURSE upon below because two fields overlap 112 x 3', 2-inch pages, joined below each signer, the trains you at home considerably. There are chapters on other in a single cover with a spiral wire à emission, conduction in gases, vacuum binding which permits the pages to lie th,r pr in iples of operation of vacuum EXPLAINS tubes. their basic circuits and other es- tubes, phototubes, C -R tubes, tuned cir- flat. This triple feature permits the re- sentials f radio
cuits, and allied topics. Sections which pairman to have three separate base Ihr ele tri cal background you must PROVIDES have apply especially to industry are those diagrams before him at all times with- the radio and electrical mathematics you control, power out flipping pages from one to the other. FILLS IN need, taking you in easy steps from dealing with industrial simple tractions to logarithm! IK rectifiers, r.f. heating, industrial X -ray Let this self -study course prepare you right work, and several others. ANTENNAE. An Introduction to Their Theory, at home for a successful future in the RADIO by J. Aharoni. Published by Oxford University Each of the 36 chapters has been field. It contains all the information you need .. . Press. 6sfi x 9% inches, 265 pages. Price $8.50. radio - electrical - mathematical - tu handle all written by a different author, each evi- A completely mathematical treatment types of radio sets, teat equipment and electronic dently, a specialist in his subject. The devices. Explains everything from time delay cir- of the subject, this book is divided into cuits to the most recent advances in the field . . information is complete and detailed, three parts, Antennae and Boundary - mechanical and wire recording sound systems - with diagrams and frequency modulation profusely illustrated Value Problems, Antennae and Integral -multiunit and mul- tables. The treatment is not wholly Equations and Antennae as Wave tieloctrude tubes, etc. This basic course in- mathematical, but the necessary formu- Guides. A number of references-both ' eludes las are given. While the text deals with A 3 -Way Set! ESSENTIALS OF books and papers -are given at the end R A D I O by Morris principles and design rather than with Even as you learn the fun- Slurebere and William Os of the text. terheld descriptions of specific pieces of appar- damentals of radio work 2 ELECTRICAL ES- the engineer will find the book a you absorb Iho practical SENTIALS OF RA atus, electricity and electrical DIO by M. Slurrbers and FREQUENCY MODULATION. VOL. I. edited W. Osterheld valuable reference source in almost any by Alfred N. Goldsmith, Arthur F. Van Dyck, theory you need. And an 3 MATHEMATICS ES- of industrial work. H. D. Robert S. Burman, Edward T. Dickey. and Yon go along the set tills SENTIAL TO ELEC sort -R. TRICITY AND RADIO by George M. K. Baker. Published by RCA Review. In the mathematics you 6 x 9 inches. 515 pages. Price $2.50. Cooke and Joseph must know clr,s you NO leo, THE PHYSICAL PRINCIPLES OF WAVE Over 1,000 illustrations! GUIDE TRANSMISSION AND ANTENNA A collection of 45 papers delivered by the essentials of algebra. trigonometry. 1953 pages! SYSTEMS, by W. H. Watson. Published by the RCA engineers at various meetings or geometry. 29 appendixes! Oxford University Press. 61/2 x 91 inches, 207 published in pages. Price $7.00. technical journals, this is r The writer of this volume, a profes- the seventh volume of the RCA technical MCGRAW -HILL BOOK CO., sor of mathematics at the University series. Due to the large number of 330 W 42 St., NYC 18 of Saskatchewan, has covered thorough- papers, the FM art is covered -though Wend your 3- volume emirs, In BASIC RADIO possibly somewhat spottily almost for 10 ne(lays' examination ,nn approval. Iu. III da, ly all types of wave guides and the cur - - I will send $4.95 and $3.00 a nano h until I ha, rently known methods of using them. completely. The papers deal with prob- paid $1::.95 or return the books postpaid. The book was written to acquaint lems in both FM reception and trans- Name physicists and engineers with the mul- mission. Addrets tiple- propagation characteristics of mi- . There are two appendices -a bibliog- crowaves. The subject is approached raphy of technical papers by RCA au- City Zone. State from an entirely theoretical angle, and thors from 1936 to 1947 and a guide to company the treatment is mathematical through- a series of articles in Broadcast News RC-11-48 out. on FM station placement and field sur- 11.. ___ _ mse mm. .J The material will be of most use to vey techniques.
A AouiRADIO TELEVISION F.M.- ELECTRONICS PRACTICAL SHOP TRAINING - NOT HOME STUDY Trained Radio men needed now. Get Radio -Tel- evision training and be ready for a real future. Learn on actual equipment at Coyne. 49 years of training experience. Not "Home Study ". Free employment service to graduates. Many earn while learning. If you are short of money. ask about Student Finance Plan. G.I. Approved. Coupon brings special plan for men of draft age. SEND COUPON FOR FREE BOOK
B. W. COOKE. President COYNE ELECTRICAL 8c RADIO SCHOOL S00 S. Paulina St.. Dept. 88.8H. Chicago 12, Ill. Send Bic Free Radio -Television Book. also your spe- cial plan for men of draft age. NAME f4pJE,bt / Suggested by Robert P. Bolin. Miami Florida ADDRESS
"Well, Students, did I make myself clear?" CITY TATE L NOVEMBER, 1948 (Printed in the U.S.A.) 96 -Pre -Holiday Specials - Index To Advertisers Air King Products . 8 CIRCULAR FLUORESCENTS Allied Radio Corporation.. 45 WESTING- GENERAL Almo Electronics. Inc. 91 WITH Almo Radio 87 HOUSE 36W ELECTRIC 32W American Surplus Products Co. 70, 71, 91 CIRCULARC BULBS CIRCU LINE Amplifier Corporation of America 68, 90 Audel Publishers ... II PRECISION $825 $850 Bargain Radio 67 RESISTORS Bell Telephone Laboratories 57 Boland & Boyce Publishers, Inc 69 "TAB" Specialists in Instrument 82 precision Bradshaw Co. resistors. 65 Write qty. Prices. NO 4Xa+aewoc4-3 Brook Electronics MFGRS. CHOICE," we ship types in stork. Brooks Radio Distributing Co. 69 Buffalo Radio Supply 76, 77 From .116 to 99.000 ohms 30e. TEN for $2.5(1 Burstein- Applebee Company 82 n 011 1 411011 _ li pill :537.1111 Capitol Radio Engineering Institute 6 47 1p II 1-,51011 : 1..0011 3M110011 Certified Television Laboratories 96 1%1100 11:::411 '.1101111 .1011111m Cinee Corporation 87 !1101111 I $11111111 (.01111 hrtuu. Clarkson Publishing Co. 96 nu11 I ": 25111111 18311011 Cleveland Institute of Radio Electronics IS 31111111 111101111 27 v.1100 1 . Instrument Laboratory, Inc. 86 35000 220000 2911111 17 Clippard Company 63 1001111 2211100 07.00 7.11001 0, Communications Equipment 65 11111 YOUR CHOICE Coradio 1 1 111111 21101111 :.1111111 WHITE CUP FOR KITCHEN Crest Corporation 66 451100 2331511,1 : ::11111 2101111 CHROME FLUSH MOUNTING It LBS. 79, 97 170011 23811110 ...,1111 370111111 LARGE DECORATIVE GLASS $1.25. Coyne Electrical School.. .SIRI VE SIZES. EACH 40e TEN for $3.s Custom Craft Manufacturing Co. 98 Training 13 1 Meg 1.8 Sleg 3. Meg 4.23 Sleg 11 S! MICROGROOVE PLAYER DeForest's Institute 1.2 2 3.47:1 4.5 11.5 Electronic Corp. of America 92 1.5 2.89E :1.:1 12.' Play Sarei, Micro - Electronic Measurements Corporation 84 1.57!1 1 9.115 Groove & Stand- Elmhurst Sound S Equipment Co. 90 ABOVE SIZES EACH 75c TEN Espey Manufacturing Co., Inc. 78 5 Precision aI ard Records With ACI.1M Ill'111 Resistors IC) Fair Radio Sales 66 11,11, 0.75. Il.s::. 11.911 Dr 011111..: I. 1.5. 2. This Dual Speed 89 uwgohm.. v 0.5%. Sulalr. $1.00l9: Ten L. - Phonograph Feiler Engineering Company NIEGSI.SX10.123leg,IIEV1f 9W. SI.3597: 10,$11,. Franklin -Ellis Company 86 SIVZ811I1',:InSleg /25KV !010'a It. $1.901:, 6 flu . General Cement Manufacturing Co. 91 SIEIIIU5I11C. I M eg. /. 3 i .1.t \29...$1.98 6,$111.11 SPECIAL General Electronic Distributing Co. 49, 83. 89 XTAL DIODES -NEW General Salvage Company 91 General Test Equipment . 96 IN:3I 1 2 for 10 for $39.90 $1.08 $2.10 $9.85 Supply Co. 65 IN21. 2I.\. 23, 23.\ each $1 12 for $10.00 Greylock Electronic 75 IN.311, 1N2e @ $2 10 for $17.50 Incl. Halldorson Company .. 84 IN35 Dual 1111111 $2.29 Fed. Tax Hawkins Radio Co. Heath Company 52, 53, 54, 55 PHOTOFLASH and 2 lampa RCA Instructograph Company 79 Licensed International Resistance Co 93 A11t- PIIOTI)F9..$II KIT II I. DualSpud ,1.lul and dual -1.,l plrkIp.. Joyce Radio Distributing 90 CORPS 15113 NEW l'asl- 1, erful 3 -11161' 1,1.11 :unplillet with sul1ll0 & bass Lafayette -Concord 61 Carry. talns Power Supply, LEC - ruls. Ilraq' S' l'SI spk. 2 Tone Lealheicite Lake Radio Sales Company 79
. tltts In meet with TIFIERR and l'ONDE. Ca.. We :III.II111C1y gllaralllee Leotone Radio Corporation 93 satisfaction nr 111001V hark in IO ,lays. SERS 50 turd. TRANS yr model 79 air :metir Sw ltehing fmlrmn L -I' In ltegular 11l -3 Lifetime Sound Equipment Company FOIISIFIIS & Relay. McGraw -Hill Book Company 97 STROIIO- :II V tl'. Weight 15 ohs. LASIPS 12 mil- Slade! IiA -2 Same Case as above. Plays New MIcro- McMurdo Silver Company, Inc. 12 lumens output. 15 lion light Lroore Records only. Attach1's In your phonograph. P. R. Mallory & Company, Inc. Back Cover :0000 Ilashrs & Itellrtrs. $19.90 to radio or cnlsole. 117V AC. Sonia! Metropolitan Electronic & Instrument Co 16 for l'OIOIt & 111W film. WE SELL RETAIL Mid -America 92 READY for use on 12V19'. Immediate Delivery. order Yours Today. all C. O. Orden Midway Sales Company 90 In addition. KIT IN- 55.00 n . i .11 Midwest Radio & Television Corp. 67 ('1.1'DES INSTIII'CTIONS Catalog oH. Please enclose postage. Mort's Radio Shack 95 l'AII7'S to Omcert to & Moss Electronic Distributing Co 84 IGV.AC. SPECIAL "TAB" BUY $59.95 RISCO ELECTRONICS Motor Industries Company 96 80 15113 SET plus six 2V 1125'1 S Rate $69.95 Murray Hill Books, Inc. 72, PIDYrOFLASII 1503 & BATS' PACK for 115VAC WHOLESALE DISTRIBUTORS National Plans Company 91 12VDC operation READY to WORK $119 25 West Broadway, N. Y. 1, N. Y. National Radio Institute 3 l'IIOTOFLSSH LASII',e & REFL. $10.95, 2 for $21.00 National Schools 5 /3nom\'int Flash Condensers Alnfd4.09V.\C $3.95 National Surplus Sales 78 15mfdi21100V ant, Ilimfd/311005 lid. $7.95 $4.50: 95 25nifiL 21011 1'1nt. $7.95: 4X8mfd /3nulVint.511,95. Newark Electric Company 10010 /l'A Ni50 Filin GHAT' Camera 3 /$1; 54 for $8.98 ANY BOOK IN PRINT Ohmite Manufacturing Company IB 16n./PAN Film GSAP Camera 3 for $I: 10 for $1.98 We pay postage. Opad Green 75
. k., Pidnll:u e.li- Opportunity Adlets 68 e ...Ii. :a. Meehan Precision Apparatus Company 85 '" It Guaranteed say- Blowers -Cool en Progressive Electronics Company 88 11.9. -d Ili: i L. I!11'3 eatal112. that Tube! `rit. nm ..1 h....k Radio Apparatus Co. 65 FREE Radio Corporation of America 59 11 ICh ill+ 11f :111.1111111 i.1,k Loiters, The Radio Craftsmen, Inc. 85 (:A) Impeller 1noCFS1 /20VACUC $ 4.95 to r CI,e,.11a. gift pP.hlell. F,'.1 If You write now -today! Radio Dealen Supply Company 95 (A f impeller lllll'ISI - I 2\-ACO( 5.95 (II) TI'OBINE 2' ICFSI'2s \'AI'DI' & CLARKSON PUBLISHING COMPANY Radio Supply & Engineering Co. 58 XFOIIMER II3V.tl' /opnn 10.95 Dept. Res. 1257 Sn. Wabach Ave.. Chicano. Ill Radionic Equipment Company 86 I(7) TURBINE 411CFM. 2,4VACDC. 45111' Ravac Electronic Corporation 66 per nain. rm.. Ira u 3.25 F. Rider. Inside Front Cover 8.95 John TURBINE 125CF'S1 ;'111VAC Risco 96 BLOWER T1tANSF 24 to 115 V,tl' 1.69 Electronics TV 5111111V Par Soppy Ill & L. Volta,. $29.95 TELEVISION RECEIVER-S1.00 The Rose Company 82 TV 1110111V l'wr Supply Ili & Ls Vnll lees- _$36.95 IIIPOIVF-It VARIABLE RADIO SCHOOL DIRECTORY ANTENNA SIAT(9IIN0: nl (Pages 94, 95) NETWORK 1001 A/I TIW American Radio Institute IRE NEW 1.5 to 7 ,w +11ng 11,11.. All for SI.OH. Baltimore Technical Institute ,Idly enlivened Io Candler System Company I LABORATORIES fets. 'IN tw k CERTIFIED TELEVISION Cook's Radio School able IN & Outpt - Inept. C, 5307 -13th Ave.. Brooklyn 19. N. Y. 15x15a23' KA('K SI l' J. Commercial Radio Institute 111111101 Coll & 2511imr/ Don Martin School of Radio Arts 71111115' Var Cnndsr /IF Lincoln Engineering School intr. Tedi manual Will Milwaukee School of Engineering ateh most ANTS. SI. RCA Institutes "TAR" SI'E('/ Radio Television Institute I BIIANI) NEW) $12.95 PEN -OSCIL -LITE NEW', roils require e e tIng . .. 9.93 Radio Training Association of Americo Iclely convenient teat oscillator for all edil AS IS, 11111 repairs rentdred 8.95 ne: aingnment Small a Self Tri -State College rea Range from 7011 vele audio to YMCA Trade & Technical 111)0emega ycles u.h.f, Output from arm to 125 v. Schools I.ow In cost-oa Used by Signal Corr write for Inrormatlon Storage &c Howard W. Sams & Company, Inc. 17 Dry Batteries GENERAL TEST EQUIPMENT Since Radio, Inc. 73 38 Argyle Ave. Buffalo 9, N. Y. N. Silverstine Company 19 Simpson Electric Company Inside Back Cover IA) RR18 /11952 /5oz, 311V min SBaty $1.49: 8 /10.00 Solar Manufacturing Corporation 4 Ilil u1'RGK'4S eV /1"IItP /dated 0/47. Special 51.08 South River Metal Products 10 IC) GOI'LD BV /11%II S'Raty USN NEW 3.98 Sprague Products Company 20 (DI BIt51 /25'/27nmp WILLAIID S'llaty 1.96 "POCKET AisLowa' Sprayberry Academy of Radio 7 (E) WILL.ARD 4\' /TILT S'Itetr 5.95 TALKIE "! /4.Ail REALLY W'OItk.S and hear 2- Instruments 81 (F) 11B2004U/2V/11AII WILLARD Y'Ba1Y. -.- 1.89 -talk Superior Company milex - FITS IN 7111 i. Supreme Publications 69 Pock :T! Uses aashrght hatter,.- - $3 Min. F.O.B. N.Y.C. Add Post. ABOt'T SIZE OF 2 PACES t'IC t Sylvania Electric Products. Inc. I4 and 253/4 le ,h F]h deposit. Money back "TAB" Guarantee. Re- kt;,r'MO SEND $1.00 Tab .. .. 96 turn Mdse Prena.d ($1.52 C.O.D.) for F:2 ta rend P ,, Technical Radio Parts Company 89 ii.senddy i1... Picture. '1 1 I,"' Transvision 74, 79 1135 rt'I!- price lists with `DETAILED CATALOGUE: ON Instrument 9 F:R PRODUCTS «CII AS: 51.00 reflln led on parts e1'. Triplett Electrical Company "TAB", Dept. RC -1 1 der 3-tube Pocket Radio Cigar Mot Transmitter. Warner Electric Co. 87 Openers. 6 CHURCH ST., NEW YORK 6. N. Y. WOrth Car real,Hnittr. Radio Garage Door Sales, Inc. 98 2.7230 MOTOR INDUSTRIES CO.. D't, CW -11. Kearney, Neb. Wells Wright, Inc. 88 RADIO- ELECTRONICS for Communications
WANTS SERVICE LICENSES Dear Editor: MORT'S Better Buys -For Radio - Television - Electronic Federal licensing of radio servicing technicians would have the following _HF10 TRUSOUND AMPLIFIER- & Specials beneficial results: Parts Equipment The 11 r lu amplifier is a general pmnns, unit M Give the serviceman new prestige and soli sl u (ii S 9- a 7'i designed for high quality TELEVISION- CATHODE RAY HIGH repraitlrt ion o In d, music and sneer!, from promote public confidence in him. [fonds, iaulo and mitt °phone. It is engineered awl VOLTAGE Eliminate the incompetents who give built In meet the high quality standards require. 2000 volt D.C. Power Supply of an su,pl l lier when used in conjunction with the For an unbelievably low price, we can supply the a bad name and destroy con- c nigh, fidelity pickups. 1,51-AM tuners and wide or ray trade iange speaker systems. completely filtered television cathode fidence in servicemen. 2000 volt D.C. power supply. Why pother with FEATURES bulky and dangerous 60 cycle supplies or ex- Give the federal government a bona 10 watts undistorted power output la watts peak. pensive R.F. power supplies when you can fide roster of qualified servicemen which Inputs: Nigh Gain for v riable reluctance pick- purchase a complete 2000 volt U.C. unit (not ups: for high impedancea mikes. Low Gain for plug into the 110 volt A.C. -AM tunen ana high output a kit). ready to would be useful in the event of war. FM pickups. low price has been Selector switch for rapid changeover. power line. The ridiculously by a of high Restrict the entrance of unqualified Hum level 70 watt.. made possible fortunate purchase db below 12 components. These units are brand Tone coo ion. Separate continuously va quality newcomers. The amateur, tinkerer, and mania base ana treble control.. new, completely tested and guaranteed. radio school product would be forced to Treble-from plus 10db to mina. 15 db at Price 10.000 e . $7.95 serve a suitable apprenticeship instead Baas -from ` plus 10 db to minus 1S db at 50 en. VOLT TELEVISION SUPPLY Note -fiat charaeterist ics obtained with control. 4000.6000 of depressing wage levels through cheap entered. Similar to the unit above. hut has a much competition with the higher priced but Output impedance 2, 4, a, 16 ana SOO ohms. higher U -C. output voltage suitable for use Straight AC for 110.130V 50 -60 cycles fused. with the new 7" and 10" television tubes. more competent individual. Tubes -65v, 68C7. 2 DVS. 573. PRICE $12.50 Benefit the public through better, Chassis and shield silver gray hammerloid finish. RADIO NOISE FILTERS Hermetically sealed components used throughout. Eliminates extremely noisy radio ffeception due to more competent servicing of radio re- Complete with tubes and cover. power line disturbances caused by luBbie, refrigerators. Stock No. TRIO $29.95 washing machines. vacuum cleaners. elevators, oil ceivers. burners, diathermy machines. etc. Attract better men to the trade F ìlters out man -made noises in the broadcast, shat wave. and ultra -high frequency bands. through better conditions. METAL CAN AEROVOX REPLACEMENT Designed for all radios, ppliances, and electrical FILTER CONDENSERS equipment consuming up to a 1300 watts 112 amperes) Organization has been tried in the at 120 volts o AC or DC. Itot,,,,s x s n ::t min s of king runs. Ut' test volt 800. x complete of Housed in a metal case I ss- 3- x 7SY past and it has not worked because Each 1$1.29 -10 for $11.75 with male and female line connectors. the lack of a common interest or bond. PRICE ONLY $1.95 Federal would go a long way 2 TUBE WIRELESS PHONO OSCILLATOR Industrial Type Radio Noise Filter -Will handle up licensing to 50 amperes. Housed in shielded case 34 a VA' 1 toward assuring a common interest in This tine niece of equipment Is being scald at almost 2't-. the price of the 11111es alone. .1 real bargain while PRICE $3.95 servicing, both in getting and renewing quantity lasts. Each $3.25 such licenses. The development of a EASILY ASSEMBLED RADIO KITS- Write for our new FREE 1949 catalog. 5 Tube AC -DC superhet kit furnished in a national organization would put power plastic cabinet of artistic design, cab- TERMS: Minimum Order 33.00. 25eä deposit. brown in the hands of the servicemen to fight Balance C.O.D. F.O.B. Chicago. inet size (9 "x5 "x6 ") with 2 tuned unethical conduct as well as incompe- Variable condenser tuned; double tence in the industry. Such an organi- Tubes used: 1 - 12SA7. 1 - 12SQ7, 1 - 12SK7, t - 50L6 zation would be stimulated by federal MORT'S RADIO SHACK I - 35Z5 and PRICE 511,95 standardrn°'p °'n° tube. 5 licensing. It could improve both knowl- Dept. RC I, 630 West Randolph Street 6 TUBE 3 WAY PORTABLE KIT edge 6, and working conditions. Chicago Illinois For operation on 110 volt AC or DC and WILLARD R. MOODY, battery Su' erheterodyne circuit Service Manager, Sanbran Co., Full vision dial Wash illytorl, D. C. High gain loop FREE ! send lot out Cabinet of Blue Aeroplane cloth finish, site 13x9 x7" Tubes used 1A7, 111S, 3Q5, 11726 and RADIO and TELEVISION 2 - 1N5 Thorough Tot ining in All PRICE $13.16 Exer: °for Viii .7575 Technical Phases RADIß BUYING GUIDE =M 6 TUBE, 2 BAND SUPERHET FOR VETERANS KIT APPROVED Bands covered BC 550.1600 KC and 6 -18 MC DAYS- EVENINGS w a complete and diversified line -up of Power supply 105 -125V AC. DC Full vision dial RCA GRADUATES ARE IN DEMAND Variable condenser tuned, with two double tuned For Free Catalog Write Dept. RC -ora electronic equipment I. F.'s 455KC systems Walnut veneer wood cabinet RCA INSTI TETRA, Inc. sound PRICE $15.75 A Servite of Radio Corporation of America recording equipment 350 WEST ITH STREET NEW YORK 14. N. Y. amateur gear A SCIENTIFICALLY DESIGNED television components and kits PHONO SCRATCH FILTER Resonated at approximately 4500 cycles effectively replacement parts reducing objectionable needle scratch without alter- ing the brilliancy of reproduction. laboratory and service Contains a HI -0 SERIES resonated circuit. Tested by means of an audio oscillator and an oscilloscope test equipment to give 22 db. attenuation with very low signal loss. Attenuation may be regulated by means of a SPECIAL r Mop,. up-:,t, r. 'r tr+nu:mds of Save time and money -buy direct from MINIATURE pain control. tided. Inlensely in arstln4 distributor! Consult the NEWARK radio EASY TO ATTACH work-good pay. Learn at rhome or buying guide. featuring all standard makes Just two wires to clip on, Compact. BOOS ' ime ra moms ...a value -packed listing of 20,000 essen- $1.65 oy"gli w,,.m. Qualify r dnulcar or commercialanmmerc,a license` Book of particulars l', tials for expert servicemen, engineers, THREE TUBE PHONO AMPLIFIER CANDLER SYSTEM CO. soundmen, experimenters, teachers, An assembled unit ready for installation using tone Dept. 3 -M. Box 928 Denver I. Colo. hobbyists. amateurs! and volume control and six feet of rubber $2.95 cord 24 HOUR SERVICE ON ALL ORDERS (Net including Tubes) UL1J CORRESPONDENCE COURSES IN With Complete Set of Tubes $3.95 free technical advisory service! RADIO and ELECTRICAL ENGINEERING PHONO OSCILLATOR i Wireless phono oscillator transmits recording for crystal pick -ups or voice from carbon milt. through ELECTRICAL ENGINEERING iá. g.îe tris' new'. NM MAIL THIS COUPON TO GET YOUR CATALOGUE Prepare >nur -en Low Coat.a for toton. Modem radio without wires. Can also be used as an Intercom., n S n.p Lñad enne demand quickly. Newark Electric Co., Inc., Dept. 11 by using P.M. speaker as mike. Price $2.95 Extra fine coq . In rama. (excluding tubes) RADÌO ENGINEERING public addmaa,r real arecalr 242 West 55th St., New York 19 work. Trains you to be . vacuum. With Complete Set of Tubes 53.95 rube technician. Servicemen rneeded badly. Diploma on Please send me the FREE Newark Buying enmweuo E SPECIAL! SPECIAL! a rdo Eto Fearningó.°..E of Guide of fine radio equipment. Mammoth assortment of and electronic E thgr radio WRITE .bolt di:.ry d p.ymemepian, :x- $ts C.wse parts, not leas than TEN POUNDS of new p.rl lilts. etc Name transformers, chokes, rondenaers, resistors. Lincoln Engineering School, Box 931.0 -117. Lincoln 2, Neb. wire, Address switches, coils, hardware, etc. A super- buy for experimenters, service- $1.25 RADIO City State men. and amateurs for only TECHNICIAN and RADIO SERVICE COURSES Satisfaction guaranteed on all merchandise. All prices F.O.B. New York City FM and TELEVISION 3 ODI fllNS WRITE FOR FREE CATALOGUE Ils a. itst i titrtYa.. Ma OW AMERICAN RADIO INSTITUTE Md 30 Sot m ow Ara b aOM 101 West 63rd St., Ns. York 23. New York MEWARK RADIO DEALERS SUPPLY CO. Approved Under CI Bill of Rights rent HR1 osme,S 33a 135 Liberty St. New York, N. Y. ¿ireneed bp New York State 1111011EIIYISIO11 20 car Sant kW ICU 1l... T. 323 Sol Wows Sbwt. boats L RL NOVEMBER. 1948 94
LEARN then EARN RADIO SCHOOL DIRECTORY in RADIO Become a Radio and
JELEVISI4N
IN 18 MONTHS! COURSES OFFERED IN Here is the opportunity you have been waiting for. Now you can get in on Broadcast Engineering the ground floor of the nation's fastest growing industry- TELEVISION. Commercial Oper. (Code) Frequency Modulation LOOK AT THIS RECORD - In 1946 only 6,500 Television television sets were manufactured - in 1947 this Announcing skyrocketed to 175,000 - already in the first four COURSES months of 1948 over 160,000 sets have been pro- SERVICE 1000á PLACEMENT SERVICE duced. This means hundreds of new jobs are being 6 to 12 Months Practical El Ity APPROVED FOR VETERANS created every month. Welding Refrigeration WRITE FOR FREE BULLETIN MSOE NOW ADDS TELEVISION - The Milwaukee Heating School of Engineering now provides complete, prac- TECHNICIAN Cook's Radio School tical, technical training in television as well as Radio 12 to 24 Months Electrotechnics DEPT. RC in its laboratories. This is not just a Jerviceman'i Radio and Television Electronics 2933 NORTH STATE ST.. course. The special 18 month's residence course in- Refrigeration, Heating dudes complete training in radio as well as television and Air Conditioning JACKSON. MISSISSIPPI - qualifies you for a successful career as a techni- PROFESSIONAL cian in all phases, AM, FM, TV Receivers and Trans- 36 Months Electrical Engineering mitters and Radio Communications. Bachelor of Science TELEVISION 1948!! Degree Train N an Institute that pl d This Technician Course Prepares You For Any Of These Jobs: Major In Machinery or 113$. Radio Servicing - AM and FM Police, Taxicab and Railroad Electronics la TELEVISION TRAINING since TV iver servicing transmitters operating Morning, Afternoon or Evening Ses- Broadcast Station Operating and receiver servicing \ sions in laboratory and theoretical in- Electronic Parts Sales Supervising and testing in radio struction, under guidance of experts, Radio and 7V sales and TV manufacturing Terms start January, covering all phases of Radio, Fre- Radio and TV manufacturing Shop managing April, July, Sept. quency Modulation, Television, lead to opportunities in Industry, Broad- casting or own Business. Licensed by Ele al Engineering N. Y. State. Approved for Veteran,. Bachelor of Science Degree MILWAUKEE SCHOOL OF ENGINEERING, ENROLL NOW FOR NEW CLASSES N. Broadway and E. State, Milwaukee, Wit. Visit, Write er Phone in 2 additional years Without obligation send me free booklet "Career Majoring in ELECTRONICS Building" and more details on course in Radio and RADIO- TELEVISION Television or coarse. £--elhoo Name Age INSTITUTE Address 460 Lexington Ave., N.Y. 17(46th St.) of ENGINEERING PLae 3-45115 2 elects from grand Castel City State m l i La 'A itdm ai lnstdutn founded 1903' Dep, RCI1441 Y. Broadway, Milwaukee, Wis. LEARN RADIO! WANTED: RADIO IN ONLY 10 MONTHS Men Women to PREPARE FOR A GOOD JOB! and Fill COURSES COMMERCIAL OPERATOR (CODE) Preparatory, Service, Broad- BROADCAST ENGINEER TOP RADIO JOBS cast, Television, Marine Op- RADIO SERVICEMAN in AM- FM- Television / crating, Aeronautical, Fre- quency Modulation, Radar. Television Servicing -IS Months If you are looking for a career with a future, why cari Join the hundreds of graduates from the Don Martin Classes now forming for midyear term Feb. Veterans School of Italia Arts now successfully employed In the 1st get 8130.00 Equipment radio industry. is SEND FOR FREE LITERATURE The demand great for qualified Entrance exam. Jan. 17 radio personnel In AM- FM- Television. Train now to Veterans. Literature. BALTIMORE TECHNICAL INSTITUTE be an announcer. script writer. disk jockey, liens. caster, orladio technician. Complete day and night COMMERCIAL RADIO INSTITUTE 1425 Eutaw Place, Dept. C. Baltimore 17, ME. classes . . the latest equipment. Free placement service. Approved for veterans. %Trite for free booklet. (Founded 19201 )s West Biddle Street. Baltimore I. Md. Don Martin School of Radio Arts 1655 North Cherokee St. Hellyao d 2e, Ca11f.
Complete Radio Engineering Hollywood Make Good in at Course. Bachelor of Science De- RADIO COURSES tmt RADIO OPERATING CODE gree. Courses also in Civil. Elec- HEelp l'xpertsau RADIO- TELEVISION H RADIO SERVICING ELECTRONICS trical, Mechanical, Chemical. Aeronautical Engi- Pinrt from Hollywood. of nds ativities. comesfirs Ì1'T A . time. F.M. TELEVISION neering: Business Administration. Accounting. ' and tested home training. Here last -easy t learn. home instruction that quickly qualifies You for REFRIGERATION SERVICING Secretarial Science. Graduates successful. 65th steady. good-pay own Radio Write for Catalog and Picture Brochure year. Enter S.mt., Jan.. March. June. Write for bite of o parts given alunno eateaa harge. Get fulfil deg tails t once! Send postal for ROOK Itow to Make catalog. Good In Radio Television." Y.M.C.A. TRADE & TECHNICAL SCHOOLS/ IS W. 63rd St. (N'r B'way) New York City TRI -STATE COLLEGE 1 GOLAOO" INDIANA RADIO TRAININO ASSN OF AMERICA. Dept. RCK 5620 Hollywood Inds Hollywood 25. Cant. RADIO -ELECTRONICS for CIlllllllllllicillions 93
FM INTERFERENCE Dear Editor: FACTORY I have just read Mr. Zarattaro's to SPEAKER THIS SIMPLE ter in the August issue and want suggest to him and others that the solu- REPAIRS tion to the automobile interference prob- Since 1927 BENCH TEST lem seems to be either spark -plug sup- CHANGIIH HAsi. I IpERS. pressors or the new resistor spark plugs li^ (see the September issue, page 86). Also, I would like to advise fellow NOISE _TER for MOBILE POWER SUP. Pl. IFS 111 -. Ilernletirally readers to beware of induction -type sup- _ . .S9 arc between REIN SA GLIDE PATH RECEIVER. 332.335111 pressors. They are likely to i'a,° $2.95 of coil, which consists of fine WITH FULL SCHEMATIC. NOW ONLY turns the R.89 schematic only 10c wire scramble- wound. The arcing makes ALNICO MAGNETS- EXERIMENTAL KIT of lo ....td. 10,11rful Bar, Block. Circular matters worse. Kit of 10 . S1.96 RCA UX 200 TUBES. Ideal mimic detector. R. J. FIEDLER, B rand NEW B for 1.00 Baltimore, Md. B ENDIX AMPLIFIER of Sight, 115V. 4011 cycle. Contain.: 3 al III, & I power trans. d oil cond.. plus many other Humli iieinn worth proves you're right saueral the price. Black crackle 11111 ch 7't x 4'. .Shoo. wt. r O ills 1.911 SUPPRESSORS STOP NOISE SELSYN CONTROL TRANSFORMER 124101), Remove the cover from an IRC con- 115V 400 cy SltpE. wt 2 Ihs. 1.49 Dear ICROPNONE. Sensitive dhohragm trol, and from any other reputable type. Small s r , III " O.D.. I.. deep) Ideal see the I read with interest Mr. Zarattaro's for RIGII.AR LAPEL or CONTAIT MIKE: or as control. You'll immediately PILLOW SPEAKER. Rul,hrr shuck -nord. metal Features in issue on ignition frame. Lias housing . e .96 superior IRC construction. letter the August 12 for $10.00 interference on FM. He is certainly that insure long dependable perform- right. Many listeners in suburbs or ance. Point by point, compare IRC's ! ! KIT OF THE YEAR ! ! design to that of any other control rural areas are plagued by the noise of LEOTONE'S "JUMSO RADIO PARTS cars going by right in the middle of an ASSORTMENT" and you'll know you're right when You can't afford to rms. this TREMENDOUS for FM B ARGAIN OFFER of n and dismantled you ask IRC! program. radio and electronic parts. 17 FULL POUNDS However, I have found that cars of: TRANSFORMERS. COILS, SOCKETS. WIRE. SPEAKER ACCESSORIES. HARDWARE. Notice -the terminals are riveted will not cause CONDENSERS. ETC.. ETC. ALL with proper suppression AND Ishpa positive electrical contact. THESE21 IMUCnIyMORE $2.95 assuring this racket. A simple distributor resistor w Gliding "5-finger" contactor provides of 10,000 or 15,000 ohms will do won- EXPERIMENTAL TUBES-Handy assortment off smooth gradation of volume. Silent ders, as will resistor spark plugs. receiving typetesting, s. rrut' research.a Spiral Spring connector eliminates is necessary to All filament tested. 20 for 51.00 An active campaign 4 TUNE CHASSIS. Punched steel for easy principal source of control noise. Re- of Parts. 10- x 4h r x 11 2 -, Shin. wt. get car owners to install these simple ï tg.f .23 sistance material bonded to bakelite but effective suppressors. Would it be s for $1.00 RECORDING SPECIALS!!-RM -4 RE- base gives an even, long hearing possible to get the FCC to do some- CORDING MOTOR. Ileavy duty 110V., Bll eyries. Admdahle to Wlit,:, TAPE: or DISC element. an causes interfer- RECORD & PLAYBACK. 38.. sit. x 2:1.1'. Less thing? If amateur Ihlt. n11g. Pl:de & reduction drive wheel. ence, he gets into trouble. Isn't a spark ehpm. wt. 6 Ihs. .95 PERMALLOY LAMINATIONS for constrileting plug really a little transmitter? TAPE: RECORDER DEAD. Per ouvrer rmltg laminar Ions .40 CHARLES C. BOEHNKE, MAGNET WIRE In wind complete TAPE HEAD. Nn. 22 l'1:-35e. No 2sIw : -59c. No. 30 SCC- Los Gatos, Calif. 45c. Kit of all 3 .l u.,ls 1.25
NYFLUX RECORDING TAPE. . Recommended ho 11ií: nt.I 1.11AÌ)' 4: penn.,m .nry. Standard 1 hr. soss) J 2.98
ADVISES GOOD ANTENNA ALNICO ERASE MAGNET :. I SPE or WIRE. l' shape. .39 Dear Editor: SCR -274- ARC -S- TRANSMIT, R P.A. COILS- In Billowing _. I :1.2.1, 2.1.4. I do not see why Mr. Zarattaro should 4 -5.3, 5.3-7, or 7..i .I ea. .49 be so troubled by ignition noises. Per- haps either his receiver or antenna is SOMETHING FOR EVERYBODY ALI. METAL CABINET not adequate. WRITE TODAY FOR ANy OF HESE FREE SUPPLEMENTS: T Add time- saying convenience to the I am located in an area with high "RECORDING PARTS & ACCESSORIES ""ALNICO A MAGNETS " other features of IRC controls by ignition noise. With an ordinary dipole "HEARING ID & MINIATURE PARTS" noise was present "RADIO & ELECTRONIC COMPONENTS" buying a practical stock in this hand- on the roof, enough "GEARS. SHAFTS & PULLEYS" this to make an annoying clatter and mar some allmetal cabinet. With investment of 18 Type D the otherwise perfect reception from TERRIFIC TUBE VALUES -STOCK UP NOW at op minimum to RO'. off list. Perfect condition; un.ealea cartons. plus switches and special my Pilotuner. When I installed a double Most types in stock, ALL GUARANTEED FOR 90 Controls NOMS! sturdy cabinet is fur- dipole with reflectors, the annoyance NO. 27, 35, 37, 30, 77. 84. 85. 5W4. 523, 39c shafts, the IIA7, BBB. BK7, or 11x5 nished at no extra charge. You pay decreased until it is barely noticeable No. 41. 78. IA7. 1LN5. 51,5. 51'4. BA4. 6117. tics, ors. 8E8, BGS. 035. OER,,. 81.0. 05.57. standard net price of the I OSD7. 05117. 05K7. 6117, 7A7, 7B8. 71'4, only the on even weak stations. believe that 49c additional antenna gain will solve the 12587. 1_547..r 58155 merchandise. Fast moving control TUNE CARTONS: Plain White stock in this IRC cabinet services problem entirely. A friend tried the 31111ialure ,1' sit x s') Per lue GT 5)5, 1114- Si). 111., -1 Inner 1.110 1.25 of the Howard Sams RED same cure with similar good results. Medlnm II I2- so. x 414^1 Per 100 1.49 90% I.arge 12' rio. X 5') Per 100 1.79 WILLIAM BANDES. JR., BOOK listings. Nescopeck, Pa. HANDY RADIO PARTS KITS No. 1 -R.F. ANTENNA & O5C. COILS. INTERNATIONAL TOO MUCH FOR HIM No. ] MOULOEO BAKELITE CONDEN- NOISE SERS .,. 2 mlI. 2011- 2.93 Dear Editor: No,tS EtEETROLV,lcS. aun. 1.9 RESISTANCE CO. I agree with Mr. Zarattaro's letter No. 9-WAFER S(1LKETS.Al2 to - .25 No.rlórVOLrACE DIVIDERS (Communications, August, 1948, page 1.98 401 N. Brood SI., Phila. 8, Penna. No .'rIt SHIELD CANS 82) that automobile ignition systems .9R In Canada: International Resistance Co., Ltd. No. 15- WIRE WOUND RESISTOR, Licensee ruin FM. I have two FM sets, an 11 -tube .9R Toronto, RCA 711V3 and a Pilotuner, both using ARM folded dipoles with reflectors located 50 Min. order $2.00. 20e. Deposit Req. on 0.0.D Yes! We're listed in to 100 feet from the street. When the P leas,. add sufficient postage. Excess Refunded the RED BOOK traffic is heavy, I have had to turn off Looking for the correct FM stations and listen to programs on LEÖE RADIO CO. IRC replocement controls for any receiver manu- 7, N. Y. AM to avoid ignition noise. 65 -67 Dey St., New York factured from 1938 to The PHILIP J. BRASSINGTON, Worth 2 -0284 19481 Just refer to Easton, Pa. Radio Industry RED BOOK. NOVEMBER, 1948 92 - - _ :01111111111icnfions NOW! WHAT'S IN A NAME SUPER VALUES CASH IN Dear Editor: I shall continue to buy RADIO -CRAFT on TELEVISION no matter what the name or cover. I buy it ìta(fl `_ for what is inside. from MID- AMERICA! The name "Radio- Craft" does not cover Stromberg - Carlson DYNATENNA the entire contents of the maga- zine, but no title will, unless you put the whole table of contents on the front This famous -make FM mitting station. Illus cover, like the digest magazines. antenna has been ad- trated instructions Old readers, too, will stick with the vertised and sold for nd all necessary magazine regardless of the title. But ma rimes the low ahardware. A screw - is only tool don't forget to leave some "craft" in price 51113- AMERICA driver - -J asks! Covers both FM needed for assembly. the contents for the boys who are just bands. Delivers FM -` Dynatenna is seam- coming into radio. They would never reception at its best. less. heat- treated. wit get started with television and u.h.f. in Complete with 60 ft. of all aluminum . . . 557 k 300 -ohm twin lead -in. will withstand the beginning. Another thing: many Line is standard ap- se, .rest weather. 10 n: people like to read about the new and proved flat -type. solid up -to- the -minute gear, even though they dielectric with weather - resisting insulation. $495 never expect to own it. FM and TELEVISION SWEEP Don't change the inside of the maga- Mounts anywhere each easily .. vertically or SIGNAL GENERATOR SS4,95 zine. It's good as it is. c4.45 each horizontally to match :\ must service W. BELL, Ir wt t for progressive shops -a J. polarization of trans- I Lny at this sensationally low price! Ac- Coatesville, Pa. urate!- Aligns FM and television re- ,-eivers. Frequency range 2 -227 MC. Out- put modulated or unmoduluted. High frequency insulation throughout. built -in I'' wer line filter and special Midline ca- LIKES NEW FORMAT pacity tuning condenser. Easy to operate use it to adjust to new TV channels. Dear Editor: .\(' only. Exceptional opportunity to I wish to commend you for the many purchase instrument of this kind direct improvements in in PERMEABILITY from manufacturer at a tremendous the magazine the TUNER past months. Reading it has always Itulld a alb' ID r1 5 air -..:ubc At' -DC .up.,n.. n -:wins! been of Takes plan old -style gang r nden.er, at : nd u an interesting, educational experience; coils: regular 455 KC intermediate frequency. MA -7167 WIRE Complete with permeability tuned oscillator coil. however, your new format and the con- 4' x 2há' x 2'4 21s' diameter dial drum. Coro . $ 24 plete with diagrams for building5 and 6 tube set-. RECORDER solidation of each article into one con- Order MA -21611 Loop Antenna 15e and tinuous unit have reading MA -21114 made a genu- Order Drilled. ranched Chassis 39c RECORD ine pleasure. Further, your expanded PLAYER coverage of the entire radio -electronic -s BANTAM 1- WATTER field makes RADIO -ELECTRONICS a fac- $109.0° tual journal of the entire electronics in- BCR- 746 -A tuning unit Complete dustry. used as foundation for with 2 spools Bantam l -W de- of wire cord K. E. FORSBERG, scribed in Jan. 1948 QST. for radio re- Makes tiny crystal- cording a n d Sauk Centre, Mitin. controlled C5V smitter microphones. Measures only 3',' long. 2'u' high. i'.- wide. Re- quires only 1,2 volts '.A . 30 to 90 volts "8 ". Draws 8 to 15 ma load. Supplied Ie CARS ARE TRANSMITTERS under , e crystal. 154 tube and plug - In coil M.A -907.. Dear Editor: SPECIAL AUDIO TRANSFORMERS Mr. Zarattaro sure spoke a parable Exceptionally high-quality universal output transformer for in his letter on page 82 of the August up to 12' speakers. Rated at 12 watts. Matches any single. issue. push-pull or parallel tubes to 6 -, ohm voice coil. 122- color - coded leads. 2' high with 2'i mounting centers for installa- I have a G -E XFM -1 receiver, with tion on chassis or speaker. Complete with instrne- Lt 1 7 9 tions for matching tube impedances. MA -1205 1 antenna 20 feet high located 90 feet Hermetically sealed Zog ohm Single 3000oho. to 4 -ohm For Pleasure or Profit from a highway and parallel thereto. CTto50.000 ohm grid. Usr as voice coil output for StL6. A be microphone transformer. 35Ln, etc. 1'« high on Vat- Simply press a button and begin record- passing truck can heard from the line-to-grid. etc. 2'.' Ce` mounting centers. Ap,( time it gets within 400 feet until it is xl'á111ry -. MA -1242 Ua01 MA -1235. . Ys7F ing- anything you can hear. it Will re- cord and play back! You can stake a the same distance in the opposite direc- permanent record, or with the money- tion. At a speed of 30 miles per hour Heavy Duty Noise saving "eraser" device use the saute wire Filters that takes about 20 seconds. This inter- Rated on 10 amps. 115 -volt AC. Measures only Fxl'ísquare. again and again. ALSO: has a TURN- Install right in amplifiers, receivers and other equipment TABLE that plays standard 10 and 12" ference is certainly the bane of FM re- where line noises must be kept at a minimum. Na: 7160 tionally-known manufacturer. MA -2164. I s71 discs! It's a 8 -in -1 machine -and sim- ception. plicity itself to operate! Microphone has Filter for mobile power supplies. Rated 10 amps, 6 -3 VI/C. record Cats equipped with radios have spark Has additional 2 mid. uu VDC condenser. 2' high. table stand attachment -lets you 2' square. MA -2166. . 599 programs without use of microphone - suppressors that render them perfectly gets improved quality. Operates on At'. quiet. This suggests the only angle from Beautiful luggage -type carrying case. which this problem can be tackled. The SPEAKER SPECIALS Size: 9'_" x 17't" x 14'," All with Heavy ALNICO 5 Slugs law should require that all cars be All Items Backed by ECA with RMA Guarantee equipped with spark suppressors and 31r' PM MA. 2062.. $1.39 4x6 Oval PM MA -2187 $1.39 5- PM MA -2071 .. S1.39 6' PM MA- 2189... $1.95 Enrlcsed find cheek (or money order) 0 la full subject them to inspection the same as 20°° deposit. bal. COO for the following: brakes and lights. Send me FREE ECA Bargain Bulletin ORDER FROM THIS AD! FM Sig. Generator S34.93. Even with the laws as they are now, a e - 4uantnies limited. get v order in 1 Mm Wire Recorder S109.00. der >1. S I don't see why the FCC can't arrest .hilqud. :r, -nd 2;'ßi, deposit. balance C.O. . Get on MID- AMERIC A's mailing list to receive BIG BAR- and fine drivers or owners for GAIN BULLETINS that list latest, greatest buys in radio Naine truck parts, electronic equipment. Send orders to Desk Iii' I1, without a and caus- Address transmitting license ing intolerable interference. MID -AMERICA CO. Inc. City Zone.... State FM has come to stay. Ignition noise AMERICA must gol ELECTRONIC CORP. OF FREDERICK E. WARD, 353 W. 48th St. New York 19, N. Y. Catauntet, Mass. RADIO -ELECTRONICS for World-Wide Statine List 91 Freq. Station Location and Schedule Help! 0100 Mutual 0500; It's 15.450 GRD LONDON. ENGLAND: to Give Us Your Order and We'll Give MUST VACATE 15.590 F21 BRAZZAVILLE. FRENCH EQUA- TORIAL AFRICA: OW. h, O61ltl: Low Prices on Your Radio and Elec- 8:,:0, In 111311 17.440 HVJ VATICAN CITY; 0715 Io 0045 tronic Requirements! WAREHOUSE -ALL PRICES 17.530 FZI BRAZZAVILLE. FRENCH EQUA. TORIAL AFRICA: 0.00 I. 111::x: Here are Only a Few Specials! 0111 to 071'.: 111111 Iu 11700 REDUCED FOR CLEARANCE 17.700 GVP LONDON. ENGLAND: 110111 to 14110: Our 3 -Item Special! 171111 Io Is.0 -* F 17.710 GRA LONDON, ENGLAND: .1015 to 0100: 1- Standard- Phono Motor -9" 'Turntable ma.0 0. 001-.: 091:. Io 1115 HOWE. HRU DC POWER SUPPLY ENGLAND: 11c::n a, 09110; 2- Crrstal.riekup -inrl. 17.730 GVD LONDON. Covered record Player Base -13 x SV. x 3b2 1710, to ho11 : :0115 1. 11030 3- 24 -28 V. at 70 amp. 2000 watts 17.750 WRUW BOSTON. MASSACHUSETTS: 1100 with cut -out for Motor . 101'. SPECIAL. ALL 3 for t 4.50 gasoline engine generator with elec- 17.750 WRUX BOSTON. MASSACHUSETTS: 1725 In Lots of 10 42.50 supply which can to Imo. tric starter. Power FRANCISCO. CALIFORNIA: Over 100 Assorted Resistors 24 equip- 17.760 KWID SAN 1.15 be used to operate -28 V. Don To .311 y. to 2 Watts 25.00 17.760 PARIS. FRANCE: 1171111 to .1901: 11110 In Lots of 25 ment, start airplane engines, charge to I2:41 50L6 Output Transformers. sa. .32 7.50 batteries, as a welding machine, 17.770 OTC LEOPOLDVILLE. BELGIAN CONGO; In Lots of 25 I2SR7 Sealed Carton Tubes .30 11300 1 1111'11: 1150 to 2:15 lighting system, or for amateur radio 100 or More 27.00 17.770 SEAC COLOMBO, CEYLON: 8110 111 11730; x 1100 to 1200 470 ohm -IOW. Resistors .07 station. 21!2" x l7!í" 249 ". 40 ohmIOW. Resistor. Lots of 100 5.00 17.780 WN81 NEW YORK CITY; 119G 111 1715: 19011 Weight 115 lbs. 89.50 a .2:111 8 Ft. GE Approved Rubber Lino Cord. each .15 17.780 KGEX SAN FRANCISCO, CALIFORNIA; Lots 01 100 12.00 in n r. Distributer Suppressors 17.790 GSG LONDON. ENGLAND: 11315 Io 0715: Lots of IOU S: ISO.. Io 10:10: 11110 to 1115 Miniature Bayonet Pilot Light Sockets REMOTE CONTROLLED COIN 17.800 KRHO HONOLULU. HAWAII: 11230 10 1115 Lots of 100 3.00 BOX rr 5601.10,1 All Merchandise Guaranteed. New and Stand- INSERT & SPEAKER 17.800 01X5 LAHTI, FINLAND: 111311 to 0.200: ard Brands. Refund In 10 Days if Returned Pre !Goo us 1131:1; usu. 10 171111 paid. Send 20.0 Deposit With Order. 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Sc gives 18.080 GVO LONDON.I ENGLAND I.:nB Each coin about two phono 18.130 PMC BATAVIA. NETHERLAND INDIES: 1.1:2" 1RM records of music I10n Io 113o W 18.160 WNRI NEW YORK CITY: Should be mounted on flat base 20.000 WWV WASHINGTON. D.C_. - .au of Stand 1,d, ACT NOW- SAVE BIG MONEY! Has Haydon Mfg. Co. timer 21.470 GSM LONDON. ENGLAND: !215 Lock installed in top (with key) 21.460 WRUX BOSTON. MASSACH Urs r IS 11110 BEAM ANTENNA ROTATOR MOTOR to 1.1 1. Easily removable coin box, size 6 x 21.460 KNBA DIXON. CALIFORNIA. 111 2230 31/2 1",í" 21.500 WOOW NEW YORK CITY: 1715 53.95 21.530 LONDON. ENGLAND: ..n tu 1.215 4 unit GS' hi I041)1(1 ftlflFlVfIO I!1 ;JI r Requires wires from power 21.550 GST LONDON. ENGLAND: I11, to 11100: 5I 11311 0 15110 A beautiful piece of equipment that 21.570 WCRC NEW YORK CITY: lo15 In 1030: $3.95 could be built to house coin oper- in 1:00 21.590 WGEA SCHENECTADY. NEW YORK: 11311 ated radio .1.1. 11, 1.111 Incl. S.v. 111111 ilr $2.50 Prr PAII: ONLY . Worth several times our asking price. 21.610 WNRA NEW YORK CITY: 1190. In 1,0311 IH' S.1 - I LONDON. ENGLAND: 0.w11 to 0900, RADILI I'1N TOOL BOX C.N. Arm)' U'po 21.640 GRZ ftrh. Volume rout rut. Price brand new 4.95 I .1:'.' pi 18:;.: 15011 In 16110 758 \. I 21.650 WLWLI CINCINNATI. OHIO: 115. to 1600: Signal Culp Pool I. 22311 41'H IiOX NEW BC -366 l'.S..t. c. switch sol. routrnl. 21.690 WLWLI CINCINNATI. OHIO: 11110 to 1630 75c ULTRA -VIOLET FLUORES- 21.730 NEW YORK CITY: 11110 to 1700 WNRX ILIPSVa, 9-11111 for 951 21.750 GVT LONDON. ENGLAND: 02011 to 0715: A!)iL CENT COCKPIT LIGHT 11130 In 1017.: 11011 to 1130 25.000 WWV WASHINGTON. D.C.: V. S. I:ure,I, ASSEMBLY ,.f 11.111 .Is: continuously day and DYNAMOTORS . ! C 26.100 GSK LONDON. ENGLAND: 0615 lo 1200 ail Brand New in original Parking Air Corps type -5. 28 V. DC oper- 30.000 WWV WASHINGTON. D.C.; l'. S. IOU -call r-.. E. Input 27 Y.U.C. output IV. .105. New $4.50 ated. Black plastic case about of $181,1 1 Io: roll Inn.usly day and KY.t ....Ea. m .1 N. Tyne II. G.M. 1,11,111 dia. x 3" long. Has adjustable mount- 35.000 WWV WASHINGTON. D.C.: I. s. A Inns 01110111 3511 3Ia 111811 V.II.C. WI s Eu. $4.95 ing flange, 3 foot two conductor . Lmdanl.; 110. h.uoudr day and Ills. UYS. new 3lolcl 233511. 61pu1 27 shielded cord and plug Includes bulb. 5'. D.C. 1.30 .Urlps Output 2055 15.1'. IbAhns Ea. 51.50 Brand new . 1.00 ea. TELEVISION STATION LIST o n' -22 /ARC Innut 2S Y. DX. 41101101. 1 . . LT Cont. 51.75 ea. Station City Channel .1:S I:Il. \'f/lit BARGAIN. Brand New KDYL-TV Salt Lake C:. U'oh 4 Y. 1E1'. 06 0'000. ).cnglh of SHAFT CO -AXIAL CABLE VALUES $5.50 ea. KSD-TV St. Louis, Mo. 5 that we KSTP-TV St. Paul, Minn. 5 Send check or money order. No C.O.D.'s. Prices Co -Axial cable values can F.O.B. K.C. on orders less than S2.06 incl. 35e KTLA Los Angeles, Calif. 5 postage. only offer to customers who buy min- KTSL-W6XAO Los Angeles, Calif. 2 imum of 100 foot per type. WABD New York, N. Y. S WATV Newark, N. J. 13 GENERAL SALVAGE COMPANY RG -8 /U cable 52 ohms impedance Baltimore, Md. II W BAL-TV DEPT. t, 29211 E. 27th Kt., Kansas City. Mo. (unmarked) _.. 2.95 per 100 ft. W BEN-TV Buffalo, N. Y. 4 WBKB Chicago, III. 4 RG -8 /U cable 52 ohms impedance W BZ-TV Boston, Mass. 4 (marked) 3.95 per 100 ft. WCAU-TV Philadelphia, Pa. 10 TO SUCCESS WC BS-TV New York, N. Y. 2 500 FORMULAS RG -29/U Co -axial 53.5 ohms imped- W ENR-TV Chicago, lll. 7 oulloni doom, pr r mh a single which ance (marked) 3.95 per 100 ft. WEWS Cleveland, Ohio S ay paid hig price. Here WFIL-TV Philadelphia, Pa. 6 300-no lens and testedi making reg anaand cor Chicago, III. 9 nroetheer WGN-TV ulously things . the ridic- Telephone LINCOLN 8328 WJZ-TV New York, N. Y. 7 ulously low price 25e. start a Cincinnati, Ohio 4 logo Is your opportunity..mlorlunuy to WLWT n pital a with mn few ñ profit' W M A L-TV Washington, D.C. 7 inppro and with undreamed profits Baltimore, Md. ran u f t TERMS: CASH WITH ORDER W MAR-TV II formulase w your own home to coi W N AC-TV Boston, Mass. 7 household expenses to the hone. Or WNBT New York, N. Y. 4 you n put then to e Ill your hop In t costs `ail much a. WNBW Washington, D.C. 4 ""r1- SURPLUS W NHC-TV New Haven, Conn. 6 Quo paying out many dollars I.. AMERICAN prollta WPIX New York, N. Y. 13 to dealers. when your. make the WP1Z Philadelphia, Pa. e thing swots-elf for ralfew cel.lr. N. Y. 1125 00 ea., u -oe. you follow I'M PRODUCTS CO. WRGB Schenectady, 4 ,..,,tile 001ructue10. WS B-TV Atlanta. Ga. B 66 PAGES. 3200 WORDS IN TEXT W SP D-TV Toledo, Ohio 13 Send for "SOO FORMULAS AND RECIPES" 4o N CAPITOL AVE Enclose 251 that's You w n't he 537 WTMJ-TV Milwaukee, Wisc. 3 for Aunt her cent no or IaLr. Sold...` .. money WTTG Washington. D.C. S INDIANAPOLIS NO WTVR Richmond, Va. 6 NATIONAL PLANS 4'OJ8PAN1- W WJ-TV Detroit, Mich. 4 P. O. Ox 26 R. STATION N. New Tura 23. N. Y NOVEMBER, 1948 90 p Presenting I, 3 Great New elitiee0 Amplifiers!
The "ELMCO" Amplifiers are de- signed for highest quality reproduc- tion of sound, music and speech. These amplifiers used in conjunction with suitable accessories will give the user most gratifying results. They have been engineered to meet enacting requirements for High Fidelity pick. MODEL A -100 MODEL A -101 ups. FM, AM, Tuners and Mikes. S Watt AC Phono AmplIfir Complete with S Watt AC Phono Amplifier Complete with Tubes. On -OR Switch, 6' linecord, built - Tubes, On -OH Switch, 61 linecord, built - In Output Transformer, Phono -Jck. in output transformers. Mic. and Phono - Jacks. Microphone and Phonograph chan. $18.75 nls can be intermixed. List $20.42 Choice Territories still List available to Mfg. Repre- sentatives. Write for com- plete details. MODEL A -102 e Watt AC Microphone and Phono Ampli fier. Built in 6 Impedance Output Trans- Dealer inquiries invited. former, Mk. and Phono Jack. Hum Level $28.65 Prices slightly higher at Normal Output: -50db. Frequency: 40 West of tn. Rockies. Write for free catalog. fo 10.000 c.p.s. List EACH UNIT PACKED IN INDIVIDUAL CARTONS WITH INSTRUCTION SHEETS AND CIRCUIT DIAGRAM.
58 -23. 79th Street Eemiteeta Saud Efeequitear ear Elmhurst, N. Y.
Io.I.. TGWA GUATEMALA CITY. GUATEMALA: GET ON THE BANDWAGON! Free. St:lllnn Location and Schedule 15.180 GSO LONDON. ENGLAND: 2::110 to l,;11u. NATIONALLY ADVERTISED TUBES pa', In _015 1.830 CONSTANTINE. ALGERIA; 0131) lo 15.190 CKCK MONTREAL. CANADA: °s15 Ill 111111; ,, OR Moor OFF. ROXED. INDIVIDUALLY ;311 I0 11y1.í: Ice 1,21. l0 1931 61 1204:6 .68 1315 1100 ...... 1 1311 I,. 00 15.190 TAO ANKARA. TURKEY: 0000 to 02110: e1 1211A0 68 11.840 PRAGUE. ail 1f30 .54 I i'I O .5, CZECHOSLOVAKIA: Diu :. ul 111111; 15.200 a5 c.v. 1 .45 Io 1115 Ice 1130; 121111 to 1215; WRUA BOSTON. MASSACHUSETTS; III'. .65 121., lo 131111 Iis Iron 11.840 VLC7 SHEPPARTON. AUSTRALIA; 22:!11 15.210 WBOS BOSTON, MASSACHUSETTS: 1:1110 49 M 111115: 1:n1) l0 1015 to ]7110: _ ,, i. yPU. .79 11.840 PARIS. FRANCE: 110311n to 01::11: 0115 15.210 KGEI SAN FRANCISCO. CALIFORNIA: -1141 1.11 Ice 03110: III'. 1 '213: 11000 to 9111.5 11".311 REPAIRMAN. 11.860 KWIX SAN FRANCISCO. CALIFORNIA; 15.220 WRUA BOSTON. MASSACHUSETTS: 1:41a 11 -1 p1), I. Iß15 11.870 I 20', MUNICH MUNICH. GERMANY; 1100 I. 171111 15.230 Deposit Required With C.0. D. Orders. 11.880 VLG6 MELBOURNE. AUSTRALIA: 23311 t0 MOSCOW. U.S.S.R.; 15211 to 1930: 01115; 1)11111 to 0113: 2 2300: RADIO DISTRIBUTING CO. 2111-, Sal to 11.880 IRR ROSARIO. a: 2100 2:311) HOLLYWOOD ARGENTINA; 011111 Io 21110 15.230 I JOYCE 28. CALIFORNIA 11.890 PRAGUE. CZECHOSLOVAKIA: 1800 MANILA, PHILIPPINES: 11400 to 111 191)0 una 15.230 MOSCOW. U.S.S.R.: 1)741 Io 11915; 11.900 KWID SAN FRANCISCO. CALIFORNIA; 10211 to 1930: 2000 to 2130: 22110 to n lu 00311 02011 11.900 XGOY CHUNGKING. CHINA: 04110 to 0530; 15.250 WLWO CINCINNATI. OHIO: 11:30 In 16311 0713 110311: 08 to I5 tu 1115 15.250 KNBX DIXON. CALIFORNIA: 111186 10 11311: 11.900 CXAIO MONTEVIDEO. URUGUAY: 1030 to 19611 to 22311 15.250 KRHO HONOLULU- HAWAII' 11100 10 11106
BUY 11.960 HEK4 BERNE. SWITZERLAND; 1615 to 15.260 11 DON'T GSI 1611 Ice LONDON. ENGLAND: 0100; ICI -. , re Il SattvdaYs 1x15 to 1815 ki,fgmt,, TAPE RECORDER 11.970 FZI BRAZZAVILLE. FRENCH EQUA- TORIAL AFRICA: 0000 to 0330: 0115 15.270 WCBN NEW YORK CITY: 121111 L. I :11 15.270 WCRC NEW YORK 1960 to IO 0800: 0030 to 1.311: lloll 1,1 20211 CITY: 2230 15.270 SINGAPORE. MALAYA: 11:::30 to 12.000 CE1180 SANTIAGO. CHILE: 0600 t0 001111: 1000 to 23110 12110 15.280 WNRE NEW YORK CITY: 11111 tu 10311 12.090 CRF LONDON. ENGLAND: 2300 to L:15; 17.0 to 21120 15.290 WRUA BOSTON. MASSACHUSETTS: 1911,1 UNTIL 12.210 VIENNA, AUSTRIA: 2315 to 1800 15.290 WRUL BOSTON. 12.260 TF1 REYKJAVIK. ICELAND: Sundays. MASSACHUSETTS: 12110 I., 111)11: to 1 17311 19110: I" 119:111 1430 715: to you the remarkable new in- QUITO. ECUADOR: 1100 tu 22511: to 18011 find out about 12.500 HC1B 15.290 0125 \H.,,. 2230 to 24110 VUDII DELHI. INDIA: 2215 In 0030; strumnt that DOUBLES your playing time In 11150; 0200 to 011111: 05110 ,1:110 - 15.000 WWV WASHINGTON, D. C.: II.8. Bureau 10 cuts your tape costs in HALF! Write today of Standard,: frequency. liver. and 15.300 GWR LONDON. ENGLAND: 121111 t0 1315 15.300 SINGAPORE. MALAYA: 113311 111 121111 for technical literature. tilrh : t r u.leasIs lvnllintr noecalls day and night 15.310 GSP LONDON, ENGLAND: 11115 III 1311: 15.100 HCJB QUITO, ECUADOR: 05011 to 1200: 231:. to 0030 1:1311 Io 22311 15.310 VLC4 SHEPPARTON, AUSTRALIA: 11275 I.. LONDON. ENGLAND; 0100 to 1000; l315: 0353 III 117,,6; 11866 to 1(145 OF AMERICA 15.110 GWG AMPLIFIER CORP. 15011 l0 1939 15.310 HERS BERNE, SWITZERLAND: 1515 to 15.120 NV1 VATICAN CITY; 0530 to 0930; 110o 16::0; 1045 l0 IS:tu to 211011, o I:11: 398-10 Broadway New York 13, N.Y. Ills 2 311 t11 22311 19:10 to 2390; 15.120 SEAC COLOMBO. CEYLON: 15.320 MOSCOW. U.S.S.R.: tun 111 2300: 05011: 117110 23:1 111 Io 1299 1111111 lo 1161111; 115311 In 1151 15311 NEW YORK CITY: 0900 t0 1815 15.130 WOOC 1 11,11 15.130 KCBR DELANO. CALIFORNIA: 191111 to 15.330 KCBA DELANO, CALIFORNIA; 11110 to 2230: 1)400 Io 10115 0:01 TALK ANYWHERE 15.130 KNBI DIXON. CALIFORNIA: 1/230 to 0315 15.330 WCEO SCHENECTADY. NEW YORK: Illy. 1o1T 3lmnlarsl Instantly To A 111 115 with Inter.Talkle! Just but- 15.140 GSF LONDON. ENGLAND; 0000 to 0715; 15.330 MANILA. PHILIPPINES: 112311 0. tons and talk to or from,, 7 E1eer. 9915 l0 11115; 1.311 In 12011: 13110 t11 o': 15 'nt o ! Nol a phnnr -L.u,l room 101111; 1615 21115; In 1111111 volume -no electric plue1na to 2300 15.330 WLWR2 CINCINNATI. OHIO: Sunday, 19110 tubes needed! Sit or hang iit! 15.150 WRCA NEW YORK CITY: 1100 to 1700; Simple and quirk to honk tr 101111 to 191111; 20110 to 21011 15.340 MOSCOW. U.S.S.R.: 2200 w l,Sn11, For homes. offices. ONLY 15.150 KCBA DELANO. CALIFORNIA; 2215 to 11 Il All tores. 1 a r m . 113:39 15.350 PA RIS. FRANCE: 2015 0, 09 ,: 1;011 Guaranteed! Write sfor fß.97 , "015; fr... details today! [ACM 15.150 SBT STOCKHOLM. SWEDEN: 0145 to 1.15: 11115 to 211::1111111 21145 CINCINNATI. 1::111) I0 10011: MIDWAY SALES CO.. Dept. RC -11. Kerney. Nebr. 11045: 10011 In 111111; 1230 to 1330: 15.350 WLWRI OHIO: 2000 to 2100 1,::01 to 1766 RADIO -ELECTRONICS for World-Wide Station List 89 In connection with the FM station list, we want to remind RADIO-ELEC- TRONICS readers that we are still on the )2adio Serviceman lookout for long- distance FM reception WEEK reports. There must be a great many of ADDITIONAL $555 FOR YOU EVERY you who have had FM dX reception but who have not written to us. Space limits the printing of names but whether yours REPAIR ELECTRICAL APPLIANCES appears or not you are contributing to WITH THE AID OF THE NEW MODEL 40 radio knowledge. UTILITY TESTER Freq. Station Location and Schedule A NEW KIND OF INSTRUMENT FOR TESTING 9.600 GRY LONDON. ENGLAND: 2:101 to 0106; ALL CIRCUITS AND 1315 to 1. ;.r. 1860 to 2215 ELECTRICAL 9.610 ZRL CAPETOWN. SOUTH AFRICA; 11300 APPLIANCES SUCH AS- In 117110: Mom to 111:01 9.610 ZYC8 RIO DE JANEIRO. BRAZIL: 1500 to RANGES *WASHERS *VACUUM CLEANERS >IIAVERS *FANS 'AIR CONDITIONERS 9.610 VLC6 SHEPPARTON. AUSTRALIA; 11100 to IlI':V'I'ERS *REFRIGERATORS Ills: 15110 to I615 "MOTORS 9.610 TIPG SAN JOSE. COSTA RICA; 11700 to Il II \ 1ì12S *TOASTERS *SUN LAMPS 23:In 1 >IIING MACHINES °ALL TYPE MOTORS 1530 to 9.620 CXA6 MONTEVIDEO. URUGUAY; H.P. TO 2 H.P. 21mí PROM FRACTIONAL 9.620 G W O LONDON. ENGLAND: 1830 to 2300 9.630 CKLO MONTREAL. CANADA; 16116 to 181111 THE MODEL 40 UTILITY TESTER 9.640 GVZ LONDON. ENGLAND; 0165 to 0100; Wil! test Thermostats under AC'T'UAL WORKING cool lo IuG; Iola 10171.5 the CUR- 9.650 KNBA DIXON. CALIFORNIA: 112311 to 0345: CONDITIONS: Will measure ACTUAL 11011 11 Inn:. 1017 N1,1100'6/ RENT CONSUMPTION of any appliance either 9.650 WCBN NEW YORK CITY; 2006 to EM A.C. to D. C. WHILE THE UNIT IS IN OPERA - 9.670 IOWA GUATEMALA CITY. GUATEMALA; TION- re'Iding will be direct in amperes -the ap- 1830 to 2330 or utility may be plugged directly into NEW YORK CITY; 1800 to 1900: 2000 pliance 9.670 WNRX front panel receptacle a special pair of insu- I1 211111 leads is motors; In- 9.6811 XEQQ MEXICO CITY. MEXICO; 0700 to lated clip -end provided for lo; corporates an ultra -sensitive direct- reading re- EQC TEHERAN. IRAN: 1200 to 1130 sistance range which will accurately measure all 9.680 0x66 9.680 LRAI BUENOS AIRES. ARGENTINA: appliance and utility resistances down to a frac- lo 221/11 DELANO. CALIFORNIA; 0400 to 0930 tion of an ohm; Will test bulbs, fuses, condensers, 9.700 KCBF field coils, etc.; Is ideal trouble shooter as it will 9.700 FORT DE FRANCE. MARTINIQUE: locate opens, shorts and Will 17::11 10 1815; and later instantly grounds; CINCINNATI. OHIO; Emu l0 2230 locate cause of failure in three way heat control 9.700 WLWS2 0730 9.710 MOSCOW. U.S.S.R.; 311111 to switches; will indicate when one side of an ap- 9.720 PRO RIO DE JANEIRO. BRAZIL; 11130 10 pliance or motor connected to line under test is IMOu; 1115 to 1115: 151111 to 2100 "grounded "; Will indicate excessive leakage be- CSW7 LISBON. PORTUGAL' 1900 to 201111 when 9.730 BELGIAN CONGO: tween a motor and a line: Will indicate a 9.740 OTC LEOPOLDVILLE. Model 40 Tester can..,, is Is :to Io 1045: 17011 to 2300 The Utility three phase motor running erratically due to Ililneae-Jap- housed in a rugged crackle än 6..., "blown" fuse; Will indicate whether the volt- 9.750 KNBI DIXON. CALIFORNIA; stem cabinet with Poaele coyer bcmn. 0400 to 1005 ,complete with all test leads are dos. :ose is 110 Volts or 220 Volts, if the current is 9.670 TGWA GUATEMALA CITY. GUATEMALA:
By ELMER R. FULLER
(t1B in Quito, Ecuador, known ABSOLUTELY NO KNOWLEDGE OF RADIO NECESSARY the world over as the "Voice of YOU NEED NO ADDITIONAL PARTS! I the Andes" is heard on 12.500 THE PROGRESSIVE RADIO KIT is the ONLY COMPLETE KIT Inc in English from 0630 to Operates 110-120 vos AC are employed in these circuits. The circuits are designed 0800; 1700 to 1800; and 2100 to 2400. DeContains everything you to provide excellent performance. Altogether. lifters, need. ndo Metal circuits are constructed, including sl 1 audso 18 in Chassis, Tubes. Condensers. and all other nec- mplii and 3 transmitters. The sets st simple Programs in other languages, all, essary radio parts. The 36-Pagea Instruction Book sent. circuits W 1 n plut rectifier. gradually w more n by eapeft inst ructors ntl ers teaches you mplrn, and finish with several examples of radio sets are broadcast at other times; and other build radios in professional manner. The first c cult built i simple one-tube detectors receiver. Each frequencies in use are 6.200, 9.900 and succeeding circuit incorporates new n ents of de. PROGRESSIVE RADIO KIT ONLY 514.75 Sectors. RF and AF amplifiers. This kit excellent for 15.100 mc. HCJB was first organized in ing the principes of transmitter SPECIAL FREE OFFER plifier design. It is used in any radio schools and Electrical and Radio Tester sent bsolutelc FREE with 1931 and now has six transmitters, both colleges. All of the commonly-used detectors artare used, each Progressive Radio Kit. PLUS FREE membership including diode, grid leak, plate and infinite- impedance. Progressive Radio Club. Entitles you to free expert a long and short wave. The languages he transmitters are designed with Hartley and Arm- v ce andWrite consultation s with licensed radio tiab,dn strong oscillators.tors, r ol.gr,d for further information or ORDER your KIT u nl .rum' tube sigh- s,i,n r ntAaation NOWT used include Spanish, English, French, WE PAY POSTAGE ON PREPAID ORDERS C.O.D. ORDERS SHIPPED COLLECT German, Portuguese, Russian, Italian, Dutch, Swedish, Yiddish, Greek, Lithu- ATTENTION Send for Your FREE DEALERS catalog and anian, Bohemia n, Latvian, Czech, RADIOMEN!! Price List Today: Arabic, Urdu, and Quechua. It is also RADIO KITS AMPLIFIER KITS FM COIL & CONDENSER KITS RESISTOR KITS known as the pioneer missionary radio CONDENSER KITS RADIO TOOL KITS FM -AM CHASSIS SPEAKERS RADIO PARTS PORTABLE RADIOS CAMERA- RADIOS TUBES AUTO RADIOS HOME station, and is supported entirely by RADIOS TELEVISION SETS TELEVISION CABINETS TEST EQUIPMENT FM TUNERS contributions from its listeners. The signals are among the strongest re- ceived in this country, and are very PROGRESSIVE ELECTRONICS CO. consistently heard. The station is al- DEPT. RC -19 497 UNION AVE. BROOKLYN 11, N. Y. ways silent on Mondays. The BBC is now being beamed to North America on 11.800 mc from YOU DON'T HAVE TO' .TEST 0600 to 0800; on 21.550 mc from 0800 -AID to 1600; and on 15.110 mc from 1400 FIRST -AID FOR RADIO -TELE to 1915. Also on 11,800 from 1615 to GRUNT & SWEAR & SWEAT SETS ONLY 2215 and on 9.830 mc from 1930 to 2215 hours. All times are Eastern when installing Wright Verified Speakers $595 Standard. Advice has been received from the with the new manager of the "Voice of Guiana," Adjustable Mounting Bracket COMPLETE ZFY, stating that the station may he heard on Sundays from 0545 to 1145 AT YOUR DEALER OR POSTPAID ANY- and 1445 to 1945 hours; and on Wed- on an old shoe WHERE IN U.S. They fit like WRITE NOW nesdays from 0545 to 0745; 0945 to LOCATES FAULTY AND RESIS- 1145; 1445 to 1945 fre- TOPS and hours. The FOR S YGCONDENSERS quency is 6.000 megacycles. This is the SUBSTITUTES 11 DIFFERENT VALUES OF CAP. OR RES. WITH SET IN OPERATION SOmmf to 4omfd 450. 600 WVDC -27 ohms to S meg. pioneer broadcasting station in the CHECKS CONDENSER LEAKAGE ON DIRECT CURRENT British West Indies and started opera- SUPPLIED FROM OWN PWR SUP. tion in 1935. At present they carry OUTPUT INDICATOR FOR ALIGNMENT -CONTINUITY CHECKS commercially sponsored programs and PROVIDES 100 VOLTS AT 100 MA FOR EXPERIMENTS. soon will have a station operating in These are only a few 01 the uses the -AID. the standard broadcast band. Their WRITE FOR CA LOG SHEET TO f signals well in Wmany TTEESTT are heard the Guianas, DEPT. II Trinidad, Grenada, and Barbados. 256 E. 98th STREET, BKLYN, N.Y. It can be expected that several of the schedules will he changed when the clocks are returned to standard time, but most of them will remain as they Get Started in Radio have been published. A major change will probably be made in the U. S. IO "HOWTODOIT" BOOKS schedules and it can generally be fig- tint =uú1 hnuulatmu to radio ured that all schedules will be moved Farh cearly un.e pn febllus.usly i trote,!. e talas . r 15.000 wards. one hour. You'll he"a zedv at the wealth of for name of nearest dors packed loto these handy Write literature and honks. Exerllelll for rerereme- litem International schedules are never as for tif notpl Iitiran.. Your Immr) distributor bark If not sallsfed. much affected as those of the stations 5 BOOKS for 50e which broadcast for local consumption, is 10 BOOKS for $1.00 of course. Remember that this list always in Time, Sent to You Postpaid Eastern Standard and WRIGHT will remain so until and unless the ma- Inc.. T lonary (leading Terms) Na. 1 -HOW Make Four t jority of our shortwave listeners prefer Doele Short Way Sets No. S -How To Have Fun 2234 University Ave. St Paul 4, Minn. No. 2 -How To M ke The With Radio another system. Please consider this Most Popular All Wave 1 No. 7 -How To Read Radio and 2 Tube Rece vers Diagrams until new schedules are printed, which No. 3-Alternating Current No. 8-Radio for Beginners will be in the January issue. for Beginner. No. 9- Smple Electrical Ea- NO. 4 About Aerials pen Mnt RADIO- ELECTRONICS needF .,lore Drfo- -All Next month we again print an FM No. 5-Beginners' Radio Dic- NO. 10- Television tos of service shops and service benehe Station List, completely revised to date. We will pay $6.00 for each 6x8- or 8x'u- Remit by cheek nr ormes nr, Ier- reelstrr letter If you Many new stations have appeared since inch glossy photo accepted. Do not "dre; our last list was printed in the Septem- up" your bench, but fake a bona -fide photo RADIO PUBLICATIONS preferably with men working. ber issue, so owners of FM receivers .5A West R'wa7. New York (7) will find the new edition very useful. RADIO -ELECTRONICS for Theory and Design at i CAPACITOR DROPS VOLTAGE When the filament- dropping resistor TELEVISION ASSEMBLY in a transformerless receiver burns out or when a new set is being built, a ca- PROJECTION TELEVISION pacitor can be used instead of the resis- tor to drop line voltage to a suitable 520 Sq. Inches ... 20 x26" Screen value for the filaments. To calculate the value of the capacitor use the formula BY TELEVISION ASSEMBLY COMPANY 2650 with All Parts and Rack C= Complete Hood V E Iibr -E III 37 R.C.A. TUBES P DUMONT INPUTUNER where Elm. is the power -line voltage, E,. is the total voltage drop across the 12" P.M. SPEAKER in and I is the rated filaments series, Pre -wired & Pre -tuned filament current. This is for a 60 -cycle line. Picture I.F. & For instance, to find the proper capac- Sound I.F. Pre -wired 30 KV WIY Tripler Fly Back Power Supply Eastman Kodak E LINE Projection Screen d f1 Aluminum Coated itor for a device using two tubes, each Top Mirror with a 12.6 -volt filament drawing 0.15 amp, with a 120 -volt line, Bausch & Lomb 2,650 f:1.9 Projection Lens C= EXPRESSLY DESIGNED V 120- - 25.2' Metal Rack, Hood .15' and Picture Frame = 3.4 pf approx. For realism, clarity, definition and Where the line is 50 cycles, substitute BIG SCREEN Televiewing, the pictures 3,180 for the 2,650 above the line in the produced by this unit hove no equal! equation; for 25 cycles, use 6,360. The This screen is absolutely flat, pre- in - answer in each case will be micro cluding curvature distortion anywhere farads. in the picture. Picture tones are true OTTO VON GUERICKE, black, grey and white -high in bril- Wiesen, Switzerland liance, yet absolutely glare -free! MANUAL OF INSTRUCTIONS AND CORRECTIONS AUTOMATIC GAIN SCHEMATIC DATA Prepared and Edited by of Six Dry - CONTROL In the diagram the -Tube JOHN F. RIDER PUBLISHER, INC. Cell Superhet, page 51 of the August, 1948, issue of this magazine, the tuning YOUR LOCAL NATIONAL PARTS DISTRIBUTOR condensers of the r.f. and mixer stages are shown connected to the a.v.c. line ONLY THE FINEST STANDARD BRAND or PHONE COMPONENTS USED THROUGHOUT through 220,000 -ohm decoupling resis- r; LOmbard tors. The rotors of the condensers Send us your name to receive FREE Almo should be grounded to the chassis and Cover.' f .) Globe 3.9225 Broadcaster magazine. the bottom ends of the secondary coils 509 ARCH ST., PHILA., PENN. connected to the a.v.c. decoupling re- sistors. Connections between the re- sistors and coils should be bypassed to ground with .01 -µf condensers. BRAND NEW SURPLUS! GUARANTEED! 3/4 RPM, HI-TORQUE ELECTRIC MOTOR
FAMOUS WAR SURPLUS AIRCRAFT FLASH UNIT PURCHASED DIRECT FROM U.S GOVERNMENT _.e, %II aunt ru ml e, :. I. .hou 1.1 have o. file $2.85 I+ atr Supply ami nt. n speed Edgerton Flash Tubes. Plat, le Sealed. l'nlrrea kal.le, 1.00nt output Ils Walt sers. total 50 mfd. made itt he t000l GOVT. COST. 540 ith Ih,lleri.., but fuminh without Change O nrr.,L.' un 110V AC. GO- cycles. ri il parlsMCRellectors. Connectors, Cool.. l e wish Piavramx and Iuntnoc Requires only 12 MFD condenser./ `lower and Trao. former S'ait OFFER Reversible. No Free Swing. Quiet. m, to CONVERT tot I lu AiC5 of COMPLETE With Full Instructions. lT)' IUwtr t a flick a of 1 the den. Money Making FOR ROTATING HAM. FM. TELEVISION AN- =-- METALIZE TENNAS MANY BABY SHOES for Success Plan AND OTHER USES. BRAND NEW -NEVER BEEN USED Allcomplete We show you BARGAIN RADIO, Dept. BR -1 A terrific war surplus bargain while they fast BIG STEADY PROFITS how to start - 249 N. Juanita Los Angeles 4. California CINEX INC. (Dept. CRI165 W. 46th St.. N.Y.19, N.Y. No waiting. Cash can start how to get or- in Cry first day. Money nuking ders rolling in WARNER SUCCESS PLAN shows .how to do every step. Learn quickly, easily with- TV INTERFERENCE TO TELEVISION TO GO? out previous training or experience. the work: how Plan backed by old established co to pyramid TV interference caused by automo- Corporation. Some of the new cars com- P ny. Your home is your headquarters. your profits. This is too good to pass up since facts Send No Money bile engines will be reduced in the fu- ing off the assembly lines have had cost nothing - now or ever. Don't Just your + r on wait. Send n and addre+ post- nd a dre..+ oon ture, according to a statement made changes built into their electrical sys- xrd today totiny Itrandell, Mgr. Postcard. WARNER ELECTRIC CO.. last month by P. J. Kent, chief engineer tems which reduce the interfering radi- ís12 Jarvis A . Dept. 2211. Chicago 2e. Illinois of the electrical division of the Chrysler ation. Results are good, he said. NOVEMBER. 1948 86
TUBESNATIONALLY ADVERTISED BRANDS TUBES YJ RCA - Kenrod - Sylvania - Tung -Sol - Notional Union - Raytheon - Philco - Hyfron N/Gh`N ek`GE All new tubes. 100 °° guaranteed. Individually brined. N /H TYPE PRICE TYPE PRICE TYPE PRICE TYPE PRICE TYPE PRICE TYPE PRICE DIA ...5 .45 3Q4 S .80 667 $ .72 6V6GT .5 .72 7E7 . S .80 32L7GT ...51.15 QUAL/T), 024 .80 365GT .... .85 6ß7G .65 6V7G .96 7F7 .. .80 33 .96 IA3 .80 364 .72 6576 1.15 6W7G ... .96 7F8 .96 34 .96 IA4P ... 1.40 5R4GY 1.15 63861 .80 6X5GT .. .54 7G7 .96 35 .72 GIFT IASGT ... .65 ST4 1.40 CSA7GT .60 6Y6G .85 7117 .80 35A5 .65 IA6 1.15 2 U4G .54 6667Y .... .85 6Y7G 1.1 717 .96 3SL6GT ... .60 THE pERFEC? IA7GT ... .72 5V4G .85 CSC7 .72 625 1.15 7L7 .80 35W4 .45 IB4P .... 1.40 5X4G .65 6SD7GT .65 6270 1.40 7N7 .80 35Y4 .65 1135 253 .. 1.15 5Y3GT .45 6SF5 .65 6ZY5G .... .80 7Q7 .65 3525GT ... .45 IC5GT .. .80 5Y4G .54 6SF7 .72 7A4 .65 7V7 .96 36 .96 .... 1.15 5Z3 .65 6567 .72 7A5 .63 7W7 .96 37 .65 IC7G ... I.IS 524 .96 6E117 GT . .89 7A6 .6 7X7 .96 38 .80 ID5GP .... 1.40 6A3 .96 CSJ7 /GT .. .60 7A7 .6 7V4 .65 39 .96 ID7G 1.15 tA4LA ... 1.15 0677 GT .. .60 785 .65 7Z4 .6- 40 .80 ID8GT 1.10 CA6 ...... 96 6SL7GT . .85 7B6 .65 I2A .65 41 .60 1E. GP 1.40 CA7 .72 CSIV7GT .. .80 787 .65 12A5 ..... 1.15 42 .60 IE7G 1.40 rA8GT ... .72 6SQ7 /GT .. .54 788 .65 12A6 .96 45Z3 .65 1F4G .96 GAB? 1.15 6SR7 .65 704 .96 I2A7 .96 4525GT .. .65 I F5G .96 CAC7 .96 6U5G .72 7C5 .8 12A8. GT .72 46 .96 1E6 1.40 (AD7G .... 1.15 6U6GT .65 7C6 6 12AH7GT . .96 47 .85 1E7 . . . 1.49 6A E5GT .. .80 6Ú7G .65 7C7 .6 12AT6 .... .65 50 1.49 IG4GT .96 rAF6GT .. .96 6V6 1.15 7E6 .65 12BA6 .... .65 50A5 .80 165G .96 6AG5 .96 128E6 ... .65 5085 .72 IG6GT ... .96 FAG7 1.15 1208 LIS 50L6GT . .60 IH4G 1.15 CARS .96 12E5 .65 5CX6GT ... .80 IHCGT ... .60 6B4G .96 12H6 .65 53 .96 1H6G ... 1.15 6B7 1.15 SPEAKERS 1215GT ... .54 56 .65 ELECTRIC PORTABLE I16G .96 CB8G 1.15 I2J7GT ... .72 57 .72 114 .72 604 .60 $1.25 12K8 ...... 85 58 .72 PHONOGRAPH ILA4 ...... 96 675, GT .60 4" PM Speaker.... 12117 .65 70L7 1.15 electric phonograph I164 .96 CC6 .72 128A7GT .. .65 71A .72 A fine playit:e ILC` .96 6C8G .96 5" PM Speaker.... 126C7 .... .80 75 .60 in a handsome case. Can be easily IL':6 .... .96 606 .60 1.25 12eFS .... .65 76 .60 .96 675 .... .80 .72 carried anywhere. This electric port- ILDS 6" PM Speaker.... 1.98 126E7 .... 77 .60 able phonograph will make a won- 11.114 .96 fiF5GT .... .60 12867 .... .72 78 .60 derful for any music lover or I1-N5 .96 6F6 .72 12SH7 .... .80 79 .96 gift INCGT ... .72 6F6GT . .60 12317 .65 80 .45 record collector. 'NCG .65 (F7 1.15 SPECIAL! 126117 GT . .60 81 1.40 Note these features that make this 165GT .... .96 6F8G 1.15 VOLUME 1231.7GT .. .85 82 .96 phonograph outstanding: I R4 .... .96 6G6G .96 12SN7GT . .80 83 .8u 1R .72 fill GT .. .60 12SQ7 GT . .54 832 1.15 Handsome leatherette cover. 164 .85 612 GT ... .54 CONTROL 12SR7 .... .80 84 .65 ISS .65 616 .96 Plays 12" records with cover 14, 'nee with switch. 14A7 .80 85 .811 174 .72 61761 .72 14B6 .80 closed. .... 3 for 99c 89 .80 ITSGT .96 6186 .96 14117 .80 l'7L7GT .. 1.15 5 for Large 5" Alnico Speaker IV ...... 80 fiK6GT .54 14R7 .80 II7P7GT .. 1.40 excellent tone reproduction. A3 .. 1.15 6K7 .60 25L6GT .60 11723 .65 2A46 1.15 6K8 .85 2 Watt Amplifier. 25Z5 .54 II7Z6GT . .85 Rim drive constant speed motor. 2A5 ...... 80 615G .96 TERMS: 25 °° with Order- 2526GT .54 VR 90 .... s6 2A6 .96 rL6GA .... 1.15 Balance C.O.D. -F.O.B. Chicago 26 .65 V R 105 . .96 List price $29.95 2137 .96 6L7GT .. .96 Prices 26A7 1.15 VR150 2 2 879 1.15 Subject to Change .96 @ c 6N5 .80 Without Notice 27 54 3A4 .72 6N7 .85 30 ...... 72 9001 .80
NET PRICE . $1 87 1291 . .96 6P5 .80 Minimum Order 52.00 31 . . . . .96 F M1000 . 1.15 A5. (955 'Dfi 1299 .. .06 6P76 1.15 32 ...... 1.15 11YI17 1.13 LOTS OF THREE 14.95
FRANKLIN -ELLIS CO. 'Dept. RC-Il+ RCh agoh7S+lieoi6
NEW G.E. WATTHOUR METER SOUND EQUIPMENT, f('e,lll ire Ili (I jeln,l pu yr 85) SOUND VALUES effect, a push on one side of the disc N RADIONIC'S without a correspondingly great pull on ke /, FREE CATALOG the other. This tends to thrust the entire SENSATIONAL TUBE OFFER! shaft to one side or the other. Side - thrust will also occur if the two con- centric magnets in the bearing system TUBES are not aligned. i perfectly IRS 6514707 125Q70T ISS 6511707 35L667 Stainless steel guide pins are fastened 174 6,0667 35W4 354 6XSGT 362567 to the inside of the fixed cavity to keep 66T6 126T6 5085 6aÁ6 13aÁ6 SOÁ70LeaTT i the moving system in line. These 61ES 126_6 65 extend 61(5C7 12S67OT down into 65 6 1251 6c the rotating cylinder through 6SJ,CGTT125X7o767 T ach i a graphite washer. Any displacement CONDENSERS Brand New `(No caused by side- thrust would make the Government Stock! FAMOUS MAKE guide pin touch the washer. Placement ELECTROLYTIC ITubu of been 25 mle ,., 25v ßOlaralc the damping magnets has ar- 20 20 mrd E. 150v 50 PRICE 50 30 mrd s 150v 55c ranged so that there is minimum side a mid 450v 35c $995 12 mrd 5ov oc t hrust. 16 men 50v SOC s B mrd . aso. SSc tor or en, s o r r y. COO'. e 3, Since 1941 the magnetic suspension PAPER IT UI,l.: rsl State Sales Tar. .1 mrd 00 15c has been on accelerated -life tests, .OS mrd 600v 13c show- .OI mid -. 600v 12e ing excellent .003 mid 600r Sc stability during tests STORE OPEN DAILY 9 to 6- SATURDAY 9 lo equivalent to 65 years of ordinary oper- an,MUFTI ores $3.00. 20°° ee,n.,t B.,i. C.O.D. &ÇTna!ette ation. RADIONIC EQUIPMENT COMPANY MULTI.FREOUENCY GENERATOR In radio service work. time means money. Locate 170 NASSAU ST., NEW YORK 7, N.Y. trouble faster. handle much c greater volume of Tribune Theatre Entrance work with the SIG NA LETT E. As a trouble shoot- Tel WOr,h 2.0421 Coble "CHANSLOR" ing tool. SIGN AL ETTE has no equal. Merely plug CORRECTION in any 110 V. AFDC line. start at speaker end of circuit and trace back. stage by stage. listening in The line cord resistor of the dual test set's speaker. Generates RF, IF and AUDIO Fre RADIONIC EQUIPMENT CO.. Deut. 1011 auenries. 2500 cycles to 20 Megacycles. Also used instrument, page 40 of the March, 1948, 170 Nassau Street. New York 7. N. Y. for checks on Sensitivity, Gain. Peaking. Shielding. 5e114 LI Tube testing. Wt. 13 oz. Fits pocket or tool kit. issue, is shown as 300 ohms. The correct t. your litfit, tutalet,C. rulliiea.'.to and bar - See at your dist. or order direct. Fain Ilota 11 a published-listing Muth.to la leading value for the tube shown is 550 ohms. manufacturers of radln- eleettlde malts suit equipment INSTRUMENT If a dropping resistor is used, it should NAME ¿r LABORATORY. have a rating of 20 watts or more. INC. P.O. BOX or STREET DEPT. C. 1125 BANK STREET We thank Mr. David Gnessin of Co- CINCINNATI 14. OHIO TOWN STATE Bed lobben write, I lumbus, Ohio, for correction. Quali wire for details. a this RADIO -ELECTRONICS for Miscellany
FOR FINER FM -AM RECEPTION THIS TUNER-AMPLIFIER COMBINATION
Fig. I -A mock -up of the suspension system.
NEW G -E WATTHOUR METER THE watthour meters used by electric power companies, to measure con- sumption have been developed to the point where maintenance needs are very small. However, since the rotating disc rests on bearings, friction eventually makes it necessary to replace the jew- eled bearing. A new meter developed by the General Electric Company elimi- nates bearing friction by using magnetic WITH suspension. Fig. 1 shows the rotating disc and REVOLUTIONARY the magnetic- suspension system. The AUTOMATIC concentric outer and inner cylinders are magnetized axially, with opposite polar- FREQUENCY ity, so that the resulting magnetic field CONTROL! supports the inner magnet with a slight downward displacement, which can be seen in the photograph. Thus the inner member hangs freely in air-a bearing FM -AM TUNER RC-11 F e a t u r e s audio inputs. Polished chrome chassis. truly without friction. automatic -frequency control, most revo- Audio cable, escutcheon, decals, anten- Fig. 2 is a detailed view of lutionary development in FM design -- nae, and detailed installation instruc- the upper entirely eliminates drift and multiple tions furnished. cylinder and a cavity. The magnets are tuning responses. Nine shielded minia- made of cunico, a highly coercive and ture tubes plus rectifier include double HI- FIDELITY AMPLIFIER RC.2 easily machined limiter and tuned RF stage in both FM High impedance input; 12 watts output material. and AM. Low -impedance loop, enabling at 1% distortion. Taps: 4, 6, 8, 15, 500 flexibility in mounting, provides low - ohms. 65 db gain, including inverse noise AM reception. Rear socket pro- feedback. Uniform frequency response vides easy access to 6.3 -volt AC and from 20, to 20,000 cycles up to 8 watts GUIDE PIN exceptionally well -filtered 100 -volt DC output. Hum 65 db below rated output. for supplying external pre -amplifiers, Tubes: 6J5, 6SN7, (2) 6V6, 5Y3. additional pilot lights, etc. Controls Durable polished chrome chassis. include separate bass, treble and switch positions and for phonograph television Write ler Descriptive Circular ''Ir ad Prices. L_T_J The RADIO CRAFTSMEN, Inc. 1341 S. MICHIGAN AVENUE, CHICAGO 5, ILL.
I OUTER lAAGNET ' INNER IAGNET L --- Fig. 2 -The shaft is suspended by magnets.
In the usual jewelled bearing, most of the weight of the rotating disc is supported by the lower bearing. The stress is on the order of 100 tons per - je r V l 1c Speea square inch. With the new magnetic °f A. M1V. problems. in bearings, this pressure is eliminated. nment' s -s -s fells HOW - There are, however, side -thrust forces the and adjustment leOr simple, direct language. alig complement Pu'chose that can cause wear. These are caused extra ea nu New 9th edition now off the press. No -obsolescent ment by the rotation of the disc and by the Equip 100 pages of valuable information. mplotal test damping magnet, which is a part of only the electrical metering system. When Employs ..... Available from all leading radio parts and the disc is made to rotate as power is equipment distributors or directly from factory drawn through the meter, there is, in ...... at only 40c per copy. APPARATUS COMPANY, 92 -27 Horace Harding Blvd., Elmhurst 4, N. Y. NOVEMBER. 1948 PRECISION Miscellany 84
Order a made) 247. 0 ixrcuard the unbelievably low frire and compare it aDlo Tfnrtr iUc Pear5 TIgo I A CHALLENGE - on the basis of appearance. gu.ulity and per onuance to any other Tube e Tesler IA NY MAKE, ANY PRICE). If you are not rnmfletely satisfied with the model 247 after a 15 day trial. ün e,nn,trall; Publications return it to us fer lull rehmd -no explanation necessary. The model 247 is In surplus nor is it a hashed over pre -war model. It is newly designed and incorforatrs mw inn below and order one today: :vlvan.r. in Tune T . br u ,i on. R: ad Po. des upt HUGO GERNSBACK tea. SO Founder Tilt NEW MODEL 247 Modern Electric, 190E Electrical Eaperimenfer 1913 Radio News 1919 TUBE Science 6 Invention 1920 Radio -Craft 1929 Short -Wave Craft 1930 Wireless Association of America 190E
%.46P-.y20 TESTER Some of the larger libraries in the country still hay ¡',G l orles of ELECTRICAL EXPERIMENTER nn file for l'II, ,,, rnl.a, loetals, Gantant jr. peanuts, interested readers. r,I, miniatures, magie eye, hearing aids, thyratrons, the nett type B.F. minia- In ELECTRICAL EXPERIMENTER tures, etr. November, 1914 Featftres: A newly designed element selector A Simply Made Loading Coil switch reduces the possibility of obso- by Stuart Sandreuter lescence to an absolute minimum. Crystal Detectors and Electrothermal When checking Diode, Triode and Action Pentode sections of multi -purpose by Dr. W. H. Eccles tubes, sections can be tested individually. A special isolating circuit allows each section to be tested as if it were in a separate envelope. Making a Hot -Wire Ammeter * The Model 247 provides a super sensitive method of checking for shorts and Electrolytic Interrupters and how to leakages up to 5 Megohms between any and all of the terminals. use them * One of the most important improvements, we believe, is the fact that the by H. Winfield Secor 4 position fast- action snap switches are all numbered in exact accordance with the standard R.M.A. numbering system. Thus, if U. S. Wireless Truck has 800-Mile the element terminating in pin No. 7 of a tulle is under Range test, button No. 7 is used for that test. Wireless on Delivery Vans Model 217 comes complete with new speed -read chart. Comes housed in handsome, hand -rubbed oak cabinet sloped for bench use. A slip -on port- ELECTRONIC LITERATURE :11.1e hinged cover is included for outside use. Size: 10't/s" z 89j" Any or all of these catalogs, bulletins, 20'; Deposit Required on All C.O.D. Orders and periodicals are available to you if you write to us on your letterhead (do DEPTNEW11ORK Y. ST. MOSS ELECTRONIC DISTRIBUTING CO. not use postcards) and request them by number. It is necessary to send only the number of the item you want. We will forward the request to the manufac- turers, who in turn will send the liter- ature directly to you. This offer void after six months.
II -I -FM AND ANTENNA DATA A 16 -page booklet of information on the Model 300 and Model 400 television - E.M.C. MODEL 300 FM antennas, issued by Tricraft Prod- ucts Company. Illustrated with draw- Vacuum Tube Volt -Ohm Capacity Meter ings, directivity patterns and perform- DC VOLTS -G ranges to 1000 volts. ance charts on these antennas. Of in- AC VOLTS -5 ranges to 1000 volts. to owners of FM and television RESISTANCE-6 ranges to 1000 meg- terest ohm s. sets. -Gratis CAPACITY -4 ranges (.000025 mfd to 20 mfd) II -2- TRANSFORMER CATALOG HAS ZERO CENTER POSITION Catalog No. 4811, issued by Merit
Model .31111. as illustrated Coil and Transformer Corp., lists speci- with leads $39.50 fications and prices of transformers and 'other models also available) chokes for replacement, amateur and See the Model 300 at your Jobber electronic application.- Gratis WRITE TODAY to Dept. 8-9, for NEW, FREE CATALOG
I I-3-PLASTICS BULLETIN Bulletin No. CDP -578 describes and ELECTRONIC MEASUREMENTS illustrates the design, moldmaking and molding facilities of the Chemical De-
C O R P O R A T I O N partment of General Electric. It lists applications and general properties of N. Y. such materials as n»'calex, silicone and 423 Broome St., New York 13, other plastic materials.- Gratis to inter- ested /311 ?1 if's SMOOTH fit SERVICING { $3.00 FOR CARTOON IDEAS Thi. VHF ALIGNMENT iv { RATIO- r'It.tFT prints seserat radin rat t,.ms every II- 4- WALSCO CATALOG WAND 2'.a.r ornr.n r.c mon, Il.. Itradrrs a ,lied to r Abut,' nmunrmis ublclt hr, n the used in T,' lit.m fm m. It i on A. el nonne FM TV a V H F Alignment Wand { tudiu i This 15 -page catalog lists hardware, v//f nut I ce ary that you draw a sketch, unless you mho, 5.500 me . wpn.nr du,. will. Instructions 60e a wish. r tools, chemicals and finishing materials, ,..aon, In blondin, el on, end di n m h e nead, nod Alt rhrrks are payable on publlral I..h Sob .. romo TRACKING. SENSITIVITY a S:N problens Tdb stAith malle by Walter L. Schott Co., for use RADIO CARTOONS. RADIO -ELECTRONICS stM ann.m ro male, .loch way and ho. much A modern shop MUST' in assembling and servicing radio and HAWKINS RADIO COMPANY 25 West Broadway. New York 7. N. Y. 621 Ens, 31.1 Sucer K Guy 3, Mo. electronic equipment.- Gratis RADIO -ELECTRONICS for Miscellany ü:Z former mutually repel each other. Hence the appearing divergency in a stream of electrified effluvia. "But though the particles of electrical BUILD THE NEW matter do repel each other, they are strongly attracted by all other mat- MODEL TV -67 ALL CHANNEL ter. . "Thus common matter is a kind of sponge to the electrical fluid. "But in common matter there is (generally) as much of the electrical as BOOSTER it will contain within its substance. If TELEVISION more is added, it lies without upon the surface, and forms what we call an elec- FOR YOUR OWN USE OR FOR RESALE trical atmosphere, and then the body is said to be electrified." With the aid of our TV -67 Dr. Millikan says, "The opening sen- INDUCTOR TUNER tence contains the simple statement of Illustrated below. an epoch- making discovery: 'The elec- trical matter consists of particles . . $350 After 200 years of research we cannot only improve the content of Franklin's con- clusion. Its obvious, axiomatic truth INDUCTOR TUNER comes com- plete with circuit and instruc- may stand forever, but perhaps at the tions for building the TV -67 end of another 200 years additional TELEVISION (BOOSTER. We will also include at no charge truths may give it a different aspect." basic circuits utilizing the TV- 67 INDUCTOR TUNER to build a Television and F.M. Signal "SAUNDERCISMS" Generator, a Television Inter Terence Eliminator and front end Epigrams from a lecture on television for Television Receiver. delivered by Albert C. W. Saunders to the Associated Radio Servicemen of Nev York (City) at their meeting June 9, 1948. No need for switching when "A serviceman's work consists of nine using the TV -67 mental operations to every manual one." "Don't be too technical with the public - your customer doesn't care whether the INDUCTOR dielectric has any specific inductive ca- pacitance or not." "Amplification itself TUNER is cheap -it's broad -band amplification that costs money." Designed to Cover All Chan- "Electricity is the fastest thing in nels 2 to 13 Inclusive. the world -but it's the laziest." CORRECTIONS TV -67 Booster Features: Data on the old Philco bakelite -cased bypass condensers is found on page 14 * Permits use of Indoor Installations. of Volume II (2) of Rider's Manual in- * Reduces or eliminates interference including Amateur, F.M., Short Wave and stead of Volume 11 as reported in the Inter -Channel. Technote, Philco Condensers, on page 72 * Permits TV reception in fringe areas. of the July issue. * Amplifies weak signals. We thank Mr. John Wohlrah of Buf- * Provides brighter and clearer images. falo, N. Y., for calling our attention to this error. Specifications: There is an error in the diagram of the Wobbulated Signal Generator on * The Model TV -67 employs I -6AK5 as a high gain amplifier; I -6C4 as an iso- I efficient miniature page 34 of the May 1948 issue. The lation amplifier and -6C4 as rectifier. Use of these highly tubes in conjunction with INDUCTOR TUNER results in maximum gain on all plate of the 6J5 cathode follower is channels up to channel I3. shown connected to ground. This should -67 provides a 6 megacycle band -width reducing Video detail be connected to the B -plus line running * The Model TV loss to absolute minimum. from the No. 4 pin of the power input socket. * The Model TV -67 is designed to operate with any antenna system indoor or outdoor impedance. We thank Mr. Thomas B. Brook of -any Twin Bridges, Montana, for this cor- * New INDUCTOR TUNER covers all television channels, 2 to I 3, inclusiv, rection. without switching.
DE FOREST BANQUET INDUCTOR TUNER comes complete with circuit and instructions for building the TV -67 Television $ 50 Dr. Lee de Forest, Father of Radio, Booster. We will also include basic circuits utilizing was tendered a special banquet at the the TV -67 INDUCTOR TUNER to build a Television Chicago Railroad Fair on his 75th birth- and F.M. Signal Generator, a Television Interference day. It was spread jointly by the Morse Eliminator and front end for Television Receiver. only Telegraphers Club of America and American Television Inc. The banquet was only one of a number of celebra- tions which marked the great inventor's birthday, the high light of them all be- GENERAL ELECTRONIC DISTRIBUTING CO. ing Dr. de Forest's coast -to -coast broad- cast on the Mutual Broadcasting Sys- 98 PARK PLACE NEW YORK 7, N. Y. DEPT. RC -11 tem network. NOVEMBER, 1948 82 Misccllsmy - -9 R -E CELEBRATES BIRTHDAY SIGNAL GENERATOR Headphone BARGAINS MOT /F1 300 Type H523 -8000. ohm imped- ance, highly sensitive.... light- weight only 9 oz. Leather cov- VOL ered Spring steel adjustable headband. 12" cord with PL54 ¡ plug attached at side out of UMW* way. lack and rubber cord sup- plied to extend length to 51/2 pllrpa11ft1is CO , feet. Removable rubber ear n FeF4,. WEN ,. cushions. Brand New -$13.50 Vo toe. Stk. No. 17A37 SPECIAL PER PAIR... $2.45 Type NS30 -8000 ohm impedance. Small yet highly sensitive. Built on hearing aid principle with ear fitting soft rubber cushions attached to receivers . . shut out outside noise. Comfortable, light metal band easily shapes to contour of The Model 300 Signal Generator features iii. head. Supplied Complete os illustrated sel 11101 of four a rural, Is' aligned freauen h -. n. with 6 foot cord and PL55 plug. shirt i-ltl riy.sial positional: ,elan lid ud clip and matching transformer for 8000
tal In adapt Ile 1 iel :loll Ito x retal fieo. id ohm impedance. Very popular for con - TI I,KVISIONlis MARKER O$t'ILI.ATOIf. Foul -version to mikes, telephone sets, minia- Hundred eyrie audio uiolulallno. In or 1111. Sopl li, -. ture crÿstal sets and all around head- 450 Ise, 195 Ke, lino Kr. .lid 15110 Kr. Inn 90'; phone use. Brand New, A Terrific Volpe' of all 1 rrirrra mxuufarlirt,l. Works noie lly urll 01lli No. 17A420X. \C -111'1 sels. ('Milhlete hull liures, and tenpin priais/. Per Poi, $1.29 Nothing else to buy. Slnlrl SrIO SI6.95 Net Model Sill, -K Complete Ial & RAY Instruct lulls 19.95 5BP4 CATHODE TUBE $2.95 Has 5' white screen. Quality make individually boxed in cushioned carton. Brand New, Perfect, Guaranteed. No. 3672 " RANGE MASTER" SPECIAL EACH $2.95 MODEL 10 ORDER NOW front this ad-include postage. Hugo Gernsback, founder, editor, and pub- lisher of RADIO -ELECTRONICS. celebrates the FREE -the big NEW 8 -A Catalog N. 491. 132 pages of Outstanding Values. Write if you have not received it. start of the magazines twentieth year of publi- cation by making the first cut in a cake espe- cially baked for the occasion and presented to him by the editorial staff. Titled RADIO -CRAFT ;e BURSTEIN-APPLBEEc.up...ul 1012-19 MC GEE STREET, for 19 years, the magazine enfers upon its KANSAS CITY 6. MISSOURI twentieth year as RADIO -ELECTRONICS. Old policy of service to all radiomen continues.
WE'VE MOVED
The 9 -in -1 Service Instrument More Space- Better Service Coven these 28 moue:- (1) CAPACITY ool -.1. il1-1. .1 10 Slfd. 3 TUBE PHONO 121 A.C. C1-IUWNT 9 .130. 11 -IS U- 11 amps. CD A.E. VOIT.1GK t to 1110 :oil 1111111 tolls. U ILC. VOLTAGE lu 11111 300 10011 tolta. AMPLIFIER 151 D.C. CURRENT 1 1l, lai 10011 miIliaWps. Ir;l RESISTANIT{ il tu Menu 10n.u011 1 megWun. 17) Sot-Mid nigh range ..lunnmler to 9 2.20 \legs. (x) Sensitive A.C. micrn:dnuuter to t1119 udrroantpa. $1.95 (9) OSCILLOSCOPE CALIBRATOR 1.19.11111 me- tered HMS Volta from A.C. line. Model 10 -P Portable Illustrated) $26.95 Net WIRED, Model lo -F' Fused 28.15 Net COMPLETELY S1a0e.1 010 Bench 23.50 Net VOLUME AND TONE CONTROLS Model 10 -K, C Diete Kit & Instructions.. 17.95 Net 'l'est ]cads .85 set of 3 tubes; SOLE, 35Z5. 1.2A6 51.1s Output trans. 51/L6 .35 ..A_ Meg. vol. control with ow. .33 1" pm speaker .9.5 " MULTI- TESTER " 5" pm speaker 1.15 6" pm speaker 1.55 FRANKLIN DISCOVERED MODEL 30 6x4" pm speaker 1.39 S" pm speaker 2.49 ELECTRON Webster pickups 1.79 The actual discovery of the electron Asiatic Cartridges L -70A. L -26A 1.19 Alliance motor & Turntable 2.511 was made in the United States by Ben - VM -.":400 INTERMIX CHANGER... 24.95 jamin Franklin 200 years ago, even G.E. Reluctance Cartridge 4.51 Phono Pre -Amplifier complete with though it is usually attributed to the tubes 4.95 English scientist, J. J. Thomson, a little Phono Oscillator complete with tubes 4.52 Oscillator Coil, 12SA7 .15 more than 50 years ago. All prices F.O.S. w.Y.C.-on c.o.o. nao Deposit. Attention is called to the fact of Write for free cata loci. Franklin's prior discovery by Dr. Rob- ert A. Millikan, president of the Cali- THE ROSE COMPANY fornia Institute of Technology, who New York 7, N. Y. A.C. Colts 0- 15.0,25 930/1250 V. 18 Park Place, Dept. C, was the first to isolate a single electron U.C. Volts 0 -5 /III -Sn I -11i /500/111911 V and make extremely accurate measure- 11.11. ('Intent 11 -I, Ilia )1A. l',rslstanee il- 19.900 Ie0.tO0 I Sleg. ohms. ments of its properties. Uribrls -Fttxn minus 11 lu Plus "d DI, Nadel 311 (1l10straledl $15.95 Net In support of his claim that Franklin Maori 711-K. Comp. Ni: 13.95 Net BARGAIN PACKAGE: (lue Sana! Genet :tor SU,alrl WANTED should he considered the discoverer of :pal -K IId tale SIIlItiTest,r >pdrl 311 -K. complete in a com- itittt prole. lest Irais an,l 1/1111u1 s. sersiee the electron, Dr. Millikan, slop lu kit form. Nnlhine else Io buy. only $26.50 Net RADIO SERVICE MEN to The American Journal Prices 55, 1111:10r west of the Rockies munication Write tor Free Catalog Experienced men with cars for part -time Gf Physiex, cites Franklin's letter to 500 your local (lisp-000',r. If lint available, write ta Dept. It. C. work on AC -DC receivers. Some traveling Peter Collinson. required. Must be bondable. Pleasant work "The electrical matter," Franklin with good compensation. Need men in or wrote, "consists of particles extremely near Davenport, Iowa. Chicago, Indian- subtile, since it can permeate common apolis. Buffalo, Rochester, N. Y.. Pittsburgh, matter, even the densest metals, with Philadelphia, Washington, D. C.. Baltimore. such ease and freedom as not to receive Md., and Boston. Mass. any perceptible resistance. . Address box number 02 NGSTON STREET differs from com- 348 LIVV,hGSiON c/o Radio -Electronics "Electrical matter Y. mon matter in this, that the parts of i.I7, N. Y. New York 7, N. Y. BRCOKLYN 25 W. Broadway the latter mutually attract, those of the RADIO -ELECTRONICS for Question Box , 2 -METER TRANSCEIVER Please print a circuit for a very compact 144 -mc transceiver. F.M.S., Mars Hill, Me. "Don't Get Your A. The simple circuit shown in the dia- gram can be constructed in a small case. The 3A4 is used for both transmitting Fingers Burnt and receiving. Note that its filaments "... FISHPOLE ANT .S'ays Speedy LI 1p,1L2 HI IMP PHONES
3A4 IOMEG 2 Use the NEW T
TI 6 Amo Miniature TUBE PULLER SINGLE BUTTON MIRE "Prevents Tube Breakage and Burned Fingers"
C 3-30»»f C2-50»nf 67 SV 1Ìs easy to remove or insert miniature tubes + 1--I 1--I'`6a5V- with the new G -C Amo Miniature Tube Puller. are paralleled for 1.5 -volt operation. Inserts or extracts tubes where fingers will not The 1S5 is modulator and audio tube. reach -into hard -to -reach places. Saves time Be sure to keep all wiring as short and money. as possible. Vary the coupling between Ll and L2 for best operation as a super - No. 5093 Miniature puller .. Net 99e regenerative receiver. The same coup- Write for catalog. Dept. D, or see your distributor. ling is satisfactory for transmission. (DISTRIBUTORS: WRITE FOR DETAILS) The coils are self- supporting and can Manufactured by be wound with No. 16 wire. Ll has five turns, % inch inside diameter, spaced GENERAL CEMENT MFG. CO. to occupy % inch (adjust to cover ROCKFORD, ILLINOIS, U.S.A. each band). L2 is one turn of the same diam- eter placed at the end of Ll. L3 and L4 are chokes wound with 50 turns of No. 36 wire on 10- megohm resistors. EVERY SERVICEMAN ELECTRONIC TIMER Please give me a design for an electronic timer adjustable to a maxi- CAN Ali""" mum of about 2 minutes. R. R. K., Vallejo, Calif. A. The diagram gives the circuit of a timer with a little more than 2 minutes' maximum time. The capacitors connect- ed to the range switch and the 10- TEST EQUIPMENT megohm potentiometer are the timing The New Model 670 117L7 -GT 2.3Rs-5Rn COIL RELAY SUPER METER II A Combination VOLT-OH M -MILLIAMMETER plus CAPACITY REACTANCE. INDUCTANCE and FINE ADJ 10MEG DECIBEL MEASUREMENTS D.C. VOLTS: 0 to 7.5. 15/75/150/750/1500 / OUTLET 7500. A.G. VOLTS: 0 to 15/30/150/300/ 1500 /3000 Volts. OUTPUT VOLTS: O to la r.o /150 /300 /1500./3000. D.C. CURRENT: 0 to 1.5 /15/150 Ma.; 0 to 1.5 Amps. RE- SISTANCE: 0 to 500 /100.000 ohms. 0 to 10 CIRCUIT Megohms. CAPACITY: .001 to .2 Mfd., .1 to 4 MEd. (Quality test for electrolytic' 1. 117VAC RELAY CONTACTS REACTANCE: 700 to 27,000 Ohms; 13.1100 NORMALLY CIDSED Ohms to 3 Megohms. INDUCTANCE: 1.75 70 : 35 to 8.000 Henries. DECI- CI C2 DPST S' to Henries r IIELS: -10 to +18, +10, to - tV, - 30 to TIME" CHARGE The model 670 o es housed in XI _ 10 rugged. c achle.finished steel cabinet complete with test lead. CI I /600V PAPER OR O.F. TUBULAR i ions. Sise $28.?, SW and operating RANGE C2-10 " " " " Sg- x 1t/í x 3". we ,manufacture a complete line of radio test eauip.nent. components. The maximum be Write Dept. fIC for FREE catalog today! time can MFD. BY increased somewhat by adding a third position to the range switch, with a 20- SUPERIOR INSTRUMENT CO. to 40 -µf paper capacitor. 227 Fulton St., New York 7, N. Y. The control switch normally should be in the CHARGE position. When it is thrown over to TIME, the timing cycle is at your regular jobber automatically started and completed. NOVEMBER. 1948 uo question Box PHOTOELECTRIC CONTROL Mil problem requires nine photo- supply. An adjustable pulse -lengthening electric circuits wired in parallel and circuit, RI-C1, assures relay operation s:1 connected to indicator lamps that light with very short interruptions of the cl when their controlling beams are inter- beams. rupted. The indicators must remain on When the slider of Rl is at A, full for 10 to 15 seconds. The light beams effects of the lengthening circuit are FREQUENCY are interrupted for about .0005 second, had; at B the effect is cut out. Capaci- Will you prepare a diagram of one of tor C2 controls the length of time the the control circuits ? -J.W., Alameda, indicator is on. Its value may depend on MODULATION Calif. the tension of the relay spring. Experi- with the value of R2 for best re- APPARATUS ment FUNDAMENTALS . A. The circuit shows one of the con- sults. A 1:1 line isolation transformer SERVICING trolling circuits and a common power may be used if desired,
TO 8 OR 9 MORE INDICATOR LAMP CONTROLS BY NATHAN MARCHAND Radio and Electrical Con- 4 POTTER- BRUMFIELD RELAY LM- II -DPDT sultant, Lecturer un Elec- 2SKn Co. trical Engineering, 2 S lumbia University. 418 pages. 6x9, over 300 illus. trations, 65.00
A modern guide C2T IOK to one of radio's Ott. fastest - growing detelopracnts
INDICATOR LAMP 117 SIMPLIFIES SERVICE -
ENGINEERING PROBLEMS! SUFFICIENT CURRENT RATING TO HANDLE LIGHT SOURCE)) It takes mote ordinary radio servicing knowledgekwnedge to handle die nnuuli,ed special tsloblems and mtWal. of nudes F'-3t tusk' This new book by a well known radio < ITS CONTROLS ABOVE LINE and electrical vs:, nit wit has been specifically aritten. first ONE CIRC.I - to help YOU understand F 31 clearly and setunti. to explain fully lust how to act about bundling N -At wink. 6.3VAC %Pill; a minimm11r of mathematics. but wnh a melons schcmatir diagrams 47 } 75MA REGT +105V; 0C3/ VR 105 0 of easily midi rstnai dlustratioos. Ma and practical on-toe job examples. it covers the complete I17VAC 6/03 field of frequent-) ao, lulat ion. Basic theory, circuits, trans- IM^IOW 5 mitters. rreivels end 11101){1e enuilrmenl are hilly e 40; 250V 3 ape. Is 200MA RECi mitnJ methods .d 1 1i$ adjustingstI and rewiring 2 FUSES + F -M etc-rivers. 90 110V at sour 1ar_01l ps ymi have everything necessary llore 82 80 250V for a complete h udnst:tutting of the subject -from cir- IIIVAC 5Wi cuit peculiarities. tuning ludiruios, to antennas, mMdle equipment. E M list units, rereii n -r alignment, general servicing c. 011il a host of other essential sub- L 270K lireeedln _LINE ISOLATION TRANS jeets. rart{rulm tceutiial rs paid to outlining the im- 3 .25 200V pontot Point, oi Lilt-irwr Liw: en rM and onli u.11s IF DESIRED 40 250V \\I hock.
HERE'S WHAT IT INCLUDES +M Fundamental. of Mod- 10. Amplitude Limiters 1 41 311/I0 u lot ion 7SMA REGT N RF Amplifiers. Oscil. Fidelity Band 1 1 "' Width Requirements latan, and Converters Intermediate F r e- and Interter 1 117VAC 6.3V/12A tTWO 6A.UNITS CAN BE USED( 2 and Audio 3Noise' once gurney requency Circuits D ì r e e t f FM Receivers II 4' Modulation 13, Frequency C o it t r o t 5 14, FM Transmitting An- ' Ctcuits tonnes RADIATION MEASUREMENT 6Direct FM Transmit- FM Receiving An- , -rs lu 1 5 leonas need a loop antetnta with a pickup known characteristics. -P. O., Chicago, Phase to F requenry Mobile FM I Equip- 7 Modulation V ment about one -half the signal field strength Ill. FM Transmitters Us- FM Servicing Phase Modulation 17. in uticrorolts per meter, 1 n'aiit to nu'as- inq No. 9 FM Detectors 18 Phasnr Calculations. nre radiation on 600 kc from wired A. Close -wind 56 turns of either t. wireless systems to make sure it does 18 or 20 d.c.c. wire on a 34- inch -square READ IT AT OUR RISK! not exceed 15 microvolts per meter at frame. The signal pickup will be ap- 7.9 liv in a field of 15 micro- R \ -' -- o'11 k it this new FRE- (t distance equal to X/ 2.1. proximately
i I t l t (jt"I:Nt'r' \ I t l l l l I \ , I UN ` tool. In day study and My receiver (its input impedance is volts per meter. The antenna should be referent,. (hat I . II gladly t-td it to ytd1 for In days' examination. Retvl it carefully. See hoc quickly It brings .300 ohms) is already calibrated in located very close to the receiver to you up -In -dale in d,veitximrms In this Tint gnm1ng field. T'tn decide -hther or nil you ant In him It or re- microvolts, so the antenna sltottld have avoid the effects of long leads. torn n it. Will t Ike the risk: Send no money, just mail the coupon now. SIGNAL STRENGTH INDICATOR I have built the .viynol Irifef'r dr- 6J7 6 E 5 i Scribe(! on page 8 of the 1946 RADIO- MICA.000I 2201' Drot. RC -I IF Murray Hill Dunks. Inc., B+ 232 Madison Air., New York 16. N. Y. CRAFT Reference Annual. I would like
eN 1 I O Send nuh u )1 u' ba Idas FIIcou 1. Y \. D[ 'T..ATTOY to install an electron -ray tube as a sig: for`t Ìn am a few of nnmage. Ill days UM end x'o, ta u, a few curds piss! age. or return balk vat- atvength indicator. Can you supply t'TO GRB 613 Privilege rota, pend on rash same re Z,, Hanford, Privilege k' . - sum in U. S. only. me with a diagram? -H. V. S. B+ ooK jet. owsidl I . ?.so postpaid.)noshn:da.l Calif. 200K 270K Name A. The 6E5 shown in the diagram is 50 .tddress inserted in the signal -tracer circuit be- tween the audio input and the grid of I v Tits. Zone, State the output tube. Some gain is added, be- ! cause the triode in the 6E5 is used as an AT INPUT Ot':vl,at hou . amplifier. OLD TRACER STAGE ADDED RAD I0- ELECTRONICS for Try This One 79 ANTENNA INSTALLATION When installing an antenna on the REVOLUTIONARY SOLDERING IRON roof of an apartment house, it is often 1 necessary to place insulators on the outer wall of the house to carry the wires down to the window. It is very Soldetron Ì::Ii, Reg., Pat. Pend. easy, when leaning over the parapet, Tr. Murk to drop the star drill used to make the For Easier, Better Soldering -on Any Job! necessary holes. Weighs only 3 ozs., yet can do the job of a 200 waft iron. To prevent this, tie a length of waxed Heats up in twenty seconds from a cold start; saves time. wire -lacing twine to the star drill. The Fingertip control; permits soldering without fatigue. wax will keep it from slipping. Tie the other end around your belt. Then, if the drill drops, you can just pull it up again with no damage to life, drill, or other property. Ready for attachment LAWSON NORMAN, and operation on lia AÁ.. 50tr0 cycles. (! e¡e Los Angeles, Calif. through transformer(60 --n supplied with Iron, or 6.8 volt A.C. or D.C. without transformer (from an automobile betterY/. CRYSTAL DIODE POLARITY Overall size 9!4" s 15/16 ": ship. wt. approx. 4 lbs. Ideal for fine precision work in "hard -to- reach" places. 7'o find the polarity of a crystal rec- Readily interchangeable tip- heads; no cleaning or filing. tifier, measure its resistance with an Retains heat with switch off up to I minute; efficient. ordinary ohmmeter. When the test leads Bakelite handle; cork covering, for comfortable cool grip. are connected for minimum resistance PRICE, including transformer and Tip -Head "A," 113.95 reading, the polarity of the meter's bat- 5'7 higher west of Mississippi; fair traded. tery voltage indicates the polarity of the fsk vilor fli.glribu?or, or for furflier infonnaiion tirile fn: crystal. TRANSVISION, INC., Dept. RC, NEW ROCHELLE, N. Y. NORRIS MCKAMEY, Davenport, Iowa TV TUBE SUBSTITUTION The Recently I built a television receiver EASY TO LEARN CODE using a 7EP4 picture tube. Not satisfied HOUSE OF A It is easy to learn or Increase speed with the picture because I had to darken with n Inatructograph Code Teacher. nords the quickest nd most prac- MILLION RADIO PARTS the room when viewing, I replaced the tical method yet developed. For be- 7EP4 with a 7JP4 with very satisfac- ``inners or advanced student a. Available tapes from beginner's No. 10Y Tubes 49c tory results. Since the tube pin arrange- alphabet to typical message. on all No. 1626 Tubes 49c subjects. Speed range 5 to 40 WPM. ments are different for the two kine- Always ready -no OBM. No. 1625 Tubes 49c scopes, the 7JP4 using a 14 -pin diheptal ENDORSED BY THOUSANDS! CRYSTAL PICKUPS socket instead of the 12 -pin one needed The Inelrvetograph Code Teacher List $6.50, our price 5I.95 place of McClintock Meters for the 7EP4, the wiring had to be e for- Ins (ructor and enable. anyonee` learn and master code without fur. changed. All left the th er eatume. Thousend of eesaful operators hove 0 -500 MA 3" square ... $1.95 voltages were acquired the rode" with the u Ìnalrn..grapht" System. Thousands of other bargains. Write today for convenient rental and purchase lan same. Write for our bulletin No. C -912 The table below shows the wiring changes: INSTRUCTOGRAPH COMPANY ijIfZe SOUND EQUIPMENT 911.913 Jefferson Ave., TOLEDODlE00 2.DHION10 Tube Pin numbers 4701 Sheridan Rd.. Dept. RC. Chicago 40. Ill.
7EP4 I 3 4 6 7 8 9 1 0 I I
7JP4 I. 2 10 5 7 9 I I 8 3 14 1. New 7' tube TEI.EKIT with latest approved ele- rnits, 13 channel factory pre-tuned Tuner. 1.F. coils JOHN URBANOWIC7., [molder maximum galn and pinure definition. EASY [Warren, STEP BY STEP INSTRUCTION BOOK. Specially Mich. posed-lins tubes 557.50 2. New 10" tube TELEKIT. same as above but using lo- picture tube. Ixss tubes 597.50 DIAL SCALES 3. Complete TELEQI'IP TELEVISION RADIO, 23 Explain! tubes and five rectifiers. In light bleeeluvl or dark for Merely Examining Mahogany ridding. wonderful performance! Equiva- To make a precise, commercial -look- Latest lent Sets of the 5350.00 Nationally Advertised Trlevlslon ing black dial scale with transparent Coyne's NEW Pay- Raising Set. with , TELEV. TUBE. SPECIALLY PRICED 5145.00 white numbers and markings (to be ALLIGATOR PORTABLE CABINET. Each Per 10 For any changer. 1714' t 17V'' used with back lighting) draw the scale Put out for 6' speaker 7.95 75.00 in normal size. Using this as a model, TINY LOOP ANTENNAS for small Here's a PRAI'TICAI. ¡et of iadlo bis,ks lust off the portable sets 4' x 614" .29 2.50 make a copy five to eight times as large p , oives you "kh ow mm" on everything In TINY IRON (`ORD I.F. TRANS- Radio today. Basle principles to newest in Televi- FORMERS 456 KC ?s x TX' X 2'. with black India ink on smooth white sion and F.51.-hov truct, Install. leniee. Pair .95 9.00 Latest trouble- ehooting methods.mn 1000 illustrations, paper (obtaining at an art goods store). goer 1500 pages. Ideal for reference or hone SPEAKERS train- 3" 450 ohm ing. To prove how valuable these great hooks an be 91.49 914.00 Your local photographer can make a In rots. Coyne 4' PM 1.10 10.00 will give you a FREE copy of our PM with 5016 output transformer 1.39 13.00 helpful "I50 New Radio Diagrams Explained" 5" 2750 ohm or high- contrast negative of this large no 450 ohm with 501 6 looking over the 5 Vol. Set. OFFER LIMITED output transformer 1.59 15.00 drawing on sheet film, the negative to --ACT NOW! We will d you 5 vol. 6' PM VERY SPECIAL 1.39 13.00 net AP- R' PM 1000 ohm or 1800 ohm PLIED PRACTICAL RADIO for 7 day. FREE 3.25 30.00 he size aminatlon, e3- IC" 5.13 50.00 the of the small original. together with Radio Diagrams. Look set Dynamic' 400 ohMagnet. or over for 7 ' 1000 This negative is the dial scale. The days. If you like It send $15 milk or 53 ohm 11.93 53.00 her 7 days and $3 monthly until $16.75 is paid. background is black and the lines and If you don't want the set, PARTS mum it and you owe 500M Chgo. Tel. Vol. Cont. a Sw. numbers are transparent. NOTHING. Either way you 3" ahan .39 3.50 keep Diagrams Book Free. All other sizes Vol. Cont. a Sw. 3^ G. P. BRUNTON, SEND NO shaft .39 5.]O MONEY! Cou- 00M 1 met and 2 met tapped Con. pon asks to see trols 69 6.50 Kingston, Ontario books free and 0 40 MM. Natl. Brand Electrolytic get sour gift book Condensers .0 3.75 FREE for 40 x 40 Mfd. Natl. Brand F. P. Con- doing it Send densers .39 3.75 BOOK _em NOWT 40 ndl. 21 Power HIGH -VOLTAGE SOURCE Eduational 70 MIL 21/s Vollt Power Transformmer 1.7] 6.50 COUPON Book Publishing Division -I 70 Mil. 6 volt Power Transformer 1.95 17.]0 COYNE ELECTRICAL & RADIO 68' Auto Aerial 3 Section .Ide Cowl 1.9 14 00 When a cheap source of high voltage SCHOOL. Dept. 68 -TI. 8N" Universal Mount 3 Section Auto 500 South Paulina St, Chicago 12. Illinois Aerial ...... 1.75 16.00 at low current is needed for experi- P 11Ií Send me. postpaid. Cmlir's new 5 volume watt. AC Amplifier with cover set. No. 6X5. 61.6. and 6007. usingLess ments, use a 5- or 10 -to -1 audio coupling ".APPLIED PRACTICAL RADIO" for 7 Days FRED I tutube TRIAL per your offer. Also send. absolutely FREE. 111.115 Write new 1948 transformer. Connect the low -turns side 750 New Radio Diagrams Explained" as a gift. for our Illustrated Catalog. to the 117 -volt line. NAME AGE NORRIS MCKAMEY, ADDRESS LAKE RADIO SALES CO. Davenport, Iowa TOWN. ZONE STATE 615 W. Randolph Street, Chicago o, 111 NOVEMBER, 1948 78 Try This me SOLDERING METAL siderably by using the ont-of -phase It is often difficult to confine solder bucking principle. to a neat, narrow band when making As the drawing shows, the regular We're GILDING long seams in sheet metal. A method for signal -pickup antenna is at right angles overcoming the trouble, suggested by to the power line. The noise -pickup an- A. J. Richards in the British magazine, tenna, half as long, is parallel to the line. Each antenna is connected to one the LILY! 2 GREASE CRAYONS BOUND TOGETHER side of the receiver's antenna coil. The center lead of a co -axial cable is used THICK CRAYON LINE for the signal antenna, and the shield- ON EACH SIDE ing for the noise antenna. OF SEAM The noise picked up by both antennas from the power line is very nearly the same. Since this places both ends of the antenna coil at nearly the same poten- tial (and the same polarity) as far as noise is concerned, the secondary of the coil picks up little noise. Due to the differences in directional orientation and Mechanics, is to use two grease crayons in length, of the two antennas they do (sometimes sold as "china- marking" not pick up the same radio signals, so pencils). signals are not cancelled to a great de- The crayons are bound together, as gree. the drawing shows, and marks are made 250 -µµf variable capacitors in series on each side of the seam. Because solder with each incoming lead would help to NEW, IMPROVED will not stick to the grease, there will balance out the noise more effectively, be no overflow unless an excessive but it was not necessary here. amount of solder is used. CHARLES C. COFFIN, Model 7 -B -1, San de Fuca, Wash. FUSE INDICATOR engineered Plastic night lights, consisting of a AUDIO TRANSFORMERS neon lamp embedded in a plastic shell, Audio transformers with a 3 to 1 or on sale at hardware and department 31,ß2 to 1 ratio are useful for giving a to meet YOUR needs! voltage gain in circuits which originally PLASTIC KITE LITE were R -C -coupled. Carefully engineered, and manu- The audio sections of some old re- factured of the finest materials, ceivers do not have enough gain to per- mit a crystal pickup to be used if the the ESPEY Model 7 -B -1 is spe- usual method of connection is employed. cifically designed to meet the A transformer, hooked up according to most exacting requirements for the diagram, will increase the effective input to the amplifier. a replacement chassis, and will FUSE Where medium- or low -mu triodes in lend itself to any type of installa- an amplifier do not give enough gain FUSE BLOCK ONGS BENT tion. This model is drift- compen- when R -C coupled, two stages can be stores, may be used to indicate blown transformer- coupled. The step -up ratio sated, AM FM, with 10 tubes fuses. from primary to secondary will increase plus rectifier. Supplied complete, Bend the prongs outward, as the ready sketch shows, and attach spade lugs to ONO to operate. the ends. Slip the spade lugs under the fuse block connection screws. When the Send to DEPT. C -11 TODAY for fuse opens, the current passing through RIAL PICKUP I:3 FREE LITERATURE the neon lamp will make it light but will be too small to cause any damage to circuits. RICHARD L. PARMENTER, the gain. Other operating conditions, es- Mass. ESPEYMANUFACTURING COMPANY, Inc. Middleboro, pecially the cathode -bias resistor, will 528 EAST 72ND STREET. NEW YORK 22. N. T. have to be changed to accommodate the NOISE ANTENNA higher plate current. The 6,600-volt power line passing my G. N. CARTER, house creates a very high noise level in Nanaimo, Canada HAM RADIO OPERATORS the receiver. I cut down the noise con- (While the transformer will step up volume when used with a crystal pickup, GADGETEERS, etc. NOISE ANTENNA PARALLEL TO POWER LINE it will almost certainly ruin the fre- Blower Type FL, quency response.-Editor) style 11711458, Serial No. KO, COAX LINE_ 300 -OHM LINE 115V 400 cycle The 300 -ohm ribbon used as transmis- 6700 RPM. Used sion line for. FM and by the army to SHIELD television antennas cool transmitting is insulated with a plastic material that tubes in Radar can be melted easily. To seal and sets. Blower ideal for weatherproof a connection to this line,
radio builders, pho- ANT POSTS ON RCVR cut a strip of insulation from a similar tography (dark room), etc. piece and melt it, allowing the material Our price ONLY $295 to drip onto the connection. This plastic PRICES FOB. KANSAS CITY SIG.PICKUP ANTENNA catches fire easily, so pick a safe place Write for new catalog to do the melting. NATIONAL SURPLUS SALES CO. ALBERT LOISCH, 723 E. 18th St. Kansas City. Mo. Darby, Pa. RADIO -ELECTRONICS for 77
RADIOMEN'S HEADQUARTERS + WORLD WIDE MAIL ORDER SERVICE ! !
with I , I;k;; ;; ;hende $49.95 1949 MODEL MUTUAL CONDUCTANCE TUBE TESTER nes(mute tithe IIIIICS ., .. of N. i - -:. L:y w ;.,,: leading "atei" nr had bug "Goal" as tal , -.aductan.e ledesse other urti u:us cmassior testers. on I dui,ii '. I.:url sud I renal lo arar the make: 1 .tntl:'.:ranre . . Large . t'alibtatol Inirr'mlho ,crop as melt as Ilad- Good scade Prom paura fuse . Individual srs k,Is for all tube base typ,. tulrates Osai .75 folla w 117 tolte anda complete,0 l stitehtng flexibility eemr all au-Ii in ant! Calure tubes to be Iral. tal aunt o ItUr ioli te elrul:ults 111 tuie Igoe .. Ie tol reg slat Iltiiilgs attics I teems toi st r isto..11al section ,f onaly 'tal aunt Inillcture tithes 1111'betillg coldtratta riti.o!... Itre oc r)eeye a11,1 voltagee'U11:igc Il'g111:1In1' attrars as íc91 as all ballast nslstor >. Name of the nuUunalbnationally Ipwmm manufacturer withheld become ut silt' : +.: pelare otter. Model "C" Sloping front counter case $49.95 Model "P "- llandsane hand -rubbed portable ease 54.95 Milt- in-toll chart with either of :hope $5.00 extra.
CONDENSERS -PAPER TUBULAR nun WV -- 00l. .002. .005 -Be; .01. .05 -9e: .1 -10e: .25 -23c: n5 --35e- ELECTRO- HEAT GUN LYTICS; amid 21815 -20e: IOtntd 35r -20e: anm }d 150v-23e: 20/20mfd -35e: lias 30/20 150v -46e; Sonild ISO, -43e: amid Streamlined past l'1 grip heat gun in void Ira hoasing, drat 475v -34e: l6mfd 3511v -65e: OIL 600v CONDENSERS: 4mfd a Ft. per minute blast of hot Iles 2mfd 600s -29e; 3X.Imfd 600v -29e. delivers powerful 20 Cubic air at 160 Fahrenheit. Ordinary blowers have small fan AC DC motor of SPEAKERS -ms -v PM speakers are the finest that are avail- motors. but this has a lifetime lubricated able. All have heat y mer.ize Alnico V magnets. the rugged vacuum Cleaner type, that produces a hurricane 3,4' either hot cold air. Perfect for blowing out dirt or 6 for of or $1.15 $6.60 systems. warm- $1.15 6 for $6.60 dust from radio chassis. drying out ignition S' 51.10 IG for 59.50 ing rep carbtuetors, tiuickdrying paint. thawing out radia- $1.50 6 for $8.70 tors or miter pipes, etc. Warning:- -Keep this away front r (Car Radio Size) 54.50 6 for $21.57 y (rife. or she will ln using it to duy her hair because 8' 10 oz. .... 53.95 6 for 520.50 it will do it in halt Mr time of her ordinary hair dryer. 8' 21 oz. . 54.95 6 for $26.50 to say nothing of her using it to thy sb'rk trig. or clothing, nu del ost the retrigeralur Instantly. Only 10- 21 oz. 6 for 530.00 $5.50 or money renmded it returned within 5 day.. 12' 21 oz. 57.95 6 for 542.00 $12.95. Satisfaction guaranteed pitpald GENERAL ELECTRIC 150 WATT TRANSMITTER Cost the Government $1800.00 Cost to You -BRAND NEW -$100.00
This Is the famous transmitter used in U.S. Armyn barbers and, ground s1 -, d u rl o.. teal'. Its design and onion rnrl1oll have been proved In service, under all kinds of conditions. all tiler too ,.sins The :.:::t lregleney range is t tered by means of plug -leaning units which are included- Each IIa1ino has Its 0.11 1n' ill :n n and pi.wcr anplillet' coils and ondentile. and alumna tuning carrells -all designed to operate at tot sable:ay within its particular fr lip laugt- Tra : liter anti accessories aro finished In hark crackle, and the milli:manli r, voltmeter, and SF ;mole hi ate mounted on the front panel- Here are the speeinrations: Flit for NI'V RANCE: 200 to 500 KI' and 1.011 lo 12,'010 Ill'. 1(\\-ill tuer:de cal Ill and 20 meter band with alight ntalithatlun for which diagrams are furnished,) OSCILLATOR: Self- excited, Memo, rtempen std, and band calibrated. POWER A-ari ra1,11:1t: class "C"' stage. using 211 tulle and equipped with antenna coupling eirrult which matches practically any length antemna1 S1V l lass "IS" -uses two 211 tubes. POWSiIt SUPPLY: Supplied emnpli a with dynamotor lhiich furnishes 10011V at Sat NIA. ton either 12 n 21 nits. Complete In- struction are furnished to operate set from 110V AC- SIZE: 21uiiuhg 91i'. Taal slapping mgt. $3101 Ins,. t apirita with all tubes. drumlintm power supply. .,tell mating units, antenna tattling unit and essential plugs. NOTE: Pl : Ito Rases to $1011.00 eg,elise OM. 1, 1948. BRAND NEW GENERAL ELECTRIC RT-1 248 1 5-TUBE TRANSMITTER- RECEIVER B1C-221 FREQUENCY METERS
TERRIFIC FpWER -,2U wallet ' n any two instantly selected. easilye predlueted-a frequencies from 435 to with calibrating Crystal and 500 Mc. Transmitter uses S tunes inrluftingWestern Electric 316 A as anal. Receiver lases 10 tunes in. eluding 055's, as rarer detector and oscillator, and 3 -707's 1 IF'. with 4 slug.tuned 0 Me. IF trans. calibration charts. A precision formers. plus a 7147. 7E6's and 7F7's. In addition unit contains K relays designed to operate any sort of external equipment when actuated by rreceived Ignel from similar set elsehere.w Originally deaigoed frequency standard that is use- for 12 volt operation, powel supply not included. as It is cinch for any raper." a connect this ful for innumerable applica- unit for 110 AC. using ray pply capable of 00 DC at 1333 MA. The ideal unit for Uwe In mobile or stationary service in the aCltisens Radio Telephone Rand where no license is cary. Instructions and tions for laboratory technician. dLmsan supplied for running the nT -124K transmitter on either code voice M o FM tranemisaion or receptionption, for use as a mobile public address 110 rM1. as o FM receiver.
service man, amateur, and ex- as Irenamiller 11 as an . leva SO nor an Iv in.Sdea.t misty hooku. for Geiger-Mueller ppliction.. la seilfa for only 121.5! two for 113.0. perimenter at the give away if desired marine or or w Men will work on either 12 or 24V DC and supply price of only $75.00. all power for sett onlyil 513.00u.the additional. RT1711 Brand New 12 Tube, 110 Volt Receiver -Indi- TERRIFIC VALUE cator- Oscilloscope complete with all tubes and power - supply. Has telescoping hood over scope tubes, which is equipped with a detachable calibrated screen. Has PORTABLE ELECTRIC DRILL centering and amplitude controls and two video inputs. (Sold at lass than established factory price so we cannot mention brand name.) A natural for television $39.95 Only s2u.09 equipped with le" .laeub s Gia r all Chuck and Rey. Nul :un huerulitent duly oh ill, but a full size , Insged lad. Sa :1111111 ,11 I: :ndle, i,almue like a six- shooter. SELENIUM RECTIFIERS. All types are rated at 130 Moll tonVeldell type trip and V.A.C. Do not assort to make quantity, Precision cut zens- tiubine One riot Ing blower- extra long Mushta. No stalling muter lit:Pir l piessun because of powerful 110 Volt AI' -DC motor and 75 MA .70 10 for 6.50 50 for $31.00 multiple ball thrust hi ;l,iug. 100 MA .75 10 for 7.00 50 for 32.50 Other hearings self -al igeing lifetime-lubricating Chrysler (nine type. 150 MA .80 10 for 7.50 50 for 35.00 Slade for toughed year Lit and ),'tout serails- In Plan or on roust Wet Ion Jobs. -Unaxing fariuly guluautee assures you M a lifetime of trouble -free use. 200 MA 1.05 10 for 10.00 50 for 47.50 perpetual deposit or P.O.D.'s. Full refund If returned prepaid within flee days. 250 MA 1.25 10 for 12.00 50 for 57.50
$595 Takes Both SCR -274N COMMAND SET The greatest radio equipment value in history BARGAINS A mountain of valuable equipment that includes 3 re- BIG ceivers that use plug -in coils, and consequently can be
1. ALUMINUM GEAR BOX I NOVEMBER, 1 9 4 8 7t'. RADIOMEN'S HEADQUARTERS -}- WORLD WIDE MAIL ORDER SERVICE ! ! BUFFALO RADIO SUPPLY, ONE OF AMERICA'S LARGEST ELECTRONIC DISTRIBUTORS, IS IN A POSITION TO SUPPLY MOST OF THE REQUIREMENTS OF FOREIGN PURCHASERS, DIRECTLY FROM ITS GIGANTIC STOCKS OR THOSE OF ITS AFFILIATES. EXPORT INQUIRIES ARE SOLICITED BOTH FROM EXPORT HOUSES AND FROM FOREIGN GOVT. PURCHASING COMMISSIONS HERE AND ABROAD. EXPENSE CAN BE REDUCED AND REQUIREMENTS FILLED WITH A MINIMUM OF DELAY BY CONTACT- ING BUFFALO RADIO SUPPLY INITIALLY. COMPRESSED AIR INSTANTLY, Anywhere!! BUFRAD CAR RADIO ANTENNAS All of our car radio antennas are made of triple plated Admiralty Portably Air Compressor and Brass Tubing. complete with low loss shielded antenna leads and tora_r tank. Ruggedly built of 4 best n. tetials using lifetime lu- high quality fittings. bricated ball- bearing on connect- SIDE ('OWL -BR -1, 3 sections extend to 66 ". Your price- single ing rod and oll Impregnated main units -$1.511: In Iota of 12 -$l.35 ea. has 4 heavy duty sections that extend bearing on shaft. Unusual design SKYSCRAPER-BR-2 I forever eliminates valve trouble. 98". This super- aerial must be seen to be fully appreciated. the roost common litait in air Your price-single units -$2.45; in lots of 12 -12.25 ea. compressors. PATENTED unique TILT ANGLE-BR -3. may he adjusted to all body contours. 3 air intake system increases rifi- sections extend to 66 ". Single unit price -161.50; 12 lot price - eleney tremendot l ver other $1.25 ea. compressors so that air output is VERSATILE-BR-4. single hole fender or top cowl mounting much greater than that from be contours. 4 sections larger mmpreswrs powered by may adjusted to conform with all body extend 56 ". Single unit 12 lot price -$2.75 ea. heavier motors. deliver apptoxi nately 351111 cu. to price-$2.90; Will mounting. 3 sec- inches of air per minute u maintained pressure or THE MONARCH -HR -S. single hole top ('owl 56 unit 12 lot 30 lbs.. or will inflate a till ro. truck tire in leso than tions extend to ". Single price -$1.90: price - one minute. Cornes complete with IDO lb. gauge. al- $1.75 ea. though finger -tip adjustment allows setting of out9,11 AFTER SEEING OUR ANTENNAS AND COMPARING, pressure at art' value. which will automatically be maintained. Work.. from any A H.P. motor. l'seful YOU WILL NEVER BUY ANY OTHER MAKE! for spraying paints or lacquer.. disinfectants, insec- ticides. annealing or brazing with natural gas, inflat- BENBIN NCR 522 -Very high Frequency Voice Transmitter - ing tires. etc. Price $14.50 postage prepaid anywhere Receiver -100 to 156 MC. This job was good enough for the Joint in the U. S. Efficient. completely adjustable syphon Command to make It standard equipment in everything that Dew, 12 of 100 lb: tested type spray gum complete with ft. even though each eel cost the Gov't $2500.00. Crystal Controlled hose available for only $7.75 with .pint container. Modulated TRANSMITTER OUTPUT also prepaid. 255E required on all C.O.D. orders. and Amplitude -HIGH Send for free catalogs of radio parts and surplus and 3 Microvolt Receiver Sensitivity gave good communication items. up to 180 miles at high altitudes. Receiver has ten tubes and AUTO -TRANSFORMERS -Steps up 110v. or step. transmitter has seven tubes. including two 832's. Furnished com- down 2211, to 110v- $1.95. plete with 17 tubek. remote control unit, 4 crystal.. and the spe- FIL. TRANSF.: 6.3r. 20 Amps. -91.98: Universal rial Bride band VHF antenna that was designed for this set. Output Trans. It Warr -89e: Ix Waft -$1.29: 50 These sets have been removed troni unused aircraft and are guaranteed to be in perfect Watt -61.89. AUDIO TRANSFORMERS: S. l'late to condition. We include free parts and diagrams for the conversion to "continuously variable R. Grid. 3:1 -7k: S floe to P.P. (Aids -79e: or It. P.P. Inputs -$1.49: frequency coverage" in the receiver. Heavy Duty Class Alt The SCR 522 complete with 24 volt dynamotor sells for only $57.95. The SCR 622 Is also Midget Output for M -Ut' .sels -69e: MIKE TRANS FORMER for T -17 Shore microphone, similar ta available with a brand new 12 volt dynamotor for only $42.95. ITC ouncer type -$2.00. Slancor Sit or Dll mike to line or arid-21.96. POWER TRANSFORMERS -Half -shell type. 110V. VACUUM TUBE VOLT -OHM- CAPACITY METER 60 ey. Centellapped 11V winding. Specify either 2.5 T1o11 a e toothily: r 1r,1 i this all purpose ordering. or 6.3V filament when Instrument l than in any 111he1 boll lm n ut 01he market For 4 -5 tube .sets -650V. 4051A. 5V á 2.5 or regardle ss of price. It wars desisurHitt, onlyta to sleet 6.3V $1.49 10,reit ,'111 hensti but to bo readily :.I :,,table to fulllro For 5 -6 tube sets -05oV. 45)1í. 5V & 2.5 or needs. At the sensationally Inn price of this precision in- 6.3V 1.75 stremenl no school. plant. lab or sersiee shop need de- For 6.7 tube sets-67;V.5V. 50MA, 5V & 2.5 or prive Itself of the "new look" in measuring equipment. 8.3V 1.90 11,íc a Ie a few of the 111311V Teatimes of this mustandine For 7 -8 tube sets -700V. 70MA. 5V á 6.3 or meter: two 2.5V 2.35 *5 Inch. easy to read. meter. For 7 -8 tube sets -700V, 711MA. 5V & 0.3 (55 * Ii Ile voltage ranges f 11 to 1000 V Minn- t.aist- C7ele) 3.60 :MIN' as high as 1 Inegoillu per ooltl. V disc For 8.9 btbe aria-709V. 90MA. 5V:IA, 2.5V *1 11 volt Ilse anuses frwnl if to lean (No drY 3.5A. 2.5. 10.5.4 2.85 rectifier 111 age and destroy Ille al..wary of this VAC - For 9 -11 tube sets -7110V. 5V á 6.3V -4A 2.85 1-l'51 TUBE \'OI.TSI ETE:III. For 9 -15 tube sets -600V. 150MA, 5V & 6.3V 2.95 * I i Itesistanec ranges fin.n ^fun 0101 to hIw,11 megollms. *4 Capuchy ranges from .0011025 to 20 SIFD. z lealanehur ESI disehnlnatOt8. box Issx7 sala inn twn)poorr- *.t ,Meer r e for Aluminum gear that * Isolating built. into probe. I , resists fill clore motors , u miroell gear tains, it Stu !y Ihiisli Lonl aissl in all Varying in felon 1, lo I heel., in * natual gears This outstanding development of one of the leading manu- elbniet.r. This omit i 1 iti -111V OM, to tillai,' . of equipment costs only $39.95 complete b,:uu antenna or any usher similar use $3.00 facturers test with all leads. as illustrated. TUBES -All mors i o. $. an', 5T on all tubes if i os of 10I er nl i Super Special- Ilicbl.1 all chrome bullet consists of a three stage. c rade 05.17's and shaped known FILTER CHOKES: 000, "OU, 400, 500 ohol light duty RTI579 CItVSTAL SliE: of 'outfight nation lily ala 35 0E'a l.uquil stagy high high fidelity amplifier brand 55.95 -59e: 2101 tor :tau ohm hears linty -99e: 2511 gain. ' insole for 1'. S. Navy, fully shielded -$I.95: 75 Wilk rn cycle. 110V mover snooty Ian hlu 51111 13%x Book on DRY DISC RECTIFIERS by H. B. Conant. ohm. steel ohm 125 ma t 25 for $4.25: -M hier type:. I11_ chassis, which is panelled b) a substantial ., . y -25c: is nationally .. on the subject pools. Slade by Western E71er- 1 Cl combina- nonor r lobes and my p. ,.ils S tapped Illter chokes 25e: Th, and .25 Spelt as a husky tion. ideal (co replere any six(' speaker tidal when trie witil tYldeal quality onllptnems installing l'S1 spr,:ker- -7k. mimer hr insfnriner mud oil condensers. 11115 milt Is STEATITE VAR!ABLE CONDENSERS s of Ifineble free norY- Tapped "n- l'l..tTTHit obviously Intended to give s' AloLs in lee and SPLATTER CHOKES-These 1111111 n Weal nur 10,1, iirls Slom- Inv with no 11 'lewd for repairs lelelellpne hm II., CIIOXES" ale used between Class 6' stagy ind from special input pone,' objectionable side band splatter. Iiiscotne01 rug In wire each. Ihr SCREW DRIVER NUT to eliminate Ií11,,,. will result In as high a fidelity resistance 50 noms. Our part No. s,;.;l S1.50. and output STANDARD I DIA. SHAFTS ADJUSTMENT D( rati lie Yota. robes,with lo wool In lo $2.110 3.2e -1u fur $LSi SELENIUM RECTIFIERS Dry dise typos Pi", 1 ". diagramaman d par's list 's included-514.95.95 15 mot lo Inn. 5.90 $.20 -I0 for $I.sn 1.2 .Imp. nlaxinuun, suitable for converting DC relays mont -In low 52.90 $.211- In for 01.s1 Al for srmplying filament su me.. In Vnr1 a bue lu anpirhet re- 34 mir 5.100- 1,1 leer 53. I11 5.25 -10 for $2.30 radios. converting 15' motels to .U'aPpllraluns.u and RT -1655 -11 tube crystal controlled Beautiful chassis 50 auuf $.15- Io tar $3.711 $.25 -111 for $2.30 also 11 r hr tord In low mire -out rharaes --90e. ceiver fm. 21 -24V IM operation. 75 mod $.50 --1l for $1.10 5.311-10 for tube including 7 $2.70 30MC 1 IF TRANSFORMERS, double slug tuned -25e. and rabt :icl. Uses latest 'Yin's 1111 111111f S 51 -lo for $1.50 5.40 -10 for $3.60 PLATE COILS miniature 1.t.1,'s. Tulss and schlIrale supplied. for $7.10 30 MC VIDEO AMPLIFIER -Slug 1111 uuof $.x11-In Ipur,!- 25e. Only a few avoidable at $14.95 pm nunf $1.1,11 Pu for S.s,50 110} I10 non( $1.m1 oleo tor $12.30 Butterfly roudensers. :Ieo has tao ball beatings and of a fa- , shaft 1000 CYCLE AUDIO FILTERS RADIO SET SCOOP. Product 13 moot. per , $.511 -10 for $1.50 311 11111r. n.r , -i."¡ > ro -111 for 55.50 Navy I'D5201O -1 low pass audio filters as mous aircraft radio manufacturer who 50 mod. per 1..c, loll S.7n -. 10 for Soi.zn mentioned in the "Peaked Audio" article in 3lanufarleirers . .r (loom s Ire Ile for Pikes on has abandoned the manufacture of table nu l. quantities. by the above num- June ('Q, and designated model radios because of the flood of WE 11.% Vu. it I it 2511.11110 V.5Itt.tBLE ber, are the exact electrical and physical rnloi `silts IN ,'roll. equivalent of commercial audio filter units government orders. All in 5 ply genuine AUTO RADIO DEALER ATTENTION selling for $35.00 wholesale. They are in- mahogany cabinets, both regular and t I. .rod "Le Nationally .dlrrris 1111111 radin that will finitely better than the surplus "Radio fit pruci ivally any r 'rhrsc : drus will be sure bleached. 6 -tube models have tone con- ore hits with You ru- nnun'I. They have plenty of eye Range Filters" being sold for reducing; appeal plie a host .,f other features that no ,nier QRM, and at 2 KC off resonance for ex- trol. Original list price given first -then raeli" I ei:luss of It can otter. Here are but a few of thhe111: ample, a 2 section filter using PD52010 -1 is your cost. Sensational discounts. Ihllt in II:Orry eh:ng.r 'hat will charge a ear bat- tery. ,lull :t for an dortrie shaver or similar rlee- capable of twice the selectivity available trieal appliance. thru the use of the Q5-er (the BC453 sec- Model 565, Mah. or blonde, $34.95 -$16.97 The Imli,, Is a powerful 6 tithe superheterodyne that has a three gang eon tenser and a stage of 1 :1Un tion of the 274N which has provided the Model 6618, Mah. or blonde, frequency mrpllthwlb,n for Increased sensitivity. The in- radio, rslmwlee with the built In battery charger and amateur's previous highest standard of $44.95- $20.97 power mete. I. Is a sionle 141111111,1 Irait 1111. I. easily terference elimination). EXTRA SPECIAL lustall +l. Sample- S411.50; Dealer price. $37.47 each 663, Mah. or blonde, $46.95- $21 -97 : Model in lots of two or mir,. -NAVY PD52010 -1 with diagram.....$ -.00 BUFFALO RADIO SUPPLY, 219 -221 Genesee St., Dept.RC -II BUFFALO 3, N. Y. RADIO -ELECTRONICS for Tcchnotcs CROSLEY 517 When these sets develop hum not traceable to a bad filter capacitor, check 742ATTRACTIVE the volume control. It may be burned or warm at one end of the element. In ALL -STEEL STORAGE either case, replace it. HURLEY D. ROBINSON, DISPLAY CABINET Pullman, W. Va. RCA 45X1, 45X2 FREE When the rectifier and pilot lamp with purchase of 12 most popular types burned out, the trouble was traced to HALLDORSON vacuum -sealed a short between the voice coil and the TRANSFORMERS. field coil of the speaker. The field coil Assortment includes input, output acts as a filter choke. Replacement of and power transformers as follows (see the speaker cone and coils was nec- Halldorson catalogue): 1- D4.600 1 -T -341 l .85.853 essary. 1-D4-604 1-B5-816 l -S -66 DONALD STEVENS, E. l -K4 -800 I -A4.777 1 -S -67 Los Alamos, N. M. 1-D4-602 1 .A4 -775 1 -S -40 FILAMENT CIRCUITS Dealer Net $24.90 When working on defective filament Just the thing for your service bench or can be circuits of portables, insert temporarily mounted on the wall ... an all -steel storage -display cabinet that holds 12 a small fuse holder, with a fuse of the most frequently used Halldorson vacuum -sealed transformers as per list proper rating, in series with the fila- above ... You pay only for the transformers . .. the cabinet is included in ment string. Fuses are cheaper than the deal at no extra cost to you ... saves trips to distributor's counter ... tubes. When the is up, trouble cleared makes stock keeping easy Good for limited time only. Act now . . . remove the fuse. ... SEE YOUR RADIO PARTS DISTRIBUTOR WRITE R. W. REID, OR The HALLDORSON COMPANY 4500 Ravenswood Ave. Chicago, III. Los Angeles, Calif. . CHEVROLET SETS If a late -model Chevrolet radio is (lead, look for the trouble in the second i.f. transformer. The trimmers short easily. ED CHRISTNER, Middletown, Ohio. RCA COIN RADIOS This contains a chassis identical to RCA's 61 -5 and 61 -10. The volume con- trols are faulty in some of the sets, the carbon element loosening and falling AT LAST!! A LOW COST POWER apart. To check a suspected unit, tem- porarily connect a 470,000 -ohm resistor in place of the control. If the set works, the control was causing the trouble. UNIT FOR SERVICE WORK LEONARD THOMPSON, Joplin, Mo. "A" ELIMINATOR KIT PHILCO 38-38 When these sets distort badly and no KC 1 -10 cause can be found, try replacing the 500,000 -ohm volume Including pic- control. torial and HURLEY D. ROBINSON, schematic only $195° diagrams Pullman, 1V. Va. +vi CI'10 TELETONE TV RECEIVERS We have found several Teletone sets For the first time, we are offering a well- engineered six volt direct current power with a faulty horizontal sweep coupling unit for auto -radio and similar service work in kit forth!! capacitor (the .005 -1d, 6,000 -volt unit This unit was formerly in the high priced range. Now, we have placed all the essen- which feeds the sync pulse to the deflect- tial centponents necessary for construction in kit form, and are offering them to you ing plates of the picture tube). The re- at this low. low price. sult is an intermittent raster or picture These kits fulfill the long- standing need of every serviceman and technician. They or complete blanking of both. are designed to operate from a 115 V.A.C. 50/60 cycle source, and deliver 6 V.D.t'. To test this capacitor, unsolder the well- filtered from three to eight amperes, with a peak rating of ten amperes. The A.C. lead from the terminal connected to the ripple percentage is held to remarkably low values. deflection plates. Turn the set on and This unit charges a standard auto battery in one day!! touch the lead to the terminal. The Do away with bulky batteries! capacitor will Now remove charge. it. Do away with corroding fumes! If there is an arc, the capacitor is prob- ally bad. Touching it to ground will Simplify your service operation! check the diagnosis. A good capacitor Order these line kits for your bench today !j will discharge, while a bad one will do with order. Shipping wt., 1J lhs. nothing. No C.O.D.'s. Full remittance Replace the faulty capacitor with a 10,000 -volt unit. OPAD -GREEN COMPANY H. L. FRAZIER, 71 Warren St. Phone: BEekman 3 -7385 New York 7, N. Y. Jersey City, N. J. NOVEMBER, 1948 7-1 People NEW ZENITH VICE -PRES. Tho Zenith Radio Corpora- tion announces that S a m Kap- lan, who recently completed his twenty -fifth year with the com- pany, has been appointed a vice - president. In 1934, Mr. Kap- lan became assistant treasurer and assistant secretary; in 1935, credit NEW Television Kits, and Equipment manager; and in 1945 assistant vice - Important Advances in TV Reception and Servicing! president. Transvision makes television more enjoyable, more profitable! CRESSON MEDAL TO COLPITTS The recipient of the 100 -year- old Cresson Med- al of the Frank- lin Institute is Edwin H. Col - pitts, director of the Engineering Foundation of New Y o r k, and (lest known to radiomen as the designer of the circuit which bears his name. It is in recognition of his scientific achieve- MODEL IOBL TV FM KIT NEW ... FIELD STRENGTH METER ments in the development of long -dis- a11"la'11,115 the n,nt ' e life of high quality Television Kits. Cabinets. tance communication by telephone and TRANSVISION Components and ,lari:d .lna pwrn t. Illusualed and listed hoe alt only a u91rr Inn of 7i .i at's leu.lin4 alars. See your distributer. radio. Dr. Colpitts previously won the channels; - aln MODEL 10BL, 'It ,'SI Kit. gi ers 115 sn. u. ismiplete Fil Radio: receives all Medal for Merit for his services with lined .Ihiwa NET $269.00 NET 8 23.50 RotoTable for M.L. In111., gives full lad. 1.11111 ì ty the National Defense Research Council. TV 60 sq. in. Orlin.; rlalsolette cabinet with Moto- Table: streamlined MODEL 7CL, Kit, gives TIBB.OL 12 channels; Ira tiumnls tuning NET .1511. Receives all NET 6189.00 same sa 71Ta except thus II a table IO.alel MODEL 7BL. I III It. ta lead -in wire. All p'ir., Include magnets. ud,.,, .,1I ,1..lrr. ,abbe M1d,L,I ,li lilt antrlma. and RECEIVES PRESIDENT'S AWARD TRANSVISION FIELD STRENGTH METER ... John D. Reid. NEW ... re- IMPROVES INSTALLATIONS! SAVES 1a THE WORK! manager of 111c,ue signal strength . . (2) Per- Has nunrerotts teatora9 and ollaul._ \i,aun. amis search of the Cros- .a :1 ne0Inle trlet isilgl set . . (3) Antenna 0rien- mils afloat pinned signal I ,n il. ,,,.i .h: 1.0 ion antenna and lead -in combinations . . ley Avco tattoo 1101 br damn r artly Ii xl. ,- ,_.. '.t Division, . . Il;) 13 111J.E(TOK 151 Useful for ehrrking effell'et I 1.11 :1.101.1' oral t tillalulI ' l'H.t\Nl.l. i i i . 1111 calürt Il- . Manufacturing rau it , l t t i k - : . . . I s Weighs tail): ... Indhldnally ( 7 ) A,,,,, lutdrs of iot,rrerini signals i 11111151 IIIIS ltdt I. n01..183 n.i 1y i a.u1l2la11lllnrata Corp., has recently I - c l Trans,sinl Fiel '.I ' now 4 120volts-sr 60ÿries. NET $99.50 the i 'Otgtt Meter. Model FSM -1. (uuplete Ntubes been awarded President's Certifi- cate of Merit for 1 outstanding work on the proximity fuze during the war. The Crosley manager of research was one of fourteen Ohio scientists. doctors and educators to be awarded the honor at a recent Recognition Day Luncheon in Columbus, Ohio. PARTS FIRM IN NEW HANDS control of General Instrument Corp.. Elizabeth, N. J., radio parts manufac- turer, has been acquired by an indus- NEW .. ALL CHANNEL BOOSTER NEW . REMOTE CONTROL UNIT KIT trial group. C. Russell Feldmann, chair- man of National Union Radio, has been TRANSVISION ALL CHANNEL TELEVISION BOOSTER elected to the same position with Gen- eral Instrument, and Richard E. Laux. 1Ie Radiomen . e . you can '` vl this . II - '41111 formerly executive vice -president of I isi ` ells in 'Tu 13 'Il . `.,.' ..111 1a'I .. Ix o.. Model a-l' LIST $39.95 GET INTO THE General Instrument Corp., has been TRANSVISION REMOTE CONTROL UNIT KIT named president and treasurer. ,.II .,.rmc au , ro.r.or tron o dl- i:nrr. Turns t on, tunes stations. control contrast and brightness. turns set off. Ideal TELEVISION Mr. Feldmann succeeds Samuel the el.. ..la Tuner milt ' a high don., :Ill.rhonnrll u ' with 'a lwut`'.0'mo n, loll .. l..l Cohen and Mr. Laux succeeds Abra- Modetutu, t ,inn i about an hour. l TRC fret' nI cable LIST $49.00 ham Blumenkrantz, from whom the Vihthout cabinetU,'with'_". S47.00 BUSINESS pmglnt 911 line controlling interest was purchased. Mr. NEW B PAGE CATALOG now bille at your d 'tributor or write In a BIG WAY with the Cohen and Mr. Blumenkrantz have re- signed from the board, as has Louis TRANSVISION, INC. Dept. R.C. New Rochelle, N.Y. TRANSVISION IN CALIF.: Scadron. Kenneth C. Meinken, president Transvision of California, 9572 Santa Monica Stud.. Hollywood 46 DEALER PLAN All prices 5% higher west of Mississippi: all pricess fair traded. of National Union, and Harry E. Collin. All Prices Subject to Change WithoutNotice. Write for details now! Toledo investment hanker and indus- trialist, were elected to the new board. RADIO -ELECTRONICS fcr Radio-Electronic Circuits 73 CHECKING A.F. TRANSFORMERS VERY often, an audio amplifier will not deliver the power for which it is designed because of inefficient trans- formers, particularly in the output cir- cuit. The efficiency of a transformer in percent is found by dividing the output TRANSFORMERS power by the input power and multiply- POWER All fully Shielded flush6 3V ing by 100. Lots of l 50 Mil - lL: SV The output power is computed by con- l' 10 Z oo Dsp SBUV T9 necting a load Type Each Eac, resistor across the sec- \ C.T. m... ondary 6U6 49 39 mtl -_G.3v....f1. and measuring the voltage de- ( 35 25 100 6Ú7G 2.95 ' amps 750V C T. C R THOUSANDS 59 49 TUBE 6V5G 2 .3V <3 OF TUBES Lots of 6v6GT /G 45 39 150 m%6 SEC PRI 49 39 omps-SV 3,39 10 6X5GT /G 4 C,T.. 53 43 omPs 75 7A4 and y b 3V l $ Type Each Each 7A7 59 49 200 RI om 4.45 ó 014 69c 59c 756 44 35 3.3 15 C T. J, A3 45 3° 1705 49 44 E2''^-MM 44 49 44 A5GT/G 59 I / 7F7 -4162-0 5 49 7)7 54 49 A7GT 44 C6 75 68 ñ 7N7 49 0 o bó XXFM 44 35 400Aí INPUT E7 99 7X7 H4 59 5_ Ira 44 35 veloped across it when power is ap- H5GT/G 59 49 INDIVIDUALLY plied to the primary. The power in watts 116 16 80 7 CARTONED is equal to the square of the voltage di- 49 as ,t 12A6 29 25 L4 23 vided by the resistance. Measuring pow- LH4 69 59 I2A8GT 35 LN5 69 59 12AT6 50 45 er input is not as simple because leak- NSGT/G 59 49 12AT7 69 59 55 49 12BA6 50 45 age inductance of the transformer RS 45 55 59 55 125E6 50 causes the input voltage and current to 74 69 55 12F5GT 35 27 36 30 12H6 39 33 be out of phase, thus producing false I U5 readings. IV 45 39 12J5GT 25 1? If a capacitor of proper value 2A5 54 43 1217GT 45 is shunted across the primary, the leak- 2A6 45 35 .q 12K7GT 45 33 2A7 49 39 i12K8Y 35 25 age inductance will be balanced out and 2X2/879 35 29 , / 12Q7GT 45 33 current and voltage will be in phase. R.M.A. GUARANTEE 12SA7GT/G 40 32 39 !259'7 35 32 The correct capacitance may be found 3A4 49 49 33 55 4? i- 125C7/1634 by using the setup 3Q5 125G7 43 37 Amazing shown in the circuit 3S4 55 45 43 Value 69 12S17GT 55 described originally in Wireless 1l'orld 3V4 79 45 35 CARTRIDGE of brand 4) 12SK7GTG Fresh stock Order SU4G 50 43 43 cstock ges (London). Load the secondary of the 39 33 125L7 new You get 12SN7 49 43 now to be sure transformer with a resistor SW4GT5X4G need. equal to the 32 you 37 -C 12SQ7GTG 4) ell SY3G 42 32 output load impedance. Connect the pri- 33 12597 35 pN88 Shure Crystal $1.69 SY3GT/G 40 65 55 mary to a 39 32 14A7 400 -cycle signal source 5Y4G 1486 59 49 CoruidOe...... _. 1.49 523 49 33 N7 Wehster Crystal through a resistor R2 having a resist- 5Z4 59 43 y IMMEDIATE ance somewhat lower 69 61 Cartridge 2.95i than the input 6A6 DELIVERY Cortnd9e load impedance. Connect the X plates 6A7 50 45 24A 49 39 Astatie Nylon of 6A8GT 49 3? 25L6GT /G 49 39 a cathode -ray tube or oscilloscope to the 6AB7/1853 53 45 25Z5 49 45 connection of input 6AC5 69 59 25Z6GT/G 45 39 SIGNAL CORPS and primary and the 65 60 re' 45 32 DUAL Y plates 6AC7/1852 26 to the connection of input and 6AG5 79 69 / 27 49 44 i HEADSETS 6AH6 49 39 59 49 6 foot cord R2 as shown. Then vary C until the pat- e; 30 2000 and to 6AK5 74 69 32 80 75 ohms. inrividP2. tern on the 'scope changes from an oval 49 38 48 c1IY Boxed..- Brand 6AL5 55,e-- 32L7GT 52 New, Brand to a straight line. C will be about .015 pf 6AQ6 9 34 69 59 for 6AQ7 69 59 35/51 42 32 the average output transformer. ALL BRAND NEW 35L6GT/G 45 39 39 35W4 43 40 Measure El, E2, and E3 with a 6AU6 49 40 vacuum -tube or high- resistance volt- 6AV6 49 39 Y4 43 6BE6 49 38 35Z3 44 35 meter. The input is 99 59 43 39 power equal to E3 X 68G6G :9 SPEAKER E2 /R2. Dividing this into the 6516 59 99 36 35 output 6C4 29 25 37 45 59 Specials power El/R1, 35 38 45 39 Tap ... . the efficiency of the trans- 6C5GT 40 ,cok- 6C6 45 32 39/44 25 19 Csr '.. , former then becomes: 45 ot absolute 6D6 49 45 41 49 ers cost. 95 42 47 41 minimum E1' R2 6F5 55 Take advantage 6F6GT 45 39 47 49 39 values 50 45 of these X100. 6F7/V770 49 39 50L6GT now! E2XE3XR1 6H6GT/G 45 39 SOY6GT 50 45 each 61SGT/G 45 39 56 55 45 Almm V S99 45 39 3.. P.M._ 69 at The effective leakage inductance of 618 73 65 57 3., p M_1 47 oz AIn.CO 1.99 38 45 39 V the transformer 617GT 42 58 M oz Aln.co is: 45 39 59 65 59 4' P -1 1.89 6K6GT/G ,' P.M.-5peoker V .99 41 39 29 Alnico E32 X C 6K7G 50 71A eP oz V 1.15 50 39 M.-I uz Alnico 6K7GT/G 49 39 75 P M -1.47 V 1.55 49 95 P M 15 oz. Alnico 6L5G 69 59 76 - AImCO P M.__2.15 oz (E3 x 2:tfC)2 -1- E22 6L7 84 78 77 35 27 V 3.69 49 39 oz Alnico 6N4 49 38 78 - P M -6.g Aimee V 4.39 40 38 8 oz V 4.95 607GT 47 39 80 I J' P M.-' oz. Alnico 59 99 83V 79 69 12' P.M -3 _ V 5.95 R2 6R7GT _6 0 oz Alnico 6SA7GT/G 44 37 84/6Z4 49 39 12" where C is in farads, E2 and E3 in 6587 55 45 85 49 45 _21 oz Alnico with 49 39 e_ 89 49 46 12" P volts, R2 in ohms, and f the input fre- 6SF5 6V6 P.P. Output field 6SH7GT 40 32 99V 35 25 Oynam.c 650 ohms quency in cycles. 35 25 Output 3.95 6SJ7GT 44 37 99X with (NC P.P. 49 39 117Z6GT/G 89 76 690 o hmsuhcld If a number of different transform- 65K7GT/G 12" Dynamic 6.95 49 47 1828 99 39 P P. Output 6SL7GT with 6V6 ohms field 5.95 ers are to be tested, it is advisable to 6SN7GT 49 47 1231 39 29 12 Dynamic 1000 make a bread board test panel with ter- 6SO7GT/G 44 37 1644 29 19 minals for connecting the transformer, 6557 59 49 MINIMI'M oscillator, voltmeter WHEN' l,1U ORDER 1.0 and cathode -ray err NN$ ulrl,x:eO. -send tube. The variable capacitor C may be uBe tendu.11('rill be rüur - replaced with a switch and a number of 9''i tlu,ul pj¡ S'ENCO txich,grr fixed of different values. R1 uiriplit capacitors ' F.U. It \9',,.n .\II and R2 may be calibrated potentiom- Dept. B, 73 West Broadway York riq, eters. New York 7, N. Y. BEEKMAN 3 -6498 NOVEMBER, 1948 -Itadio-Electronic :Wallis LEAKY CONDENSER TEST ings of the OZ4, but we have had no trouble from this source. indi- An ohmmeter does not always A standard synchronous vibrator is cate the true condition of a leaky con- connected to the power transformer in denser. To make a better test, discon- the normal manner. The center tap of nect the ungrounded lead of the con- the secondary is unused. When the vi- denser and touch one lead of a voltmeter brator reed contacts points A and C, B to it. Touch the other meter lead to some becomes positive by the full secondary in receiver which B -plus point the at voltage, and the OZ4 conducts between P2 and the cathode. When the reed is in the opposite direction, B and D are grounded and A is positive, causing plate D2 to conduct. If there is no out- put from the cathode, reverse the con- nections to A and B. To 6+ JOE MACE, Garnett, Kansas ANY OPEN CHASSIS LEAD, OR CHASSIS ix the voltage does not exceed the condens- KEYING MONITOR Just Published! er's rating. (Caution: make sure the B- pltts voltage falls within the voltmeter This keying monitor works on ap- PRACTICAL range.) proximately 6 volts of B- supply. The The reading of the voltmeter will be voltage is obtained from a resistor in TELEVISION SERVICING proportional to the amount of leakage the cathode circuit of the transmitter's By 1. R. Johnson and 1. H. Nrwdt through the condenser. keyed stage. When the stage is keyed, 375 pages. 6 a 9. ever 23U illustrations M. B. SYMCHYCH, the oscillator produces a tone. The value Price only $4 Saskatoon, Sask. At last. you can get it Lark that really Oyes you the 6C6/6D6 Ial -dons on trio Lion s e that tells step by Oct, what Io ,: and .d +e guides you specifically on pre - AUDIO TRANS autiuna to lab, and the mistakes to be asolded. PRAC- 3:1 IIMITTER TICAL TELEVISION STIC'ICINU Is all the name Im- CRYSTAL -PLUS RADIO Plies -a nanplrt r. Jewell -i m,arth working annul for those .01 eh s .m1 (0 duel till 11.11,1 MM icing fully, get This crystal receiver uses a 1N34 and a,laiglpened Imt Olt the 51,4 amount of M I$infornlatlon that is creeping into the teievisi,nl picture. and really includes a two -stage audio amplifier. be able to du television s, i icing sulk. The tone quality is satisfactory, and se- NOT a Book of Mere Theory lectivity is good for a crystal set. This Isn't a book of h.oty, mathematles and general dis,iisimo. The AMINO', one radio editor. the other a The receiver works on 117 volts a.c. wall -known engineera a,t +ally mused and operated a tele- vision .Irar,n g^ the sperllle. how- toclo- it h,hr, or d.c. Do.not ground it, as the chassis Oral hat they nee' pass ahmg to you In easily undersloal is hot. The antenna trimmer shown was for tn. III :uldit Lem to a elear ekplanaliem Id lam television of the resistor should be chosen to give Bvendetta-Ws. e a sr1milp 41,1 mterarlot ,over fern radb, used with a 15 -foot length of wire. ury slum ...aidly mmr to in down all snel -itie ISlerallals in about 6 volts, though a somewhat higher ti.nlóleshaah,g. diagnosing and remedying television re- ARTHUR S. BEAN, voltage will be as satisfactory. The edier troubles. You dot Y bother with needless theol y. Baltimore, Md. You are ael unlit slua.n Low to do the wink! transformer is any 3:1 audio unit. MAKES TELEVISION REPAIR WORK 28D7 R. L. BRIDGES, .00014 4 Los Angeles, EASY TO UNDERSTAND 3Y30ppf 11434 Calif. Illy .ul,ieen +w od: 5008 I. Television Is Hero 10. Test Equipment and 2. Fundamentals of the Alignment SPAR CARBON MIKE TRANSFORMER Television System II. Wiring and Repair 3. The Radia frequency. Techniques _ 365oPt 6 When a carbon microphone trans- Intermediate -frequency 12. Common Troubles in Receivers former is needed in a hurry and none and Detector Section Television 411A.. 4. Video Amplifiers 13. Troubleshooting 25/25V can be found, a bell- ringing transform- a. Cathode Ray Tubes 14. Servicing Hints and er will often work. Connect the low- 6. Synchronising and Case Histories Sweep Circuits 15. Color Television voltage secondary to the mike, with the A. Intermediate Fre- 7. Power Supplies mike battery in series, and the primary quencies of Standard 117VAC/DC .01 2 8. Antennas and Wave Receivers between grid and ground. Propagation B. Receiver Layout T°, 9. Television Receiver Diagrams c 40/150VrT These transformers will sometimes Installation C. Glossary work, too, as emergency output trans- FACTUAL SERVICING DATA ON formers. Where the secondary is rated VOLTAGE DOUBLER flow to rest f or ,,, iot. nni rr,v,r peilinll roil at 6 -8 volts, a hell transformer will sup- or rnnafor m This vibrator power supply circuit is ply filament voltage; but if only a few as ¡low, to gist a sill over a mountain Whet to do when the linearity of the picture one that I have found useful for oper- filaments are to be connected across the in poor ating mobile equipment requiring high transformer, check the voltage under Ilote to Geri$ flea( propsri f live king video roaronne nalr a square Wass voltage at moderate current. Standard load and insert a small series resistor if it -hen to use misa raparitora in plus of ottci replacement parts are used. it is too high. Hopea anda of otherorbe It is a bridge -type circuit using a com- NORRIS MCKAMEY, ,r, c, al nidos -soma bination mechanical and electronic rec- Davenport, Iowa SEND NO MONEY tifier. It has twice the voltage and half of (As an emergency microphone - COUPON the current conventional circuits. trans JUST MAIL With the components used, it delivers former, a bell transformer might work 650 volts at 50 ma. This exceeds the rat- well. It would probably not do so in oth- er jobs where more Dept. RC.118. Murray Hill Books. Inc.. 232 Madison Ave.. New York 16. N. Y. A current is carried. C P2 024 Bell transformers ciaiPI Lt's 141 uo .h buson & New; PRACTICAL TF.idì ' r 12H/75MA tON SERVICING fir nl LIY% exan,htarml ..n .005I 2.5MH are designed for 1 a few mots a 650V +650V approval. In 10 days still seul 11. plis = poslugr, e tenon] bask poetics Id. Waage paid on IOOMA 50MA rare intermittent euh of deus: sae lebel privilege. 1ita,ks sent ,xt o-o -2NV post- aPturus cl in U.S. only. Pi tee outside U.S. 11.511 PI .01 use and are inten- paid). / IAVT tionally built to B TR8T1 Name STANDARD have very high pri- 600 SURGE PEAK VIO. A Address SYNC. 5- -'000' + mary impedance ALL CORDS LINE CHOKE 6V X NOT USED and extremely poor City, Zola -, State SOV a regulation. - Ed- Om -up :d oat itor) RADIO -ELECTRONICS for 71 War Surplus Bargains Sold As Used Unless Otherwise Specified!k Micro -switch completely standard, metal Tube socket, RCA, for 866 or Filter condenser, oil filled, 4 Mfd. C 300 grate well cast, rated 15 amperes ® 115 similar type tube bases, new, .35 volts, DC working voltage, size about volts normally open type, plunger has Tube socket, wafer octal type, 2" x 2" x 3½" high, shipping weight override feature. New .35 excellent mica insulation. new, .10 about 2 lbs. New .35 BC -654 -A RECEIVER AND rube socket for 813 type tube, Condenser Industrial Cond. Corp. 5.2 mfd. TRANSMITTER Johnson type 237, new .60 50 volts DC. I" x x 35a" .35 Tube socket, for Acorn type Filter condenser, Industrial Condenser For frequencies. 3800 -5800 Kc. Used but tubes, made by Millen Co., new, Corp., oil filled, I Mfd. C 3000 volts in good operating and mechanical condi- .20 DC working voltage, size about 214" x tion. many times the Worth price for Tube socket, porcelain octal type, 31/2" x 5" high. well insulated terminals. parts. Complete with all necessary tubes. less mounting ring, new _.. ,10 Shipping weight about 3 lbs. New, 2.00 Shipping weight 40 lbs. Each 29.75 First IF transformer for BC -348 Condenser, electrolytic, 100 Mfd. @ 300 type receiver. 915 Kc., new 1.00 METERS -Brand New volts, 212 " diameter, 41/2" high, metal Kit of potentiometers, twenty -five All checked for accuracy! can, shipping weight 2 lbs. Brand new, :,snorted sized carbon and wire 0.500 Ma. DC 31i2 " round, NX35 West- wound. New 2.25 2,00 inghouse 3.00 Resistor, voltmeter multiplier Cond Industrial Cond. Corp. 8 Mfd. 0 -5 Amps RF 31 " round. NT35 West- type, rated at 2 megohms, 2 kilo- Lï, 600 volts DC, I" x 31/2" x 5" inghouse. Internal TC 4.50 volts insulation, I Ma. maximum high 1.50 current, about I" diameter x 51M" 0 -3 Amps RF 21/2" round. NT33 West- long, mounts New _ .75 inghouse, less TC 3.50 Condenser, bath tub type, .1 Mfd. @ in clips. 1000 volts DC. new .20 Resistor, 100 watt type, 5 sections 0 -15 MA DC round 312 " bakelite ease having 7500, 3000, 23, 23 and G. E. type DO -41 Int. Res. 71/2 ohms 3.00 Condenser, Tobe, oil filled, 3 x .1 Mfd. (oi 75 ohms (total of 11,269 ohms) 0 -IO & 0 -250 Ma. DC combination. 600 volts DC ,25 resistance. I1 +" diameter by 81/2" round, DW4I G.E. 2.50 long. New .35 0 -3 Ma. DC 352 " square, 327A Trip- Filter Bond , Aerovox, oil filled. 2 Cord CD -132, has PL -55 type lett 4.50 Mfd. u 600 DC working-volts, size about plug and 9" cord, with spade 0 -500 Volts AC 31/2" square 337A Trip- I' x I1/2 x 5" high, shipping weight type lug tips .35 lett 6.00 about I lb., new .35 Sylvania type 1N26 crystal, New, 0 -2 Volts AC rectifier type 10,000 ohms/ .35 volt Cond , Cornell -Dubilier, oil filled, 4 327A Triplett. 31/2" square 15.00 Mfd. et 1000 volts DC working voltage, Resistor 20 watt, one -half ohm. 0 -50 Ma. AC 337A Triplett 31/2 " square, size about I x 21/2 x 5" high, shipping New .10 7.50 weight 2 lbs., new 1.75 Fuse holder for type 3AG fuses. New .10 RELAYS -All brand New Radiart VB -3, 6 volt bat- Vibrator, for Amphenol co -axial chassis con- RBM DPDT 110 V. 60 cycle, make before tery operation, used in vibrator supply nector, new, type 83 -1R .40 break .75 PEI04 -which is used with BC -654A Amphenol co -axial angle plug Leach type II27 -FR 110 V. 60 cycle. transmitter -receiver. Type J -4, new, 1.95 adapter, used, type 83- I AP, .40 DPST 1.50 Automatic Electric Co. DPDT 24 V. DC Vibrator, Radiart VS -3 for 6 volt battery Connector, bakelite insulation, 6 Amp. silver tungsten contacts .40 operation, used in vibrator supply PE 104 male and female section, 6 pin Automatic Electric Co. delay relay, 20 is used with BC -654A polarized .50 -which transmit- ohm, silver tungsten contacts .40 ter- receiver. Type J6 (probably exactly Canvas bag, moisture & fungus Starter relay. 28 volt operated, heavy same as J 1.95 -4), new proofed, with carrying strap, duty construction .50 leather re- enforced corners, volt Switch, pushbutton type DPST, on /off Relay, 110 60 cycle AC plunger weight 3 lbs., size 9" x 14" x 12" type. to fit standard type for door interlock, new .85 switchbox. IO amps high. Ideal for tool case, for at 250 volts .25 sportsmen, etc. New 1.00 type, Switch, toggle type, bat handle, DPDT Lord Shock Mount, heavy duty base Argon bulbs watt, ideal for heavy duty size 3" x I1/2" -2 contacts ,35 square high -%" diame- transmitter tuning, night light, Plastic coated ter bolt may be used. New .35 Assault wire, twisted 2- etc. 35c ea, Carton of ten 3,00 conductor No. 20 -7 strand tinned, Filter conde , 8 Mfd. @ 700 100 Ft. or more .Ole per ft. Dual volume control wire wound, each Television section 25.000 ohms, new .35 volts DC working voltage. Oil wire, 2- conductor -300 ohm. filled, well insulated terminals. 250 Ft. spool 5.00 Toggle switch, bat handle, DPDT, new, Size about 2" x 41/a" x 5" high, 4- Conductor wire, 16 gauge impregnated .30 with mounting flanges, gray metal rubber coated sheathed stranded copper case, 4 wire .... 100 Ft. Transformer, I IO volts 60 cycle input; shipping weight about 6.00 output being two secondaries -each giv- Ills. New 1.25 BC ing 1 4 volts u I I amperes, which can Filter condenser, Cornell Du- -645 ULTRA HI- FREQUENCY be used alone, in parallel, or in series for bilier, I Mfd. tt 4000 volts DC TRANSMITTER -RECEIVER various voltage and combinations. working voltage, oil filled. Size current You read about it recently in QST! Orig- Size about 31/2 x x high. about 214" x 4" x 7" high over 3'2 4" Ideal for inally operated in the frequency band operation of propeller pitch motors used 111. Shipping weight about 4 lbs. from 450 to 500 Mc. Can for beam antenna Shipping Heavy stand -off insulator type be converted to rotation. 420 Mc. amateur band. Consists of com- 7 terminals. New weight lbs. Manufactured for our com- 3.75 plete transmitter and pany, brand new modulator system, 5.95 and receiver. Complete, brand new, with Telephone LINCOLN 8328 15 tubes 11.95 Microswitch, completely weather -proofed. PRICES F.O.B. INDIANAPOLIS metal -clad or cased, rated 1 5 amps at 1 1 5 volts, normally open type, plunger has TERMS CASH WITH ORDER LS -3 SPEAKER override feature, new .35 6" PM type, housed in heavy metal case. Contains output transformer to match Battery type BA -38, 103.5 volts, used in AMERICAN SURPLUS 4000 ohm impedance. Used but guaran- Handie -Talkie, Mine detectors or for any teed okay. Size about 8" x 8" x 4 ". Ship- purpose where low current drain is re- PRODUCTS (O. ping weight approx. IO lbs. Has jack quired. Size I x I x I11/2" long. Out- For plugging in cord to receiver. Ideal for dated, but tests O.K. 3.00 537 N. CAPITOL AVE. B -C -348 receiver 8.50 INDIANAPOLIS, IND. NOVEMBER, 1948 70 IWar Surplus Bargains Sold As Used Unless Otherwise Specified! MUST VACATE WAREHOUSE PRICES REDUCED FOR CLEARANCE (CRV- 46151) AIRCRAFT SCR -625 MINE DETECTOR DETROLA AIRCRAFT ARB (brand new) RECEIVER RADIO RECEIVER rec. The most sensitive mine detector on the If you want a good 28 V DC 6 tube, 4 band, super- heterodyne For miners, treasure operated 200 -400 Kc. aircraft - with built -in dynamotor. Designed for re- surplus market. CW hunters, plumbers, electricians, lumber receiver -just don't pass up this ception of MCW (tone or voice) or ea. Kc. to mills, etc. 59.50 bargain. A few left at 5.75 within the frequency range 195 9.05 Mc. Complete with brand new pilot's control box and brand new receiver AN PRS -1 MINE DETECTOR JACK BOX BC -1366 tuning unit 27.50 (brand new) Contains 2 pole 5 position switch, A very depend:,ble detector only 22.50 rheostat, 2 phone jacks, etc. In aluminum case 31/4 x 41/4 x BC -221 FREQUENCY METER Complete with headphone set Covers 125- 20,000 Kc. Battery or IIO TURBO AMPLIFIERS adapter to match high to low V. AC or vibrapack operated. A beauti- Used for parts or small phono -amplifier, impedance .. 1.50 ful instrument. The finest we have ever shipped complete with the following had 69.50 I tubes: 7C5's, 1 -7Y4, -7F7. Our 2- R ARN -5A GLIDE greatest bargain. See July 1947 "Radio - -89 BC -221 FREQUENCY METER, with Craft" for conversion data 1.75 ea. PATH RECEIVER modulation 89.50 Formerly used tor blind landing, but adaptable to many other MICROPHONE WILLARD LEAD ACID CELLS uses such as receiver for new po- T -17 -B CARBON (Brand new) 6 V. (dry- charged) 3.00 lice or citizens band. Band of Iiandmike. Brand new 1.75 6 V. in metal carrying case (dry operation 326 -335 Mc. on any of Telegraph Keys. new .75 4.00 charged) its 3 pre- determined crystal con Headphone extension cords .75 1.265 (Add electrolyte specific gravity - trolled frequencies. Contains I I any drugstore) tubes, 6 relays and other valuable parts. For 24 V. DC operation. INTER VALOMETER BC -348 Communications Receiver Size 131/4 x 51/4 x 6%8 ", Electric timing device. Was used for re- Ideal for dark- SCR Commond Set Price complete, 12.45 leasing bombs at intervals. and or -274N room timer, model train control. Contains Power supply for 110 V. operation, with 7.95 relays, switches, pilot light. resistors, complete instructions AIRCRAFT RADIO RANGE knobs, etc. 3.25 FILTER FL -8A BC -375 GE MOPA XMTR. For helpful reduction of QRM of CW bands. When at- C -1 AUTO PILOT GYRO Transmitter only - 19.50 crowded Tuning units TU -5B, TU -6B, TU -7B, TU- tached to output of any communi- Operates from 24 V. DC or I IO V. AC. will pass sig- Adaptable to many interesting hobbies. 8B, TU -9B, TU- I OB, TU -26B- choice, cations receiver: (I) 2.50 nal of 1020 CPS, eliminating 7.95 others, (2) will pass voice fre- Dynamotor PE -73C . 4.95 Antenna tuning unit (BC -306A) 4.95 quencies and eliminate 1020 CPS TELRAD 18 -A FREQUENCY code signal. Compact. light- weight, with switch. Size 23/4 x STANDARD BC -357 MARKER BEACON 2%8 x 33/4 ". 2.25 Checks signals in the range of 100 Kc. RECEIVER to 45 Mc. with a high degree of accuracy. Operates about 75 Mc. Ideal for control- Self- contained power supply for 110, ling remote circuit and model aircraft, BC -733D LOCALIZER 130. 150, 220 and 250 V. 25 -60 cycle boats, etc. Signal easily altered to 2- RECEIVER :\C. Complete with tubes, dual crystals Tubes used and included- and instruction book. One of the best meter band. -\. part of aircraft blind landing 12C8 and I2SQ7. Sensitive relay, circuit equipment. Operates on any of its buys on the surplus market today. While 338 x diagram inside case. Size 5/8 x 6 pre- determined crystal con- the few that we have left last 39.57 5 t/4 ". For 24 V. DC operation 3.95 trolled frequencies in the range SCR -510 RADIO SET, new 69.75 of 108 -120 Mc. Contains 10 SCR -522 (100 -156 Mc. receiver & trans- mitter), complete with tubes 39.75 T -39 APQ -9 RADAR tubes -3 of which are W.E. 717 - TRANSMITTER A's -and crystals. Ideal receiver for conversion to 144 Mc. ham BC -406 -A RECEIVER -Brand New many excellent parts for the Contains band or mobile telephone bands. Western Electric. 165 VHF experimenter such as a cavity oscil- Manufactured by For 24 V. DC operation. Size to Mc. operation. IF frequency 19.5 lator using 2 -RCA 8012 tubes rated at 205 Tubes are forced 141/2 x7x45 ". Mc. IF band width .7 Mc. Easily converted full output to 500 Mc. Price, with dynamotor motor which is 6.95 for operation on other ultra -high fre- aircooled by 24 V. DC Price, without dynamotor 5.95 to 110 V. AC operation. quencies. Operates from 110 V., 60 cy- easily converted this amount Other valuable parts such as a pair of ele. AC. Worth many times MODULATOR with carbon mike for tubes and parts. Tubes -one 5T4, 807's, 6AC7's, 1 -931, and I- 2- input (with dynamotor) for SCR - 954's. 6AG7 tubes. ceramic switch, potentiom- two 6SJ7, Four 6SK7, one 6N7, five 274N Command Set 4.75 Also con- eters. gears. revolution counter. etc.. one 955, one 6F7. one 6N7. 12.50 tains small I IO V. operated motor, 34.50 Telephone LINCOLN 8328 Condenser, mica. .25 MFd. ® 250 volts, -1 ALTIMETER PRICES F.O.D. APN RADIO INDIANAPOLIS new .15 A complete 460 Mc. radio receiver and which can be converted for transmitter TERMS CASH WITH ORDER Jack Box BC- 631 -B, size about 2" x 2" x ham or commercial use. Tubes used and 4 ", aluminum case, contains 10,000 ohm 12SH7, 12SJ7, 2 -6H6, included: 4- 3- volume control, knob, Jones Barrier strip, I 2 2 -9004. Other -VRI 50, -955, AMERICAN SURPLUS brand new .40 components such as relays, 24 V. dyna- motor, transformers, pots, condensers, push- button type DPST, on /off etc. make this a buy on which you can- PRODUCTS (O. Switch, fit standard switch box, IO am- not go wrong. Complete in aluminum type, to 537 N. CAPITOL AVE. peres @ 250 volts, new .25 case 18 x 7 x 71/4" 10.95 INDIANAPOLIS. IND. RADIO -ELECTRONICS for New Patents 69 KINESCOPE PROTECTION COMPLETE RADIO HANDBOOK CIRCUIT RED HOT BUYS! Patent No. 2,444,902 CO -AX CABLE RG59U, 100 ft. $ 5.25 Charles Edward Torsch " 500 ft. 24.75 Lancaster Township, Lancaster County, Pa. The RADIO TWIN LEAD -IN, 300 Ohms, 100 ft. 1.95 (assigned to Radio Corp. of America) " 500 ft. 7.95 " " 1000 ft. 13.75 Many television receivers derive their high DATA voltage from the scanning circuits. If these circuits fail, no high voltage is applied to the BOOK PM SPEAKERS IAlnicoNo.5Mag.) kinescope. In other cases, the high voltage contes from a separate source such as an r.f. oscillator. 4" $1.19 8" $3.95 Section I. The 150 Basic 5" 1.39 4.95 If the scanning circuits become defective an Circuits in Radio 10" intense spot is formed on the screen because the Section 2. Complete 1.75 12" 5.95 Test Equipment Data. Section 3. Testing. ---- Meensuring and Align - OUTPUT TRANSFO RMERS Seetion 4. All about Antennas MATCHING, 50Ló, 25L6, 43, etc. $ .39 Section 5. Sound Sys- PUSH PULL (2 -25L6) .59 tems Section 6. Recording MATCHING, 6V6, 6K6, 6F6, etc. .65 Section 7. Complete MATCHING. 6L6. heavy duty .79 Tube Manual Section 8. Charts, UNIVERSAL, any tube setup .95 Graphs and Curves Section 9. Codes. Sym- AC -DC CHOKE, 50 ma, IO henrys .39 bols and Standards + Section 10. 50 Tested Circuits Designed for STANDARD VOLUME CONTROLS Opt imam Perform- ".i ?OBER SUPPLY ance 10K, 25K, 50K, 1/2meg, Imeg, 2meg, Section 11, Dictionary of Radie and Elec- Less switch 19c HOR12 POWER tronic Terms With switch 39e Over 1000 illustrations! Mention shaft desired, we ship nearest size. 12 complete books in only one. Less than 42c a book! iLA'PZR the only radio hand) k of its kind . , 1148 I.F. AND OSCILLATOR COILS pages . 12 sections, each covering a radio sub- ject more completely than any other book! -39 ANYONE. and every one in radio and electronics I.F. TRANSFORMER, input 456kc $ can use this book! I.F. TRANSFORMER, output 456kc .39 OSCILLATOR COIL, 456kc .19 HORIZ OEFL ON SALE NOW ONLY $5.00 OSCILLATOR COIL, short wave .19 COILS FM -I.F. TRANSFORMER, 10.7mc .83 FM- LIMITER TRANS. I0.7mc .83 FM- DISCRIM. TRANS., I0.7mc .83 COMPLETE TELEVISION MANUAL FM- OSCILLATOR COIL .19 X -TO ANODE OF CR TUBE FM ANTENNA COIL .19 T -HOR12 OUT TRANS g& V I D E O HAND BOOK WIRE SPECIALS beam is not deflected. This may damage the 6 FOOT LINE CORD. incl. plug $ .12 kinescope. ANTENNA HANK. I5 -ft. spool .15 The circuit shown here eliminates the danger Sec. I. Television. Past. RESISTANCE CORD, 150 ohms .39 h) :uttunntt ica lly removing the high voltage if Present- Future. The See. 2. I nndamentals RESISTANCE CORD, 180 ohms .39 the scanning circuit fails. rectifier filament of Television. is headed from the horizontal output transformer. See. 1. The Television STEP -DOWN CORD. 220 to 110V .79 Unless the sweep circuit is normal, full (sower Station. ZIP CORD, 20 gauge, 500 feet 6.75 See. 4. The Television will not be applied to the filament and high receiver. voltage will be reduced. Sec. The Television AUTO RADIO ACCESSORIES Antenna System. There is also protection in case of trouble in 6. a Tele- Sec. Creating VIBRIVI OR, 4 non synch the damping circuit. The induced voltage (across vision Show. prong, $1.19 Sec. 7. Descriptions of WHIP ANTENNA, side mount 1.95 the secondaries of the output transformer) is Modern Television due mainly to the abrupt damping of the primary Receivers. GEN. CONDENSER, 5 -200V .22 current. For example, if the deflection coils See. 8. Installing Tele- vision Receivers. should open, full voltage will not be applied to See. 9. Servicing Tele- PHONOGRAPH ITEMS the rectifier filament again serving tu reduce the vision Receivers. high voltage. See. 10. Television Test PHONO AMPLIFIER, incl. 3 tuber $395 Equipment. PHONO MOTOR, incl. turntable 2.95 It is sufficient to protect against failure in Sec. 11. Building a Television Receiver. CRYSTAL PICKUP. incl. hardware 1.95 the horizontal scanning circuit. If only the See. 12. Data Section. vertical scanning fails the spot will be swept Sec. 13. Television CRYSTAL CARTRIDGE, fits most pickups 1.45 across the screen to form a line. This is not Terms. PERMANENT SAPPHIRE NEEDLE .49 Sec. 14. Bibliography. likely to cause damage. NEEDLE CCI', automatic spring door .... .07 cast in The amount of information contained TOGGLE SWITCH. SPST .15 this book can only he briefly outlined here. The VIDEO HANDBOOK contains 768 pages- over TOGGLE SWITCH. DPST .25 BOTH BOOKS FREE 800 illustrations- thousands of vital facts. TOGGLE SWITCH, DI'D'f .37 ADVANCE SALE -ONLY $5.00! MISCELLANEOUS ITEMS MAKE SURE YOU GET YOUR ONE POUND ROSIN SOLDER S .59 COPY -ORDER NOW! 100 WATT ESICO ELEC. SOLD. IRON 2.36 - - - --1 BROOKS INVERTER. 110 V. DC to AC 8.95 r------SEND THIS COUPON TO YOUR JOBBER OR I FM CONDENSER & COIL KIT, w, inst 4.95 DIRECT TO: CHASSIS PAN, incl. 8 mounted sockets .39 BOLAND & BOYCE, INC., PUBLISHERS LOOT' ANTENNA, oval AC -DC type .39 I MONTCLAIR, N. J. RC -II SELENIUM RE( "rI F'll:lt, 100 ma .59 ME PLEASE SEND VARIABLE (70NDF:\5FR, 2 gang, 420.162 .68 THE RADIO DATA BOOK 55.00 I$5á0 foreign) VARIABLE. ('u \Dtv \slR, triple 420 mmfd 1.45 THE VIDEO HAND BOOK 55.00 155.50 foreign! VARIABLE tu \I of. \ Fa(, FM, 88 to 108mc .95 , I ENCLOSE 55 FOR EACH BOOK I TUBE. 11. \.- slvania, list .39 ;] I ENCLOSE 51.00 AND WILL PAY POSTMAN RADIO $2.65 BALANCE ON DELIVERY (IN U. S. ONLY) 100 TUBE CARTON,. 1:1' type ,95 100 TUBE CARTONS. peanut type .75 I NAME 100 ASST. CONDENSERS. .001 to .02 3.95 ADDRESS 100 ASST. SOCKETS. Ioct., art., min. 4.95 ('ITY ZONE 100 ASST. RESISTORS. -. watt L50 Fill,: to every reader of No suri, _ 1110 ASST. KNOBS, screw & push on 4.95 ii` uoe. nw in r.e Diacr:,oa.° gives hints. STATE short e the , dtauaoismradio s log ASST. PILOT LIGHTS, 44 & 47 4.95 ' Ì\,S IP1, i.dtoll 111,1 .,sad n,,,d.i rm:e'` BROOKS RADIO DIST. CORP. 80 VESEY ST., DEPT. A NEW YORK 7, N.Y. SUPREME PUBLICATIONS Chicago 23.t hl LL. NOVEMBER, 1948 ss New Patents RELAY TUBE MEASURING ELECTRON OPPORTIlNlTY AD-LETS Patent No. 2,443,511 VELOCITY Michael Parcaro, Arlington, N. J. Patent No. 2,442,961 (Assigned fo Penn Electric Switch Co., Edward G. Ramberg, Feasterville, Pa. Goshen, Ind.) (Assigned to Radio Corp. of America) The life of a tube can be prolonged by operat- Electron velocity can be measured by its ef- ing its heater only when needed. However, if fects on a photographic film or screen. This in- the plate voltage is applied before the heater vention interprets velocity in terms of a colored N,w Venk 7. N I,r-tlr.lun,.,. 'ü w. ertaaway. reaches operating temperature, the plate current film. Two films are separated by a metallic de- will c1.115e high evaporation of the emitting ma- posit which slows down electron particles. Each terial on the surface of the cathode. This short- TUBES: All.tr'rol{. USING 2 t11Nl.t- film hits maximum sensitivity to electrons of the \ t tor 121{s. :nel & 1211.t.t ens its life considerably. same velocity. Therefore the second film gets .parc than mlgival lulu. and The primary purpose of this tube is to prevent which had a . Nothing else t buy'-just pÌUg maximum exposure from electrons o . o11ey-bark 1411111 11111r1.. 1211% higher initial velocity. To determine which film ''dt. mot. u,plia _Je rank; lo 'mils fol. If_2.:,1 has received exposure, each is mixed with a dif- 1Y1 11 Irr.. har-.oll ,t:.lalog. l'.nlllllelrial ltadin, ile dye. ... Iti:.rt1, ISI,. R,nl,nl, \1:,s.. ferently colored The shown here is made of a glass MAKE plate LADIOMEN. SERVICEMEN. BEGINNERS - support, a red photographic screen, a metallic ore money, easily. gmrkly. Wu weekly possible. We deposit as magnesium) and a green screen. how you how. Information free. Merit Products, 210 -321, (such 32nd Avenue. Springfield Gardens 13. New Yolk. Each screen has maximum sensitivity to electrons of 50 kv velocity, and the metal is sufficient to GRADUATES OF W}:IJ.- vSS.E.- -l'}ID G110111 OF 11EN. slow the velocity by 20 kv. Each screen is ar- 'noun bad, 14.111M/1. dosa, employment in Radio Field. - III Ravel anywhere. Qualified in radio servicing, instal ranged in checker -board patterns with the dye ollelallon. etc. Contact olion. tea. iu..tlnnuuls. . -Trail patches of one corresponding to the spaces be- 'Ian -went Urpl., Easter. Technical School. SSS Fill chase aurei. Nrw Itrdtnld. Mass. plate current front Rinsing until the filament is tween dye patches of the other. fully heated. TO do this the inventor has included RED SCREE 4311 BOWEN LAS,'AS'l'En. .tlJ.tt'IN F: k noll'l}:1., a thermal delay relay in the grid circuit of an Building. Washington 3. U.C. Registered Patent Attorney.. METALLIC DEPOSIT Mike. Validity and otherwise normal tube. Ihartire Mole United slates patent GREEN SCREEN In, eeilgati'v- .nul Oninioo. Booklet and 111I'ugrnanl In the diagram, the usual control is - fo,, "Es idem,-,' cf Ibu,rpt ion" fol. arded upon request. grid per nutnently connected to the bias supply. When the 1t1thT.t1NS FO11E310S'r RADIO tI11NTIILY. l'ILN'- filament and plate voltages are first applied the TlC.tl. WIIIELESS, e,uI all user the stolid tu "hams.' ELECTRON SOURCE tech - bias on the control grid prevents any plate cur- 70KV ELECTRONS__ llll,l,aed Elll..neali I o:io deseloplllrnls. Leading uirlans drsrNhr 111.v Ih 1'1.11 ideas and 111111'11 valuable ad- rent flow. i hnlh a u.ueur and emul. Indispensable tire published tu, After the filament has heated, the bimetallic I who w-ms lo "keep to 111. kv el lernlau kebushot 50KV ELECTRONS ahead" ,d for all U\ 'twine' who listen nut adre .Ulan - strip Ii distorts and makes contact with the ti,-. F,., anomal eabseripll, u 1.111141 Mort from Ianl.lml. seOul eentrol grid. The normal signal or grid -control '1113 $2.011 to 1;r111 141. Nenas Lld. I PW. 131. 312 dalli m All nur. New Yolk IT. voltage is connected to the strip. When contact is made the excitation as well as the bias voltage SCITCAS-E SIZE RA IIii SIIOI BUILD IT AND appears on the control grid and operation is walla,- huge pr,tus. Free liuelattur. tale: Irrand Federal. SUPPOR 331E Wnoilev,l, Kau -as COY 3. Kansas. normal. In effect, the internal relay takes the place of the external relay in series with the In the presence of 50 kv electrons the green YEARS }:xP}:ItIF:NrE I1A111O ItEP.til{ING AT 13-supply often used with medium- and high - screen becomes dark after developing. If the sllanll' s'eten you can fnl- your lillgmIlns. Eve pell..eled power tubes in transmitting equipment for this entire plate is then held to a light these areas low by OM, calculations. Cuts tep:lir lime to nli1dn11:ItIN'Irlear.11llllabemF': at1 111111111111.1 or COD. same purpose. will look red. When the plate is exposed to 70 Money-back guarantee, Sins Radio 1101:.-T t:IanJricor, kv the red screen becomes dark. There. While many uses could be made of this inven- electrons, Detroit 27. M lrl,igan. fore looks when held to a light. tion, the inventor refers particularly to use in the plate green YOU CAN ACCURATELY ALIGN SUPERHETERODYNE unattended relay -control circuits. In several ap- Different color shadings correspond to slightly re aallnl signal geetalm, Complete lnalrurliefa different electron velocities. $yloc.yhaekLci. guarante.. Chas. Gates, Pecos 2. Texas. plications the filament could automatically be switched on and off intermittently but with usual MAGAZINES IRAC'K 11.%'rEDI- FOREIGN. DOMESTIC, tubes this is not dune because Of the severe de- COMPASS booklets. subscriptions. -ups. le. Cata- INDUCTION arts. Boole. pin terioration caused by plate- current flow log ll,' tsal ndedl. Cox rune's. 803 FR 51 Ave., New before Patent No. 2,444,290 Volk IT, N. Y. the filament is fully headed. This tube would allow intermittent operation with a consequent Carl -Erik Grangvist, Lidingo, Sweden OUR DETAILED TELEVISION: Rt'IL11 Ylll'It OWN. saving in filament wear. (assigned fo plans $1.1111. TeleplinL s341.í E. 74111 St.. l.m Angeles 1, ('alit. Svenska Aktiebolaget Gasaccumulator, Lidingo, Sweden) A31ATEt'It 1111110 LDE.NSES. COMVL1l'E. THEORY A.C. REGULATOR I/1 e fm- :.,n :orur radio examination. )lone compass indicates direction parallmi passing Patent No. 2,444,715 This electronically. telly and lu'sident I-O men Snook-an stadio Institute. A filter is connected between the instrument 1111 %Ye,l .Anal Sn.. Sea il\'uk lily. 5,c Intl ail ml Pas, ' -.. Alec H. B. Walker, London, England and the line to remove second-harmonic dis- F:LEUTItII' EYE. ANI1 .vt11PI.IFIEIt KIT- 1N1.1.111}s (assigned to Union Switch & Signal Co.. tortion which may produce error. Then the a.c. i. ily , cul Inlay. uu VliRrr, punehen phepu,'11. sinsii Swissvale, Pa.) is connected to one coil of a wattmeter W and rhasei., . auleo>els. re. s :do m, .Ragrams. t.'. Industrial qnr r vil aiudirable dl o'unting. stating. burglar arms,la also through a phase -shifter to a coil LI. The nee Several improvements are included in this 1 N n, lin Stn,- ad.e11icillg 'I( 'puss's, delnnlsllaliml%, stabilizing transformer. field due to this coil is shown as Hm. or ue'r I nail l'ad rultrool. Visible äu71 infra -red sen.luxe, Two more coils L2, L3 are. shown to left of Co.. 311m? F'nl- SPEI'L11, 57.'.l, I.wtpubl. Eleenic l'nrols The line is connected left -hand N. 1 across the Between them is a rotating core C which o L. 1 LI. winding. Output is taken from ¡t pair of wind. is stabilized by a gyro. The rotating core C and VW ings around the other two legs of the core. the two fixed cures (within L2, L3) are horizon- i' These are series -opposing. The right -hand leg - tal. operates at as flux density aluve saturation. Two fields are eut by the rotating core. One The ender Icg includes an :air -gap, therefore is the field Hm and the other is the earth's its flux density is much lower. magnetic field Hh, shown as making an angle d W with the first. As C rotates it causes a voltage RECORDER be I.S. This is rectified C1 to induced in L2 and MAGNEIIC and amplified by a screen -grid tube. The plate APE circuit is tuned to the line frequency. The a.c. DOUfLES component is passed on to one wattmeter roil. The wattmeter indication is proportional to YOUR PLAYING TIME.. the ensile of the angle d. The reading is zero when the three cores point north and south. In CUTS YOUR TAPE COSTS this case Hm and llh are in the same direction. IN HALF? GYROSTABILIZER literature. Write today for technical Hh OTOR LI PHASE SHIFTER AMPLIFIER CORP. OF AMERICA L2 398 -10 Broadway New York 13, N.Y. Defense appropriations approved by The output voltage is due mainly tu the wind- the last session of Congress will require ing around the right -hand leg. This is opposed of $1,000,000 of electronic equip- and stabili'rel by the voltage induced in the a total renter leg winding which is more sensitive to ment over the next two years or $500,- load changes. A third winding is connected to 000,000 in each year. This will mean a series condenser and iron -core inductance which that the radio industry Will be forced to resonate at the third harmonic of the line fre- FILTER quency. The harmonic is greatly reduced, leaving convert 25': of its facilities to the pro- a pure output wave. LINE duction of electronic equipment for de- The transformer may be designed for 1:1 ratio fense by the end of this year. or for voltage transformation. RADIO -ELECTRONICS for 67 NEW SERIES 16 SUPER DE LUXE AM-FM CHASSIS 30 DAYS TRIAL Here is the last word in radio' engineering ... a powerful, world - ranging, magnificently -toned radio that is unsurpassed for performance, selectivity, - sensitivity, and advanced engineering features. Uses RO these !.test-type tubes, rectifier and tuning indicator: three 7A7. three 7A4, two 7C5. one 7A6, one 7Q7. one 6ßA6, one 6BE6, one 6C4, one 6AL5, one 5U4, one 6U5. Comes corn- 4N!ii plete with satin stripe copper finish front panel attached, Magna - Tenna Loop Aerial and giant 141/2" Electro- Dynamic Panasonic Speaker. Requires only a few minutes to install, plug in and play. LOW FACTORY PRICES ... EASY TERMS ... 30 DAYS TRIAL. Send TODAY for FREE 1949 Midwest Radio Catalog of separate Chassis and beautiful Console and Table models. OUTSTANDING A Complete Line of FINE RADIOS and RADIO- FEATURES Including the PHONOGRAPHS ... Available in SEPARATE Exclusive Midwest 16 -FM CHASSIS Like the POWERFUL SERIES AM FLASH -O -MATIC Model above or in COMPLETE CONSOLES like this... Volume and Band Indication TELEVISION Beautiful Audio Switch -Over SYMPHONY GRAND FIDEL -A -STAT AM -FM Radio- Phonograph with Color -Ray Tone Selection TELEVISION Audio Switch -Over TRI- MAGNADYNE and NEW Intermix AUTOMATIC Coil System RECORD CHANGER ...Plus NO -DRIFT FM A Magnificent musical instrument and and many other features masterpiece of cabinet design -the finest Midwest Radio in 29 years of manufacture. Offers world -ranging ra- dio reception and newest automatic Intermix Record Changing Phonograph. Uses Series 16 Super DeLuxe AM FM RudCi 0Z zee 1434" Panasonic Speak eared," Chassis. Giant er; Tri- Magnadyne Coil System: Built - FILL IN COUPON AND MAIL TODAY OR JUST In Loop Antenna. Other luxurious con- SEND NAME AND ADDRESS ON Is POSTCARD sole and table model cabinets available with Series 16, 12, and 8 chassis -on MIDWEST RADIO & TELEVISION CORP. Free Trial. Easy Terms and 30 Days Dept. 383 90Y Broadway, Cincinnati 2, Ohlo BUY DIRECT FROM FACTORY and SAVE! Please send me your new FREE 1949 Catalog., NAME MIDWEST RADIO & TELEVISION CORP. ADDRESS IDeep t. 383 909 Broadway, CINCINNATI 2, OHIO' CITY ZONE STATE r NOVEMBER, 1948 Foreign News 66 I UN ASSEMBLY USES RADIO COMMAND RECEIVER - SELSYN TRANSMITTER AC POWER SUPPLY AND INDICATOR RADIO coverage of the United Na- AND SPEAKER tions General Assembly in Paris called for "the most complete and effi- BC 454 COMMAND cient installations ever made in France's RECEIVER history," according to officials of the to G Megacycles. Corers 75 n 1 80 meter amateur band. French Broadcasting System. Pire with who- $6.95 lice, new The installations, thrown open to the TUNING CRANK for Comm. world's lLreicors ea. radio correspondents and com- 65e mentators during the Assembly sessions. Ideal as Radio Beam position indieutor. for Hint. Tele- AC POWER SUPPLY AND SPEAKER vision, or, commercial use. Complete with I -S2 ¡ils ¡nett were made by the French Broadcasting Completely sum,' power sun. indicator. Authsyn Trans. 12 Volt r:0 Cycle transformer. System in cooperation with the United Wy and speaker. with voluto., and wiring instructions $7.95 euurol C W and on and OIT Price: NEW Nations. They included the first use in .wilrh, housed in metal cab- I.82 Indicata only 94.95 inet, size 4%" x 'Y" a any international session of the French - 1',í ". For above receiver or any ether typo command re- made Magnetophone, a tape- recording (elver, ready to plug into re- ANTENNA MAST MOUNT or rack. and 110 Volt device which reproduces sound with tceiver:t Cycle line. Multiple Mast )loom -C in be P.,tomeI o. Chimneys. on gable, slanted, or flat orner, such astonishing fidelity Price completely $14.95 roofs or on sides or that even Wired M brick or flame walls. Ideal for holding all popular trained musicians are types of Television and Ftit A111141t°s in S up Io said to be 'unable Price kit of I!í' dlameter, Slade of aluminuut, will, .Steel hard- to distinguish nnrts oily 9.95 are. plated. Complete with Irabdin; for rhimrte3 its recordings from live hunting performances. B 19 MARK II TRANSMITTING AND Price $4.50 RECEIVING SETS Less banding 53.00 In addition to the numerous broad- COMPLETE with are parts including 1' sp. tones. Set ready ' - front 12 tot 24 Volts In'. casting booths installed in the plenary Frequency range s Mc 140 and ter.. Separate 2 15 Mc Trans. DYNAMOTORS NVERTERS- session and committee looms, six studios and two tube an,pluier, Price: New ... $59.50 -I MOTORS for special interviews and commentaries MARKER BEACON RECEIVERS were built into the Palais de Chaillot. m' 1023 Receives 75 Mc. Modulated Signal. be MG149F lupus varied from 62 to MO 11c. Operates self.rottaineds' INVERTER. 24 Volt UC: O itVe relay that ran be used to operate equipment fnn; Tnlfs 400 cycle 250 V.í r 115 S'Ml lcc,I $9.95 the General Assembly's temporary note point. Nee,ix only 12 to 14 Volts O(' for ilia. ryelt 400V.í. Reconditioned and tested 1,t and plate voltage. Complete with 4 tube.,, home. A battery of 13 recording ma- MOBILE O r -'b m a tic. Shock mounted. Size 5a,e DYNAMOTOR Volt input. t ' 5"k" x 25 m.1. b J 7;16". New, um original boxes. Cou Input.oui put 2x, Vol' chines manned by France's outstanding Price S1.í. /135X. 33.95 $3.50 DM New recording experts was available to PM DYNAMOTOR -12 , 24 Colt i the INTERPHONE AMPLIFIER BC -347 Colt S6 M.í: 6 Volt input. °Mind 261 t $ 1 .95 world's radio reporters. Live broadcasts Army Aircraft Typ, : uses 01M Tube. Contains two 121 Ill MA. New -J Midget lfigl, fidelity IITC mower transformers (s were relayed through a special control ark'). 1 °put 200 Ohm to single or push pull Grid. MOTOR - -6 or 12 Volt .íC -fir. Meaty' Lillo . Output 200 ohm from single or push Pull plate. moor with 5/16. 7/16" shaft. room by Plug resistors, condensers" etc. - New $2.95 wire and cable to London, Brus- closed. .ire 2íF" x 4' x 0" Less Tube -only sels, Holland, each 79C MOTOR -R Volt at' -DC Motor ideal for a and Geneva, and by short- motels, etc. Shaft '3" x 74 ". Or 3 for 52.00 Used, tested $ 1 .50 wave radio to the United States. Com- ADDRESS DEPT. RC Prives F.O.B., Lim Ohio 25 "o DEPOSIT On C.O.D. Orders plete broadcasts of the sessions were also short -waved throughout the world 132 SOUTH MAIN ST over the French Broadcasting System's FAIR RADIO SALES LIMA, OHIO facilities - Much of the equipment provided by the French Broadcasting System was manufactured DRASTICALLY especially for the occa- SLASHED PRICES sion, and a hundred of France's top RADIO TUBES in this FINAL RADIO- EQUIPMENT CLOSE -OUT technicians were assigned to the opera- Buy at Distributor's COST! tion of running and servicing it for the For immediate shipment Only a few of each assembly. First Orders Given Preference R.M.A. Guaranteed Quan. Description r,ce Each 6 110 Masco Slush-sit Contact Mike a .20 4 w'C20 Masco Musical Contact Mike 5.50 Individually Sealed Cartons 3 MA35 Masco Amplifier. with Tubes 1.60 3 MA25 Masco Amplifier. with Tubes 34.90 2 MAS:tS Masco N,rtuble S 72.50 CT Types 1 MAS25 Masco Portable Systen, 66.30 2 MAS17 Masco Portable System 52.30 7 11P.43 Masco Electric Phom,gmph 21.75 6K6GT 40 1S5 .50 2 S1PT4 Masco Electric Phii«npi, 23.5 17 101 Mason 12' Speaker Cabinet 3.60 O 102 Masco In' Speaker Cabinet 3.10 6K5GT 46 1T4 .55 21 103 Masco 8' Speaker Cabinet 2.0 21 104 Masco 6' Speaker Cabinet 1.95 7 Model M Masco Microphone Floor Stand 4.00 6V6GT 45 1R5 .55 5 4 212QíWI Webster Raul/and Master LUnit. 39.90 29 4005(W) Webster Rauland Remote Unit. 9.00 6SA7GT 46 3S4 .55 2 3212 r 45 15 3 2450 Ttiiplett Volt O meAMeter 71.15 6 2413 Triplett Tube Tester 39.50 6SJ7GT 45 6BA6 2405 .50 Jackson Condenser) Tester 39.00 't 640 Jackson Test Oscillator 39.00 6SK7GT 46 613E6 642 Jackson Vnit Ohm Meter 49.50 .50 t 04:1 Jackson Volt Ohm Meter 35.00 :t 845 Jackson Vacuum Tube Voltmeter 55.00 46 2 Jackson 60.00 6S07GT 6AT6 .42 Kilt Cismstat Volume A Tone trol Con- 12BA6 Clamera[' Volume Controlx 12.SÓ 6X5GT 40 .50 clamant Resistors 23 ohm to 2000 ohm .10 Clarostat 10 watt Resistors. 1 ohm to 12SA7GT .46 12BE6 .50 50.000 .16 AemV,nt -Close Outs 1}1 Electrolytic Capacitors 12SQ7GT .46 12AT6 A2 Mica Capacitors 10pó below Paape, Capacitors Distributor Cost Rors 1 12SK7GT .46 35W4 .42 (Write us far SMM'irrc cost) 1:t S43 Snyder Antenna Hemisphere 1.90 ,i Cr Snyder Antenna Big Hoy...... 1.85 12SJ7GT .46 50B5 .55 FC4 Snyder Antenna Cosm°mlitan 2.90 1 73 10M Snyder Antenna Window 1.50 SKffrteatet7 by 35L6GT .40 Nationally- Advertised Nationally- Advertised Grego Bans?. od., Tubes Tubes Quan. Price Each (van. ries Lac, 35Z5GT .32 450 IQ5GT .60 IOT 51.35 ... loi, 1260,. .60 1200 3Q5 17 -. 12610 .60 50L6GT .46 250 354.60 .69 eon InY ^r .55 200 6SA78T . .50 . 11 .50 23^6 DEPOSIT REQUIRED 100 6SC79T .70 CORRECTION ON C.O.D.-2% C.O.D. 100 0646 1.00 lose DISCOUNT ON LOTS OF 50 OR MORE 250 75370T .60 1b. Tu7.1 1.25 250 6SK7OT .50 I : - .9 Sol 0SQ71lT .50 .95 Mr. Gene Conklin informs us that the inn 0060 .e0 .33 yearly license fee fol' radio servicemen RAVAC ELECTRONICS CORP. [11 nfC.CT .60 1.50 ... i,... 1.00 in Costa Rica is $10.00 rather than 432 Fourth Avenue 25.0 Deposit with Order -Balance C.O.D. $100.00 as stated in his article, "Radio New York 16, N. Y. CREST CORP., Dept. C -3 in Latin America," on page 69 of the 3,149 Forest Park Blvd.. St. Louis 8. Mo. August issue. RADIO -ELECTRONICS for Foreign News I 65 owner of any car who has fitted an interference suppressor to its ignition system can obtain one of these free of charge from the Radio Society of Great Britain. He then fixes it to his wind- shield, telling the world that he is doing The NEW Brook his bit in the warfare against television interference. I haven't the least doubt that the idea will be a success. To "sup- T press" an auto costs so little and means 10 WAT so much to televiewers that in television service areas the owner of the vehicle All- Triode whose windshield doesn't carry the ' sticker will soon come to be looked upon Amplifier Model 12A3- Twe.onit remote -control amplifier. Dec- orator- styled control cabinet for living -room use. Also available os Model 12A2 for table or rack operation. THIS CAR HEBE it is at last -an amplifier of intermodulation and harmonic dis- incomparable performance - tortion reduced to the vanishing HAS BEEN FITTED built up to the highest standards of point at any power up to maximum. WITH A Brook engineering -in the moderate Frequency response is flat within price field. 0.2 DB from 20 to 20,000 cycles. SUPPRESSOR Within the range of its power rat- Now for the first time, the distor- TO PREVENT ing the new Model 12A3 is equal in tion -free all -triode performance INTERFERENCE TO all respects to the world -renowned which the Brook Amplifier alone Brook 30 -watt amplifiers. provides is available at a new low TELEVISION The use of low -mu triodes in all cost. Orders will be filled as rapidly RECEPTI ON stages, together with Brook -designed as production permits. transformers available in no other Write TODAY for copy of de- amplifier, permits the cleanest am- tailed Distortion Analysis and Tech- plification ever achieved . .. with nical Bulletin SL -8! Inquiries Invited Standard Discounts Apply Fig. 2-Stickers identify "suppressed" cars. Dealer - as a public enemy. It's a really good idea; I take pleasure in passing it on. The BROOK High Quality Amplifier Olympic retrospect - Designed by LINCOLN WALSH Quite apart from our admiration of BROOK EbECTRONICS, the wonderful performance of competi- 6R K tors from the United States in the 'p 34 DeHart Place, Elizabeth 2, N. J. Olympics, the coming of so many Amer- icans to watch the athletic and other * POLICALARM events has given us a great deal of F. M. RADIO pleasure. RECEIVER GREYLOCK One point of special interest was the A Dependable Name in impression made on American visitors $3995 by our television. Naturally, I was anx- Excise tax included. RADIO TUBES F.O.B. Indianapolis ious to learn how the received images CT. Glass 6 Miniatur, Types $10 cash, rest C.O.D. All Tunes in Individual Cartons compared with those on American view- Slightly higher west. SARGT 12AT6 IRS ing screens. As the BBC televised most of Rockies. 6AT6 12BA6 ITS TUNES 152 -162 MEGACYCLES 6BA6 128E6 IU4 of the big items of the Games, there was 6BE6 t2K7GT 155 plenty of opportunity for comparison. It 6 -tube superheterodyne, ready to operate. Veneer 6K7GT 1207GT 354 cabinet 91/z x 61/4 x 51/4 deep, wt. 6 lbs. Schematic 607GT 12SA7 304 2SK7 was good to experience the U. S. A. en- inside back cover, warranty outside. 2 stages high 6SA7GT 3V4 6SK7GT 12S07 I2A U6 39` find how the gain 10.7 megacycle I. F.'s. Guaranteed reception thusiasm and to surprised 6S07GT 2516G 12BF6 from local F.M. transmitters with attached antenna 25Z6G T No Americans were that our 405 -line sys- 6V6GT 35W4 3585 each -police, cabs, others. Ready to plug in and use. 6x4 5085 35L6GT tem could accomplish so much. 115 volts, A.C.D.C. Power consumed 28 watts. I2ABGT 50L6 35Z5GT Actually, it's all wrong to imagine SOME CHOICE DEALERSHIPS OPEN ... WRITE All 39e Tubes may be pur that definition is fixed by the number SPECIAL OFFER! chased In eta of 100 as- sorted. at 535.00 per 190. a of lines. You can't, of course, drop be- RADIO APPARATUS CO. 729 N. BANCROFT ST. INDIANAPOLIS 1, IND. 6A7 6A U6 6G6G low a certain minimum number (prob- 6ÁC5 66H6 6SN7GT having a poor 6A K5 6816 12AU7 ably about 300) without 6A05 6C6 25Z5 }49c image. But once you send a reasonable GAGS 6D6 75 each number of lines, the most important 6.4.15 6SL7GT 11713 is range of modulation fre- STEADY PROFITS IHSGT I9TR II7L7 factor the N5GT 70L7 616G J} 59c quencies genuinely transmitted and 32L7 84 53 each properly handled by the receiver. Unless Your Own SPECIAL!! 6BG6G 6 .89 this is sufficient your screen picture is Business 'tandem aeidanvnew \OJ.r>IE CONTROLS. \II Ise' shaft. less switch. each S .24 "muzzy" and seems not to be sharply 34 with 53 Rh t SI.8T switch. each focused. This happens because the video With LIST Switch. each 39 impulses are not square enough, with PM SPEAKERS Less Trans. CORADIO I- with :thii,o \' Slagtnt 51.14 the result that the different shadings with Alnico C Magnet 1.14 The Coin Operated Radio With .\III Ir,, \' Slugnrt 1.49 merge gradually into one another in- Place these specially built radios that 4- PM with Wasik cone. and 8 -ox. Alnico \ 1.35 play I or 2 hours for 25c in the thou- Stegner stead of being sharply defined. Our fre- sands of hotel "s l- PM with Alnico \' Magnet 1.19 available rooms, tour- 1.49 quency range is 2.7 mc-a total band ist courts. etc. They yield immediate wIaSSTER Ail Pickup. plastic arm profits and steady income. Install SELENIUM RECTIFIERS width of 5.4 mc. This, with the very Coradio, the finest made. Inc Sta. .59 49 efficient cameras which have been de- Limited capital required. Send for Sta. further information. Write today. TERMS: Net C.O.D.. F.O.B. N.Y.C. 35e Handling veloped, seemed to me to give images Charge on all orders under 55.00. CORADIO Coin Operated about as clear as one could wish. I was Radio Write for Bargain Catalog C -II Dept. B. glad to hear from American visitors ELECTRONIC SUPPLY CO. 212 Broas.way, Phone:BEekman 3- 0038 -9 GREYLOCK that they were agreeably surprised by 30 Church Street New York 7. N. Y. the definition and the depth of focus. NEW YORK 7 N. Y. -NOVEMBER, 1948 641 Foreign News European Report By Major Ralph W. Hallows RADIO -ELECTRONICS LONDON CORRESPONDENT than those which were available to our zinc can of the original Leclanché dry grandfathers. The zinc -sal ammoniac - cell is still there to form the negative manganese dioxide- carbon cell had been contact. There is, again, a central car- good enough for them, and for a long bon rod. But the electrolyte is caustic time it seemed that it would be all that potash (KOH) and the depolarizer mer- we would ever get. Though it has a good curic oxide (Hg0). The top of the car- many things to recommend it, that com- bon rod is pressed hard against the tin- OUTHEND is bination of electrodes, electrolyte, and plate cap of the cell. A boss in the cap ea to Londoners depolarizer is a very long way from forms the positive contact. As the what I imag- ideal. The worst of its shortcomings is Kalium cells are made in sizes identical ine Coney that it has a continually falling e.m.f. with those of the familiar Leclanché Island is to New while under load. True, it recuperates cells, they can replace them anywhere - Yorkers. Lying to a large extent when given a rest, but they have the same diameter, the same near the mouth of the Thames estuary, it never quite regains all that it has length, and the same contacts. its main industry is to provide seaside lost. During a rest the e.m.f. rises, but But there's a vast difference in their fun and games for visitors. Londoners it never reaches the point at which it performance. I've just tested out some flock there in thousands. Though it in- was when the previous discharge be- of the new Vidor cells of the 61 x 32.5 sists on calling itself Southend -on -sea, gan. mm size. I was asked by the makers to the town is, as a of some matter fact, All this is due to the effects of polari- treat 'em rough, so I did. Each cell was few miles up the river. But the estuary zation -and incomplete discharged continuously and with no is about seven miles wide here, and depolarization. the Polarization means that positive hydro- rests through a resistance of 5 ohms. town dweller gets the impression of a gen ions arriving at the carbon electrode As the initial e.m.f. under load is about vast expanse of water, which is certain- to give it its positive charge stay 1.25 v, this means a nominal current of ly there salt. after they have been neutralized by 0.25 amp. Try that test on the best Since the estuary has shallows extend- grabbing electrons reaching the carbon Leclanché cell of the same size and see ing a long way out from the shore even from the outside circuit. In theory the what happens. The needle of the volt- at high tide, Southend had to build one manganese-dioxide depolarizer should meter moves visibly downward, and be- of the world's longest piers to enable hand out enough oxygen atoms to enable fore so very long reaches the cutoff of the steamboats, which bring so many of the hydrogen molecules to combine with 1.0 v. The new cells are perfectly happy its visitors, to use it as a port of call. them and form water. In practice it with this load. They settle down almost That pier is actually over 1% miles in doesn't. Both short-term and long -term at once to an e.m.f. of 1.15 v and main- length and juts out right into the main polarization occur. During discharge the tain it. My tests showed that the e.m.f. channel, through which there is a cease- chemical combination is not sufficiently was constant within ± 0.025 v for the less passing of ships to and from the rapid to cause all the hydrogen mole- first 25 hours of such continuous heavy Port of London. discharge. Then it fell gradually for a Could there be a better place than l-- TINPLATE CAP further 10T/z hours until it had reached the end of this enormous pier at which 1.0 v. After that it was a landslide; to set up a school for training future ESCAPE VALVE FORMED within an additional 1 %ß hours it had radar operators of the mercantile ma- BY VENT HOLE AND SHEATH fallen almost to zero. The e.m.f. may SHEATH FORMS SEALING GASKET seem rather low, but I rine? Radar apparatus situated there POLYVINYL CHLORIDE SHEATH must say I pre- has its as well supplied fer a moderate e.m.f. which screens with PLASTIC SEAL stays put to "breaks" caused by passing ships as a nominally higher one which doesn't. though it were carried on a vessel The Kalium cell is available right s afloat in mid -channel. CARBON ROD down to the 35.5 x 20 -mm and 51 x 14- DEPOLARIZER :MERCURIC OXIDE mm sizes. The rather complicated series That is just what has been done in AND POWDERED CARBON the last few weeks. Some of the most of chemical reactions during discharge ELECTROLYTE: PAPER SOAKED IN is still a matter of some doubt; but up -to -date ship radar equipment has CAUSTIC POTASH SOLUTION been set up. The scanner provides a don't be surprised at that, for electro- lookout extending many miles upstream \PLASTIC BOTTOM WASHER chemists still wage fiercer battles of Fig. I -Vidor Kalium has and downstream; the display is exactly cell extended I;fe. words over those of the lead -acid sec- the same as in shipborne radar. Classes ondary cell. Those of the Kalium cell of student operators are undergoing in- cules to form water. Short -term polari- are probably: zation thus occurs because tensive training. of the forma- 1. Zn =Zn (OH),+2H tion of a film of hydrogen gas round +HOH But don't forget that Southend is (formation of zinc hydroxide and the carbon rod. The internal resistance hydrogen) above all things a holiday town, all out goes up, and down goes the e.m.f. to entertain its visitors. The opportunity 2. 2 H + Hg0 = Hg + HOH of showing them "the wonders of radar" When the cell is rested, the MnO, de- (removal of hydrogen) was too good to be missed. And it polarizer does further cleaning -up 3. Zn (OH), + 4 KOH = K,ZnO, + hasn't been missed. A repeater work; but it never entirely catches up 2H,0 + 2KOH. PPI tube with its job. has been installed in a room open to After every discharge and (Removal of zinc hydroxide) all. Do the holidaymakers like it? They the following rest the film is a little The only snags are that this cell is do indeed! The radar cabin is now one denser, the internal resistance a little more expensive to produce than the of Southend's most popular sideshows. greater, and the e.m.f. a little lower. Leclanché and relatively is not as effi- Two noteworthy attacks on basic cient under light loads as under heavy New dry cell problems of the dry cell have been made ones. It needs, in fact, vigorous chem- recently. One resulted in the Ruben -Mal- ical reactions inside it to be at its best. For the best part of 50 years the dry lory cell; a second has just led in Brit- cell just stagnated. Until recently we ain to the Vidor Kalium cell. The Vidor The war on interference operated our flashlights or portable cell, whose internal makeup is shown in I'm sure you'll approve of the auto- radios from cells little more efficient Fig. 1, has many interesting points. The mobile sticker shown in Fig. 2. The RADIO- ELECTRONICS for 4; 3 DYNAMOTORS VOLTAGE REGULATORS 30' U.S. ARMY S'ONAL CORPS RADIO MASTS i:muttlete 71 f pr i of a ft111 flat oa.t; not ion teloieo. $39.50 MAGNETRONS Input Output Radio TUBE FRQ. RANGE PK. PWR. OUT. PRICE No CHP lo; 92.138 r. 15 Type Amps Amps Set Mfg. Raytheon: Volts Volts Price 2.131 2,10 2s00 me. 2, li.W. 515.00 amps. 57 ni 6:1 ry. I phase. Si,'; 115 V. 7.13 :OPP. .82 BD 77KM 11 10 10011 .350 lte 191 020.00N 2.121.4 9315 9105 (Ill' 5to K.W. 25.00 KVA. 90-PF. \attains Illy following ciattlaatistts: Rego- 11.001,N 2.122 :1207 3335 me. 2o5 1:.W, 15.00 lator 'frattsforiner; Heel 1096 UX9145. Pri: 92-138 r, FE 73 10119 .3511 1W 375 24.511N 110 1 v. 0111115. 24 19 2.120 2992 31119 me. 275 19.W. 15.00 e9., 1.11. Ser: 200.5811 5.5,3.20 4000 DM 21 3.3 235 .1190 It, 312 3.11N rilo leSt. ii 2.127 29115 -2992 me. 275 K.W. 15.00 DM 2ICX 28 1,4; 225 .090 111' 312 3.15N 111ter Reactor: .156 Ity, 1 atups. 40011 v test, Raytheon 2.133 ....7511- 20211 me. 25, 15.00 DM 25 12 2.3 ;:7.11 .1rol 81' 3117 2.19I.N K.W. l'X 9517. DM 28R 24 5.25X 275 .1170 111. 318 5.73 2.1:1s Pkg. 32 i9 3203 me. 25.00 Transformer: Prl: 18G r. 5 amps: See: 115 V. 7.2 amps. DM 33 20 7 510 .250 III' 150 5.5i-9 :..1.3, PR, 3107 -3333 me. 8.7 K.W. 25.00 Entire unit is enclosed In grey Metal cabinet with mount- DM 42 11 111 515 .110 $CE 5. 0.7cl0LN 2.155 Pkg. 9315 -9-105 me. 50 K.B'. 25.00 ing facilities. Size: Irr20s29.. Net wt. Il 11111ml 1. 2511 lbs. 1030 co. 3.1:11 21.11110 me. :15 I.W. 55.00 No,. as slanot $99.50 2, /1 5.1311 39.50 41 PE 55 12 25 500 .100 $CR 215 5.231.N 71 IAY 15.00 KS 9688 Plate Transformer: Pri. 117 v. 60 cy lapped in 2s 1,25 250 .11011 3o1 3.95 PE 86 III' vive 2750.2.170/2240/ on seroutlary at 750 11111. 110 CT. 729BY 241011 inc. 1000 K.W. 50.00 PE 101 C 13/2.1 I2.11/ 400 .135 $CR 515 5.25N 7000 0014 insulation ...... $34.50 0.3 500 .11211 721111' 50.00 VOLTAGE REQ. -Trans121. Atnertran Type 1111" 2 Kva 9 A1 1.12 725-.9 25.00 Load. Input: 00/130 v 50/60 ey. Output 115v . .540.00 IT! Circuit reaker. 115 amps. 000v ...... $15.00 BD AR 93 28 3.25 373 .150 4.910 730-A 25.00 STEP DOWN TRANSFORMER: 0ri: 440 220 110 volt,. 0.0. 23350 27 1.73 285 075 APN-1 3.50X KLYSTRONS: 723A/11 $12.50: 70711 $20.00: 720.3 $15.00 60 Cycles. KVA. Sec. 115 v. 2500 volt Insulation. 35X045/3 2s 1.2 250 .1160 Size 12"x 12. x 7' 540.00 2A .0515 12 21 1/2 500 050 3.91N MAGNETS F IL XFMR: Pei: 115v. 00 ry. Sec: 4v. 10 amp. 25v. B-19 pack 12 9.4 275 .1111 Mark II 9.95N 1.75 amp. 5 kv. Insulation 52.50 Si,,, .1nu For 2.1:11 725-.1, 2.122. 2.120. 2.127. 2.1:11. 2132. and N.V. F IL. XFMR, Prl: 115v, 60 ey. See: 2.5v. DM c.0.. 'N- New. I.N 'Like New. 3.1'.1 Each 58.00 3 kv. ins. A01111.1 1.011 57.50 457. 114.1. F I L. . 112.9899. Pm: 115 V. 60 ey. See: Two 55'. lm,. :,- pole f .11-1.S. ;!1 " 111110 i11011 8.00 HAND GENERATORS 5.5 Amp WrIga. 211KV T0Ft ...... $24.50 1300 Gauss. 112.' bet. pole races. Ite. pole Main- 8.00 115 . ON.35:.001910: :4-01 1;11 nut, hand ORMER: Pri: 230 v.a.e.. ,60 , 8 v. 2.4 anip. less ...... V. 5020.00 crank $7.50 Sec: 21.000 100 ma. SELSYNS: r. oe :12e 7 per pair In $7.75 TUNABLE PKG'D -CW'' MAGNETRONS OIL CONDENSERS inT59 2079-290n NIcs. ilKol 2971 11111 Mrs .1 mfd. 10 KVDC GEPYR r 14E101 515.00 10031 281111-31125 Mrs. 1110112 31511-i':175 Me,. I r,Inmil, 10011 vde S 3.25 COAX CABLE 1 vile Arn1VON NEW-545 each New-655 each 5 nifil 00011 512.50 _. 20,000 vile RI. . .. S .51 'ft. .25 517.50 lo ioni. 10011 SIC . 1.79 10 - - i , L. .. ; . . -,. ,. ., ,.;; ed 5 .50 ...... 'ft. 3.10 niftl. delta et ...... cleil ..yneltro-capaeitor. 00 v 110 2. l', '41 ..100 nap. pulse ,able. l tot on .: min. 41arl - A COMPLETE LINE-MICROWAVE EQUIPMENT IN 00 eyeles. OF . S 4.95 log voltage 17 K V $ .50/H. 1 nifd. 6000 DEPYR 251,50002 S 3.8S 3CM. 1.2 CM. SEND FOR tle. RG 35X. 70 ohm imp. aimotecl S .50/1t. STOCK: 10CM. MICROWAVE FLYER. POWER CHOKES Sxing. Choke: .1.5 fly: .2 m 1 amp 510.95 COAX CONNECTORS. .03 uy. 2 amp. ...5 1.45 .35 hy. .35 amp. 57.50 831R $ $ BIRTCHER TUBE CLAMPS 8.5 by, 125 ma. ....5 1.50 Dual 2.5 Ity. 131, out. $1.25 25 hy. 65 ma. 1.10 .1 by. 12 amp. 40 83ISP $ 35 UG 86'U ... 5.95 926.A 926-135 II by, 150 100. 1.50 Ohms 831AP $ 35 UG 254 U $75 926.A2 926-B33 Dual 7 hy, 75 ma, 11 Dual .5 l'y. :DM nm. S .95 831HP $ 15 UG 255/11 $ 85 926.13 926-C by, 00 ma. 5 liy. 40 nut. 312 Hamedell male 10 type 'N" male adanter $1.25 926.131 Dual 2 liv. 100 ma .551.5755 ohms S .65 by. .15 amp. 2 hy. 2011 ma. S .75 All sixes 5.14 Eaels .116 54.50 QBG-1. ECHO RANGING DRIVER-RECEIVER .01 hy. 2.5 amp. 51.50 Dual 120 hy. 17 ma. S 2.45 Complete ontleiltater sound iglial Iralisnilssion 001 temp lieu unit xi. range 14 21111 to 61111 yil, told freq. range of 16 111 27 8r. New. complete stith hatterY $85.00 11.5 KVA TRANSTATS box in chest. Ic- SPECIALS (AMERTRAN) SELEXIUNI RE, TIFIERS. 11010: 115 vae. 00 es. Out: Input: 0-115 v, 50-60 1.0.: amps. Full Wave. F. T. & It. .1.1.:11 59.95 cycle. Maximum output: BAND PASS FILTER 120 powEn swill:II. 4 pos. 1111 ampf. Gflii vile. Arrow 115 V, 100 SOM. All .711173. S II a r ii band pass II&II 54.25 units are new. guar- peaked at 700 cps. High-ti,. IBYTAItY .sl'ARK GAP. 24 vde 1100.9. 4 shark gap elce- anteed ....$75.00 Each high impedance. Can be troth,. p, o Xintr 111,' 11181-TO $5.50 plugged into 'phone output of CODE TA PE. paper 11/10 wide. 8 Itlulli. tolls ....5.50 receiver for good results. l'ABLE ASSEMBLY, 95 pr. 102' L. Telephone olio WE 400 CYCLE TRANSFORMERS Cuts out QRM. New, with .e D1110(019 $20.00 per length SONAR SOUND Den.:("rolc. l'ndowater detector with 4100: I,: 115 V. 40U es.. Sec: 0.3 v. 2.7 amp: circuit diagram $2.25 V, : 0.:1 V. 21 7 microphone milts encased In rubber sheath. Nlislel 0.3 .66 amp. 52.95 323:12t Pei: 115 V. 400.2400 ev. St-e: 400 vet Jlt 512.50 31ma: 0.4 V. 2.5 ann.: 0.4 V. .13 atop. 52.25 s. INSTRUCTION MANUALS Radlaart V112, G v. DC. MN5211 Azimuth control box for aircraft radio 352.7170: Pri: 115 V. 400-2400 cv. See: 6.3 o 0-pin special 1.40 $1.25 12 inim et. 2511 v. 100 nta: 5 v. 2 anm 53.50 In 412, BC :142 $1.25 pos,, 3 toMO: PM: 115 80 v. 400-2600 ev. See: 650 vet SCR 281 $1.25 Mn 0. qualdilles In all types ARC3 Althorn° radio series reldarenlent relays. Types SI nut: 6.3 vet. 2 amp: 5 vet. 2 10110. . $2.15 .ZA Eqpt. .75 available. 55526, 55251, 55342, 555211. 55531. 55583 5 60 ea. 352-70101: PM: 115/80 V. 401,-24011 vv. Sec: 2.5v Slink II .75 1.75 amp. 3KV 5v. 3 amp: 6.5 v. 6.5 amp: PI SE HOLDER. GK typo EL-1 51.00 6.5 v. 1.2 artip...... $3.95 SCR 5118 1.00 ...... XMTR TUNING UNITS Indi- KS 0007: Pri: 115 v. 400-2400 me. See: 734 VCT. SX-32 .75 From IR' :175: TU-9 i7.7-10 .41.11ERTYPE RECORDING FILM. 50 fl. lengths 177 ma. 1710 wt. 177 me. 55.95 110-12.5 Vitlually boxed S1.00 per length D.1611333: Pri: 115 V. 400.2400 ey. See: 6.3v VIBRATORS me): Tr111 tile): 0.0 amp, 7.7 V. 0.365 amp. 52.75 TU-22 1350050 ki.1; TV-211 TRANS. ARC s 91611. posh iu,,ll 807 s 12111. 12 vile. 5 MDDCLATION 0K 7471057: 1,1: 100 P110/120/130 v, 400-2.100 TR pin $1.20 101. cif 2 In 51.65 (200-5101 Each $2.25 III Plaits .d screens 807s parallel el, See: 2.5 V. 211 atop. HV ins. .. . $4.85 OAK v-0675, 24-32 For BI' 010: Tr-47 12-2.5 13.10325i: Pri: 115 v. 400 cy. See: 0.3 V. 12 an, vile. 7 1 pin 1.10 met Ti' 441 12.5-1 inc); 6.3 V. 2 amp, 0.3 V. amp. P 0 AN .APQ-5 .$5.85 XS 0685: 1,1: 115 v. 400.2100 cy. Sec: 6.4 vet. Mal. 'Type 11.34C. TU 53 18-12 nicO E.0.11 1.75 7.5 12' vile, 5 pin 1.25 amp: OA V. 3.8 anti,: 0.4 v. 2.5 atnti $4.35 For BC 223AX: TV 17 12-3 GREAT TUBE VALUES PLATE XFMR: Prt: 115 V. 400 ev. See: 0800 V or Mal. Typo (11129-C. niel: TU 18 13-4.5 me/. 8600 v O 32 ma tIc. 512.50 12 vile, Pin 1.15 Each 1.95 01-A S 45 5430 39.50 5:11 45.00 HMI 5.00 Plate Xftnr: Fri: 115 v. 800 CV. Sec: 4550 I 0 SC7 1.00 5:12 3.95 8012 3.95 =12033. 11124 4.85 vet. 250 ma...... 57.50 1115 .sS t1AK5 .95 550 4.00 9002 .65 KS 0445. Per Xfmr. Prl: 115 V. 4'011.2400 ev 1N5 .60 11424 .38 502 90.00 0004 .47 Ste: 592 vet. 120 ma. 6.3v, 8 amp: 5 v. 2 ampus.so VFO METERS 17.4 .6C III; 2.00 f115 .89 0000 .47 XFMR. Prl: 115 V. 4110.2400 ev. See: KIT-80 6.16 703-A CEQ PLATE 2C21 .69 1.00 7.00 7, 1.95 .1500 V. 6 Ina...... 5650 ARC-5, Xtiltr M.O. parts and cirenit Il,, Ili.,l 1180' V'0- .69 01(7 .55 704-A .75 El.. 50 .79 ...... consists 2C22 37143. Pri: 113 c. 400 ry. Ser: 6.3 V. 7 song, exeiter. KO of the fidioning: 1..701129 5(0 coil: 2421-A 25.00 (RAGA 1.00 705-A 2.85 F.-11,18 .75 8.3 V. 14.11 amp: 6.3 v. 1.3 52.50 1-25632 lulling eondenser: I - t 4999 padding eaP. 2.122 15.0C OSC7 .70 '707-B20.00 F-127 20.00 FIL XFMR: PM: 115 v. 400 ey. See: 6.3 v. 0 amp: I- # Alte-5 Xintr. schematic. (\antilete kit $2.75 2.126 15.00 1181.7 1.00 714AY 15.00 EC 258A 13.3 vet. .65 amp: 2.5 v. 3.5 amp: 2.5 V. 3.5 11111,. 53.25 2.127 15.00 11V6 .79 715-0 12.00 165.00 Prl: 115 v. 400 Y. Sec: 5.000 V. 200 nu, 7C4 Ks 05144. HEADSETS 2.191 25.00 1.00 720BY 50.00 FC 271 40.00 v, 10 How, sloe: 7"36 10.8 ...... 515.00 1)ynatnic mike and headset tombitiatIon. A high 0001113. 2J32 15.00 7E5E6 1.00 720CV 50.00 GI, 502 75.00 PLATE XFMR: PM: 115 V. .1110 ...... 1150.0. 3.138 25.00 7 .72 721-A 3.60 61.023 75.00 oto. 080631 ediclent milt. used ln 11.19 tank Xittlrs. Mike and 11110111, 1150 v, 40 G.E. 5175 2.139 25.00 17 AO 723.A 12.50 01.697 75.00 1 Few efellplele, $2.75 2J55 25.00 I2A6 .35 72411 1.75 M1.100 60.00 28 VDC 04 38 amp. Output: SO mom $oon olutts It 300-A. Input: 11.15 headsets: tubber twill:ix, 3.131 35.00 I2GP7 14.95 724-D 2.50 91K 50 45.00 tiy). 500 volt-amps. 800 cycles. Leland. New. complete Comes with 8' eon] and 11111g I 9. 55. Neu 52.95 2X2,14711 .ss 12KSY .65 725-A 25.00 (IF 00 45.00 with enclosed relay biter. instruction hook .. 512.50 125F7 .49 7214.A Head and Chest Set BS 19. Carbon mike magnetic phones. . 15.00 QK 61 55.00 PE 218: Input: 25-28 VDC 02 amps. Outlmt: 115 3111.1 125H7 .72 800 2.25 QK 02 Poor physical New. complete olili plug P1.-51 $4.50 2.25 55.00 Vol" 0 1500 volt.amps. 3163.500 c,les. 31'24 .00 1511 1.40 s01-A 1.10 RCA 032 .65 but mood running condition $25.00 MICROPHONE ELEMENTS 3C30 .70 2.37 .75 9.95 VII 01 1.00 306 .79 :10 1 spi-e.) .70 2.50 Vlt 110 1.25 (1arbon tranicluicler element for T$11-J, Tx211.1., T$13-E, :UPI is 13.50 .99 830 1.15 VR 115 1.25 TS15-.9 75 ea. 35Z5 .66 1.95 VIt 117 1.25 311121-11 45 iSper.) .59 BEAM MECHANISM Element for inietoplione T-24. 30 ohm resIstanee.. 95 ea. .21 g171 .59 VR150-30 .95 The most powerful, compact as 3E19 ' .79 800 15.00 St' 120 1.00 :19 . 44 .49 sendtly offered on surplus for 3E1,7 1.20 861 40.00 Vt 134 1.00 beam rot,tion. 90:1 gear ratio 35 51 .72 WI. 332 4.75 um, CROSS POINTER INDICATOR 3691 3.5 211 .75 874 1.95 WN 150 3.00 turned 10,. 24 vile motor .79 227A 3.85 870 4.95 will run on 12 var. 0409t-le type Dual 0-200 microamp, movement in 3Q5 WT 200 5.00 sprocket for ea..y rooming to 510'1 1.20 225 8.80 11405 .35 3" case. Each movement brought out 25118 any shaft. 91/.."L 61 eW .491 5111,4 .95 7.95 1013 .95 }with cavity to 6-term. receptacle at rear. Origi- 2011.A 20.00 Cavity "nil' .1,11 mounting faellily. New. 51-P1 3.7S 315., 19.50 .21 5.00 vuaranteril. romplme with III 1 raTL- nally used ill ILS 51,1, 3.50 i t7N 22 TO 1 11:1 1 .85 vac to 12 .14)w., ment. New .00 - 8.00 00,00 .35 Phohs-ell Conner 516 50 All merchandise guaranteed. Mail orders promptly filled. All prices, F.O.B. New York City 131-C. Send Money Order or Check. Shipping charges sent C.O.D. PHONE Liberty St. New York 7, N.Y. COMMUNICATIONS EQUIPMENT CO. I :Tin NOVEMBER, 1948 Construction Instrument Voltage Supply A cheap and simple power supply that provides up to 50 ma at exactly 90 volts for instrument use , s- By R. L. PARMENTER VERY frequently resistors that The cabinet was constructed of Suitable values would then be around are in the order of megohms masonite and wood. 80,000 ohms for Rl and 20,000 ohms for have to be checked. Usually an The unit described was built to be R2 (to give it a little extra adjustment external battery is used with a used with the volt -ohm -milliammeter range) . limiting resistor to extend the resistance shown in the photo, which calls for a To measure a resistor, connect the range of the average ohmmeter. A B- 90 -volt external battery for the ohms circuit of Fig. 2 to the multimeter battery will last a long time and its cost x 1,000 range and provides readings up through the milliampere jacks on the is not too great, but there are advan- to 10 megohms. With any similar meter, panel. Short the test terminals A and where jacks are provided for connecting B, and adjust R2 for full -scale reading. SW 75/IW IOOMA = 16N/SOMA an external battery, the 90 -volt supply Now insert the unknown resistor be- can be connected to these jacks and no tween the test terminals and read the 117VAC SEL RECT IK IOW further equipment is needed. value from the ohms scale, multiplying When the meter has no provision for by the proper factor. 10 t r r10 connection of an external 150V 90V battery, a cur- The circuit of Fig. 2 can be used with I/4W NEOt. rent- limiting resistor and a zero adjust- any milliammeter, even one not cali- er must he added. A separate box can brated in ohms. Having found the total be used for these, or they can be built series resistance necessary for full -scale right into the power -supply case. meter reading (Rl plus R2), use the OB3/VR90 To find the values for these resistors, following formula to find the value of the builder must know the basic full- an unknown resistor: Fig. I -A regulator tube fixes the voltage. 90 tages in having a small power supply Rx = - (R1 + R2), -Im available for the purpose. This small regulated supply provides where Rx is the unknown resistor and 90 volts at 50 ma. There is no warm -up Im is the milliammeter reading (in am- period; the potential is there as soon as peres) with the unknown in the circuit. the line switch is snapped. Such a power For instance, if the meter is a 0 -1 -ma supply can also be used as a B- supply unit, Rl plus R2 will equal 90,000. If for servicing battery receivers up to its the meter reading is 0.5 ma (.0005 amp). limit of 50 ma. This limit might be the formula will read: extended somewhat by using a heavier- 90 duty choke. The cost of the unit is nom- The voltage supply and a 90 -volt ohmmeter. Rx = 90,000 = 90,000 ohms. inal, about twice the price of B -bat- .0005 teries, but it will last indefinitely. With scale range of the meter movement. This An easier the OB3 /VR90, a regulated potential of can usually be judged from the voltage approach is to calibrate the 90 volts is meter with a number of known resis- obtained. Since this is a mul- ratings: a 1,000- ohm -per -volt multi - tors, and paste a chart or table on some tiple of the batteries commonly used in meter has a 1-nia movement; - a 10,000 convenient of ohmmeters, the resistance readings of ohm- per -volt unit has a 100 -µa move- part the instrument. the instrument can generally be multi- ment; and so on. When taking readings, beware of plied by the proper factor without need shock. Even 90 volts can be uncomfort- of recalibration. In other words, if a able. 4.5 -volt battery is normally used in the 90V SUPPLY RI R2 ohmmeter circuit the multiplier would lie + 20, since 90 divided by 4.5 equals 20. A The circuit diagram is shown in Fig. UNKNOWN RESISTOR 1. The 1,000 -ohm, 10 -watt adjustable resistor is for setting the current flow s through the regulator tube to the proper Fig. 2- Circuit of high -resistance ohmmeter. value. This may lie done very easily by inserting a 0 -50 -ma meter between the The circuit is shown in Fig. 2. R1 plus resistor and the tube. Adjust the slider R2 equals the total series resistance until the current flowing through the which, when the test prods are shorted. tube is about 20 ma. This will provide will give a full -scale meter reading. If good regulation even when the line volt- the meter has a 1 -ma movement, age varies rover a considerable range. The '/4 -watt neon bulb is used as a pilot E 90 lamp. Observe the polarity of the recti- R=-=- = 90,000 ohms fier unit when wiring. I .001 The panel shelf makes construction easier. RADIO -ELECTRONICS fo- 61 t!;\N/CAGO LA AYETTEG R Q 3 Great ELECTRO NEWS Mail Centers To Speed Orders 29 Years of Service- 500,000 Satisfied Customers NEW L.C. CATALOG ELECTRIFIES RADIO MEN MADE TO SELL FOR S14950 Economy- minded hams, set builders, service men overwhelmed THE BARGAIN COUNTER NOW AN AMAZING $5995 by giant new book! "Never saw anything like it! "... "As Here's your chance to pick up some of the latest developments at big money good as money in the bank! " - typical comments. savings. Everyone a bona-fide "buy": Listen -how would you feel if you opened UNBELIEVABLE Law Upholds Landlord on your mail box this A.Y. and found an envel. ope stuffed with crisp new fives and tent TV Antennae That's how veteran bargain hunters react VALUE IN A when they open their copies of the giant Under the law, landlords appear to be new Lafayette -Concord 1949 Catalog, now 10" SPEAKER within their rights in refusing permission in the mails! SUPE33 AC for erection of antennae by apartment ten- Grab up a couple at this ants. They may ban aerials entirely, or give r arAt IT'S THE NEXT BEST THING amazingly low price. TONE CONTROL 1 BAND RECEIVER to some residents and bar others, They're top quality 10 wrmissionithout being held answerable to those who Covers: 540 -1725 kc and 1.8 -5.8; 5.8 -15.5; PM speakers. 4.8 oz. Alnico V magnet. Voice are denied this favor. Courts have held that 17.1.22.2; 14.5.17.1; 11.17 -12.2; 9.28-9.8 me. TO A BANKBOOK coil impedance 3.2 ohms. Up to a booming h the rental of an apartment does not give the h" I'M dynamic speaker delivers an undis- watt Ideal extra speaker lessee any proprietary right to attach any 180 pages solidly crammed with sensational capacity. 4.5 3 condenser. radios, public address, etc. torted watt output. gang equipment to a roof or the other exterior "buys," made possible by the purchasing for 3.345 BF stage. Supersensitive. 110 -220 V. AC. No. 99N71119R parts of a building. power of the largest radio supply organiza- Guaranteed foreign reception. Beautifully tion in the world everything in fa. (_. . -..f .A:1.2:, ea. -l.,. t. of Y `'1.'. o ea. -plus finished cabinet. All heavy duty components. The property owner also is held to be within mous braids! There's hardly a page with. Quantity limited so rush your his rights in removing an aerial which has out some real "find" in TV, Hi -Fi, Ham, MICROGROOVE PICK -UP order. 13', x2G',s xl l s1 -. 35 lbs. $5995 been set up without his permission, pro- AM & FM Radios, P.A., Tat Equipment, No. 1N811R vided he takes the precaution of returning Parts, Tools. etc. he equipment intact to the tenant in his FOR NEW LP RECORDS ° idea of the year building. SPECIAL! PORTABLE IDEAL, USEFUL GIFT BICYCLE SPECIAL! RADIO For the new long- playing re n.. crystal Battery operated. phono pickup for reprduction..f lateral cut Can be easily long playing microgroove records at 33%3 mounted or car- Excellent frequency response for voice ried as a personal. rpm. FOR and music. Output voltage apprnx. Suppliedcomplete AAA 1 volt. Extremely low tracking $495 with all bicycle tP force. No. 99N35 7 7 R. Wt. 12 oz.... T ting hardware and telescopic antenna hichwu plugs into radio. Slide rule dial. Vet.. RECORDS nier tuning. Full size Alnico X5 speaker. THIS IS IT! NEW VM Operates on inexpensive flashlight cells and standard 67 Ss volt "B" battery. Attached DUO SPEED CHANGER! handle. Lightweight. Case beautifully ro- ished. Anti -theft feature. 714x451 a. . NEW 33'/3 RPM PLAYER Weight: 3lbs.,3 ox. No.1N42012 $1995 EVERY DAY YOU LET GO BY WITH- Battery kit, 31.84 Get se,eral for the top names on your Xmas list. Sure to make a hit; OUT THIS CATALOG IS COSTING everyone wants it; practically no ONE THIRD one has it yet. 33./., rpm. motor (110 YOU HARD CASH! volts, 60 cycle) for sensational long - LESS THAN playing records. Webster micro- groove pick- up,with life -long needle. rv3J r11W YOU'D Portable cabinet covered with simu- V lated leather, handsomely lined. OVERSEAS CUSTOMERS Playa 12' record with cover closed. ORDINARILY R.C.A. phono jack with CLIENTES DE ULTRAMAR 5' cord, to plug into radio. $16 95 Send your communications PAY FOR No. 34N2257712 Attention Export Division FOR NEW 331/3 AND THIS BIG 15" STANDARD 18 RPM RECORDS CO -AX HI -FI SPEAKER RUSH THIS COUPON AT ONCE t th Four hours' continuous entertainmru Ideal for quality FDI -ADC receivers. 15- dual a stack of 331A rpm. records; one hour r,m. with FOR YOUR FREE CATALOG and speaker system built -in frequency net- tinuous play at 78 rpm. (Takes both 12' work. Tweeter and woofer reproduce entire ... Iii. records, intermixed.) Universal dual audible range with magnificent realism. 1 K.8 cycle, SHOP IN PERSON Lafayette.Concord Dept. speed motor..@ ick, quiet -changing With built-in load resistor. 8 takes less than 4 seconds. Automatic shut- A 1 ANY ONE Of 901 W. Jackson Blvd., Chicago 7 MAIL NOW and ohm act impedance. off, single tone arm returns to rest No. 99 7n14R21 lbs. OUR surins: 100 Sixth Avenue, New York 13 mechanism shuts off after last record. l're- 265 Peachtree St., Atlanta 3 cision testing insures perfect performance NEW YORK adjustments. Dual needle reversible SPECIAL BULLETINS 100 Sixth Avenue cartridge; single speed control. Mounting miss copies of our two stem Don't ,netting 542 E. Fordham Rd.. Please rush Free catalog No. 89 space: 13.'..- wide; 1214- long:long; Free bulletins. One on TV, the ther a Bronx 715' will sore Free Christmas Gift Catalog. Both CHICAGO Send Xmas Gift Catalog No. 34N22564R you money! The Xmas book's a real No. 34N22563R -same as above, mounted eye- opener ... full of unusual ideas and 901 W. Jackson Brod. I enclose f....- Please fill ,attached order. in handsome walnut and maple base, 334.99 grand values. Send the coupon. 229 W. Mad,son St. Shipping charges extra. ATLANTA 265 Peachtree St. IOSTON LAFAYETTE- CONCORD 110 Federar St. ADDRESS...... - ...... Cen nal Ave. CITY. SANE...... __. STATI ____._...... the world's largest rodio supply organization NNSWAaK NOVEMBER. 1948 New I evices TUBE PIN man, but it can also be used in homes the range, giving fairly constant output where line voltage is too low or too at all equcncies. TV ALIGNMENT STRAIGHTENER high for proper radio or television MARKER chassis operation. Hytron Radio & Electronics Corp. A tap switch may be set for the avail- SQUARE HOLE CHASSIS Vision Research Laboratories Salem, Mass. able line voltage. Three a.c. output PUNCH Richmond Hill, N. Y. This miniature receptacles are provided: LOW. ME -tube pin straightener Pioneer Broach Co. Model TM -100 is an absorption trap takes care of nine -pin tubes and is a which can be used with any visual -align- companion device to this company's Los Angeles, Calif. seven -pin straightener. Miniature -tube This chassis punch operates on the pins are actually thin wire extensions same principle as the familiar tube- of the tube elements and are easily mis- socket punches made by Greenlee and aligned, sometimes making the tube others. A hole is drilled in the metal useless. The straightener can be screwed to accommodate the cap screw. The die to the bench. Each tube is inserted in it and the punch are placed on opposite before being plugged into its socket. sides of the metal and screwing down the bolt makes the punch go through the metal, cutting out a clean square ment generator as -a marker. Instead of hole to accommodate transformers or the usual pip on other rectangular the 'scope screen, a components. small dip appears on the curve. The Any shape of hole having square cor- unit uses no power and is hand -cali- ners may be cut out with the new DIUM, and HIGH. These brated. Frequency range is from 9.5 to provide 105. punch. It is offered at present in two 117, and 130 volts, respectively. 28 mc. The sizes, and a/. inch. serviceman can use the low voltage to 313 test oscillator stability and the high voltage to "pop" components which DUAL CLIP are ready to fail. In all cases, the unit Mueller Electric Co. adds to working safety when repairing Cleveland, a.c.-d.c. equipment. Ohio The new No. 22 Twin -Clip has two BICYCLE RADIO jaws. one at each end, as well as a Trin Radio Co. DISC RECORDER screw terminal in the center. It can be. Risco Electronics used to connect two pieces of wire tem- Brooklyn, N. Y. porarily or to connect a lead to two or Attachment devices are offered for New York, N. Y. more other leads for test and experi- mental purposes. The cyclists who like to listen to a radio en Records may be made at either 78 or TWO -SPEED PHONO spring is in the route. The devices are clamped to the 33 1/3 r.p.m. with this portable unit. center and both jaws may be opened at handle bars and will hold battery re- A swinging- arm -type cutting mechan- TABLE once by squeezing the spring. Squeezing ceivers of any height and measuring up ism is used. The recorder includes the clip at either end causes only one Alliance Mfg. Co. set Laws to to 74/ inches in length and 6 inches in a recording and playback amplifier, a of open, without disturb- Alliance, Ohio ing the other. The Twin is width. The brackets absorb shocks, pre. crystal microphone, and a 6 -inch -Clip made of venting damage to the set. speaker. The new two -speed turntable is de- cadmiu ^olate- steel. signed for playing Columbia Micro- groove records as well as ordinary phonograph discs. A dual version of SPEECH CLIPPER this manufacturer's Model 80 table, the Electro- Voice, Inc. unit uses two motors, one for each Buchanan, Mich. speed, a single lever controlling both speeds. It has a center off position, in Model 1000 speech clipper is a diode which both motor shafts are disen- unit designed to increase the effective gaged from the idlers to prevent flats output of a transmitter without exceed. OSCILLOSYNCHRO- from developing on the idlers and ing 100% modulation. As much as 20 db causing wows. SCOPE Browning Laboratories, Inc. MULTITESTER Winchester, Mass. Triplett Electrical Instrument Co. Model O1-15B Oscillosynchroscope is Bluffton, Ohio a new laboratory instrument for ob- Model servation of transient and recurrent 630 volt- ohm- milliammeter has sis d.c. voltage ranges phenomena involving wide ranges of at 20.000 ohms per volt and six a.c. ranges at 5,000 frequencies. A S -inch cathode -ray tube with 4,000 volts accelerating potential TV -FM ALIGNER ohms per volt. Top voltage on each is 6,000. Five d.c. ranges are included, provides and defini- Philco Corporation the tion o. lowest 60 pa full scale and the highest Philadelphia, Pa. 12 amperes. Resistance up to 100 meg ohms and to +30 of clipping can be Model 7008 precision visual -alignment -30 decibels may be accomplished. A measured. low -pass filter attenuates the harmonics generator for television and FM con- created by the tains in one instrument all the gene- clipping action. A 65C7 and a 6H6 are used. B rators and indicators necessary to -plus (150 volts ad- at 5 ma) and 6.3 just FM TV receivers. volts at 0.6 amp for and The basic unit the filaments must furnished is a 4- 120 FM generator be from -mc with sweep an external supply. adjustable up to 15 mc. An AM gen- erator tunable from 3.2 to 250 mc can be used by itself or as a marker for BATTERY TESTER the FM and' TV alignments. A crystal calibrator provides check points every Chicago Industrial Instrument Co. 5 mc to maintain the reset accuracy of Chicago, Ill. the generators. The AM oscillator car Batteries of are voltage from 1.5 to be modulated by the infernal 400 -cycle I50 may be tested with Model 471 bat- a.f. generator to produce a modulated tery Merchandiser. The battery is tested test signal. under the recommended the load. A 5!r2- Above generators on the saine inch meter is divided into three regions: panel is a 3 -inch cathode -ray tube with NEW. USEFUL, and REPLACE. its controls. This oscilloscope unit is operated from the same power supply as the generators. Sensitivity of the 'scope circuit is better than 25 my per Other features include a Vert . inch (vertical). Phasing and plifier band width of 6 mc. recurrent blanking sweeps of from controls are included on the sane 5 to 500.000 per second, metal panel. and driven sweep rates of 0.25 micro- AUDIO OSCILLATOR second per inch to 200 microseconds per inch. An internal trigger generator General Electric Co. is also provided, as well -as a variable Syracuse, N. Y. delay circuit which may be used to pro- The VGA -4 vide audio test generator is delayed riggers .r a delayed intended primarily for the serviceman. sweep either internally c externally The entire range from 25 to 16,000 triggered. A cycles calibration device pro. is covered in one band. Output has low vides measurement of c, ction sensi- distortion and is constant at any set- tivity through 5 ! the ampli ting of the volume control within -1 db The vertical amplifier, is linear over the band. without positive slope fr O cycles to REACHING TOOL 6 mc, has a transient resr s. e such that Emco Enterprises a 1004c square wave wh,- ses or falls Chicago, Ill. at the rate of 56) volts : ,crosecond is faithful - r. r.rcJ ^J- Flex -o-pic is a flexible tool for pick ing up small parts in hard -to -reach lo- cations. It uses flexible cable of the ISOLATION type employed in speedometers and TRANSFORMER which can be furnished in any length. A Output is controlled by a shielded claw at one end, operated by a button Radio Corporation of America attenuator. To compensate for the loss at the other end, picks up small ob- Camden, N. J. in gain usually present at the higher jects. frequencies, output of all generators in- The unit may be taken apart for The Isotap variable- voltige isolation creases about five times at the high cleaning. It is chromium -plated and transformer is designed for the service. frequencies over that at the low end of acid- proof. RADIO -ELECTRONICS for .:!1 Electron microscope, perfected at RCA Laboratories, reveals hitherto hidden facts about the structure of bacteria. Bacteria bigger than a Terrier Once scientists, exploring the in- ture this: man magnified 200,000 microscope as a practical tool of visible, worked relativeh "blind." times could lie with his head in science, medicine, and industry is Few microscopes magnified more Vashington, D. C., and his feet in another example of RCA research than 1500 diameters. Many bac- New York.... A hair similarly mag- at work. This leadership is part of teria, and almost all viruses, re- nified would appear as large as the all instruments bearing the names Vashington monument. mained invisible. RCA, and RCA Victor. Then RCA scientists opened new Scientists not only see bacteria, but windows into a hidden world -with also viruses -and have even photo- When in Radio City, New York, you the first commercially practical elec- graphed a molecule! Specialists in are cordially invited to see the radio, tron microscope. In the laboratory this other fields -such as industry, mining, television and electronic wonders at instrument has reached magnifications agriculture, forestry-have learned un- RCA Exhibition Hall, 36 West 49th of 200,000 diameters and over. 100,000 suspected truths about natural re- Street. Free admission. Radio Corpora- is commonplace... sources. tion of America, RCA Building, Radio To understand such figures, pic- Development of the electron City, New York 20. RADIO CORPORATION of AMERICA NOVEMBER, 1948 Test Instrumentsnts 58 l Nere s o SIGNAL TRACERS ARE POPULAR SFNSAT/ONAI Dey, (Continued from page 56) COMBINATION sot obtainable, the time spent in wind- if the instrument is to be a first -class ing them with a high -value carbon re- job. INTERCOM & RADIO ,istor as a form, well repays the trouble. A REAL MONEY (Winding 4,700- and 15,000 -ohm re- Operating the tracer Customers Say- MAKER FOR YOU sistor's with resistance wire is not too The tracer is easy to operate. When "Intercom alone is wort) easy, and the likelihood of any con - using the r.f. probe, the a.f. gain control your low price. structor's getting the same residual in- should be kept at maximum, and any ductance and capacitance values as You get free o adjustment of gain should be made on those in the author's instrument seem 6 tube radio in the r.f. gain control in order to keep fairly remote depending pretty much a this deal plus/ tube noise to minimum. When using on accident. Possibly ordinary carbon the a.f. probe, the r.f. stages are not in real utility!" resistors could be used with small r.f. use and the gain control may be turned chokes in series. -Editor) down. While not essential, this will !motors Master Intercom Sub-SUlise Slakes, Including i.Tube Retie make for a clearer signal. An excellent indicator Let us suppose that the receiver Combines a top -quality 6 tube superhet receiver. plus office or home intercom system in handsome The 6E5 has proved itself an excellent under test has poor quality. The first walnut- veneer cabinets. HiAmplirication 3 tube detector. It is especially useful in one thing is to tune in a local station or intercom permits instant communication between radio -master and up to 4 remote sub -stations. Any instance where other indication devices inject a signal from a generator into remote station can call the master while radio is would be more or less useless -on a the antenna terminal of the receiver. playing; call can be returned to any remote station. Operates on 110 volts AC or DC. weak unmodulated carrier provided by The second is to silence the receiver's It's handsome -It's easy to install -It's easy to use! the local oscillator of a superheterodyne speaker as we shall be using that in the Price Includes Radio Master, I Remote, SO' wire receiver. It is obviously impossible to tracer. Probably the best way to silence Original retail price woe detect by ear whether a local oscillator the speaker is to disconnect the speaker SB4.50 with 4 remotes. Buy from RSE and SAVE OVER $2995 is oscillating; but, by placing the rif. transformer secondary and replace the 50 %. prod of the tracer on the plate of the voice coil with a load resistor. In that Brand new -only 400 avail- oscillator, a clear indication can be ob- way no damage can be caused to the able. (Mk Recules 33.9S tained from the 6E5 by the partial output tube or transformer. closing of the eye. Naturally, the re- Now by placing the r.f. probe on the MIDGET I,F.TRANSFORMERS various grids and anodes signal can Back again -by demand! sponse of the eye is not as great as it the popular be made to in RSE scores again with a new and better would be normally, but it is sufficient appear the tracer's I. F.! 400 -500 KC range -11/4' square x for the purpose. speaker. If no fault is apparent up to 3' high- ceramic based mica trimmers - high gain iron cores -pep up old receivers, It is essential that stray pickup should the second detector, change over to the ideal for new construction -and now avail- be guarded against, and therefore metal a.f. probe. Once the faulty section has able in either input or output types -for peak performance! Individually boxed 6J7 and rectifier tubes should be used. been found, the bad component can often in the colorful RSE carton. list price $2.10. If possible, an open -ended shield can be determined by injecting a signal at URI- input; 1.R2-output; should be placed round the 6E5. various points of the input to the tube Specify Type. Mats had Egg Crate The instrument is built on a chassis and using the probe. Each Pair Dozen of 100 inside a 6 x 7 x 10 -inch metal cabinet. Occasionally a receiver will be found 36c 69c $3.95 $29.00 Fig. 2 shows the probes. Notice that in which the signal, if there at all, is so the shielding is made continuous from weak as to be inaudible on its own VOLUME the probe tip to the tracer jack by bond- speaker. In such cases, if the signal is CONTROLS ing the probe case to the cable shielding. not audible when the r.f. probe is placed This tracer has been found extremely on the first detector plate, it can be Our own private brand -made by a nationally known manufacturer. The useful on outside service jobs, on ac- assumed that the local oscillator is not same kind that net for 51.09. Noise -free carbon con- of functioning, and checking can be done struction, standard shaft and bushing. Individually count its lightness and portability. boxed in our colorfulcortoncarrying the R SE equality seal Its weight is little more than that of on that basis. On the other hand, al- of approval. Complete with switch, full range of sixes. the average battery- operated multi - though the signal is strong at the re- 10 M ohms 100 M ohms ceiver input, it may 15 M ohms 250 M ohms each range meter. arrive at the 25 M ohms S00 M ohms 59c speaker distorted and weak. Tracing SO M ohms 1 Meg ohms per 10 through with the instrument, a stage 2 Meg ohms A bigger instrument 500 M Knurled Shaft asstd. s5 50 will be reached at which there is a 500 M ohms less switch, 39c each, 100 for $35.00 For bench Mork, a much more elabo- marked diminution in the gain. Some rate instrument is used. The circuit is measure of the actual loss can be se- TUBES shown in Fig. 3. cured by rotating the r.f. gain control "The All- American Five" As a bench analyzer may frequently and noting how much rotation is needed Here they are-the fastest m vérs be used to trace very 'weak signals, con- to bring the signal back to its former ever made -at RSE's long discount. Brand new, tested top -grades with siderable r.f. gain is advisable. Two r.f. strength. regular RUA guarantee. Individu- stages incorporated, both of them With experience the will ally boxed in eye -appealing are operator cartons; Know your supplier -his being resistance - capacitance -coupled rapidly become familiar with these and reputation. Shoot us an order to- and having the r.f. gain control in the many other faults indicated by day -watch your profits zoom to- the morrow! common cathode leads. These are fol- tracer and will find that it is one of the 12SA7GT...6S 12SK7OT...65 12S07GT...59 lowed by a cathode- follower detector, handiest bits of gear any service tech- 3SZSGT... .49 50160T. ...65 "All-American Kit ", one each of above .. $2.9$ chosen for its signal- handling prop- nician can possess. erties, high fidelity, and minimum There are four rules to remember ORDER INSTRUCTIONS damping effect upon the previous stage. when using a signal tracer: (1) Always Minimum order -52.00. 25% de- posit with order required for all The signal is then passed on to a 6C5 see that the power pack of the receiver Demand This C.O.D. shipments. Be sure to include audio amplifier (into which the a.f. prod on test is O.K. before switching on. Seal of Quality sufficient postage -excess will be refunded. Orders received without is fed), and finally into a 6V6 output (2) Always start tracing from the an- postage will be shipped stage. tenna end of the receiver and proceed express collect. All prices F.O.B. Detroit. Notice that two terminals have been toward the output stage. (3) When 1 1 II connected to the voice -coil leads for in- using the probe, keep the a.f. gain con- SUPPLY & sertion of an external a.c. voltmeter trol at maximum, and regulate volume KHVIV which can be used as a visual indicator. with the r.f. gain control. (4) When ENGINEERING CO., Inc. Bonding between chassis and panels using the a.f. prod, turn the r.f. gain 85 SEIDEN AVE. DETROIT 1, MICH. and all other shielding must be thorough control to minimum. RAD I0- ELECTRONICS for 57 Pipe The waveguide connects with antennas, which are oriented in azimuth with antennas at next Circuits station. At right is complete repeater station. UNLIKE radio broadcast waves, microwaves are too short to be handled effectively in wire circuits. So, for carrying microwaves to and from antennas, Bell Laboratories scientists have developed circuits in "pipes," or waveguides. Although the waves travel in the space within the waveguides, still they are in- fluenced by those characteristics which are common to wire circuits, such as capacitance and inductance. A screw through the guide wall acts like a capacitor; a rod across the inside, like an inductance coil. Thus trans- formers, wave filters, resonant circuits - alI have their counterpart in waveguide fittings. The waveguide continues upward through the Such fittings, together with the connection roof of the station toward the antennas. sections of waveguide, constitute a wave- guide circuit. From Bell Laboratories research came the waveguide circuits which carry radio waves between apparatus and antennas of the New York -Boston radio relay system. As in long distance wire communication, the aim is to transmit wide frequency bands with high efficiency - band widths which some day can be expanded to carry thousands of tele- phone conversations and many television pictures. Practical aspects of waveguides were demonstrated by Bell Telephone Labora- tories back in 1932. Steady exploration in new fields, years ahead of commercial use, continues to keep your telephone system Base of a waveguide circuit in a repeater station the most advanced in the world. of the New York -Boston radio relay system. BELL TELEPHONE LABORATORIES EXPLORING AND INVENTING, DEVISING AND PERFECTING FOR CON- TINUED IMPROVEMENTS AND ECONOMIES IN TELEPHONE SERVICE. NOVEMBER, 1948 Test Instruments Signal Tracers Are Popular By T. W. DRESSER FOR a considerable number of years prodded their way hopefully around a.f. capacitances, was sufficient to resonate the equipment used by most service circuits with. such a combination with- around the high -frequency end of the technicians consisted of a good out realizing to what extent such gear coverage and thereby give a slight lift multirange meter, a signal genera- could be elaborated! to the response curve at that end, re- tor, an emission -type tube tester, a sulting in a fairly level characteristic soldering iron, and an assortment of A simple tracer where otherwise there would have been pliers, trimming tools, and other odds Although still very useful in a.f. a considerable falling off. Inductive and ends. work, a pair of phones would be ob- wire -wound resistors are, therefore, a With such equipment the more ob- viously useless on r.f. It follows, then, worth -while feature; and, if they are scure faults such as distortion, inter- . mittent signals, or low sensitivity or A F PROBE 8+250V selectivity could not be located, and the c=4:=1".'" trouble shooter had to resort to the 1 time -honored method of guess and sub- stitute. Surprisingly enough, it often 470K worked -the radio man has always been .0001 2 - n PHONH .1 MICA rather a genius at putting his finger on 50.41 the spot-but generally it was a temper - `moi n .2MEG frazzling and time -wasting business. 500K 6E5 RF PROBE v Then came the introduction of com- pact portable oscilloscopes. Fault find- ing, for those who could afford to buy a 'scope, became much easier. Even so, it took some time for the serviceman Fig. I simple but efficient visual signal tracer. The 6E5 is detector and indicator. to familiarize himself with the sig- -A nificance of the various traces. that we must have a detector for de- RF PROBE The man who could ill afford the high modulation, and an a.f. amplifier to cost of such an instrument was still left boost the signal. These are minimum SOLDER PLUG to get along as best he could on the requirements, but around them a useful LUG hit -or -miss principle. Only compara- tracer can be built. SHIELDED COAX 30 "LONG 1 1 t tively recently, with the advent of sig- The one shown in Fig. was con- rl, nal tracers, has he had the break he structed by the writer for portability. I 1 "--50uur COND deserves. The circuit is almost self- explanatory. Signal analyzers or signal tracers A 6J7 is used as an r.f. amplifier into - ` ELECTROLYTIC CAN take your pick; the instrument is one which the r.f. probe feeds directly. The and the same thing -have continued to signal is then passed on to either a 6E5 grow in popularity. or 6U5, which is utilized as a grid -leak Af PROBE There are two very sound reasons detector and also as an indicator. The r PLUG SOLDER for thi; increasing popularity: low phone signal is 6E5 SHIELDED CO-AR 30" LONG the taken from the plate LUG initial cost and light running, costs and via a 0.1 -µf mica condenser. High - replacements; and the fact that, where impedance phones must be used. receivers and amplifiers are concerned, Inductive wire -wound resistors were -S05a RESISTOR a signal used tracer localizes the fault as in the plate supply of the 6J7. ELECTROLYTIC CAN easily and as quickly as an oscilloscope. There is a very sound reason for choos- Possibly the first signal tracer was a ing such resistors: it was found that pair of phones and a blocking condenser. the small amount of inductance present N.B.-SOLDER LUGS ARE BOLTED TO CANS Literally thousands of technicians have in them, combined with the stray circuit Fig. 2 -One of many ways of making probes. IS5 105 r-z- AC VOLTMETER 155 .1 .1 J275 f---Ii-- r 475 AF PROBE IIfo l SPSR a5uut .002 RF PROBE ti r I ME G 00K 'IOOK 8 I.IT SOON 25 4705 8 8/450V l 4 MenA --1 HI 220 220 .0005 AF GAIN 25V I.BK 50/508 220 l :47K 250V á RE GAIN 20K Ì 1852 /6AC7 1852/6AC7 6C5 6C5 6V6 5Z4 Fig. 3-A much larger -but still untuned- circuit for service bench work. Two r.f.'s and a cathode follower feed two a.f. stages. RADIO -ELECTRONICS for S J 'cey HEATH SURPLUS 1aef A L L Q U A N T I T I E S L I M I T E D S U B J E C T T O PRIOR SALES BC 645 GENERAL ELECTRIC RCA NAVY COMMUNICATION RECEIVER APN /1 RADIO ALTIMETERS NO. 202. The last of these NO. 200. The last chance TRANSCEIVER beautiful RCA sets. Covers 195 to get a complete new 14 NO. 201. Complete Kc. to 9.1 Mc. continuously. tube radio altimeter. Con- 15 tube transmitter - Supplied complete with tubes, tains 420 Mc. transmitter receiver. Ideal for control box, tuning unit, 24 and receiver, power sup- new citizens band Volt dynamotor, band change ply, range switches, two 460 Mc. for commu- motor, plugs and circuit dia- antennas, meter indicator, tation between of- gram. Superheterodyne circuit all plugs and instruction fice and car, home, covers aircraft, broadcast, short manual. This unit makes boat. etc. Conver- wavoi, marine, foreign broad- excellent amateur station sion article in August ELECTRONICS Maga- casts. Has sharp or broad I.F.'s as it is right in the band. zine. Brand new in original G.E. cartons B.F.O., etc. Shag. Wt. 30 lbs. $29.50 Shipped in original ex- with tubes. Add postage for 25 lbs. $34.50 port crate. Weight 87 lbs. $19.50 Rotc$35.00 PE 125 TRANSMITTER G.E. BC 375 TUNING UNIT . . 2 POWER SUPPLY NO. 203. Model TU1OB PE101C Dynamotor for NO. 223. Operates from 12 to use S 10 Mc. to 12.5 Mc. New com- car 3.95 24 Volts and supplies 500 Volts :' plete with aluminum cabinet. 110V 60 Cycle Power Supply at 160 MA. Extremely rugged The best buy of surplus. Over for home or office use $14.50 construction used in Army tanks. 530.00 worth of new variable Complete with fuses - relays - condensers, toil, dials, switches, 132 TABLE MICROPHONE Filters, etc. Ideal for boats. $12.95 Shipping Weight 73 lbs. etc. Add postage for 20 lbs. NO. 210. One of the Army's best. Built by Kellogg, ideal for factory G.E. 50 AMP CIRCUIT BREAKER FM PUSH BUTTON TUNER call system, public address, amateur ten NO. 204. New General Electric NO. 224. Brand new push but- use. Brand new in original cartons. ton FM 50 Amp 220 Volt AC circuit tuning assembly from Army $ 2.95 Add postage for 5 lbs. $2.95 receiver. Contains 4 gang 100 MMF EACH - breakers. 100 Amp when used silver plated tuning conden- 110V. Add postage for 4 lbs. MINIATURE ELECTRIC MOTOR 37.50 on ser. Add postage for 10 lbs. EACH NO. 211. Tiny Delco motor only 1" x $2.50 2., BC 347 AIRCRAFT INTERPHONE 24 10,000 RPM. from 6 RG 8/U FLEXIBLE to 24 V. Excellant for mod- CABLE AMPLIFIER toels. Add postage for 1 lb. $2.95 COAXIAL NO. 205. Interphone amplifier con- 4 F `\ NO. 225. Standard television lead tains 6F8 tube, Ouncer transformers, in 52 ohm. Any length up to 1,000" diagrams, etc. in aluminum cabinet. vii PER FOOT '%ft. Add for postage. Add postage DYNAMOTOR .: NO. 211 2. Dynamotor only from for 4 lbs PE 103 power supply. Input 6 or 12 POWER TRANSFORMER gtiee a t Volts, output 500 Volts at 160 MA. NO. 226. Primary 117V. 60 cycle.:: SET ACCESSORIES Brand new original cartons. Ship- $5.95 274N COMMAND ping Weight 29 lbs. Secondaries supply 746 V.CT at 220 r NO. 238. 5" PM Speaker with out- MA, 6.3V. at 4.5 A., and 5V. at 4A. put transformer matching head- Will handie 13 tube radio receivers. tOLT3500001AA phone output $2.80 DYNAMOTOR Supply is limited, order early. Ship- NO. 213. An ideal dynamotor for ping Weight 11 lbs. each. NO. 239. Dual receiver rock FT277A mobile operation in taxicabs, police with connecting plugs $1.00 cars, sound systems and amateur sta- $3.95 . . 3 for $9.95 NO. 240. Single transmitter rack tions. Supplies above voltage from 12 OUTPUT TRANSFORMER FT234A 51.00 Volts or 500V. at 350 MA from 6 NO. 241. Spline shaft for tuning Volts. Complete with starting relay, NO. 227. Push pull 6V6's to 6 - 8 ohm command receivers. Allows use of and fuses. New. Our Dynamotor A. coil excellent $5.95 r regular tuning knob on BC 453-4.5 Shipping Weight 72 lbs. cvoiceharacteristics, 3 for $1.95 receivers S .39 DM -36 DYNAMOTOR TRANSMITTER TRANSFORMER i BC 451 CONTROL BOX NO. 215. W Electric 24 Volt input, 220V. at NO. 228. The transformer for Transmitter NO. 236. Control box for 274N 60 MA out. With filter assembly. Power Supply, 600 Volt at 200 MA and transmitters. Contains proper cw- Shipping Weight 6 lbs $2.95 4 Amp. filaments of 3 to 24 Volts. Also voice switch, 4 channel switch, 5 Volts at 4 amperes for rectifier$9.50 f jack and tele- power switch, mike BC 306 Shipping Weight 12 lbs i77 graph G.E. ANTENNA key. TRANSFORMERS Add postage for 2 lbs... $1.95 TUNING UNIT MILITARY POWER NO. 231. Matches any aerial to 150 NO. 229. Convert your military re- Watt transmitter, used on BC 375. Brand "A" ty withoutt 500 the filament. METER SPECIAL new. Add postage "A" type supplies 500 VCT at 50 MA, NO. 237. Brand new Delur Model for 20 lbs $2.95 5V. at 2A. and 24V. at t/2 A. "B" 312 0-800 M.A. D.C. Square 3" 0 -10 type supplies 500 VCT at 50 MA, 5V. M.A. basic meter with built in W.E. BC456 MODULATOR at 2A. and 12V. at 1 Amp. State i, shunt. Probably the best buy ever NO. 217. Modulator from 274N com- whether A or B type desired $ Weight 4 lbs offered in a surplus meter ;2 et nd transmitters contains 3 husky Shipping 95 Shipping Weight 1 lb 95 relays, 3 tubes, VR150, 12J5 and 1625. Brand new. Add postage for 11 lbs. $3.9541 HOME WORKSHOP GRINDER KIT A -62 ARMY PHANTOM ANTENNA BE 77 TELETYPE TEST SET NO. 230. Easily assembled 110V AC or DC boll bearing fully en- NO. 206. Contains tuning condenser, NO. 218. Contains zero center volt - closed motor from Army surplus coil, resistors, tuning dial, tuning in. milliammeter, switches, relays, voltage dynamotor. Purchaser to make divider, binding posts, steel case, use- divider resistors, neon indicator, eta `. simple changes and shaft exten- ful for building amateur transmitter. Excellent foundation for radio tester. sions., detailed instructions and all Add postage $7.95 Shipping Weight 10 lbs. parts supplied. Motor approxi- for 8 lbs $1.95 FINDER mately 5,000 R.P.M. Ideal for BENDIX MN 20E DIRECTION LOOP tool -post .grinder, flexible shaft NO. 219. boat type loop excellent ¡\ $3.95 UNIT tool, model drill press, saw. Ship- BENDIX MR9C COMPASS CONTROL for use on boat or aircraft. Extreme- ping Weight 6 lbs. NO. 207. Tuning and control unit ly rugged construction. Low im- for Bendix MN 26 radio compasses pedance manual HEARING AID HEADPHONES contains tuning dial, bond switch, postage for 8ylbs. 57.7 EACH NO. 216. The Army's best - eliminate Rat noise. with crystal switch, AVC switch, volume LP FINDER LOOP ears and outside Complete control, fuses, phone 18C DIRECTION transformer for conversion from low to lacks, 220. Motor driven streamline etc. Shipping Weight 5 lbs. ;9 50 NO. pod high impedance. With cord and plug type loop used on automatic direction complete. finders. Has Selsyn transmitter and Add postage for 1 lb $1.00 BC731 CONTROL BOX motor, fits most military direction finders. Add postage TELEVISION CONDENSERS with Weston Model 476 AC Voltmeter EACH for 20 lbs. a G.E. NO. 208. Excellent buy in motor control NO. 221. Tobe triple .2 NO. 222. Pyranol MFD 4000 V.D.C. Filter capacitor .25 MFD 6000 box. Size 8 "x10 "x512 ".Contains Wes- KIT SP ECIALS Army radar. V.D.C. Porcelain insu- ton 0 -150V. AC 3, 2" voltmeter, motor POTENTIOMETERS SOCKETS used on starting switch, 28 fuses all 33 Amp Ideal filter for H.V. lated, an outstanding NO. 232. Kit of 10 ex- NO. 233. Kit of 20 high television set. Add buy for high voltage 110V. and 8 fuse holders. Fuses ana cellent shaft type po- quality sockets several holders alone worth the price e postage filters. Add post- tentiometers $1.95 different for 3 lbs $3.95 age for 3 lbs $3.95 Shipping Weight 18 lbs 17.95 good variety types w$1 .00 SRI" DR OW TO ORDER WEIGHTA OWNMNORORDDR DEIcNDREIR T$12000 W DDViIOSSTHIPEC O "7tie HEATH COMPANY DEPT. C . e . BENTON HARBOR, MICHIGAN NOVEMBER. 1948 54 ELECTRONIC BARGAINS EXPERIMENTERS a«d HOBBYISTS I I E S S U B JçE C T T O SALES A L L Q U A N T T LIMITEDj PRIOR NEW DM 64A 12 VOLT DYNAMOTOR STANCOR FILAMENT TRANSFORMER BRAND ARMY AIR FORCE NO. 269. Input 12V at 5 Amps. NO. 242. Heavy duty Stancor No. Output 275 Volt 150 MA. New. ST355 supplies 5V at 6 Amps, 5V at Shipping Wgt. 3 3 ASTROGRAPH Amps and 5V at Amps 7 lbs. Each. $5.50 from 220V 60 Cy. primary NO. 259. The case of or 1/2 above from 110V. this unit makes the DM 32A COMMAND SET DYNAMOTOR Cased type. Ship.$1 finest tool and service NO. 270. Part of 274N Command Re- Wgt. 7 lbs. Each .50 kit ever designed. Ply- : ceivers. Input 28 Volts, output 250V G.E. THYRATRON TRANSFORMER wood construction, 14 x 60 Shipping 4 lbs. Each NO. 243. New G.E. Transformer sup- 11 x 10" high, with 8 Wgt. plies 2.5V at .100 KVA, has 3KV in- covered compartments DM 21 12 VOLT DYNAMOTOR sulation 100V 60 cy. primary. Ship - in the bottom for repair NO. 271. Used in Army BC 312 ping Wgt. 13 lbs. pats, leather handle, Volts at 3.3 Input 12 reinforced Each $9.50 steel covers, Volts at 3 Amps. Output 235 hinged lid. Also excel- MA. New, original RCA SATURABLE REACTOR TRANSFORMER Volts at 90 lent as case for radio cartons. Shipping Wgl. NO. nt New RCA AC $5.50 phonograph, movie projector, camera, shel case, 8 lbs. Each .7 current 750 DC currentusent 2 Amperes. fishing kit, picnic kit, etc. The astrogroph itself, Rated 1.75 henries. Ship- (which cost the government 5125.00) makes an PE94C SCR 522 POWER SUPPLY ; ping wgt. 4 lbs. Each $1.00 IV excellent contact printer, and can be used for a NO. 272. Complete dynamotor 12.6V POWER TRANSFORMER foundation for enlarger, strip map' holde, etc. power supply for the SCR 522, oper- with NO. 247. New cased 110 V 60 cy. The case alone worth twice the $3.95 ates from 28 Volts. Complete Power Transformer. Supplies 440V Ct. give -away price of controls, filters, etc. Original car- at 60 MA, 6.3V at 2A. and 12.6V at ton. Shipping Wgt. $8.75 AN27, ARN5 ANTENNA 34 lbs. Each 1 Amp. Excellant for military sets. 260. Standard blind Shipping Wghl. PE101C BC645 POWER SUPPLY $1.95 landing antenna system. supply 6 lbs. Each. nd ew original NO. 273. Complete power for BC 645. Operates from 12 or RCA INPUT TRANSFORMER Bin te. Ship. Wingt. 14 lbs. $9.50 both AC and DC NO. 248. Heavy duty RCA No CRC- 24 Volts. Supplies required. Shipping ': 30529. Input has primanes 600 to 200 AS114 /APT ANTENNA SYSTEM lbs. Each and 25 ohms secondary 250,000 ohms Wgt. 13 $3.95 C.T. Shipping Wgt. DM 35 12 VOLT DYNAMOTOR 2 lbs. Each _. ... $1 .00 NO. 261. New blade NO. 274. New input 12 Volt at 18.7 type REPLACEMENT POWER TRANSFORMER antenna complete $7.50 Amperes. Supplies 675V at 275 MA with case assembly, NO. 251. Excellent value transform- or .'2 above voltage from 6 volts. Ex- in original carton. Shipping Wgt. 9 lbs. es mode by one of largest trans- cellent for auto use. Ship- former companies. 110V 60 cy. Pri- AS115 /APT ANTENNA SYSTEM ping Wgt. 11 lbs. Each $7.50 ory supplies 746 V at 150 MA. PE 86 DYNAMOTOR Ct. $ 7.50 5V at 4A and 6.3V at 4.5 Amps. gig===, NO. 214. A popular 28 Volt re- Shipping Wgt. NO. 262. New blade type ceiver dynamotor used on present 7 lbs. Each $2.95 antenna complete with case !1 military equipment. Supplies 250V FEDERAL POWER TRANSFORMER assembly, in original carton. Ship. Wgt. 11 lbs. at 60 MA. Shipping Wgt. 4 lbs. Each $5.50 NO. 252. New cosed 110V 60 cy. AT38A /APT RADAR ANTENNA `.. Transformer. GN 58 HAND GENERATOR Power Supplies 480V CT NO. 263. New radar dome type on MA 2.1 Makes excellent home at 50 and 6.3 V at Amps. A tenno with mounting base and con- NO. 275. #,. by wind beautiful transformer. Ship. nections, in original car- lighting plant, operated ping Wgt. 4 lbs. Each $14.50 propeller, waterfall, gas engine, or $1.50 ton. Ship. Wgt. 11 lbs. -24 VOLT VIBRATOR hand crank. Reduction gear allows HEAVY DUTY 6 -12 supplies NO 253. A husky vibrator ANIO4A BLADE ANTENNA full output at slow speed; army transmitter. NO. 264. Standard blade 6 volts at 2.45 amp., 425 volts at used on New. Add Rated 30 amperes at 6 Volts $1.50 antenna used on many mili- .115 amp. lbs. Each 220 cycle with contacts for tary fighting planes with postage for 28 $7.95 12 and 24 Volts, Synchronous coaxial connection at base. Handles for GN 58 S .50 each type, has many industrial ap- Shipping Wgt. 3 lbs Connecting cord for GNSB plications. Ship. BENDIX MT51C TRANSMITTER CONTROL BOX with plugs C01086 51.50 each Wgt. 3 lbs. Each NO. 235. Contains channel switch, COLLINS AUTOTUNE CONTROL HEAD 4 CHANNEL emission switch, send receive NO. 278. Brand new controls used switch, power witch and indicators on the ART /13, 100 Watt, Trans - PUSH BUTTON TUNER for Bendix aircraft trans- mitter. Types 7, 8, 10. and 11 avail- tuner from $5.50 NO. 254. Permeability mitters. Ship. Wgt. 3 lbs. able. Get a spare while available BC 728 containing RF, first detector, as new cost is over $22.00 each. 2 to 5 BC 670B REMOTE CONTROL BOX and oscillator coils. Covers MC. Shipping Wgt. 3 lbs. Price any type Complete circuit diagram furnished. NO. 265. Motor starting control box has starting and stopping (mention when Shipping Wgt. ordering). Each $4.50 2 lbs. Each $2.50 switch, indicator, cable and plug. Wooden case. Ship. MC 432 VHF ANTENNA LOADING UNIT CONDENSER SPECIAL Wgt. 6 lbs. Each $1.95 NO. 279. Contains 2 pole, 5 position 255. An ideal oil power BK 22 RELAY ASSEMBLY rotary switch with silver ceramic supply filter used in army 16 tube NO. 266. Used on SCR 269 variable cond , and coils for unit, has 2 5, 2.5 and 5 MFD all t Radio Compasses. Contains matching VHF Transmitter to AN109 600V D.C. rating. Shipping stepping and control relays antenna with 50 ohm line. Many Wgt. 3 lbs. Each $1 .50 - ¡unction box of aluminum. useful parts. Shipping AEROVOX Brand new. Ship. $3.95 Wgt. 2 lbs. Each $1.50 Wgt. 7 lbs. Each TELEVISION CONDENSER 148 OUTDOOR TELEGRAPH KEY NO. 280. Rugged enclosed type NO. 256. Aerovox Hyvol .05 MFD at HEINEMANN CIRCUIT BREAKER eh.for army 7500V. rating. Excellent television coup- NO. 267. Heavy duty type 7 Amp. outdoor use, built for to hard Com- ling cond with mounting bracket. 24 Volt D.C. Many uses around withstand useage. sho Shiping plete with cord and PI.55for plug. Shipping Wgt. Shipping Wgt. 3 lbs. Each $3.50 Wgt, 2 lbs. Each.. _. $1.00 $ 2 lbs. Each $2.00 CUTLER HAMMER 746 BC TUNING UNIT ONE KILOWATT ADJUSTABLE NO. 257. Plug in transmitter MOTOR FIELD CONTROL tuning unit from army Walkie NO. 285. Rated 10 ohms. 3.2 Amps. ANTENNA LOADING COIL Talkie Contains antenna and Maximum. 612" diameter with knob NO. 282. Huge porcelain coil 4" tank coils, tuning condenser, and mounting feet, can be used to diameter 81/4" long, has S transmitting and receiving crys- regulate generator output voltage. sliders for adjustments. Ship- tals. Ideal transmitter founda- Shipping. Wgt. ping Wgt. 5 lbs. tion. Wgt. 5 lbs. Each $2.50 Shipping 300 MA SELENIUM RECTIFIERS 1 lb. Each $1 .00 PENN THERMO RELAY NO. 209. Rated 300 MA at 36 (Same as above except trans- NO. 268. Thermo Relay with a mitter crystal in 80 meter ama- Volts, complete with mounting range of 45 to 100 complete brackets. Shipping teur bond 52.50 each) with 5 Ft. flexible cable to im- Wgt. 1 Ib. 3 FOR $1.00 MICROPHONE mersion bulb. Ship- T30 THROAT $3.50 DUAL NO. 258. Makes excellent contact ping Wgt. 6 lbs. SELENIUM RECTIFIER microphone for musical instru- B 8 W 11 to 14 MC TANK COIL ment or vibration pick -up. Ship- NO. 283. Two units mounted on NO. 281. Plug in type used on bracket, each section - Wgt. 1 lb. .. . $1.00 each single ping BC 610 Transmitter. New, original rated 15V. at 1/2 Amp. Shipping Extension cord with switch for cartons. Shipping Wgt. 1 lb. '- above S .50 each FOR Wgt. 2 lbs. Each $1.50 2 $1.00 PART HOW TO ORDER UNDER T$2. 0.,. WEWILLOSSTHIPEC.O.D. DEPT. C ... BENTÓN HAR¢B;OR, MICHIGAN 5:3 TEST EQUIPMENT wATHKIT FM and TELEVISION ew E E P G E THE BASIC FMNERATOR SERVICE INSTRUMENTTELEVISIOp¡ KIT Covers 7 - Tube * 2 M. to * 5 Circuii. * r62 226 Mer. cy transform Large calibrated * Supplies either * dial. Variable RF or FM..M * Variable phasing * Triable sweep Sweep control. width * outputput for APP. 10 Mc. * No bond cop switching necessary. * Uses new miniature At the HF tubes. lowest costost service FM possible, anyone and television can service sweep receivers. now generator T oscilloscope ea d coverso rt wif!t ncie A few all s Qu kit peasant since s °n' fir share organization the profits in position Every of the FM to part suppliedPPlied aV boom. two color - grey crackle calibrated panel, penche d, formed all metal plete detailed and plated. Parts instructions 5 coin. se. Shipping for assembly weight 6 lbs. and HEATHKIT HIGH FIDELITY AMPLIFIER KIT 3 -TUBE HEATHKIT ALL -WAVE RADIO I N T E R P H O N E Build this high fidelity 110 -volt AC operation 2-WAY CALL SYSTEM KIT amplifier and save two - An ideal way to learn $8.75 rodio. This kit is complete thirds of the cost. Push Ideal coil and com- pull output using 1619 ready to assemble,emble, with tubes (military type tubes and all other porte, J MANI munication system for 61.6'1). two amplifier Operates From AC. Simple, homes, offices, factories, stages using o dual clear detailed instructions nivr- stores, etc. Makes ex- triode (65N7), and o make this a good radio cellent electronic baby phase inverter give this training course. Covers reg - 1Ml watcher, easy to as- broadcasts and short amplifier a linear repro- ular semble with every part ten times wave bonds. Plug -in coils. duction equal to amplifiers selling for supplied including sim. this price. Every pan supplied; punched and formed Regenerative circuit. Oper. chassis, transformers (including quality output to ates loud speaker. ple instructions. Distance 3 -8 ohm voice coil), tubes, controls, and complete Add postage for 3 lbs. up to 1/5 mile. Oper- $14.50 instructions. Add postage for 20 lbs. ates from 110 V. A. C. HS 30 Headphones per set S 1.00 3 tubes, one master and one remote speaker. 12" PM speakers for above 56.95 2t'z" permanent 51 95 magnet loudspeaker Shipping Weight 5 pounds. NEW 1948 HEATHKIT 5" OSCILLOSCOPE KIT A sty for thenewer servicing technique in FM and television at a price you can afford The Heathkit is complete, beautiful two color panel, all metal parts punched, formed and plated and every port supplied A pleasant evening's work and you hove the most in teresting piece of laboratory equipment available. Check the features - large 5" SBPI tube, compensated vertical and horizontal amplifiers using 6517's, 15 cycle to 30 M cycle sweep gener- ator using 884 gas triode. 110V 60 cycle power transformer gives 1100 volts negative and 350 volts positive. Convenient size 8, 2" x 13" high, 17" deep, weight only 26 pounds. All controls on front panel with test voltage and ext. syn post. Complete with oll tubes and detailed instructions. Shipping weight 35 pounds. Order today while surplus tubes make the price possible. 110 V. A.C. TRANSMITTER 110 V. A.C. MILITARY RECEIVER POWER SUPPLY KIT POWER SUPPLY KIT For 8C -645, 223, 522, 274N's, etc. Ideal for powering military transmitters. Supplies 500 Ideal way to convert military sets. Sup- to 600 Volts at 150 to 200 MA plate, 6.3 at 4 Amps, 6.3 at 4 Amps and 12V at plies 24 Volts for filament - no wiring C.T. 4 Amps. Can be combined to supply 3 -6 -9- V. changes inside radio. Also supplies 250 12 or 24 Volts at 4 Amperes. Kit supplied D.C. plate voltage at 50 -60 MA. Connec- complete with husky 110V 60 cycle power 41114144._ tions direct to dynamotor input. Complete transformer, 5U4 rectifier, oil filled con - with all parts and detailed d , cased choke, punched chassis, and $ instructions. Ship. Wt., 6 lbs. 5.95 all other pans, including detailed instruc- $14.50 tions. Complete - nothing else to buy. DEPT. C .. e BENTON HARBOR, MICHIGAN NOVEMBER, I948 * Save 7,1 the cost. KIT * Gain valuable knowl- N IC SWITCH edge. E L E C T R O ANY SCOPE THE UTILITY OF * Achieve better work- ext manship. traces controllable two separately * Learn many new appli- on any scope. inputs traces, loco'.: cations. dividuol and output both the input See etc., immediately. Ideal training for use. phase shift, Bonin¢ * distortion, controls and po Individual gain rote cor - fine sweeping Heathkits are regular Coarse and control. matches otheformed factory quality test Complete Heathkit trots. are punched, equipment unassembled All metal parts tubes, 5 tubes, Complete with but with all forming, and cadmium plated. and insu,' blueprints punching, calibrating I parts, detailed lbs. and printing already Wt. 13 s. Shipping completed. thing si THE NEW HEATHKIT VACUUM TUBE VOLTMETER KIT The most essential tool a radio man can have, HEATHKIT now within the reach of his pocketbook. The Heath- kit VTVM is equal in quality to instruments selling CONDENSER CHECKER KIT for 575.00 or more. Features S00 m mp meter, transformer power supply, lob glass y enclosed di- A condenser checker anyone can afford vider resistors, ceramic selector switches, 11 meg- to n. Measures ow capacity and leakage ohms input resistance, linear AC and DC scale, 1000 from to MFD on calibrated electronic AC reading RMS. Circuit uses 6SN7 in scales test with voltage up to 500 volts. balanced bridge circuit, a 6H6 as AC rectifier and No need for tables or multipliers. Reads 6 x 5 as transformer power supply rectifier. In- resistance 500 ohms to 2 megohms. 110V cluded is means of calibrating without standards 60 cycle transformer operated complete Average assembly time less than four pl with rectifier and magic eye indicator tubes. hours and you have the most useful test instrument Easy quick $1950 assembly with clear de- you will ever own. Ronges 0 -3, 30, 100, 300, 1000 tailed blueprints and instructions. Small volts AC and DC. Ohmmeter has ranges of scale convenient size 9" 6" x 43,4 ". Weight 114é .[9 times 1, 100, 1000, 10M and 1 megohm, giving 4 pounds. This is the one of handiest range .1 ohm to 1000 megohms. Complete with instruments in any service shop. ELSE TO BUY detailed instructions. Add postage for 8 lbs. ELSE TO BUY HEATHKIT HEATHKIT SIGNAL GENERATOR KIT SIGNAL TRACER KIT Every shop needs a good signal gener- Reducesuce service time and greatly in- ator. The Heathkit fulfills every servic- creases proftsof any service shop. Uses ing need, fundamentals from 150 Kc. to crystal diode to follow signal from 30 megacycles with strong harmonics antenna to speaker. Locates faults ediately. Internal amplifier available over 100 megacycles covering the new for speaker testing and internal speaker television and FM bands. 110V 60 cycle available for amplifier testing. Connec- transformer operated power supply. tion for VTVM on panel allows visual tracing and gain measurements. Also 400 cycle audio available for 30% tests phonograph pickups, microphones, modulation or audio testing. Uses 6SN7 PA systems. etc. Frequency range to 200 as RF oscillator and audio amplifier. Com- Mc. Complete ready to assemble. 110V 60 cycle transformer operated. plete kit has every part necessary Supplied and de- with 3 tubes, diode probe. 2 color tailed blueprints and instructions enable panel. all other parts. Easy to assemble, $ detailed blueprints and instructions. 950 the builder to assemble it in a few hours. $1 qso portable Large easy Small 9" x 6" x 474 ". Wt. to read calibration. Con- 6 pounds. Ideal for taking on service NOTHING ELSE venient size 9" ,i 6 " calls. C.C. Weight 4'2 ELSE Complete your service shop with TO BUY pounds. its kicg TO BUY this instrument. HEATHKIT SINE AND SQUARE WAVE $3450 AUDIO GENERATOR KIT Shipping Wt., 13 lbs. The ideal companion instrument to the Heathkit Oscilloscope An Audio Gener- ator with less than 10o distortion, high calibration accuracy, covering 20 to 20,000 cycles. Circuit is highly stable resistance capacity tuned circuit. Five tubes are used, o 6517 and 61(6 in the oscillator circuit, o 6517 square wove clipper, a 6SN7 as a cathode follower output and 5Y3 os transformer power supply rectifier. The square wave is of excellent shape between 100 and 5.000 cycles giving adequate range for all studio, FM and television amplifier testing. Either sine or square wave vailable instantly at a toggle switch. Approxi- mately 25V of sine AC available at 50,000 ohm output impedance. Output + 1 db. from 20 to 20.000 cycles Nothing else to buy. All metal parts are punched, formed and cadmium plated. Complete with tubes, all pans, detailed blueprints and instructions. DEPT. C ... BENTON HARBOR, MICHIGAN RADIO -ELECTRONIC` fo Test Instruments .i ing, even though not a single resistor is changed! The amplifier, used on the lower ranges, also has negative feedback, achieved by leaving part of the cathode resistor unbypassed so that good fre- quency response is obtained throughout the audio range. A certain amount of high- frequency compensation is gotten by connecting a 20 -µµf condenser between the amplifier cathode and ground. Constructional details The layouts of the front panel and chassis are shown in the photographs. For the panel, a black crackle finish is used, lettered with white drawing ink. Where the panel is to be lettered, the paint is first smoothed with fine sand- paper, then moistened with saliva and allowed to dry. Layout of the chassis is not particu- larly critical, no more so than that of a microphone preamplifier. Main points are shielding the 6J7 -G, if one is used, and short leads from the hot input terminal and from the control grid of the first tube. The range switch should be covered with a grounded metal shield can. Warning: do not attempt to omit the power transformer and use an a.c: d.c. vC VOLTS 117V AC The chassis layout. Notice the shield covering the 6J7-G. RI and R7 are on strip at right. IDON TO VT VM GROUNDED SIDE OF LINE Fig. 2 -Setup for calibrating the voltmeter. circuit with a line -cord resistor. You can't hope for reliable readings if one side of the power line is connected to the chassis. Calibration Set R1 so that the meter reads a very small value, but not zero (say about .01 ma). Mark this point zero on the meter scale. A calibration setup will be needed. This can consist of a 100,000 -ohm po- tentiometer connected across the 117 - volt power line, with a reliable a.c. volt- meter between the arm and ground. Test with an incandescent lamp to make sure which is the grounded side of the line. The arrangement appears in Fig. 2. Be careful not to touch anything but the grounded leads. Before going further, adjust the values of R2 and R3 for the indicated B- voltage. Then set the arm of the calibra- tion potentiometer for 20 volts. Set the hum pickup and instability. v.t.v.m. range switch to the 20-volt po- Wiring under the chassis should be rigid and short to minimize sition. and adjust R4 for full -scale Set the range switch at 200 and adjust low- voltage ranges. meter deflection. Adjustments on this R5 and R6 so that the meter again reads This type of meter gives readings de- and other fixed resistors can be made 10. pending upon the peak value, although either by substituting other resistors or, The remaining scale can be calibrated the scale is calibrated to read r.m.s. or if the resistor is an uninsulated carbon by setting the range switch, feeding in effective values. The presence of even type, filing it down to obtain higher re- the proper voltage, and adjusting the harmonics can be detected by reversing sistance. The scale can be calibrated 6- megohm resistor on the 0.8 -volt range the input leads to the v.t.v.m. If there is now by varying the input voltage and and the 38- megohm resistor on the 4- a difference in the readings, second marking in the various values on the volt range for full -scale meter reading. harmonic is probably present. Inade- meter. The 0.2 -volt range should be calibrated quate shielding of the supply may also Next set the test voltage at 10 and first by setting R7. R7 should be left cause hum to be picked up with one make sure the v.t.v.m. reads properly. alone while calibrating the other two polarity but not with the other. NOVEMBER. 1948 50I Test Instruments Sensitive Vacuum -Tube Voltmeter A practical instrument which uses an extra amplifier tube for the lower-voltage ranges By JOHN W. STRAEDE* Just one control, the range switch, appears on panel ANY voltage measurement that only and must be well designed to take proximately from 25 to 20,000 cycles. can be made by a v.t.v.m. can care of frequency response, tube aging. At the low- frequency end the response be made by some other means, and variations in B- voltage. A follow- is down about 2 db at 10 cycles. It drops but a tube makes a very port- ing amplifier must be direct- coupled off below this at about 6 db per octave able, convenient, stable, cheap and ver- and must have a current bucking device on the higher -voltage ranges. On the satile device. to correct for drift. lower- voltage ranges the response drops Vacuum -tube voltmeters are used to Chief advantages of the meter de- off below 25 cycles. measure voltages: (a) from a high -im- scribed in this article are: (1) independ- The response in the r.f. range de- pedance source. (b) that are very small, ence of supply voltage (20': change pends on care in layout. Poor layout re- (c) of very high frequency, and (d) gives no detectable difference in reading quires excessive shielding, resulting in whose wave form is unknown -or un- at the center of each scale and only poor response. With good layout, the usual. Voltages in class (a) can be slight changes at the ends) ; (2) good meter still works (though well down) measured by certain types of electro- linearity of scale and the same linearity in the r.f. range. static voltmeters which contain no re- on each range, so that only one scale is This particular meter was designed sistance across the input, but it's easier required; (3) separate sensitivity ad- for checking phonograph pickups and and cheaper to use a buffer amplifier justment on each range, so that the for general audio -frequency amplifier with a special tube requiring no grid meter can be adjusted at intervals to testing. Lowest range is 0.2 volt, full leak and to follow it with an ordinary be "dead accurate "; (4) an input re- scale, and highest is 200. The basic cir- meter. sistance higher than 1 megohm per volt, cuit, that of the triode in Fig. 1, is a Very minute voltages can be meas- except on the higher -voltage ranges plate detector with complete negative ured with an Einthoven string gal- where it is desirable to avoid special feedback, obtained by having all the load vanometer or by a potentiometer, hut high -value resistors; (5) good fre- in the cathode circuit. Plenty of feed- again it's easier to amplify the small quency response over the audio range; back means stability and constancy of voltage and bring it into a higher range. and (6) no false reading if the input is calibration, with consequent freedom High -frequency voltages can be meas- shorted -d.c. continuity or otherwise of from troubles due to B- supply variation. ured with rectifier -type or thermocouple the source of the voltage being meas- So self- adjusting is this circuit that re- meters if special compensation networks ured does not affect the reading. placement of the triode by a pentode are used, but the effective ohms per volt The useful frequency range is ap- has only a negligible effect on the read- are rather low. No matter what the wave form, it is 6J7-G /6SJ7 R5 9MEG R6 2MEG possible to devise a v.t.v.m. will that MATV477 6C5 /6J5 6X5- GT measure peak, average, or r.m.s. value, 260 (- 3 5 whichever is desired. .25 350V o 20V -1 Any detector circuit can be used as a 2MEG 5 --. 350v o 111 V AC v.t.v.m. There are three types of detec- 4V 36MEG tors: the grid -leak (very sensitive for .6V 6 low 6MEG 6.3V input voltages); the anode -bend 0-1 MA q loo with feedback (very linear but compara- .2V IN tively insensitive) ; and combinations of these with an amplifier preceding or Q I t- RI 40 following. I I 2op>r 250K 501( I R4 K The preceding amplifier usually I makes the instrument suitable for a.c. I50K Lecturer in electronier and electro- acoustics, Melbourne Techntrnl College. Australia. Fig. I -Pin numbers of detecto tube refer to 6J7 -G only. RI is the zero -adju tment control. RADIO -ELECTRONICS for -19 MONEY BACK GUARANTEE- We believe units offered for sole by mail order should be sold only on a "Money- Back -If -Not- Satisfied" basis. We carefully check the design, calibration and value of all items advertised by us and unhesitatingly offer all merchandise subject to a return for credit or i refund. You, the customer, are the sole judge as to value of the item or items you have purchased. BUILD YOUR OWN SIGNAL TRACER and SAVE!! The Only Signal Tracer in the Low Price Range Including BOTH METER AND SPEAKER!! We are pleased to announce we have obtained an exclusive franchise to distribute the well known Model CA -12 Signal Tracer in kit form. The Model ('A -12 sells regularly for $29.95, here is your opportunity to save $8.00 with the added advantage of com- plete familiarity of design and operation made possible when you build your own in- strument. FEATURES: * Comparative intensity of the signal is read directly on the meter -quality of the signal is heard in the speaker. * Simple to operate only one connecting cable - -no tuning controls. * Highly sensitive -uses an improved vacuum -tube voltmeter circuit. * Tube and re- sistor capacity network are built into the detector probe. * Built -in k high gain amplifier- Alnico V speaker. * Completely portable- weicrl 71 8 pounds- measures 5!(_" x tit," x 9 ". THE. MODE1. CA -12 KIT COMES 195 COMPLETELY ASSEMBLED MODEL CA -12 Kit includes ALL PARTS a --I mbled and ready Can he wired in 311 minutes. Components am' circuit guaranteed lo meet the follow- for wiring. circuit diagram and detailed opcl.Iling data for the ing: rntulllttcd in- Irunlcni ...... $21.95 MODEL CA -12 COMPLETELY WIRED READY TO OPERATE $29.95 THE NEW MODEL 670 The New Model 770 - An Accurate Pocket -Size SUPER METER VOLT-OHM MILLIAMMETER (Sensitivity: 10(10 ohms per volt) SUPER METER. A Combination Features: VOLT - OHM - MILLIAMMETER Compact- mensures 3t,ß" x 7Tg" v. 2'4" plus CAPACITY REACTANCE. Uses latest INDUCTANCE a n d DECIBEL design 2 accurate 1 Mil. \SUREMENTS. D'Arsonval type meter. Same zero ad- ME justment holds for both resistance ranges. 0.r. VOLTS: n to 5'15 75 150.7511/ It is not necessary to readjust when A.C. VOLTS: 1- OUTPUT 'witching from one resistance range to enotiser. This is on important timesav- Ui II Illl NI ing feature never before included in a RESISTANCE: V.O.M. in this price range. Housed in .Lm,. o Ili .tl.do0w -. CA round- cornered, molded ease. Beautiful PA: I IV: .001 to .2 'alti.. .1 to 1 \h black etched panel. Depressed letters X11. Irst for cicrtn'Iyiles.I REACT- ANCE: Ton to ii7.I100 Ohms: 13.00o (hul- filled with permanent white, insures long- lo 3 Slegnhnms. life even with constant use Specifications: 6 INDUCTANCE: 1.75 to 70 Henries; 35 A.C. VOLTAGE RANGES: n- 15m 1701 3011 1500 311110 sons. 6 D.C. VOLTAGE RANGES: n71í /1.5;75/ I ,: Ott 10 to +18, +10 to +38, 150 - 1 Caiii udle, 4 D.C. CURRENT RANGES: 0- 1!4/15 /I50 The model 670 comes housed in a rugged, \Id, a -11- Atop, crackle-finished steel cab- 2 RESISTANCE RANGES: 0 -500 ohms. 0 -1 inet card with test 5111 col leads and operating in-eat The Model 770 comes complete structions. Sire 51/a" x $2840 with self -contained batteries, NET 39NET0 71.4" x 3 ". test leads and all Operating $' Instructions. The Model S -35 - a POWERFUL The Model 88 - A COMBINATION SIGNAL GENERATOR REFLEX PROJECTOR AND COMPLETE WITH WESTERN ELECTRIC BUILT -IN DRIVER UNIT SIGNAL TRACER ',Etta! Generator Specifications: I. 1.1. RATED 35 N'I1.1. EASILY CONSERVA';\ AT wA'r'rs- frequency HANDLE l P TO 55 WATTS WITHOUT BLASTING Range: 150 Kilo- des to 50 Megacycles. *The Ileavy gauge alumiomu iii the main trumpet sertion completely eliminates blast- S.F.. Signal Frequency is kept I ing and blaring. New plastic diaphragm s the 1 aul peak. of the completely constant at all out- old type; also It is absolutely impervious to t atmospheric s changes whereas the old type was subject to at ulospherie core put levels. Modulation is ac- melon. Complete unit unnsiditiooall complished by Grid -blocking ac- guaranteed for mie year. tion which is equally effective for alignment of amplitude and Specifications frequency modulation as well as POWER (CONSERVATIVE) -35 for television receivers. R.F. ob- WATTS: AIR COLUMN -31', FT.: tainable separately or modu- DISPERSION -80 °: POWER (PEAK) lated by the Audio Frequency. -55 WATTS: BELL DIAMETER - Signal Tracer Specifications: IMPEDANCE ohms: FRE- -15'; -8 'Uses the S 5Ieania TN:1 te r. QUENCY RANGE -130 to 5000 maid tool ry -ia1 Diode w Meln - C.P.S. PROJECTION mile: bbed WWI a IcstStancecdpaeiry pen - - vmk provides fro FINISH Attractive gat'lle)' r Inge of 31111 two tone crystalline. cycles to 50 Slegaf1'rlrs. /t O The Model S -35 Comes S with The Model 88 comes complete with all test leads and operating L ]Y( Complete Built-in r r Diver Unit ONLY NET instructions. ONLY OJ 20'. DEPOSIT REQUIRED ON ALL C.O.D. ORDERS PARK PLÑC. GENERAL ELECTRONIC DISTRIBUTING CO. NEW YORKl79ß NOVEMBER, 1948 48I Television qe9 &utd 7ee6oa4et A companion to last month's preamplifier By I. QUEEN The preamplifier has two provement requires a better location or position for cutting out the preamps en- tubes and two controls. a more efficient antenna. tirely would be a good idea. To prevent Only one booster may be sufficient in long leads under the chassis (these will but it is possible reduce amplification and cause instabil- LIKE the booster described in the a particular location. that both high and low hands will re- -1 October issue,the one diagrammed booster and r LF PREAMPlI quire amplification. This -0 RCVR is based on the cascode circuit, I NOPREAMPO2 in October can be com- using two tubes in a novel circuit the one described same FPREAMP Fig. It. bined into a single unit on the arrangement (See 1). oper- same power supply. ates on the h.f. television band. chassis and with the -band unit included a pow- Both the input circuit and the output Since the low er supply, all that is necessary is to OUT POWER LEADS OUT circuit are tuned. L1 and L2, made of the high -hand unit to the same HF PREAMP LF PREAMP heavy wire, are self -supporting. Each is connect supply. As a matter of fact. this am- IN IN formed of 11.. % inch in diameter. turns plifier was built on half of the same A spac- L_ little experimenting with turns sawed -in -two chassis. ing will be needed to tune over the band. Even the simplest switching arrange- With four -plate midget tuning condens- ment within either preamplifier will in- o- 1 ers, channel 13 comes in near minimum troduce long leads and add too much capacitance. Channel 7 requires about capacitance. When combining the two ANT two -thirds maximum capacitance. The on one chassis, switch 300 - preamps the Fig. 2- Proposed low -high switching circuit. tuning controls track closely. ohm lines from the antenna and to the Input and output coupling coils, L3 receiver. Construct each amplifier as a ity), use a long switch shaft and posi- and L4, are also self- supporting and are complete unit (except for power sup- tion the switch gangs close to the ter- made of push -back wire. Each has 11.E ply) and use a rotary selector switch to minal points. The switching diagram of turns. Maximum gain is provided by transfer input and output transmission Fig. 2 gives a suggested arrangement. coupling as tightly as possible to the lines from one to the other. A center Use low- loss -type switch wafers. tank coils. Choke L5 is made of four turns % inch in diameter. L6 is 6 turns of wire and 1/a inch in diameter. Use No. 18 to 22 enameled wire. The booster has been tried on chan- nels 7, 11, and 13. Using the conven- tional signal- strength scale, it raises the signal about 2 S- points. Gain is slightly less near the upper end of the band than it is on channel 7. Unless the noise level is already too high, this booster will bring in a clearly visible (though weak) picture where the receiver alone tunes in one which is practically invisible. When added to an average TV set which has an r.f. stage, the booster pro- vides as much gain as can be used in most cases. This is because the noise level is also brought up. Further im- 6AK5 6J6 Z=3000. 5 I 2 6 5 L3 LI I 6 r L2 E4 Yf 2.300A CI 13+ 120Y C- 4 PLATE MIDGET C I- I7Snuf BUTTON TYPE Fig. I -Unit is a cascode with double tuning. Underchassis view. Parts layout and manner of winding coils can be seen from the photograph. RADIO- ELECTRONICS for 17 Capitol Radio Engineering Institute - Pioneer in Radio Engineering Instruction Since 1927 Chief Engineers, Studio Engineers, Transmitter Engineers for more than As of Sept. 1948: 618 FM stations on the air. 818 FM stations with construction permits and conditional grants. Yes, Plenty of Good - Paying Jobs... BUT Only for those Qualified FM is actually corning into its own in \\'hat does this mean to you It means 194849 . . more than 111111 FM stations ou must study not only to hold the job with permits and grants now on the air, you now occupy ... but study to qualify or soon to be. Over 1700 standard broad- for the better job you want. CREI modern more cast stations now in operation -1200 technical training can (within a compara- applica- with construction permits and tively short time) qualify you for the bet- tions. Television receivers are on muss help enable you to step ahead production lines. Hundreds of new TV ter jobs and MAIL COUPON TODAY have to improve their stations will he going on the air -over a of those who failed FOR THIS 24 -PAGE hundred ronstruct permits now issued ability through technical training. FREE BOOKLET! -over 300 TV applications now at the Beginning right now CREI can provide FCC. the on- the -job training that equips you t Radio -electronics is not only expanding with the technical ability to go after -and in job opportunities but it is also growing GET -the important, high salaried jobs. Capitol Radio Engineering Institute in technical complexity. Rapid develop- Get all the facts today about the unprece- 16th and Pork Road, N. W., Dept. RC-li ments in every branch of the field are dented opportunities that await you. Learn Washington 10, D. C. leaving many radio technicians and en- spare training can help Gentlemen: Please send me your free gineers far behind the parade of progress. how CREI time booklet. "CREI training for your These are the men who fail to realize that you as it has helped thousands of other better job in RADIO- ELECTRON- radiomen advance to better ICS." together with full details of their technical knowledge must grow with professional your Home Study training. I am at- the expans. rnf tile indu -tr. .fobs during the past twenty years. taching a brief resume of my experi- BILL ence. education and present. position. VETERANS! CREI TRAINING AVAILABLE UNDER THE "G. I." Check One Course: Practical Television Practical Radio -Electronics Name Capitol Radio Street City Engineering Institute An Technical Institute Tone . State..___...... _..._..._ Accredited I am entitled to training under RC -11, 16th and Park Road, N. W., Washington 10, D. C. the G. I. Bill. Dept. San Francisco 2 : 760 Market SI. Brrut,h UjJirc.c: New York 7 : 170 Broadway NOVEMBER, 1 9 4 8 461 Television very much like shunt-peaked circuits but ground. If the output capacitance is Fig. 8 shows the series -shunt peak- they have sharper cutoff. The voltage larger than the input capacitance, R1 ing network used in the RCA 641TV. developed across RL is applied across will normally be connected to the grid The 22,000 -ohm resistor across L2 flat- the grid leak of the following stage, Rg, (low -capacitance) end of L, as in Fig. tens the response peak that may be due and C2. Since Rg is large, the series 6. If Cc has a large capacitance to to improper ratio of Cl to C2 or to dis- ground, this will add to the input capac- tributed capacitance of L2. Ignoring the itance and C2 may be larger than Cl. wiring capacitance, Cl is the output A L 1 Cc capacitance of the 6AU6 and C2 is the .1. L2 IaOyN 8K8 RL TC ?C2 input capacitance of the 6K6 -G. 9 is a schematic of 1 Fig. partial the .05 1 I Rg iconoscope preamplifier used in the 6+ Navy ATK airborne television trans- C2=2xCI mitter. The output of the iconoscope 4-O LI 9304 1.2 EG 330 Fig. 5 -Basie diagram. series peaking circuit. consists of signals ranging from about 20 cycles to 4 mc or higher at a very resonant circuit, L and C2, works as a 3.3K 10 e20K low level. This signal appears across the 470,000 -ohm input resistor of the 1649. reactive voltage divider. The voltage -18v across C2 -and Rg -rises as the reso- -2V 6.aK The input capacitance of the 1649 nant frequency is approached. (The value a+275V shunts the resistor and reduces the sig- of L is chosen so the resonant frequency 6 +135V nal level at high frequencies. Ll and is outside the high -frequency cutoff Fig. 8- Commercial series -shun+ high peaker. L2 constitute a series -shunt peaking cir- point of the amplifier.) This compen- cuit with all reactances negligible up to sates for losses caused by Cl shunting Check this by moving Cc to the plate 1 me. The load impedance of V1 is the RL. Cl and C2 are portions of the shunt end of L (A in Fig. 5). It is even worth 2,700 -ohm resistor. Above 1 mc, the ris- capacitance between the stages. The while to try turning Cc end -for -end. ing reactances of Ll and L2 in combina- In Figs. 5 and 6: tion with the shunt capacitane -' boost the gain gradually to 4 mc. This com- L Cc 1.5 pensates for some of the losses at the J. RL - TC1 C2 RL input of Vl. The 22,000 -resistor across V6.28 X f X C Rt and L = 0.67 X C X RL 5+ where L is in henries, C in farads and 1 2 3 4 15 1 2 3 4 5 6 7 5 7 Fig. 6 -The value of CI is twice that of C2. f in cycles. Best results can be obtained Fig. 10 (left) -The ideal VI -to -V2 esponse. by winding L on a form with a variable Fig. 11 (right)- Response of the high peaker. shunt capacitance, Cs, powdered -iron core. The core can be ad- i array) divided by C is into Cl and (" L. justed for the best high -frequency re- L2 controls its Q and assists in obtain- The major disadvantage of series peak- sponse. Series- peaked circuits cut off ing the desired response. Fig. 10 shows ing is that there should be a 2 to 1 sharply, so the further f is from the optimum response between the grid of ratio between the capacitance of Cl and cutoff frequency, the flatter the fre- VI and the plate of V2. C2. This is not always easy to realize quency response curve. In some in- The "high- peaker" between V2 and in practice. The circuits work best when stances, it may be necessary to shunt L V3 completes the restoration of highs RL is on the low- capacitance side of the with a resistor about 5 to 10 times RL lost at the input of V1. The degree of network. In Fig. 5, RL is connected di- to flatten the response. peaking and the point at which it oc- rectly to the plate of the tube so C2 Series -shunt peaking is, as the name curs may be varied by adjusting C2. must be made equal to 2C1. implies, a combination of both compen- Fig. 11 is the response curve between It is difficult to balance the shunt capacitance properly and the positions ICONOSCOPE 1649 16 49 of in be L2 the components the circuit must NI PEAKER found by A good 'scope experiment. and v3 a square -wave generator are required I for this. Connect the 'scope to the out- 560K I put of the generator, feed in a 400 -cycle square wave and observe the wave shape ----1 6.5-3 410a on the 'scope. Adjust the generator and 2.7K 'scope controls until a good square wave is obtained. Now connect the generator to the input of the amplifier and the 5 +4005 ` ).8.4-4005 10 j33K 'scope to its output. If the leading edges are badly rounded, try altering the po- 5 +318V sitions of RL, L and Cc. Position the N0n:- 164915 A SPECIAL NON- NICROPHONIC SAC? components for the best possible wave shape -giving particular attention to Fig. 9 -Navy ATK airborne transmitter uses an R -C high peaker and L -C stage compensators. the edges. sation methods. The basic circuit is the grid of V2 and the plate of V3. Even in the most carefully planned shown in Fig. 7. Here, Ll corresponds The compensating system employed circuits, Cc, the coupling will capacitor, to L in Figs. 1 and 2 and L2 corresponds depends largely on the desired gain and add considerably to the stray capac- to L in Figs. 5 and 6. In this circuit, permissible phase shift at the highest itance. If it is paper, the major capac- the 2 to 1 ratio of Cl and C2 should f. In an between frequency, uncompensated itance will be the outer foil and be maintained. In this case, LI and RL amplifier, gain at f is 70.7': of the gain may have large capacitance to ground at mid -band. With shunt peaking, the L2 and it may be necessary to connect the response at f is equal to the response shunt peaking network at A on the at mid -band. With series and series - CI C21. Cc plate side of L2. In Fig. 7: shunt compensating methods, the rela- tive gains are 150'; and 180',5 when 1 I - L I Rt RL = 1.8/6.28 X fC, compared to the gain at mid -band. is RL If phase shift important series 6+ L1-0.12X RL- XCs peaking is the most desirable system to Fig. 7- Combination series and shunt peaking. and L2=0.52XRL`XCs. use. RADIO -ELECTRONICS for -15 ALLIED'S NEW 1949 RADIO CATALOG 180 VALUE -PACKED PAGES ,Seemd 01 a ocoad WORLD'S LARGEST STOCKS The Preferred Radio Buying Guide Everything in radio for everyone In radio! ALLIED's huge stocks are the It's ready for you -the new 1949 ALLIED Radio Catalog! world's largest, including complete Get the Radio Buying Guide that's the first choice of thou- lines of oll leading makes of parts sands of expert service technicians, engineers, soundmen, and equipment. Get everything you need from one dependable central- Amateurs, builders and experimenters. The new ALLIED ised source- ALLIED RADIO! Catalog- Radio's largest and most complete- brings you 180 pages packed with the widest selections of the newest TELEVISION & HOME RADIOS and finest equipment, at today's lowest, money- saving prices! 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Get receivers, transmitters, parts, station the of radio's most liberal Time Payment Plan. equipment -the biggest and most details, too, complete listings in Ham radio! Write today for your FREE copy of ALLIED's newest and greatest Catalog -the preferred Radio Buying Guide! NEW SOUND EQUIPMENT Packaged, ready -to -use Sound Sys- QUICK, EXPERT SERVICE tems; amplifiers guaranteed for one LARGEST STOCKS full year; high -fidelity sound corn ponents; everything in speakers, mikes, P. A. accessories, intercom Send for your FREE copy of and recording equipment -head- Radio's Most Complete Catalog. quarters for Soundmeni Radio's Leading Use the coupon below - NOW! Buying Guide.... ALLIED RADIO CORP. 833 W. Jackson Blvd., Dept. 2 -L 8 THE WORLD'S Chicago 7, Illinois LARGEST 0 Send FREE New 19.19 ALLIED Catalog. RAD/0 Name SUPPLY Address HOUSE... City Zone State. NOVEMBER. 1948 Television Compensating TV Amplifiers Special circuits bring up h.f. response By ROBERT F. SCOTT VIDEO amplifiers are resistance- Fig. 1. The inductance and shunt capac- shunt capacitance present use the coupled amplifiers with special itance, Cs, form a parallel tuned circuit, formula compensating circuits added to Fig. 2, resonant at some frequency out- increase the over -all band -width. side the high- frequency limit of the am- 1 These amplifiers are commonly used in Cs - television, radar, special oscilloscope 6.28 X f X Req circuits, and in numerous other applica- where tions. It was shown in "Wide -Band Am- plifiers" (RADto- CRAFT, March, 1948) RL X Rp X Rg that high- frequency response is limited Reg- by the wiring and interelectrode capaci- RL x Rg + RL x Rp + Rp x 11; tances shunting the output impedance of the tube. In "High- Fidelity Ampli- The wiring capacitance can be found by fiers" (RADIO -CRAFT, May, 1948) we subtracting the sum of the input and output found that high- frequency response can Fig. I -L and Cs are parallel tuned circuit. capacitances of the tubes and the be increased -at the expense of gain - input capacitance of the v.t.v.m. from by decreasing the size of the plate load plifier. The resonant frequency should the measured shunt capacitance. or coupling resistor. The gain at high be approximately 1.41 times the h.f. cut- These measurements are made on an frequencies is equal to off frequency for best compromise be- uncompensated amplifier. If peaking in- tween linear amplitude, linear phase re- ductors are added later, their capac- Gif sponse, and voltage. In an amplifier using shunt peaking, RL is made equal to the reactance of V1 4- (Req /Xcs)' the shunt capacitance, Cs, at cutoff fre- where Gif = gmReq, Xcs is total shunt quency or capacitive reactance and 1 RL X Rp X Rg RL = Req = V6.28 x f X Cs RLXRg -4- RLxRp- -Rg +Rp where f is the cutoff frequency in cycles If Rp (the internal plate resistance and Cs is the total shunt capacitance in of the tube) and Rg are many times farads. Input and output capacitances Fig. 3- V.t.v.m measures shunt capacitance. larger than RL -as they should be for can be taken from a tube manual and itance to ground will add to the stray good h.f. response -RL will be approxi- wiring capacitance can be measured or capacitance and make previous calcula- mately equal to Req. High -frequency re- estimated depending on the accuracy de- tions useless. If exact measurements are sponse varies inversely as the shunt sired. The stray wiring capacitance av- desired, connect a single pie of a small capacitance and RL and directly as gm. erages between 10 and 15 1gtf in a well- r.f. choke in the exact place where the peaking coil is to be mounted. Be sure Table I to short -circuit the pie before beginning gm Figure of the Tube imicromhos) Merit measurements. 6AK5 5100 750 The value of the necessary peaking 6AG5 5000 602 inductance can be found from 6AC7/1852 9000 562 6AC7 11,000 536 CXRI) EF -50 6300 484 L = 6AB7/1853 5000 385 Fig 2- Equivalent circuit of that in Fig. I. 2 807 6000 333 25L6 9500 322 designed video amplifier that has been Fig. 4 shows the shunt peaking con- 65H7 4900 316 carefully laid out. stants used in a video amplifier with 6Y6 7100 308 To measure the total shunt capaci- high -frequency response flat to 2.5 mc. 6AK6 2300 308 tance, connect a wide -range oscillator The inductances are wound on forms 6L6 6000 272 and v.t.v.m. to amplifier as shown in with adjustable powdered -iron cores. 6ÁQ5 4100 216 Fig. 3. Set the oscillator to about 1,200 813 3750 123 cycles and adjust the output to about 10 The advantage of one tube over an- volts or some convenient value. Measure other can be determined by dividing the the output of the amplifier. Increase the transconductance, gm, by the sum of the frequency -keeping the output of the input and output capacitances of the oscillator constant -until the output of tube. The resultant is called the figure the amplifier drops to 70.7'; of its value of merit. Table I shows the figure of at 1,200 cycles. When the output of the merit and gm of a number of tubes suit- amplifier has dropped to this level, the able for video amplifiers. shunt reactance equals the resistance One of the simplest methods of com- formed when the internal plate re- Fig. 4- Peaker gives flat response fo 2.5 mc. pensating for the effects of shunt reac- sistance, the coupling resistance and the Figs. 5 and 6 show circuits for series tance is to insert an inductance L in grid resistance are considered in par- peaking to compensate for high -fre- series with the load resistor RL as in allel. In order to calculate the total quency losses. These circuits function RADIO -ELECTRONICS for Television a 10 -inch set when the station changes from one sync generator to another, or from a local to a relay program. (2) The line voltage at the receiver may change. This changes the deflection voltages and high voltages, both of which affect the picture size. (For this reason also, a TV set that is adjusted in the service shop for correct size may be found to have a smaller or larger pic- ture on the owner's power supply.) (3) There may be some drift in the picture size or centering during the first hour of operation. For these and other reasons, experi- ence has taught that it is a practical necessity to make the picture extend slightly beyond the mask. The test pattern should be designed with this in mind. For example, if the pattern has small circles or other infor- mation too close to the corners, it may cause unnecessary headaches for the technician, because when the picture is made larger than the mask, the designs in the corner may be partly hidden. Some TV owners want to know why. The two arcs of circles in the NBC pattern (Fig. 1) are an aid in adjusting horizontal centering. The main black Fig. 2 -With this monoscope pattern fhe edges of screen can be checked as well as center. circle is used in adjusting vertical cen- tering. provide additional wedges in the corners black; and with contrast too low, the The television controls the in- to show whether the focus is good on the lighter greys become washed out. signal are too tensity of the electron beam in the kine- sides and top and bottom, compared with If brightness and contrast set scope. This beam produces a fluorescent the center. high, the definition will suffer, owing kinescope spot. spot of light on the inner face of the If focus is not reasonably uniform to "blooming" of the kinescope. It is this spot that "paints" over the entire picture, it may indicate When the spot is too bright, it grows the picture. need for repositioning of the ion -trap larger, and best definition depends on a For good definition or resolution, or magnet, or the focusing coil and focus- small spot. ability to make very small details evi- ing control. Instead of shading blocks, some test dent and distinct in the picture, the spot If the test pattern does not have patterns have a section of light grey must be small and round. It should be wedges in the corners, the horizontal scanning lines can be observed to check 1111111) small enough so that the horizontal line mum 1111111 structure can be seen distinctly, and it focus over the entire screen. NIEI11 should be round in order to get the best When focus must be adjusted on a EEEENN =EIE1N11 without the help of a test pat NNEE EINI11 definition from top to bottom and from program, MUMMYNEE 11EIEIENIliI to tern, it is generally satisfactory to ad- soon I10111ZONTALLV a000 N011 ZGITALLV COOO V NTICALLY left right. /OM VIA CALLV ANO VERTICALLY POOR I0111ZONTALLY If the spot is slightly elliptical or oval just for the finest scanning lines near (>ITACTOIEO AT Tat') (3TAITCIIIO AT LW) the center of the picture. shaped, instead of round, it may be ro- Fig. 3 -Grid pattern is good linearity check tated by adjusting the focus control, as In projection receivers, there is the described below. usual electrical focus control for the background with white lettering, and a The vertical and horizontal wedges kinescope, and the mechanical focusing section of darker grey background with are used in adjusting focus; they pro- adjustments for the optical system. To black lettering. This serves the same vide a check on the shape of the spot. prevent confusion, and to get the best purpose as the shading blocks, and is Closely examine the separate lines to- possible pictures, it is important to ad- more fool -proof, because few persons ward the narrow end of the vertical just the electrical focus first while look- are aware of the significance of the wedge, and adjust the focus control so ing at the kinescope, or at the reflection shading blocks. these lines are in best focus, or sharpest. of the kinescope in the spherical mirror. Many test patterns are designed with Then look at the lines toward the nar- The optical system should not be touched a grey background to secure an. average on row end of the horizontal wedge, and until the test pattern as seen the modulation of 50r; . This reduces the see if a slight readjustment of focus kinescope is sharp and clear. need for readjusting brightness and improves the focus on these lines. If the test pattern has crossed lines contrast when the station switches from If best focus on both the vertical and in the corners and in the center of each the test pattern to an average program. horizontal wedges is obtained at the side, and in the center of the top and The horizontal wedges show lack of same setting of the focus control, it may bottom, they are very helpful in adjust- interlacing by a moire pattern, or wavy be assumed that the spot is round. ing the reflective optical systems that effect, toward the narrow end of the If the setting for best focus is slightly are used in some projection receivers. horizontal wedges. A moire pattern is different for the two wedges, it indicates somewhat similar to the effect that is that the spot is oval. In this case it is Contrast and brightness seen when looking through two pieces of generally preferable to adjust the con- Almost all test patterns include 'some window screening, or at a piece of satin. trol for best focus on the vertical wedge. form of shading blocks to assist in ad- The appearance of poor interlacing In most test patterns, the narrow ends justing contrast and brightness. can usually be duplicated by turning the of the wedges are intentionally placed The shading blocks have at least five vertical -hold control slowly until the pic- near the center of the test pattern. By shades: black, dark grey, medium grey, ture is just beginning to move down. focusing here, it ensures that the picture light grey, and white. The contrast and At this point the moire effect will be will be in best focus at the center, which brightness should be adjusted so that seen on the horizontal wedges. Also the is desirable. each shade is distinguishable. With con- horizontal scanning lines, instead of in- Some test patterns, such as Fig. 2, trast too high, the darker greys become terlacing, will lay over each other. NOVEMBER, 1948 Television Using TV Test Patterns By JOHN R. MEAGHER Reprinted from RCA Radio Service News. RCA Tube Department, Harrison, N. J. WHEN something goes wrong controls for height and vertical linearity linearity on all stations in the area. But in a television receiver. it should be adjusted so that: it is preferable to select the station that generally shows up as a defi- (1) The circles in the test pattern are is most likely to have correct linearity, nite symptom in the picture. as round as possible, and and adjust the receiver on this stat.on, In no other type of electronic equipment (2) The test pattern is slightly larger because in time the other stations will are the troubles and symptoms so clear- than the mask appearing in front of the correct their nonlinearity. ly displayed before our eyes. kinescope. Frequently, it is necessary to install If we learn to recognize these visible If linearity is not correct, the circles and adjust TV receivers at night or symptoms, we can quickly localize the will be flattened or egg- shaped. when there are regular programs, but trouble to a particular portion of the In judging vertical linearity, it helps no test patterns on the air. In such set. Even the complete absence of pic- if you lay your head on your shoulder cases, it is possible to use a "bar gener- ture and raster tells us to suspect cer- and look sideways at the picture. This ator" which produces a number of ver- tain definite parts. makes vertical nonlinearity more ap- tical and horizontal bars on the picture. There is no standard test pattern in parent. These bars are "synchronized" by the general use. The nearest thing to a Many TV owners are extremely fussy sync pulses so that the bars remain sta- standard is the RCA "Indian head" about having the circles exactly round. tionary on the picture. The set is then monoscope, which is used by a number Some of them check the circles by hold- adjusted for equal spacing between the of TV stations. RMA has proposed a ing a small plate in front of the screen, bars. standard "resolution chart," but for var- and others measure the wedges to see if A very useful hint for checking and ious reasons it has not been adopted by they are equal lengths. In some TV adjusting vertical linearity when there TV stations for air use. areas, this makes life extremely difficult are only programs and no test patterns Many TV stations have designed their for the television technicians, because it on the air, is to turn the vertical hold own test patterns, which, although dif- is an unfortunate fact that some sta- control so the picture keeps rolling slow- fering in appearance, are all intended tions do not transmit good linearity. ly from top to bottom. If the vertical to facilitate adjustments and checks in Also, the linearity may be different from linearity is good, the black vertical - both the transmitting equipment and in one camera to another. In one particular blanking bar will remain the same thick- the receivers. city, if the receiver is adjusted so the ness in all positions from the top to the Two typical test patterns, the NBC test- pattern circle is round on the first bottom. There is no similar easy way to and the RCA Indian head. are shown in station, the second station will he egg - check horizontal linearity. Figs. 1 and 2. The various elements are shaped vertically, and the third station In a few test patterns, all circles are named in Fig. 1, and these names will be will be egg -shaped horizontally. intentionally omitted: regularly spaced referred to in the following discussion. In the latter case, it is sometimes horizontal and vertical lines are used to The controls for width, horizontal necessary for the technician to adjust check and adjust linearity, as shown in drive, and horizontal linearity, and the the receiver for the best compromise Fig. 3. This design of test pattern is the answer to the technician's prayers, be- VERTICAL WEDGE, ADJUST FOCUS FOR HORIZ. WEDGE, TO cause it avoids the trouble of the fussy TO CHECK HORIZ. BEST DEFINITION CHECK VERTICAL customer who insists that the circles he RESOLUTION., HERE RESOLUTION exactly round, yet it provides a satisfac- tory means for adjusting linearity with- in reasonable limits. Of course nothing that has been stat- ed here should be used as an alibi to SHADING BLOCKS excuse poor linearity that is caused by TO CHECK incorrect adjustment of the receiver or ADJUSTMENT by failure or change in value of com- OF CONTRAST ponents in the deflection circuits of the & BRIGHTNESS receiver. The question of whether the station or the receiver is at fault can be determined by experience with a number of different receivers, or by the use of a bar generator. Most TV set owners complain if the picture does not completely fill the mask, but do not complain if a small portion of the picture is hidden behind the mask. CIRCLES & ARCS It would seem reasonable to make the TO CHECK/ picture exactly the same size as the LINEARITY mask, but this is impractical, because: (1) There is considerable variation in the horizontal and vertical blanking WEDGE POOR INTERLACE time on different stations, and on differ- CALIBRATION SHOWS MOIRE ent sync generators in the same sta- DOTS EFFECT HERE tions. Actually there may be as much as Fig. 1 -This typical test pattern helps owner and serviceman adjust set for best picture. 14 -inch difference in height or width on RADIO -ELECTRONICS for Electronic% -- 41 Another type of pressure recorder Four of these are mounted on the arma- The instrument is so constructed that makes use of a very ingenious adapta- ture and the other four on the frame. the bridge is balanced and no current tion of the Wheatstone bridge. Fig. 4 One end of each element is fixed to an flows through the galvanometer when no is a photograph of this device, which is armature post and the other end to a pressure is applied to the diaphragm. known as an unbonded resistance wire frame post. strain gauge. Its circuit diLg-.am, which The rod extending from the right is that of a Wheatstone bridge, is repre- side of the assembly is fastened to the sented in Fig. 5. armature. In the assembled instrument, Whenever a wire is subjected to stress the free end of the rod is attached to a it becomes longer and thinner and, metal diaphragm. The device operates within limits, returns to its original just as does the photoelectric recorder, . length upon removal of the stretching the changes in fluid pressure causing force. Also, as the wire elongates and the diaphragm to bulge and relax. The Courtesy Statham Laboratories narrows, its electrical resistance in- movements of the diaphragm are trans- Fig. 4- Unbonded resistance -wire strain gauge. creases. Therefore, the change in resist- mitted to the armature via the rod. ance and the reading of the galvanom- Hence, whenever the rod (and conse- Whenever the diaphragm is subjected eter can be used as a measure of the quently the armature) is pushed to the to pressure, the stretching of one pair force producing stress. left, the central pair of resistance-wire of elements and the contraction of the The construction of the gauge is shown elements increases in length and the two other pair unbalances the bridge. Cur- in the photo. It consists of two major outside elements contract. When the rod rent flows through the galvanometer parts: a frame, and an armature which is pulled to the right by the diaphragm, and the galvanometer deflection is pro- moves with respect to the frame. The the movement of the armature to the portional to the pressure of the fluid armature is supported by two very flex- right will relax the central elements and on the diaphragm. ible suspensions. The metallic filaments stretch the outer pair. It is these four Fig. 6 is a photograph of a perman- vhich undergo resistance changes with metallic filaments which are connected ent- magnet, six -trace galvanometer as- stress are strung on the eight posts. together to form the Wheatstone bridge. sembly. Small reflecting mirrors, which replace the pointer needles, pivot with the galvanometer suspension. They can 6SJ7t27 be seen through the focusing lenses in the inset. This instrument throws a 4505 DAUB 54 moving reflected image of the light source upon a traveling light -sensitive surface to produce a permanent tape recording. The author wishes to acknowledge the cooperation of the various manufactur- ers who supplied photographs for this article, particularly Statham Labora- tories for providing technical data on their strain gauges. 65 7 65N7 6.3V DC +22.5V B- +90V +45v +67.5V +'ì5'V Hg. 3 -This is e typical direct- coupled amplifier for amplifying output of the phototube. ' Il' Fig 5- Strain gauge i a Wheatstone bridge. I oto coif dust/ llti/and Research Corp. Photograph of the blood -pressure measuring device diagrammed in Fig. 2. Plug is for wires. Fig. 6 -This is 6 -trace optical galvanometer. NOVEMBER, 1948 Electronics Electronics in M edicine Part III -- - Photo-tubes and photoelectric cells find extensive use in medical diagnosis and examination By EUGENE THOMPSON THE photoelectric technique most and inflates. This procedure is some- very low frequency. If a d.c. signal is widely used by the medical profes- what inaccurate, does not permit contin- applied to the input of such an amplifier sion is photoelectric eolorinI(t,y or, uous blood -pressure recording, and is and maintained, the galvanometer or as it is sometimes called, photom- not very suitable for determining the recording arm connected to the amplifier etry. The reason for its great popu- venous blood pressure. It is being re- output will be deflected and maintained larity is the astonishing rapidity and placed in many institutions by the direct in the deflected position. If an a.c. signal precision of this method of perforating method in cases which are serious is superimposed on this d.c., the record- laboratory analyses. as compared to the enough to require more than the routine ing device, besicles holding an initial de- older, time -consuming. and often inac- physical examination. flection proportional to the d.c., will curate chemical procedures used for the In the direct method of blood pressure fluctuate about the d.c. point in step same analyses. measurement the physician inserts a with the superimposed a.c. In photoelectric colorimetry the physi- hypodermic needle into an artery or The d.c. component is the phototube cian treats the blood. urine, or other vein (depending on whether the arterial output for some mean value of blood material containing the substance to be or venous pressure is being measured). analyzed, so as to produce a colored Fig. 2 is a cut -away view of one type of HYPODERMIC NEEDLE product. The color intensity is then pro- instrument used. A photograph of it portional to the concentration of the appears on page 41. SIDE OUTLET TO CALIBRATING substance in the blood, urine. or other The device is filled with sterile iso- PRESSURE BOTTLE sample. tonic salt solution, and the needle intro- 3 WAY STOP COCK The depth of color of the solution is duced into the blood vessel. As the blood SALINE SOLUTION IN measured with the photoelectric color- pressure varies, the pressure changes RECORDING CHAMBER imeter as indicated in Fig. 1 -a. The light are transmitted through the needle and r LENS source and the battery are held to stand- salt solution to the recording chamber. ard values, and the rheostat is pre- As the transmitted fluid pressure rises viously calibrated. When the filtered and falls within this compartment, the ® . PHOTO TUBE - SOURCE flexible diaphragm bulges and LIGHT light rays pass through the test tube rubber I FLEXIBLE RUBBER DIAPHRAGM METAL LIGHT GATE I containing the colored solution, the relaxes in step with the fluctuations. amount of light striking the photo tube The movements of the diaphragm alter Fig. 2- Taking blood pressure with phototube. varies with the depth of the color. The the position of the light gate cemented amount of light, in turn, determines the to its surface. This motion of the gate pressure. The a.c. component is the vari- resistance of the phototube and the read- produces variations in the amount of ation, above and below this mean value, produced by the tube in response to the b PHOTOVOLTAIC CELL a LIGHT RAYS 4-IRON fluctuations of blood pressure above and below its mean pressure. Only direct - coupled (d.c.) amplifiers are usable be- COLOR FILTER cause other types will not pass the d.c. E ENIUM component (the mean blood pressure), PHOTO but only the a.c. signal (the periodic LENS a "-- TUBE variations). Hence, they are of no value LIGHT SOURCE COLORED SOLUTION IN TUBE for quantitative analysis. Fig. I- Photoelectric colorimeter analyzes a substance by measuring the depth of its color. Modification of this pressure recorder ing of the galvanometer G. Comparison light reaching the phototube, the output makes it useful for other measurements. of the reading with a previously made of which varies accordingly. For example, if a length of small rubber curve showing current versos concentra- The resulting signals are then fed in- tubing with a balloon at its free end is tion gives the physician the desired to a direct- coupled amplifier -such as substituted for the hypodermic needle, information. the one shown in Fig. 3 -the output of the device can be used for studying the Another type of photometer employs which actuates an optical galvanometer activity of the lungs, the stomach, or a photovoltaic cell. The circuit is shown or electro- magnetic recording stylus. any part of the gastro- intestinal tract. in Fig. 1 -b. The physical arrangement Both of these recording devices were de- For the latter application, the instru- is the same as that of Fig. 1 -a. scribed in a previous article on electro- ment is filled with some material opaque One of the most important items of cardiography (RAnto-CR.AFT, Marc h, to X -rays, such as barium, and the bal- information needed by the physician is 1948). loon and tube passed through the mouth the arterial blood pressure. This may be Resistance-capacitance-coupled, trans- and clown the throat. The barium per- determined by the indirect method using former-coupled, or impedance-coupled mits the physician to see the position of the familiar cloth cuff which the physi- amplifiers cannot be used. Direct - the tube while it is in the patient's body cian wraps around the patient's arm coupled amplifiers respond at zero or on a fluoroscope. RADIO -ELECTRONICS for Electronics ELECTRON TUBE CONFERENCE Nt1T so long ago electron tubes were associated exclusively with com- munications. Now more and more are required for special instruments such as computing machines, one, the ENIAC, using 18,000 tubes. Many electronic in- struments require great uniformity and precision in tubes. The increasing use of tubes in re- search and industry inspired an Elec- tron Tube Conference which was held recently in Philadelphia. Tube makers met tube users, and there was an oppor- tunity to exchange recommendations. The most frequent defects in tubes are short circuits, broken beads, uncer- tain life, and low emission. Among suggested improvements were a 10,000 -hour life span, lower hum and microphonics, freedom from unexpected Fig. 5-The Modernair uses a book condenser for tuning. Case and chassis are white plastic. failure, and 10'', tolerance in character- istics. because the electromagnetic vibratory rule tuning indicator is moved by a gear The following basic tube types were system is so small. on the tuning shaft. The on -off switch is discussed at the conference: double- The editors were surprised at the high on the rear of the case. The plastic diode (6H6), pentode amplifier (6SJ7), sensitivity of such a low- priced (under "chassis," shown on the left in Fig. 5, gating tube (6SA7), double- triode $5.00) toy telephone. Conversations holds all components except the tuning (6SN7), and beam power (6L6). Elec- were held without difficulty and with indicator. It fastens to the back of the trometer and voltage regulators were good intelligibility. case with three machine screws. Bat- also analyzed. The Little Orphan Annie Portable teries are exposed at the rear for easy One of the most common circuits used Radio- Phone, a small radio receiver replacement. Two pen -light cells and in electronic instruments is the trigger made by the same manufacturer, ap- miniature 22',_s -volt batteries are used. circuit which usually employs a 6SN7 or pears in Fig. 3 alongside a regular tele- A standard single earphone is perma- similar type. For example, about half phone instrument. Inside the red plastic nently attached. A tryout showed about of the tubes in the ENIAC are 6SN7's. base of the Radio -Phone are the com- the same results as the previous re- Experience shows that this tube has a ponents, consisting of a tube, coil, con- ceiver. life expectancy of about 150 years of denser, and batteries. See Fig. 4. An on- General Electric's toy record player, intermittent life, provided it passes the off switch is on the front of the case and shown in Fig. 6, is all- electronic. A first 100 hours without developing a antenna and ground clip -leads come standard electric motor is used. The am- defect. For trigger use, it was recom- from the rear. The headphone is con- plifier, powered from 117 -volt a.c. or d.c. mended that the tube be kept within tained in the handset, in the same place lines, puts a maximum of three -quarters closer tolerance than at present. The where a telephone receiver would nor- of a watt output into a built -in 4 -inch most important characteristic is the bias mally be. There is, of course, no trans- PM speaker. Two tubes are used, a rec- required for plate current cutoff. mitter in the handset. tifier and an amplifier. The pickup is a In pentode amplifiers, the important The set is tuned by rotation of the high -output crystal with replaceable factor is uniformity. Of course sufficient telephone dial. The tuning element is a needles. Since it is made especially for degeneration cancels out the need for coil with a movable core. This perme- children, care was taken to make it safe. tube uniformity, but more gain is then ability tuner is linked to the dial by a All electronic parts are inside the case required. If the 6SJ7 could be made dial -cord arrangement. The dial is not away from prying hands, and the metal more nearly uniform, it would be pos- calibrated though the numbers from pickup arm is sufficiently isolated from sible to get higher gain in each stage. 1 -0 can be used as a guide. the power line to avoid any shock. In some cases stages could be eliminated. While an outside antenna aids recep- The player will handle ordinary 10- Tubes of the 6SA7 type find different tion, especially in weak -signal areas, and 12 -inch records, as well as those uses in communications than in indus- clipping the antenna lead to almost any made for children in the 6- and 8 -inch try. For radio the present tube is satis- metal object will suffice if there is a size. factory. However, industry requires a strong local signal. The inside of the Though the amplifier will operate on gating tube. The two controlling grids cover of the box in which the radio d.c. the motor will not. must have independent control over the comes is metallized and a terminal is output and each should operate from provided for attaching the ground wire. cutoff to the positive grid region. It was This counterpoise ground also helps re- recommended that an entirely new tube ception. In downtown New York City be developed for this purpose. the box cover was attached to the an- A more rugged, longer -life tube was tenna lead and the radio was carried recommended for the 6L6 beam tube. around, giving good reception almost all Improvements were asked for in leak- the time. The sound was not always age, hum, microphonics, and noise. The loud but it was sufficient. tube would have to be redesigned me- The Modernair, pictured in Fig. 5, chanically to stand shock and vibration. uses almost exactly the sanie circuit as The plan also includes more conserva- the previous set. It is made by the tive voltage, current. and temperature Vaugh Manufacturing Co. The tube, ratings. without much change in the however, is a 1L4 and tuning is done present gain and output. This could be with a "book" condenser. This condenser, done by redesigning the tube structure. which looks like a large -size compression It is felt that the conference will re- trimmer is compressed and expanded by sult in improved tube design. the plastic tuning shaft, which screws A second conference on electron tubes in and out of a threaded hole. The slide- Fig. 6- Complete G -E phonograph for children. is planned for next year.-/. Queen NOVEMBER, 1948 38 Electronics ELECTRONICS kin. the Toy World ufactured by Da -Myco Products Com- esting that it well deserves the attention pany of New York. Although there is of telephone receiver manufacturers nothing supersonic about this toy, it who wish to try for the greatest possible does give very usable 2 -way communica- sensitivity. They work on the electro- tion without any batteries. The two magnetic principle first discovered by Alexander Graham Bell. The earphones are, therefore, reversible -each can be used also as a transmitter as, in fact, By it is. In the usual earphone a rather thick RICHARD HENRY soft iron diaphragm is used. Its diam- eter is usually about 2 inches. If very strong magnets are used the entire dia- phragm is pulled down; this greatly im- pedes vibration making a fairly strong current necessary for operation of the telephone. THAT this is the age of electronics The makers of the new toy have is made clear by the multitude of gotten around this difficulty and actually electronic devices which appear E made an earphone which is self amplify- every day in business and at home. MAGIC 3A4 COVER 0001 The younger generation also has a place s's in the world of electronics, for even very young children will enjoy many of the PHONE new electronic toys put on the market recently. Among the devices especially 2 A made designed for children are a sound -pow- Fig. -Parts of the earphones. -Cap B- GND A +I SV B +22.5V ered 2 -way telephone, a small all -elec- of plastic; B- Diaphragm; C- Reinforcing disc A- tronic record player and miniature radio on armature; D- Armature; E -Wire connecting Fig. 4- Diagram of Orphan Annie Radio -Phone. on batteries and armature to diaphragm; F- Cushion ring; G- receivers operating tiny ing. instead of the 2 -inch diaphragm, $5. These devices Plastic case; H -Brass shell; J -Coil winding; selling for less than Alnico magnet. Units receive transmit. they have used a very small iron dia- life K- and widen the gulf between a child's to- phragm measuring inch in diameter. day and the rag -doll- and -coaster -wagon identical instruments used are shown in This is fastened rigidly to a thin brass era of a few years ago. the photograph and cutaway drawings amplifying cone which is able to swing One of the most interesting of these of Figs. 1 and 2. freely under the influence of the small gadgets is known as the Buck Rogers Each is a diaphragm. A powerful electro- magnet man- instrument specially de- Supersonic Two -Way Transceiver, signed earphone. These highly ingenious can now he used without hampering self- amplifying earphones are, of course, vibration. An Alnico magnet is used in a toy, but the principle used is so inter- the toy. Great sensitivity is available Fig. I -The Buck Rogers phone instrument. Fig. 3 -Toy radio at left is tuned by turning the "telephone" dial. Standard phone at right. RADIO -ELECTRONICS for FA I 37 first. The discriminator is a Foster-See- oscillator that the phase of the signal cellular type of construction. The tubes ley circuit using crystal diodes. The varies with the audio signal at the grid and all components associated with each 2E36 a.f. amplifier is transformer - of the modulator. Transformer coupling stage are on plug -in sub -assemblies. coupled to a receiver in one end of the is used between the microphone and the This type of construction simplifies handset. A switch on the handset oper- control -grid of the modulator. servicing and reduces to a minimum the ates the filament changeover relay to The phase modulator is followed by a time a unit must remain out of service switch power to the transmitter. 2E36 buffer operating straight -through. for repairs. As soon as a defective stage Two tripiers and a doubler raise the is isolated, it can be replaced by a good The transmitter phase modulated signal to the operating one and the unit put back in service. There are 8 tubes in the transmitter; frequency. The second tripler uses a pair The defective unit can be repaired at two are miniature and the others are of 2F. ;6's in parallel. a more convenient time and placed in subminiature types. The 5672 crystal stock for replacement purposes when oscillator, No. 14, is wired with the Construction needed. crystal between the grid and screen Construction and maintainance of a Metering points are provided for grid. The signal from the oscillator goes 19 -tube unit as compact as this Handie- trouble -shooting and adjusting the to the 2E36 phase modulator. This tube Talkie transmitter- receiver would pre- transmitter power amplifier or the re- is so connected across the output of the sent many problems were it not for the ceiver mixer and limiter circuits. PA METER GRAMOM MAW I 02 j io e2 o2 141502 lo e2 lo 2. Ie le o IIé1 17 I I{ U Ito 19 Isé e3 0 4e e3 1 40 3 4e o3 Ie 40 03 ¡ 4e 40 3 doIo 03 é IICOIINNIII _ Ì 3 e I 0UTPUT TRANS JUMPER I f `..e..iIIIIM...._ ------HANDSET CONN L SNIELD ANT CONN Mii-.1111111111111111.1. T0001 - M. ItMpr3.79442/2 .lo e4 3o 34,864 - L. 3e 4 3e o4 303°4 30 04 3o eb 3o e{ el 2o el 2o 5o1 2o el ' 2o el 2e 2o el HIELO r 2. el 2o 2o30' I ro I i Ili=i=imii - FIL.CNANGEOVER RELAY' I 5 - 1 r II 10 y67.5V 1 rt i I 1 67.5V T ?__.IT- T T I T I.SV EACHr f/ L J 2E36 5672 126µf 5672 5672 XTAL OSC ''1560 MULTIPLIER I I .0001 TAL OSC,MULT XTAL I .0001 MOD 1 I .0001 oHE- I I 1-O ri( `\lo Bry solzµ 17 tr., ' kut +10 I I a) ¡ (9 II (o t INDICATES USE IN 30-40MC I I II BAND ONLY 1 I I L4 2.2 50664 I = MEG III ALL CONES á 10 out ti II 56 470KS I R1000 OOKo lj a I 0001 2.2K .008 -IE- LII 1P ' II II 22K '90µM1 r I I I '' ;,000 I I I I 2.2K .05 1 33K II lutG 6K SUB-MIN TUBE INDEX 7 KEYWAY I I PIN LOCATIONS T I I 4 J 2I I , o T 2 ;3 II J I -113 _ .002 o o 1.0001 1-0-013 I I o 0 4 II 1`1J4 _Fri-TJ4 I 12 4 i 1J{ ll II I 15 I 14 13 I L------JL------J ------L J I 2 3 4 5 DOT XMITTER RECEIVER 2E32 2E32 2E32 2E36 2.IMC AUDIO 3RD IF 2.1 MC 1ST LIM 2.IMC 2ND LIM 2. MC DISCRIM I I O-1 lr, O- Po- 1 1 I 30116f 301Mµf I µoll 30 6f I N SOHO L tt I .0001 .0001 \ á 11 \30 o II Fy II --i l I l 4.7 33K I IOOK IOOK MEG - I .0001 -.0- 06 II II I .0301 I L IMEG L___ 22Ó 56K K /I: I .05 S ( I .1 L .0005 1 27KSA02 1_ .000q 33K .002 _ .~000 471 `.Ó0z - .00012 - 2 3 2 3 -2 3 '2 3 2 ] - I - o ou°- , r o0 Fo °ú I ¡ 1-OLJ I I IO I I I I 1 o 1 J - -- JL_-- J- { ----J L------__JL- NOVEMBER, 1948 FIAI 36 1 Crystals for the high -frequency model range from 6.15 to 7.98 me and those in the low-frequency set are between 4.65 and 6.31 mc. L3, in the screen - grid circuit, is adjusted to resonate at three times the crystal frequency. The third harmonic of the crystal is amplified and coupled to the grid of the 5672 frequency doubler, No. 13. The out- put of the doubler -six times the oscil- lator frequency-is the heterodyning frequency. It is coupled to the input of the mixer, No. 4, through L4 and L5. The heterodyning frequency is 2.1 me lower than the operating frequency. The mixer works into a 3 -stage 2.1- mc intermediate -frequency amplifier. Miniature i.f. transformers are used. The primary and secondary coils of each are tuned by varying the position of powdered -iron cores within the coils. of i.f. trans- The top cover and nine of the plug -in units have been removed to show chassis construction. The secondary the output former feeds into the grid of the first stage of the cascade limiters. Both lim- iters have the same time -constant but the second limiter is operated at a lower plate voltage than the first. This second stage removes any amplitude variations that may pass through the r HANDSET CONNECTOR I I L_____J ANT LOADING COIL HANDSET j Each of the plug -in units has a plug at the bottom. There are wiping contacts at the top. L 3B4 IS4 2E36(2) 5672 2E36 IST MULI BUFFER MULTIPLIER I 2NDMULT I I .0001 3RD 1 .0001 IOuuf POWER AMP I I .0001 ID-31 2/6 -oh-. a---1/ L2 S11.1 ' 7 f Ì{D° I / I I I I I I 3 IODUfy. I 3 I 1 I I rT 5 róo`r2 4zée I 7 NC 1euuf IMEG r 2.2µufV I I 220K I. I 22CK 33R 6.eH I 10H 390 =.002 I I 1,002 1002 022 410A 2 3 2 3 II I I rI2_13 II I Ira a I I ll 4 1 Ló ]4 oL-Q JIL 4 16 1 Ji18 JL17 J L------J RMITTER f- RECEIVER 2E32 2E36 2E32 2E32 2E36 IF 2.I MC MIXER 2. MC IST IF 2.IMC 2ND l IST RF I I 2ND RF I I I o- o-- o- f 1"-- 30 130 311uu1l 1.40 31µµfi}} 1041W LM °Orufl I IOÿuµf tt IOiuµl u tt WI Lft I . II 11 I T r T I II I II 11 I ° T °II t._.1 11. II I <®2 L5 ' I r - - - 3 I I I T--- i I I00N (( I I .008 I I I .00e = II _me : ¡ 1.o0e : II I I r 100 II a II 0001 I I IMEG 1 I I I I I J I L- _ _ J - I R- 27K .0Ó-2-1- IiIMEG *Kt)02 I( 00 I I = 071 .Ti, 3 2 3 22N - 2 2 2 I J1L II o , I I Ir o- 4 I 4 4 I -0u 6 L------IL3----'----jL------I L6 RADIO -ELECTRONICS for FM 135 Cover Feature FM Hatidie-Talkie Radio for Industry Radio can be used as a vital link between working teams. The new Motorola FM Ilandie-Talkie unit is suitable for many industrial applications THE new Motorola FM Handie- Talkie* transmitter -receiver unit is designed for use by police, fire- fighters, public-utility and construe.. tion workers, rescue and emergency This is the portable radio set. The antenna,handset teams and in other applications where and bottom cover have been removed. a light- weight, low -power transmitter - The receiver tank coil of the transmitter. This is receiver is required. Its 9.8 pounds in- There are 11 subminiature tubes in the common antenna secondary coil for clude an 8 -tube transmitter and 11 -tube the receiver. They are: 2E36, first r.f. both transmitter and receiver. L2 couples receiver. Its case is 10 inches high, 12% amplifier; 2E32, second r.f. amplifier; the resonant coil to the antenna when inches long and 34 inches wide. It is 5672, oscillator- multiplier; 5672, multi- transmitting and receiving. All coils be- designed to be carried in the hand or plier; 2E36, mixer; 2E32's as first, sec- tween the antenna and the grid of the strapped to the body. A handset clips ond and third i.f. amplifiers and cascade mixer are tuned to the operating fre- into a cradle on top of the case when limiters; and a 2E36 audio amplifier. quency. not in use. Crystal diodes are used in the discrim- Low -frequency crystals are used in A 43 -inch base -loaded whip- antenna inator circuit. the crystal oscillator-multiplier, No. 12. is standard equipment, but any 50 -ohm The grid of the first r.f. amplifier, The crystal is between plate and grid. antenna can be used to increase the cell No. 2, is capacitance- coupled to the A third harmonic is developed in the range when the unit is used in fixed or plate end of L1, the power -amplifier screen circuit. (Cont. on next page) semi -fixed locations. It is normally sup- plied with a battery power pack. Vibra- tor packs and a.c. supplies are also avail- able. A power switch is located on one end of the case. The receiver remains on when the switch is closed. The trans- mitter is turned on and the receiver off in the standard manner by a push -to- talk switch on the handset. The trans- mitter and receiver are crystal con- trolled. The Handie -Talkie radio is available in two models. The FHTR -1AL and FHTR -1AH operate on any predeter- mined frequency in the 25 to 40-mc and 39 to 50 -mc bands respectively. The units are tuned to the desired frequency at the factory. A unique cellular construction is used in the chassis. There are 19 cells, each housing a complete plug -in stage. These cells are shown in the photographs and are numbered and separated by broken lines on the diagram on pages 36 and 37. Trade mark of Motorola, Ine. Four of the nineteen plug -in stages are shown. Cellular construction simplifies servicing. NOVEMBER, 1948 34I- RAI the ratio detector, connect the network trimmer for maximum output. Set the for maximum audio output. Adjust the from plate to ground of the next to the generator and receiver to 92 mc and balancing trimmer (C2) for minimum last i.f. tube. In Philco sets, connect it cheek tracking of the converter grid audio output. The output should in- from plate to ground of the last i.f. with a tuning wand. A decrease in sig- crease sharply on either side of the min- stage. (It is important to keep the sig- nal when either the iron or brass end is imum setting. nal generator output as low as possible inserted in the coil indicates proper for all i.f. and r.f. adjustments.) tracking. If the output increases with Ratio detector First place the load network across brass inserted, spread the coil slightly; Connect the d.c. indicating meter as the proper stage as outlined above and if the output increases with the iron end adjust the secondary trimmer of shown in Fig. 3. (Use the 10- or 50- that inserted, compress the coil. Repeat all volt range of stage for maximum output. Then re- oscillator, converter, and the meter.) Connect the r.f. adjust- generator to the grid of the next to last move the loading network and connect ments until maximum results are ob- it from the grid end of the same trans- tained. i.f. tube; connect the loading network from plate to ground of this stage. Re- LAST IF _ AUDIO OUTPUT set the generator to the center inter- Limiter and detector mediate frequency, as indicated by a In receivers using two limiter stages, maximum reading on the d.c. meter. Re- the second limiter must be adjusted be- move the loading network. fore proceeding to the detector. First adjust the diode trimmer (C2 With the d.c. indicating meter still in Fig. 3) for maximum output, then I connected as before, connect the signal adjust the plate trimmer Cl for maxi- generator to the grid of the i.f. stage mum reading. Remove the d.c. meter Fig. 3 -Meter connection for ratio detector. preceding the first limiter and connect and retrim C2 for minimum audio out- the loading network from plate former to ground. to put. Output should increase sharply on Align the primary ground of the same stage. Then care- either side of the minimum trimmer for maximum output. Follow setting. fully retune the generator to the cen- The Philco detector (Fig. 4) is this routine through to the first i.f. ad- stage, adjustments ter intermediate frequency, as indicat- justed by tuning the oscillator section being macle with the ed by maximum reading on signal generator connected the meter. to zero beat with the signal generator. to the con- Remove the loading network and which is verter control grid. After the adjust- con- tuned to the center intermedi- nect the indicating meter to the grid ate frequency and connected to the ments have been completed remove the of the last limiter. With loading network. the generator i.f. stage immediately preceding the de- connected to the first limiter grid, con- tector. nect the loading network from the With Front -end first the audio output meter across alignment limiter plate to ground. Adjust the in- the speaker voice coil, connect the gen- Connect a 70 -ohm resistor across the put trimmer of the second limiter for erator to the input of the last i.f. stage signal generator output terminals and maximum reading. Then, with the load- and the loading network across the pri- connect the output leads to the antenna ing network connected from the second mary of the last ii. transformer. terminals of the receiver. With the gen- limiter grid to ground, adjust the first With the oscillator grid (pin 2 of the erator and receiver set at 105 mc, ad- limiter plate trimmer for maximum out- FM1000 tube) grounded, modulate the just the oscillator trimmer for maxi- put. Remove the meter and loading net- signal generator and retune to the cen- mum output. Set the receiver to 88 mc work. ter intermediate frequency, as indicated and check oscillator tracking by tuning For detector adjustments, an FM sig- by maximum audio output. (For this the generator slightly to either side of nal generator and oscilloscope should he adjustment keep the generator output as this frequency. Spread or compress the used to observe detector linearity. If low as possible.) Then remove the short turns of the oscillator coil very slight- these instruments are not available, and take out the loading network and ly, if necessary, to bring the signal gen- proceed with the AM generator. For all output meter. erator in at the 88 -mc setting. Then re- detector adjustments, use an insulated, Short pin 4 of the tube to the audio peat the adjustments at both ends of nonmetallic alignment tool. Alignment load resistance R (Fig. 4). Then turn band until no further improvement is procedure depends on the type of de- off the generator modulation and adjust noted. tector circuit incorporated in the re- the oscillator trimmer Cl to zero beat. FMIOOO REACTANCE CONTROL SECTION ceiver. Remove 4 the short and adjust the re- LAST IF TRANS X With the Armstrong discriminator, actance- control trimmer C2 for zero T r---1 S connect an audio output meter across beat. This + ' ____}l adjustment is rather sharp; the speaker voice coil. With the signal use a very low input signal from the cllt1 C I generator connected to the grid of the generator. i.f. stage preceding the limiter (but This step -by -step alignment proced- I II I with loading network and d.c. indicat- ure is the one recommended by Philco --J ing meter removed), FM DET TRANS tighten the dis- for alignment of FM receivers without criminator balancing trimmer to detune FM -J OSC SECTION AUD OUT an signal generator or oscilloscope. -L--- X the circuit. With the output of the sig- The Philco Model 7070 r.f. signal gen- SHORT TO GND WHILE ALIGNING AUDIO LOAD R 2 nal generator as low as possible, ad- erator was used 4 7K ° for making the ad- IF TRANSFORMERS just the plate trimmer (Cl in Fig. 2) justments. SNORT POINTS X TO X WHILE 10,x, ADJUSTING OSC SECTION = + _ Fig. 4- Philco detector contains oscillator. FM STAT IC SHIELD Set the generator and receiver at 105 My FM receiver was picking up auto- U- shaped trough and held that way mc and adjust the converted trimmer mobile spark interference. Working on with heavy wires. It is mounted on the for maximum output. Rock the tuning the theory that noise travels in straight mast (which passes through a hole in condenser of the signal generator when lines, I made a shield and placed it on it) just below the dipole. making this adjustment. the antenna mast so that it intercepts The shield eliminated about 907. of If the receiver has no r.f. stage, make ignition radiation from cars on the the noise. the adjustment as follows: connect two road below, but allows the FM signals HAP KINGSLAND, 30 -inch lengths of wire to the signal to pass over the top of the shield and Mountain Honte, Idaho generator and two identical lengths to strike the antenna. The scheme is shown FM DIPOLE the receiver antenna terminals. Bend in the drawing. FAI SIGNAL-* 4- FM SIGNAL each to form a simple dipole and place The shield is made from metal lath á the generator several feet away from such as in SPARK NOISE / that used as a plaster base 180 "APPROX the receiver. Set the generator and re- most houses. It can be obtained at any ceiver 105 to mc and adjust the r.f. lumber yard. The sheet is bent into a 6-HIGHWAY LEVLE RADIO -ELECTRONICS for FM 33 l ig f. i ii g FM Receivers You C: align any FM receiver without an FM generator or '.rope. This article gives the alignment procedure in step -by -step fashion By JOHN B. LEDBETTER IT IS a relatively simple matter to been placed physically close together, The Philco detector has a special tube align an FM receiver when the serv- past the point of critical coupling, so (FM1000), part of which acts as a Col - ice manual is available and the prop- that a flat -topped response curve is ob- pitts oscillator operating on the center er instruments are on hand. But when tained. Transformers of this type can- intermediate frequency. The i.f. output a new or unfamiliar receiver comes into not be aligned by peaking for maximum is fed into an injector grid of this tube, the shop without alignment instructions output. An attempt to align overcoupled and the reactive coupling between the or when the FM signal generator and transformers by peaking would throw pentode section and the oscillator causes oscilloscope usually specified in the serv- some or all the i.f. tuned circuits off the latter to lock in and follow the fre- ice manual are not available, proper the center frequency. quency variations of the i.f. signal. In a alignment becomes a more difficult un- Single -peak i.f. transformers are de- receiver employing the Philco detector, dertaking. signed to have relatively high gain at the oscillator control grid must be short- Most FM receivers can be aligned the center frequency, at the same time ed to ground before the r.f. and i.f. with an AM signal generator, provid- having a Q sufficiently low to give broad stages can be aligned. The pentode sec- ed the generator's frequency range ex- response over the required band. They tion then acts as a regular AM detector; tends to 105 or 110 mc, and provided may be peaked for maximum output. and r.f., i.f., and oscillator adjustments the serviceman knows the proper func- Three basic types of detectors are in can be peaked with a modulated AM sig- tion of each stage of the receiver. The use. They are the Armstrong discrim- nal generator for maximum output. only additional equipment needed is an inator, the ratio detector and the Philco. output meter, a 20,000- ohm -per -volt d.c. The Armstrong system employs a I.f. alignment meter. an insulated alignment tool, and duo -diode frequency discriminator, pre- First determine the type of detector a tuning wand. ceded by one or two limiter stages. An employed. Then connect the signal gen- amplitude -modulated signal cannot be erator accordingly. In the Armstrong Circuit characteristics used for alignment because the limiters detector the generator is connected to In an FM receiver, the r.f., converter, the last i.f. stage preceding the limiter, and oscillator circuits may be aligned or to the first limiter if two are used. by peaking for maximum output. They LIMITER In the ratio detector, the generator are heavily damped to allow broad re- should be connected to the control grid sponse, and present no unusual prob- of the next to the last i.f. stage. lems in alignment. (Alignment is always begun with the i.f. last i.f. stage and worked back to the The main difference between Fig. 2 -This is the Armstrong discriminator. transformers in AM and FM receivers converter.) In the Philco circuit, the is the band width. The maximum width remove most of the A M component from signal generator is connected to the con- requited in the best AM receivers is 10 the i.f. signal. However, since the i.f. trol grid of the last i.f. tube. kc, whereas an FM i.f. transformer signal causes d.c. grid -current flow in With overcoupled i.f. stages a loading must have a flat -top characteristic over the limiter which is dependent on the network, consisting of a 0.1 -µf con- signal amplitude, i.f. alignment adjust- denser in series with a 4,700 -ohm re- LIMITER sistor, must be placed across the coil IF ments can be made with an ordinary 20,000 -ohm -per -volt d.c. meter as the opposite the one being tuned, to allow tuning indicator. (See Fig. 1.) To pre- each coil to be aligned for maximum vent detuning the limiter a 100,000 -ohm output without affecting the center fre- resistor should be inserted in the test quency of the other. If you are not prod when it is attached to the Arm- sure whether the receiver has over - strong circuit. The meter may be used coupled or single -peak i.f. stages, con- for all r.f. and i.f. adjustments; it nect the loading network anyway and should be connected across the first lim- proceed as if the stages were over - iter output if two limiters are used, then coupled. Use of the network will not af- Fig. I -Meter placement for aligning i.f.'s. connected to the second limiter for fect the tuning adjustments in single - a band width of 200 kc. Two basic meth- alignment of the first limiter stage. peaked stages. ods are used to obtain wide -band re- In the ratio detector, which also uses In the Armstrong circuit, the load net- sponse: overcoupled transformers and two diodes, a high -capacitance condens- work is connected from limiter plate to single -peak transformers. er is charged at a varyipg rate by the ground (first limiter plate to ground For overcoupling the i.f. coils have i.f. signal. if two limiter stages are employed). In NOVEMBER, 1948 ßraadcastiag sod Cowimaaicatiaas 321 RY1 opens contacts 6 and 7 to turn off ther to the regular line terminal for proximity to the receiver speaker and the recorder. normal operation or to J2 by means of the operator's microphone. The recorder When a signal is received, C8 charges a connector cord for automatic opera- will continue to operate automatically through contacts 3 and 4. When RY1 tion. S2 permits the sensitivity of the and will record both sides of the traffic. opens, the condenser discharges into the keyer to be set to operating point by It is possible this type keyer will grid circuit of the GSJ7. This positive means of R3 and the indicator lamp have two advantages over the better - pulse makes RY1 act quickly and posi- before the recorder is turned on. The known voice -operated circuits, especial- tively without chattering. The 0.5 -pf outer conductor of the connector cable ly as used in radio networks. The in- condenser across RY1 bypasses surges between J2 and the recorder is used to stant a carrier appears in the receiver resulting from static and random noise complete the ground return between the the keyer will start the recorder or other in the receiver. two units. This is necessary to reduce device before audio is present, thus al- Terminal No. 2 ends in a phone plug, hum in the recorder. lowing the recorder to reach operating which is inserted in the receiver meter- An ordinary wall receptacle is used speed and eliminating wow. Also, in ing jack, and the metering switch is for connecting the power cord of the re- FM receivers the saturated limiters pro - turned to No. 1 position (or if separate corder. It may be necessary to polarize duce terrific audio, due to amplified jacks are used, to the appropriate jack). this receptacle because of the transmit- thermal noise, when the squelch is The grid of the GSJ7 will then be in ter keying circuits introduced into the opened by weak and undesired signals No. 3. For as is often the case. This noise audio 7C7 7C7 keyer through terminal this 7A8 reason the power cord of the keyer is would trip a voice -operated keyer and IST LIMITER 2 2ND MIXER attached in the transmitter across the the result would be considerable loss as I.7MC IF - 1 1' line fuse block to insure against possi- far as recording is concerned. ble mixup. All cables and terminals are In actual operation the keyer de- I. " color -coded. S1 is the power on -off scribed can easily be tripped by signals r -. r, switch. received from 50 -watt stations operat- 200 -foot towers in the 1 In the event the radio equipment is ing from the I -way 30 -40 -me band in excess of 125 miles I I not remote -controlled, the two re- I IMEG ,{ cording can be obtained with the record- and by mobile units 40 miles distant. Its 1 of application in the 72- and 156 -mc bands 1KR I er microphone instead connections I from terminal Nos. 4 and 5. Simply will prove just as effective according to place the recorder mike in common the area covered. L _ J L_TI 47K1 .0021 / .002133K NEWLY- DEVELOPED RECEIVING TUBES / R+ Three new miniature tulles were an- nounced recently by RCA and a new TO 2ND LIM` type of tube construction is being used 0 0 by Raytheon. 12 3 TO DISCRIM OUT The new tubes are 6BA7, 12BA7 TDDISCRIM IN METER JACK and GAR5. The 12BA7 has the same appearance as the 6BA7 shown on the left. The 6AR5 is shown at the right. Fig. 3- Low -frequency i.f. of the FM receiver. Both the 6BA7 and 12BA7 are penta- either the grid circuit of the low -fre- grid converters with the same char- quency i.f. tube or the first limiter. acteristics as the standard -size 6SB7. A grid resistor is unnecessary in the Differing only in filament character- 6SJ7 circuit. The grid return is through istics. these two min;atures are espe- R1 and R2 (Fig. 3). cially recommended by RCA for service Terminal No. 3 is connected to the hot in the 88- 108 -mc FM band. or ungrounded side of the plate trans- The GAR5 is a beam power tube. It is former primary in the transmitter. When intended for use in the output stage of the transmitter is turned on its plate automobile and compact a.c.- operated transformer is furnished line voltage by receivers. It delivers a moderate power w the keying -elay in the transmitter. This output with relatively small input voltage. Within its feeds line voltage to the a.c. relay RY2 maximum ratings, it is the performance equivalent of the in the keyer from terminal No. 3 and ßK6 -GT. the recorder is started to record the The heater of this tube operates at 6.3 volts, 0.4 amperes. f transmitted message. Note this is done Maximum voltage is 250 volts for plate and the screen - through points 1 and 2 of RY1. Thus, grid. When operated as a class -A amplifier, plate and primary voltage cannot be placed back screen are operated at 250 volts. With 16.5 volts of bias, on the primary of the transmitter plate maximum plate and screen currents are 45 ma and 10 ma transformer when RY1, due to received respectively. The gm is 2,400 micromhos, plate resistance signal, actuates RY2, as the points 1 65,000 ohms and the load resistance is 7,000 ohms. Maxi- and 2 will have opened the line to ter- mum power output is 3.2 watts with 7': total harmonic minal No. 3 and the plate transformer distortion. With 18 volts of bias; plate current is 33 ma, in the transmitter. R5, R6 and R7 are screen curs ont is 10 ma, gm 2,300 micromhos, plate resist- taps on a voltage divider. A 100 -watt ance 68,000 ohms, and load resistance 7,600 ohms. Maxi- size is used for ease in adjustment of mum power output is 3.4 watts with 11'; distortion. Re- the taps. The total value of the divider sistance in the grid circuit should not exceed 100,000 ohms is 15,000 ohms, and the bleeder current, for fixed bias or 500,000 ohms for cathode bias. used to help stabilize circuit voltages, The maximum plate dissipation is 8.5 watts and screen must be taken into consideration in set- dissipation is 2.5 watts. Do not permit the voltage between ting tap points, the values of which the heater and cathode to exceed 90 volts in either direction. are shown in the schematic. The Raytheon Bantal -type tube has increased ruggedness The recorder itself must be modified due to an 8- pillar support construction. Each tube has an to permit all internal circuits to remain internal shield, short leads with wide spacing and other hot except the motor. An added d.p.d.t structural advantages. The Bantals are at present manu- toggle switch in the recorder permits factured to replace the 6SA7 -GT, 6SJ7 -GT, 6SK7 -GT and throwing the hot side of the motor ei- 6SQ7 -GT. RADIO -ELECTRONICS for Broadcasting and Co unicntions e A Carrier- Controlled Recorder Messages are logged automatically By RHETT McMILLIAN' IF I just had a recording of that!" cuit will be limited to its intended use 6J5 below the point required to activate That, of course, being some with an FM receiver. No alterations or the relay RY1. Upon receipt of a signal, piece of monitored air traffic changes are necessary in the receiver. the low- frequency i.f. tube (first lim- ii which, having come fleetingly to Phone jacks or one jack with a selec- iter in some receivers), Fig. 3, will be one's attention, is as quickly irrevocably tive switch are usually provided for driven to a point where a negative volt- gone. Such expressions are familiar to measuring voltage or current while tun- age is developed across its grid load R1. all in communication circles. Too many ing the FM receiver circuits. One of This negative voltage drives the 6SJ7 to times has an occasion abruptly shown these metering voltages triggers the cutoff, making its plate -and the grid the need of an exact replica of a certain keyer. The keyer is set off by the nega- of the 6J5 -more positive so the 6J5 will transmission in such fields as police, fire, tive voltage developed across the meter- pass current and actuate RY1. This taxi, marine, railroad, and other ing resistor in the grid return of the closes contacts 6 and 7 to excite the branches of the so- called emergency low -frequency i.f. stage in the double- coil of RY2. When RY2 closes, a.c. is services. superheterodyne receiver. applied to the motor of the recorder Wire recorders are satisfactory for The schematic of the keyer is shown through J2. When the transmitting sta- copying such transmissions; however, in Fig. 1. It is essentially a d.c. ampli- tion goes off the air, the 6SJ7 conducts the longest average recording time of fier with the 6SJ7 drawing enough cur- more heavily, making its plate less posi- most of these instruments, without re- rent to reduce the plate current of the tive. The grid of the 6J5 is cut off and threading, is one hour. It being impos- sible to predict when a call will be re- ceived over the radio system, the re- corder is normally run continuously to assure a record of all transmissions. D5 r¡1 +.5 This results in miles of dead wire and METER JACK 161l numerous later hours wasted in play- ió1 I6MA d I HEN SIDE OF 17V AC RELAY Io back monitoring. Also, because of the I .1 necessity of changing wire spools every PLATE TRANSI I 2._T T r 13. I `CVR OUT 5 I hour, the recording equipment must be 1 .02 a yI RY2 J 0 L' placed in the dispatch room so the op- REMOTE AMP L_.1 .L 5 t 6 I erator may have access for servicing. JIQ DoT Ì Satisfactory operation may be impaired TO AF IN OF RECORDER L because of operator failure in attending 52 the equipment, especially in the event of EI. 6.1K 7. K .005 irregular traffic in which the personnel L RECORDER MOTOR TO 117V is involved. SEE TEXT 100W cm The keying device shown in Figs. 1 and 2 was developed to turn on the re- 117V.. TO RECORDER AMPL corder whenever a signal is being re- ceived or transmitted. When the keyer .GND SIDE OF LINE is used with a recorder, several hours 1 -and often days -can be reduced to one IIIVAC SI ON R3 hour of continuous recording. The net a ° recording time will naturally be influ- enced by the amount of the traffic load on the net. Fig. I- Receiver develops voltage to cut off 6SJ7 and trigge relay in plate circuit of 6J5. The device described was designed to work in conjunction with a Motorola FM 30 -40 -mc receiver and associated transmitter, one of the many popular brands of emergency radio equipment. There should be no serious difficulty in adapting the keyer to operate from practically any receiver, including AM a.v.c circuits. However, to design such an instrument to operate from all the many types and makes of receivers would be highly impractical from a field service standpoint, especially inas- much as one radio system will not or- dinarily employ more than one type of manufactured equipment. The greater majority of emergency services now use or intend to use, frequency -modulated equipment. There- fore, the discussion of the simple cir- Chief, Communications, Florida Highway Patrol. Tallahassee, Florida Fig. 2 -This 3 -tube relay unit operates recorder when a signal is transmitted or received. NOVEMBER, 1948 lerricim.' 30 The listeners must be trained -they are played through the signal generator. important, of course, to leave the volume have to know what to listen for and how The standard of comparison (the "other control strictly alone during this test. to describe what they hear in terms of radio ") may be an audio amplifier. The An easier but less informative way to treble, bass, muddiness, brilliance, fuz- British HMV and Decca records have judge the frequency -response would be ziness, tinniness, boominess, presence, outstanding fidelity. to connect an a.c. voltmeter across the and sometimes in unprintable terms. It The record -playing equipment used in loudspeaker terminals. The voltmeter is best to have one or two other radios this laboratory is a Rek -O -Kut tran- readings (converted to decibels) may to compare with the one being tested. scription turntable with a Gray phono then be plotted on graph paper. This The listeners should be blindfolded so arm and a G -E cartridge and Gray pre- test does not take the speaker into ac- that they are not influenced by knowl- amplifier. These can be switched from count, of course. the signal generator to a Fisher ampli- In the listening test, pay attention to fier and a Stephens co -axial speaker in sibilants -they should be audible, but a bass -reflex cabinet for comparison not exaggerated. As an over -all test for listening. trebles, triangles will be completely in- audible on some radios. A record with a Testing FM and television sets good bass to listen to is the Victor re- Tests of FM radios are quite similar cording of the Lt. Kije Suite, side 4. The to those for AM sets. The frequency - tympani are completely inaudible on response test differs mainly in the fact radios with poor bass response and too that an FM signal generator is used - loud on boomy ones. the Boonton 202 -B. Since this does not The sensitivity of an AM radio is usu- have a built -in pre -emphasis circuit, an ally given in service notes as the voltage external one is attached between the on the antenna terminals. This is all audio oscillator and the FM generator. right for checking whether the set is in Also, instead of a transmitting loop, a proper operating condition. As a matter dummy antenna is used between the sig- of fact, it has been recognized for some nal generator and the receiver. time now among radio servicemen that In measuring the sensitivity of an FM the easiest way to locate hard troubles set, there is a choice of several kinds of is, not to measure d. -c. voltages and re- sensitivities as defined in the IRE stand- sistances all over the place, but to make ard. From a home listener's viewpoint over -all gain measurements with a serv- the quieting signal sensitivity appears ice oscillator and an r.f. vacuum -tube to be the most appropriate, since it voltmeter. Of course, for this purpose measures the sensitivity when the audio one must have nominal gain figures for signal is 30 db stronger than the back- each stage. Such figures nowadays are ground noise. obtainable from the better service notes. One very bad fault of early postwar For evaluating two radios to find out FM radios was frequency drift with which is more sensitive, the loop an- time and frequency shift with changes tennas must be included in the test. This of line voltage. These have been largely may be done by placing them one by one overcome even in the cheaper sets, but in exactly the same position on the table the listener should still be on the look- or on the floor, so that their loops are in out. As far as drift is concerned, the exactly the same position. The set that listener is probably interested in know- can bring in the weakest station the ing whether he has to retune during the clearest is the more sensitive one. In first half hour of listening (by that time making this test, be careful that there is chances are that he will have tuned to no metal table, metal floor or wall in the another program anyway) and whether vicinity since results will then -to a he has to retune the next clay after turn- great extent-depend upon which radio ing off the set in the evening. These has its loop of the latter method mount- is mounted in a rack. Automatic ink recorder facts can be determined the hard way ed so as to be farther from the metal. edge of what radio they are listening to. -as outlined in the standard, by plot- One test that cannot be made by Since the listeners are human beings ting an oscillator frequency -drift curve actual comparison of two sets is the in- and not indicating instruments, their -or by simply listening. The results of terference- rejection test, that is, unless ratings have most value when they are the latter method are even more signifi- the i.f.'s are at exactly the same fre- unanimous. If all the listeners agree cant because drift by itself is not ob- quency. The interfering station may be that a radio sounds bad, the inescapable jectionable-it is the audio distortion at just the right frequency for one set conclusion is that the tone really is (if any) resulting from drift. and not for the other, while it is the poor. second set that is really bad. If the two Listening to radios must be done at Service shop tests i.f.'s have been aligned to exactly the both ends of the radio dial, since the The average serviceman can perform same frequency, then at least the image tone at the two ends may be different in similar tests with a minimum of equip- interference and i.f. interference fre- AM sets. It should be done on a number ment, though with less precision. quencieswill be the same, and a compari- of different stations, because all stations For frequency-response charting, one son test would be valid. Again, if the are not operated the same way with re- can use a service oscillator if it has con- test is made during the day, there may gard to frequency response, hum, and nections for external modulation. Unfor- be no interference on any set. Listen for distortion. It should include different tunately too few servicemen and experi- interference after sundown. kinds of selections, such as male and menters own an audio oscillator. If none A very enlightening analysis of inter- female speech, vocal and musical pro- is available, the cheapest thing to do is ference is published by RCA Victor Di- grams. Live programs are best. to buy a frequency record (see page 46, vision, Camden, N. J. (Interference An- In listening to midget radios the most October issue) and play it through a alysis and Its Radio Reception Efjectsby important single requirement is that wide -range pickup into the external IV. J. Zaun). It gives the i.f. frequencies the radio reproduce sibilants. If you modulation connections of the service to which radios in given cities should be can't hear the s's, don't bother buying oscillator. The relative loudness of the aligned to avoid interference. Service- the radio. different tones as they come from the men might avoid a lot of birdie troubles Another way to set up listening tests loudspeaker may be checked with an if they followed such a chart and used is to broadcast your own test programs. amplifier system of known flat char- one of the crystal service oscillators for For this purpose high -fidelity records acteristics and an output meter. It is exact aligning to the proper frequency. RADIO- ELECTRONICS for nervichas 129 the output started dropping at about sired signal, while the worst one could the signal generator output is increased 2,000 cycles; and by the time the audio not stand i.f. interference 13 db lower from this point, the signal -to -noise ra- oscillator had reached about 5,000 cy- than the desired signal. tio improves; and if it is decreased, the cles, there was no output at all. Taking It was also found that on some radios signal -to -noise ratio becomes worse. The the 10-db -down point as a reasonable the selectivity was so good that an ad- field strength (in microvolts per meter) jacent signal (10 -kc separation) could about the receiver loop at which the 0000000000000000 be as much as 4 db stronger than the signal -to -noise ratio is 16 db is taken desired signal, while on others the ad- as a measure of the usable sensitivity of jacent signal had to be 12 db weaker the radio. This is usually less than the 1 ARM not to cause interference. absolute sensitivity, but the usable sen- I no11111A!ii The interference rejection tests are sitivity has more significance for the 11111 11 1/1111a1Gr1 performed in slightly modified forms listener to local broadcasts. The abso- image be in- i 111111i111tlI W for three types of interference: lute sensitivity figure might of interference (birdies), adjacent -channel terest to long -distance listeners, but I 111111E1 111111 11 interference, and i.f. interference. For even so, the noise in some expensive IlllllM 111111 1 the i.f. test the desired signal and the radios makes them completely useless I 1111111'a 111111 f test radio are both tuned to the low - with the sensitivity and volume controls frequency end of the broadcast band. turned fully on. Fig. 2- Sample receiver response curve chart. Sensitivity Listening tests measure response, the radio The sensitivity of a radio is best test- The tests so far described are the of limiting laboratory might be said to be good from 150 cycles ed under operating conditions -not at most important of the tests home radios. These to 3,300. This was a good table -model the antenna terminals but through the performed on tests very in an shield- radio. Good console FM radios will go built -in loop antenna. The setup is take place electrostatically both lower and higher. similar to the frequency- response test ed room, which also must be sound-iso- shown in Fig. 1. The main difference is lated so that outside noises don't get in Interference rejection that no recorder is used. The transmit- and sound- treated so that the sound Another thing that affects the way ting and receiving loops are placed very doesn't bounce around inside the room a radio sounds is its liability to inter- carefully so that they are exactly 50 cm too much. lis- ference from stations other than the one apart and so that each is at least 5 feet A radio must also be subjected to to which it is tuned. A -gen- away from the metal walls of the test tening tests. A frequency response two- signal measurements (at erator, interference- rejection test imi- booth. The standard -signal generator is curve and distortion tates actual listening conditions. The 30% modulated with the random -noise the present state of the art) do not sounds good or radio is tuned to one signal generator, generator. The volume control of the tell you whether a set and the other is cranked its receiver and the output control of the bad to the ear. For listening tests a through have some range to find interfering frequencies. standard -signal generator are then ad- room is needed that does justed until the audio signal is 16 db reverberation-like a typical living The "desired- signal" generator is page) tuned to a clear channel mid -band, and stronger than the noise. Naturally, if room. (Continued on following the radio under test is tuned to it. The signal is adjusted to be strong enough to be usable on the particular radio (16 db signal -to -noise ratio). The volume control of the radio is adjusted for av- erage loudness (80 db on the 40-db scale of the sound -level meter). The modulation on the desired signal is then turned off, and the undesired signal is turned on and cranked through a wide frequency range to catch interference. If interference is heard at any spot, the generator is stopped and its output re- duced until the interference practically vanishes. The ratio of the outputs of the two signal generators is then a measure of the goodness of the radio as regards interference rejection. In other words, the bigger an undesired signal must be (compared to a desired signal) to pro- duce interference, the better the radio. Signal ratio is expressed in decibels. In testing a group of 14 expensive 1948 radios, it was found that on the average it took an interfering image signal 30 db stronger than the desired signal to cause interference. However, on the best of sets there was inter- ference only if the signal was 60 db stronger, while on the worst a signal 9 db stronger caused interference. In the same group of radios the best radio could tolerate an interfering sig- nal on the intermediate frequency as much as 18 db stronger than the de- Photos ron rira., of Conan torrs Union These are four of the high -precision gen- erators used in the laboratory for com- paring performances of receivers tested. NOVEMBER, 1948 Careful laboratory meas- urements determine the qualities of a receiver Laboratory technician tests a receiver. Sound- absorbing material covers walls and a metal shield encloses room. tadio Performance Tests THE worth of a radio receiver is altogether the characteristics of the ceiver is then tuned to that frequency determined by its performance, op- loudspeaker and the cabinet. (A radio and its volume control adjusted to av- erating convenience, durability, might be pumping both low bass and erage loudness. (The 40 -db scale of a ease of maintenance, hazards to the high treble frequencies through its out- sound -level meter is used for this pur- user and to other property, and appear- put transformer, but the speaker may pose.) The microphone is placed in front ance. Probably the most important point be unable to reproduce them.) of the speaker and the amplifier gain is is performance. Many radio repairmen A good acoustic frequency-response adjusted to deflect the recorder pen 15 and experimenters have sufficient equip- test on the other hand is very compli- db below the top of the graph paper. ment to make some of the tests which cated- mainly because of such things The audio oscillator is then cranked to show exactly how a radio performs. To as standing waves -and the equipment the 20 -cycle position, and the paper furnish some guidance on the testing is very expensive. A suitable compro- drum is aligned so that the pen falls on methods, we shall describe how one lab- mise may be reached by leaving the the 20 -cycle division on the graph. oratory compares different receiver loudspeaker in place and using a listen- The motor switch is then turned on. makes and models. ing microphone about 12 inches from As the audio oscillator dial passes 50. The most important aspects of per- the loudspeaker in a reasonably well 100, 200 cycles and so on, the pen at formance are tone, interference rejec- padded room. At such a small distance the same time passes the correspondimr tion, and sensitivity. The exact meaning from the speaker, the standing waves markings on the graph paper. In the of these and standardized ways of test- are relatively small at the microphone, curve of Fig. 2 the radio evidently had ing for them, are described in standards but the resulting frequency- response little or no output below 100 cycles. The published by the Institute of Radio curve is not entirely accurate. output then rose rapidly to a peak at Engineers. The first of these, issued in The fidelity test is best described by 260 cycles. At the high frequencies 1938 and still useful, is entitled Stand- a block diagram. Fig. 1 shows the setup ards on Radio Receivers: Methods of with names and model numbers of the GENERAL RADIO 605 -C Testing Radio Receivers, 1938. Another equipment used in the author's labora- STANDARD AM SIG.GEN. important one is on tory. Standards Electro- STANDARD LOOP,RMAI I - acoustics, 1938: Definitions of Terms, What the setup amounts to is a broad- Letter and Graphical Symbols, Methods cast transmitter (the signal generator), of Testing Loudspeakers. And there is a receiver, and a listening microphone. RANDOM NOISE GEN the latest one, Standards on Radio Re- The transmitter is modulated by an ceivers: Methods of Testing Frequency - audio oscillator which is cranked by a Modulation Broadcast Receivers, 1947. motor through the whole audio -fre- RECEIVER UNDER TEST These standards are highly recommend- quency range -from 20 to 20,000 cycles. ed to anyone interested in radio receiv- The same motor pulls the frequency- ers. They have been published as sepa- response chart under a pen; the pen rate pamphlets at 50 cents each by the rides up and down on a moving strip of GENERAL RADIO 759 -8 Institute of Radio Engineers, Inc., 1 graph paper as the loudness of the SOUND LEVEL East 79th Street, New York City 21. loudspeaker increases and decreases. SOUt{D APPARATUS FR -I METER Probably the most interesting test of The result is a curve like that shown GRAPHIC RECORDER BALLANTINE 1:21 a radio is measuring its frequency re- in Fig. 2. VTVM sponse. The usual way is to disconnect To perform the test the audio oscil- the speaker voice coil from the output lator (or else a special random -noise .ú transformer and connect a dummy load generator) is adjusted to give 30', DUMONT 241 resistor o -a of the same value as the modulation of the standard -signal gen- CRO loudspeaker impedance-across the out- erator; the latter is tuned to a free AUDIO OSC.4-- GENERAL RADIO 913 B put terminals. Of course, this leaves out channel somewhere in mid -band and its `SOUND ISOLATION AND ABSORPTION Head of the Electrical Division of Consumers output adjusted to give an average in- SHIELDED BOOTH Union of U. S., Inc.. New York. N. Y. put into the receiver under test. The re- Fig. I -Set up of the measuring equipment. RADIO -ELECTRONICS for gerricia8 I 27 example, metals in contact, plus modu- alignment, but no one was able to show former with a high -gain one, as, for ex- lation of a carrier wave by the rectified a satisfactory method. ample, replacement of the i.f. trans- signals. Station X's signal reaches some former in a cheap 5 -tuber with a high - BX cable, in a building, which is touch- Home -built receivers gain i.f. transformer taken from a por- ing another piece of metal, the bimetal Anyone who has used a single -tube table, may result in oscillation. Of contact acting as a detector and produc- regenerative set will recognize the signs course, too high an a.c. line voltage may ing an audio current. This affects an- and sounds of oscillation. High sensi- cause trouble, and an external antenna other carrier, which is modulated by the connected to the loop on the set produces audio current. Of course, it has its own .0001 ASA7 oscillation. modulation as well. The result in the A common cause is a defective or listener's receiver is two sets of voices omitted bypass condenser, particularly or music. 47 the screen bypass. Try substituting MORE TURNS The same phenomenon occurs in the GANG COND SECTION . condensers of known good quality for set when, in some circuit before the sec- those in the set. A cathode bypass con- TURNS ond detector, there is rectification of one LESS denser may need to have a larger ca- signal and modulation by it of a second pacitance or a condenser should be used carrier. External cross -modulation may Fig. 3- Grid -cathode winding is the largest. to shunt a cathode resistor where none be recognized by the fact that other appears in the set. Even so small an sets in the same location will have the tivity, instability, and a rushing sound omission as failing to shield the small same trouble. plus a squealing or squawking which openings in the top of an i.f. can may Several excellent articles going into increases with an advance in the volume result in oscillation, due to feedback the causes of interference due to har- control setting, mark oscillation in the to the loop. Be sure that every i.f. can monics and heterodynes have appeared wrong place in an a.c: d.c. set. How to is thoroughly grounded to the chassis. in past issues of RADIO- CRAFT, notably cure it? Sometimes rebuilding the home - Most servicemen familiar with small "Interference Analysis" in November, built set seems the only method. Screw- sets have found some that persisted in 1941. Cross -modulation was dealt with ing down one i.f. trimmer condenser and oscillating when everything was "just in detail by the article "Station Riding" unscrewing the other trimmer of the right" according to the instruments. which appeared in RADIO-CRAFT in Jan- same i.f. (stagger- tuning) or shunting Note in Fig. 3 that the tapped oscillator uary, 1945. the primary or secondary of the i.f. coil. coil has its outside ends across the vari- Oscillation is likely to be found in with, say, a 50,000 -ohm or higher re- able condenser terminals, and that a commercial sets when the location of sistance may cut the oscillation but larger portion of the winding is between wires has been changed by some service- naturally will lessen signal strength and grid and cathode of 12SA7 than between man and also in homemade sets. The selectivity. the tap and ground. A resistance check cause is generally more difficult to lo- Filter condensers again may be caus- will reveal the larger winding. cate and cure than either hum or inter- ing the trouble and should be replaced Sometimes omission of a line bypass ference. Perhaps the chief reason for for a trial or shunted with paper or will not only bring in clicks and hum oscillation in a well- designed set is at- mica capacitors. Proximity of grid and but will also cause oscillation. When the tempted alignment "by ear." Homer L. plate leads (particularly in the i.f. sec- tuning condenser is not connected to Buck and others after him caused con- tion), lack of shielding, or improperly chassis directly but through a fixed con- siderable controversy in older issues of grounded shields may result in oscilla- denser, sometimes a larger condenser RADIO -CRAFT by advocating "by ear" tion. Replacement of a low -gain trans- will stop oscillation. OFFER TO ORGANIZATIONS WICHITA SERVICEMAN IN BUSINESS 15 YEARS ADIO- ELECTRONICS has discov- ered that many active radio repair- men's associations are unknown outside a small area. It would be advantageous to these associations to he in touch with the larger radio technicians' organizations and federations, and with magazines which encourage radio servicemen's or- ganizations. It would be equally ad- vantageous to the larger organizations and State federations to he able to keep in touch with all the local associations. To establish continuing contact with all radio technicians' associations, RADIO -ELECTRONICS is offering a sub- scription to each active association of servicemen in the U.S. and Canada. To qualify, send us the names and addresses of your officers and a report of the latest meeting. RADIO -ELECTRONICS will also he glad to print any interesting events in the lives of the associations, such as cases of customers' complaints settled or other instances in which the association was useful to the local radio technicians or to the public. Write immediately and get your as- sociation's name on our roster and The photograph above shows the service bench of the Chase Radio Service, Wichita, Kansas. RADIO -ELECTRONICS in your library. C. F. Chase, the shop's owner, shown soldering a lead back in place, states that he has been will Lists of active local associations servicing for over 15 years, Because of his progressive business methods, the small shop lit be printed in the magazine from time is less than 100 square feet in area) provides a comfortable living for a five- member to time. family. First- quality parts are used, tube testing is free, and all the work done is g teed. NOVEMBER, 1948 26J Servicing Servicing a Noisy Set This article pires the causes and cares for hum. whistles. and cross -modulation By H. A. NICKERSON HUM-M-M. What shall we do minais, or there may be a leakage or age; it may bring in motor and other about it? First, test filter con- partial short there. Test all bypass con- noises. Most a.c. -d.c. sets have some sort densers in the B- supply. Test densers and try substituting similar or of line condenser. Check it. You will them for leakage with a milli - slightly larger capacitors of known good sometimes find that it has been omitted ammeter or with an ohmmeter. Test quality. The X's in Fig. 1 indicate com- or is defective. them for capacitance if you have some monest sources of hum; the ?'s less Sometimes one broadcast station will sort of capacitance meter. They may common ones. seem to have a carrier hum. This may test reasonably well, but a new pair will See if changing the location of the or may not be due to a defect in the set. sometimes work wonders on the hum. output transformer with relation to the Substitution is the real test for poor rectifier causes a reduction in hum. Image interference filters. Sometimes shunting each filter Sometimes a slight change in the place- Servicemen unit with a good paper or mica condens- ment of grid and leads remote from powerful plate -ahead of stations may not realize er of .001- to 0.1 -0 capacitance will do the second detector. particularly -will the troubles the trick. found in congested areas. A little con- cure hum (and oscillation). Some lead sideration So it wasn't the filter condenser? Test may be of superheterodyne principles too near the a.c. input line or will explain the tubes, particularly the output tube, the pilot light leads. the origin of the whistb If the negative heard on most d.c. five for leakage. A tube tester of modern de- return lead is connected to the chassis a.c: -tube sets. sign will generally show leakage. but through a condenser, try a different con- WEEI RCVR OSC WMEX try two other similar tubes in the out- denser of the same or larger capaci- 4605C -,ie-- 4605G ---+1 put stage to see if there is a change. tance. Addition of a cathode bypass, Maybe the set was designed with one of if there is none, or a new, larger con- Fig. 2 -WEEI is desired station, WMEX image. those old a.c. -d.c. chokes not intended denser, may cut hum. The location of In Boston. for instance. it appears to carry the milliamps at of plate current the plate condenser on the output tube one side Of WEEI, which has an as- required by a 50L6 plus the other tubes may be shifted so that the end away signed frequency of 590 kc. To tune in in the set. Or perhaps the filter choke from the plate is connected to cathode WEEI at 590 kv, the oscillator must be has shorted turns, or the hum -bucking instead of chassis, or vice versa. Some- 460 lie higher than 590, or coil 1050. There in a speaker using the field for a times connection of the cathode bias re- is a powerful station near Boston, choke is connected backwards. sistor and condenser to different spots WMEX, operating on 1510 kc. When The 35Z5 or other rectifier tube may on the chassis may result in hum. Shield- the set is tuned cause for WEEI and the oscil- a hum. Test the coupling condens- ing of tubes and proper grounding of lator is at 1050, the difference between er between second detector and output existing shields may be required. the oscillator frequency and WMEX's tube. If you are using an ohmmeter, It still hums? Get the wiring diagram 1510 -kc frequency is also 460, which is after one flicker of the meter pointer, of the set and hunt for omitted bypasses the set's i.f. So WMEX, being powerful intermittently touching the probes to and wrong values of condensers and re- enough to get the through the r.f. tuned terminals of that condenser should sistors. Figure that the serviceman circuit at the input of the converter, will not register any more flickers on a 10- who repaired it before you could have also he amplified by the i.f. megohm scale. and heard made a few errors which you have to in the speaker. See Fig. 2. This inter- Take a look at the pilot light and locate and correct. ference from a station whose frequency socket. Some other serviceman may have There may be some external troubles. is on the wrong side of the oscillator's is dropped soldering paste on the ter- The a.c. line may have too high a volt- called image interference. A slight change of the setting of the i.f.'s, use of 50L6 a wave trap. rotation of the set so the loop points another direction, or pur- II chase of a six -tube set, may alleviate the interference. If there is no antenna coil or external antenna, the wave trap must be something that affects the loop. Another loop, shunted by a variable mica compression condenser placed clos" to =.002 the set loop and parallel to it, may E6 4t- he tuned to cut down the signal from the interfering station. 50L6 12557 125A7 1250 Cross modulation 2 7 2 7 2 7 35Z 5 much has been written about cross- 4565C IF modulation. This manifests itself as SRSR FIX X a 450.4 background of unwanted signal which Xaver appears when n7V .05S. the set is tuned to a want- 7 ed signal. The cause often is external ® to the receiver. External cross modulation arises Fig. I -A typical a.c. d.c. set. X's mark the common sources of hum: l's occasional ones. from rectification (detection) by, for RADIO -ELECTRONICS for Amateur brackets for the mounting screws as loss connectors could be used. plate voltages, mounting of the various seen in the front view. This has to be Any good exciter delivering 10 watts parts to fit each constructor's ideas, clone carefully so that the amplifier will or more will drive this amplifier to full and so on, but the tuning unit sloes pro- go into the rack at the proper place. The output, even with 2,000 volts on the vide the basis for making a good final best way to do it is to actually fit the plates. The output coupling system will amplifier and most of the work, espe- panel to the rack, with any other rack - work into almost any coupling network cially the tough metal punching, is al- mounted equipment in place, and meas- or antenna with nonresonant feeders. ready done. ure for the holes. The ends can be cut Coupling should be adjusted until the Of course, some of the GI's who lived off a standard rack panel for the pur- cathode current is at its proper value with the BC -375 may think they would pose, but most of these are 'K inch thick, at resonance. This will be found in the prefer never to see the gadgets again in a fairly heavy gauge to cut with a hand tube manual. any form; but with ham electrons hacksaw. If a machine shop is available, The circuit is standard in every re- coursing through the coils and con- they can do the job. The heavier metal spect, so no trouble will be encountered. densers, the picture takes on a different will be worthwhile because of its ex- No doubt different arrangements will hue. For three bucks one has most of tra strength. suggest themselves, such as the type of the makings for a pretty good final am- Take one plate out of the center of plug used to carry the filament and plifier, even if it is a bit GI- looking. the stator and remove about 1,4 inch or more from the center of each side of the stator frame. This produces a split - stator condenser with about 55 µ11f per section. This is just right to tune the 55,u1 PER SECT,OII 6-turn amplifier coil to 28 mc. This coil SEE TEXT L5 LI SEE TEXT I,1 will be used as the push -pull tank coil o L3 of the amplifier, so place a tap at INPUT the center for B -plus. Push the link L4 10W OR MORE OUTPUT into the center of the form and remount .o 0 the switch, coil, and condenser. Con- nect one end of the link and the switch 5M arm to terminal on the right side of the case. The original oscillator coil and con- r* 3C24/24 G(2) RC denser will be used for the grid circuit 6.3v/6A DPDT SW of the amplifier. Remove two turns from + M-1.5nV/15oMA the winding and tap it at the center. z5 Wind a two -turn pickup link L1 around METER the center of the coil, using flexible GRID _ CATHODE wire. After remounting the coil, con- Fig. I -This simple push -pull amplifier can be built on few nect the 50 -µµf condenser across it, the TU -10 -B chassis in a hours. and connect the link to terminal strips mounted on the left side of the case. The link is used for connecting to a driver or exciter stage. Cut the shield plate into strips and drill mounting holes for sockets and other components as shown in Figs. 2 and 3. Bolt the strips in the case and complete the wiring. Connect filament plate, and ground leads to the heavy jacks in the rear or to a cable connector like the one behind the grid coil in Fig. 2. The .0004 -Icf, 5,000 -volt grid and filament bypass condensers are ob- tained from the tuning unit. (If you plan to modulate the amplifier, better use .O1 -µf filament bypass condensers. -Editor.) The r.f. choke was also taken from the original unit. The neutralizin3 condenser we used is a dual unit with Fig. 2 -This photograph shows the rotors connected with an insulated underside of the amplifier. The grid coil is at the left. shaft. Standard neutralizing condensers can be used if desired. Their value and plate spacing depends on the tubes and the plate voltage used. Capacitors variable between 0.25 -µpf and 4 Isµf are suitable for the 24G's. The voltage breakdown rating should be about twice the sum of plate and grid bias voltages to avoid the possibility of arc -over. A 100 -ma d.c. meter measures cathode and grid currents. When the meter switch is in the grid -current position, it is shunted across a 25 -ohm resistor. The shunt in the cathode circuit, Rl, is made by shunting enough No. 26 wire across the meter to make it read 300 ma full scale. Isolantite crystal- holder sockets were used for connecting the input and output links. Any type of low - Fig. 3- Looking down on the amplifier from the top. The original tuning condensers are used. NOVEMBER, 1948 2.1 Amateur Ten -Meter Final From TU -10 -B Metal extensions allow placing panel in standard rack. An excellent final amplifier can be built very cheaply fromom standard components of By L. W. MAY, W5AJG the surplus BC-I91 and BC-375 THE drawer -type tuning units from lows. Though the figures do not show it, panel. The link is inside the form at the BC -191 and BC -375 have been there is some overlap in the ranges. the cold end of the power amplifier coil. plentiful on the surplus market kc We selected 3C24/24G's because they for some time. These units, TU -5, TU-5 1,500 to 3,000 are efficient at most amateur frequen- TU -6, etc., contain a large number of TU-6 3,000 to 4,500 cies and will work well with the 1,250 - parts useful in amateur transmitters. TU-7 4,500 to 6,200 volt power supply we had available for They contain all the tuning circuits for TU-8 6,200 to 7,700 them. A number of other tubes -not an m.o.p.a: type transmitter using 211's TU-9 7,700 to 10,000 necessarily triodes-will work equally as a v.f.o. and single -ended final ampli- TU-10 10,000 to 12,000 well. The components in the tuning units fier. Available for less than $3, these are suitable for use in most medium - units have been purchased in large num- The number of the tuning unit is usually power transmitters. The variable con- bers by hams who have either converted followed by a letter that indicates the densers have a breakdown voltage of them to variable- frequency oscillators series of the transmitter for which it 1,500 volts or higher. Unless you have and transmitters or dismantled them was designed. There is little, if any, some way of finding out exactly what for the parts they contain. Here at difference between tuning units with the breakdown voltage is in the case of W5AJG, we converted a TU -10 -B to a the same number although they may be any particular condenser, it is probably 200 -watt final amplifier that works so TU -5 -A and TU -5 -B. Either the A or a good idea to keep the B- supply voltage well that we plan to build similar units the B will be satisfactory for conversion at or below 1,500. for the other amateur bands. For 90/0 to use as an amateur power amplifier. The amplifier uses a standard push - of the components needed for a 200 -watt The TU -10 -B was selected as the pull circuit (Fig. 1). It is simple and amplifier, $3 is not a particularly high foundation for the 10-meter amplifier. takes only a few hours to build. After price to pay. The oscillator tuning circuit consists of removing the top, bottom, sides, and There are 12 different types of tuning eight turns of No. 10 wire tuned with center shield, take out all components units in the series designed for the a 50 -uuf variable condenser; the power except the dial drives. Do not discon- BC -191 and BC -375. Since all of these amplifier circuit has six turns tuned nect the switch from the link coil. If look alike, be sure to get one nearest with a 116 -it sf condenser. Both circuits you plan to mount the amplifier in a the frequency you wish to use. The fre- are tuned from the front panel with standard 19 -inch relay rack, cut strips quency ranges most commonly available slow -speed dial mechanisms. The power from 1/16 -inch sheet metal and holt and most useful for amateur conver- amplifier coil has a tapped link connect- them to the ends of the panel to make sions are listed in the table which fol- ed to a six -position tap switch on the it 19 inches across the front. Notch the RADIO -ELECTRONICS for AMIN) 23 Besides the sale of hearing aids to in- free engineering service to their repre- dividuals, the Audiphone Company in- sentatives where a particular installa- stalls group hearing -aid systems in tion exceeds normal requirements in churches. A group hearing aid consists size and complexity. The manufacturer of a microphone at the pulpit and an will cooperate with the dealer in the de- amplifier which is usually concealed sign of special control panels, and will within the pulpit housing. A master furnish necessary wiring instructions cable from the output of the amplifier is and schematics. run beneath the church flooring for the To facilitate installation and service entire length of the room. From this work, manufacturers also publish serv- cable branches are tapped off, each lead- ice bulletins which contain trouble- ing to a pew section and coming to a re- shooting procedures, normal wiring ceiver jack. The hard -of- hearing mem- methods, and schematics. Since each bers of the congregation are furnished manufacturer sells cable, junction with individual earphones which they boxes, and other accessories necessary plug into the jacks under the pews. Vol- for the best hookup of his particular ume can be regulated to suit the individ- line, the radio repairman finds the ual by a special volume control in the transition to intercommunication system cord running to the plug. Over -all vol- and PA work a comparatively simple ume can be adjusted at the amplifier. matter. This company has also had a number of calls from clinics, schools, and otol- Other sound work ogists for audiometers, devices which are Another branch of sound which shows essentially audio oscillators calibrated promise is the rental of or wire tape Radio to read hearing loss. These come in units recorders to schools and clinics, where Service Shop does large sound business. to read individual hearing losses as well they have proved valuable in speech factories, to the use of intercoms in the as in models designed to read the hear- study. home for baby -watching or basement ing of groups. The popularity of electronic organs workshop communication. For its intercom business, the Audi - and organ attachments for pianos has Sound offers a wide variety of po- phone Company depends on newspaper opened another field for the radio re- tential money makers for the radio re- advertisements, telephone directory list- pairman. The Radio Service Shop has pairman. When you've successfully de- ings and some direct -mail literature to already contracted with several manu- veloped a particular line, you'll agree potential customers. Word -of-mouth ad- facturers for local service and repair. with many others who have built suc- vertisement by satisfied customers has Many other possibilities exist, from cessful sidelines that "sound is a sound also been a contributing factor in sales. wired music for hotels, restaurants, and business." They have felt no need to list intercoms on their store show window, feeling that they are not an over- the -counter sales item. Besides advertising locally, they have the benefits of national advertising, for most intercom and hearing aid manu- facturers pass on leads which result from inquiries. When such leads come in, the customer receives a personal visit from one of the owners of Audiphone. A demonstration is a great aid in clos- ing sales. The repair department is manned by two competent technicians who handle all the repair work necessary on inter- coms, audiometers, and hearing aids. Because of the small size of hearing aids and intercoms, the repair space is not as large as would be needed for radio serv- ice work. Desks are used because of their convenience; the drawers are ideal for storage of small replacement parts. The test equipment used here is sim- ilar to that found in any radio shop- multimeters, vacuum -tube voltmeters, 'scopes, gain- checking devices, and sim- ilar items. The two organizations mentioned are representative examples of how much business there is in sound. The newcom- er would do well to secure literature from various manufacturers and fa- miliarize himself with representative standards and variations. A franchise for the sale and service of public ad- dress systems or intercommunicating systems can then be obtained from the manufacturer or distributor whose prod- ucts are considered the best in their price range. (Some manufacturers sell directly to appointed representatives while others work through distributors.) In most cases manufacturers furnish Intercoms, hearing aids, and amplifiers are tested and repaired on Audiphone's bench. NOVEMBER, 1948 Any serviceman has enough knowledge to enter the PA business. Rental and service help bring in extra cash. come from it often exceeds that from their radio repair service. Both Van Nest and Brindley are agreed in attributing their success to the fact that they concentrate on giving good service. They take turns personally supervising the installation of their pub- lic address systems, making sure that the microphones are placed properly and that the gain of each is sufficient for the use to which it will be put. Main store entrance of the Audiphone Company. Hearing aids and intercoms are sold. Intercoms and hearing aids Another store which does exceptional - !y well in the field of sound is the Audi - ;dione Company, also of Trenton, which Teals exclusively with sales and service ,,f intercommunication systems and [INH NEAPS VElU nearing aids. This business is a good example of what can be done with sound. In a little ever six years the volume of business in ales and repair has reached enviable proportions. They have consistently ex- íf YUlE VIINEY ceeded their yearly quotas for Western Electric hearing aid sales, and have in- stalled intercoms in country clubs, state offices, business places, stores, and insti- By MATTHEW MANDL tutions within a 50 -mile radius of their location. SOUND- either as a sideline or an repair business profitable and decided independent business -offers un- to expand. Their shop was too small to ,Isual opportunities for the radio allow them to go into radio sales, so, The repairman. It provides a means after some debate, they decided to take for augmenting his yearly profits, and on PA systems as a sideline. The equip - RADIO SERVICE at the same time opens another avenue ment required no floor space in the shop along which his business can expand. and could be stored away when not in SHOP Since the average serviceman is already use. RADIO and ELECTRONIC quite familiar with audio amplification, They acquired a 10 -watt amplifier, TECHNICIANS he will encounter no difficulty in work- two microphones, and three speakers. ing with public address systems, inter- To start off, they ran an occasional 24 YEARS EXPERIENCE coms, or any other sound equipment. newspaper advertisement and lettered E I S I O N The most popular sideline with the "PA Systems" on their delivery truck. T E L V radioman today is the renting and sell- A box in the classified section of the SOUND EQUIPMENT ing of PA systems. This does not mean, telephone directory also helped. From DAVID VAN NEST however, that it is the only one with the first. they found their investment 611SON 1RINDLEY money-making possibilities. Many shops paying dividends. have clone exceptionally well in the sales About a year after their entry into 2 -4742 and service of intercommunication sys- the PA business, their entire sound sys- TRENTON teins, the gross income from which often tem was burned beyond repair at an 11011 /2 Hamilton Av. exceeds that secured from PA system amusement park fire. rentals. Others have done nicely renting They bought new and better equip- large phono amplifiers to lodges, ment, until today they have half a churches and schools for their special dozen indoor -type PA systems, ranging AUDIPHONE CO INC events. Still others have concentrated on from 10 to over 50 watts in output pow- servicing office sound equipment, such er, and three portable amplifiers, two of INTERCOMMUNICATING as dictating machines. There are also which were built in their own shop. SYSTEMS Etc good markets for tape and wire record- A number of lodges, churches, and For ()floc", Horpt ta I s, Worehouc es, SOUND EQUIPMENT er rentals, as well as the of civic groups have become regular cus- furnishing AUDIO ENGINEERING SERVICE recorded music for factory workers. tomers of The Radio Service Shop. The TRENTON. N. 1. A good example is The Radio Service owners make a specialty of repairing 244 E Sucs Trenton 3.93u Shop operated by David Van Nest and permanently installed PA systems, and Gibson Brindley in Trenton, N. J. Short- their public address business has ly after opening the shop they found the reached such proportions that the in- These ads appear in the classified phone book. RADIO -ELECTRONICS for Editorial 21 1 HOW TO BREAK INTO SERVICING A new era in servicing lies ahead . . . By HUGO GERNSBACK WHEN the radio boom first started in the early able servicing information. Then there are several excellent 20's, servicing of radio receivers was an entirely servicing organizations that make a specialty of publishing new development. The then radio experimenters, and supplying such data to servicemen at a reasonable cost. radio amateurs, and other radio enthusiasts soon Experience with actual radio and television receivers is, heard the servicing call. As the new radios went out of however, a paramount requirement. It takes some time order the laymen owners could not put them into condition before the average new serviceman becomes proficient in again and it was not long before radio technicians who locating the various troubles -it cannot be learned over- understood something about the intricacies of radio sets night. Furthermore to do efficient servicing and make a were called in. That was the birth of radio servicing. living from it, it is of the utmost importance that you have At present we are again in the midst of another -but the proper tools. The days of the screw- driver- and -pliers- much greater -radio boom. This time it is television. serviceman are gone forever. Modern receivers, particularly Authorities are convinced that during the next few years television receivers, are most complex. To work efficiently there will be a tremendous upswing in the servicing indus- and hunt down receiver failure in a minimum of time, good try, far greater than was ever the case with AM receivers. servicing instruments are an absolute necessity. The new Millions of new television receivers will be in use in the serviceman requires as a minimum the following: near future. Indeed, it is quite conceivable that at the end A 20,000 -ohm -per -volt multimeter with HV range or of the next ten years the television receiver will have re- multiplier to 8 or 10 kv. placed to a great extent the present -day radio receiver. Standard signal generator with a.f. output terminals. The editors are now constantly in receipt of letters from Tube tester, mutual conductance type. men anxious to climb on the television bandwagon in one VTVM (high -frequency type). way or another and those who wish to get in on the ground Scope, with triggered sweep, blanking and calibrated floor in television servicing are no exception to that rule. scale. Here is an excerpt from a letter received recently: FM and TV sweep generator (best available). The above represent only a modest beginning. Later on Editor, RADIO- ELECTRONICS: the experienced serviceman will wish to add other items "Just a few lines to you from a friend and a sub- to help him work more efficiently and guarantee him a better scriber of yours since my early school days. I am 38 living. today. If you have a reasonably good radio background it should by any means but I "I am not a radio engineer not take more than three to four months to become a self - am also no tyro -how could I be with all the informa- supporting radio and television serviceman. But remember tion you and your staff have crammed into my head this important point: even if you are the greatest radio through the years? wizard in the country you will still not be a success unless "Have always used Radio as a hobby while working you have the ability to sell yourself to the public. The inde- at something else. pendent serviceman nowadays in many localities is often "If I don't get into radio and television servicing now under a cloud. This is due to no fault of his, but because a I never will. I am not trying to say that I know all small minority of unscrupulous servicemen -the outer that there is to know about Radio. But I can get along; fringe -are exploiting and have exploited the public. It is my education is fairly good. this very small minority that has given the industry a black "What are your suggestions? eye in the past. It takes no more than five per cent of such "When you get a free moment, please drop me a men to give the whole group a bad reputation. line. I grew up with the name Gernsback as familiar The new serviceman should always remember the cardinal to me as Babe Ruth to baseball fans. rule that honesty is the best policy in the long run. When John J. Bergen, Paterson, N. J." an unscrupulous serviceman charges $5.00 or more for The present time, indeed, is a most auspicious moment cleaning the contacts of a tube, or tightening a loose wire to start out in a radio- television servicing career. Further- connection, such tactics invariably come home to roost and more in order to become established in the industry there plague him and his industry. Sooner or later the public are no great handicaps, no secrets. Nor does it take a catches on to these underhanded methods and becomes not great deal of money. If you have a good radio background only suspicious, but antagonistic towards the whole servic- -you need not be an engineer -if you are industrious, if ing trade. The serviceman who is successful in the end is the you are willing to study and work hard, you should be able one who makes no charge whatsoever for little jobs such to make a good living in television servicing. as the ones mentioned above. (It is presumed that the The first and most important requirement is good radio receiver was taken to his shop; if he was called in by the technical knowledge. This can be gained from schools or set owner, then a small servicing charge is in order.) Such by studying radio publications and textbooks. The second is treatment will be remembered and when a serious repair actual and concentrated experience in repairing radio and comes along next time, the set owner will have confidence television sets. If you have a good theoretical radio knowl- in the serviceman -an asset that will pay big dividends in edge, if you understand circuits, if you know a fair amount his future. of mathematics, you should have no trouble in getting along. In short, if you wish to make a success in servicing, it can To be sure, you will require the service manuals and best be summarized in the following five points: 1. (.00d servicing data of the various receivers. This information radio knowledge. 2. intelligent work. 3. Honesty and fair fortunately is tendered to you nowadays on a silver platter. play. 4. Good personal appearance. 5. Keeping everlastingly The radio set and television manufacturers all issue valu- at it. NOVEMBER, 1948 20 .. "PENNY-ANTE".pE Stak WhyW play is at stake? your business when "bar - or unknown by buying inferior keep rep eating is why we omers good-will, gains. Thais de- A good reputation, be Reputation dtrthe b est tmeans stbugño "Your best!" A many deserve the built by single dissatisfied cus- by is too valua- Sprague. reputation Your P pennies "saved. forchefew bicble to risk Midget Dey Eleclrolytic,l SPRAGUE TM TUBULARS- The fin? truly practical MOLDED Pope, Tub., lor Capacitors, SPRAGUE ATOMS-Universal SPRAGUE LM- Univo,al Mounting Replacement./ SPRAGUE EL- Self -Moen? ng Midget Can Type/ THESE SPRAGUE PRODUCTS ARE SPRAGUE for d UNCONDITIONALLY GUARANTEED! es, you re Right! When used at their capacitance and voltage ratings, these K OW Sprague Products are unconditionally guaranteed to render satisfactory performance. *KOOLOHM CAPACITORS RESISTORS SPRAGUE SPRAGUE PRODUCTS COMPANY, North Adams, Mass. (JOBBING AND DISTRIBUTING ORGANIZATION FOR THE PRODUCTS OF THE SPRAGUE ELECTRIC COMPANY) RADIO -ELECTRONICS for 19 JP PISCES