120 Cohassett St Pittsburgh11 Pa Here's Why Vibrators Are Quiet, Reliable and Longer Lasting!

aaíTtliitaaaass re3« aft=I=an aa 4'14 agaaaa :aAnts

Vol. 14 AUGUST, 1949 No.8 CORNELL-DUBILIER ELECTRIC CORP. Hamilton Boulevard, South Plainfield, N. J. Sec.562, P.L.&R. U. S. POSTAGE POSTMASTER:Ifundeliverable for any reason, notify stating reason, on Form 3547 postage for PAID which is guaranteed. So. Plainfield, N. J. Permit No. 1

MR BLRTR ÁM B HOFFMANI-11 120 COHASSETT ST PITTSBURGH11 PA HERE'S WHY VIBRATORS ARE QUIET, RELIABLE AND LONGER LASTING!

C -D designed electronic micrometric equipment re- moves guesswork in contact point setting and assures consistent high quality.

Exclusive C -D polepiecedesign and armature weight resultsinaperfectly -balanced unit with greater efficiency.

Exclusive C -D base mounting results in "a full floating unit.That's why C -D vibrators last longer.

Unit completely enclosed in new floating sock- an exclusive with C -D vibrators.Eliminates usual difficulties found in other vibrators.

New stack design will take peak voltages of even 4,200 volts with no damage to vibrator.

For the best in Vibrators insist on C -D's. Now at your local C -D distributor. 1949 Or write for full details to Cornell- Dubilier Electric Corp., Dept. H09, South Plainfield, N. J. Other plants in New Bedford, Worcester, and Brookline, Mass.; Providence, R. I.; Indianapolis, Ind.; and Cleveland, Ohio. A GREAT NAME IN CAPACITORS A GREAT NAME IN VIBRATORS.

For your nearest C -D Distributor, consult your local Classified Telephone Directory THE HOW AND WHY OF VIBRATORS History and Development

PART II

Intheprecedingissuethebasic switch and magnetic coil, energizing theory upon whichthesatisfactory the latter and pulling the switch arm operation of a vibrator depends was toward it. This opens the transformer developedandillustrated.Itwas circuit and releases the magnetic pull shown that in order to have a satis- of the switch coil, allowing the switch factorysubstitute forasetof "B" toclose, again starting the cycle of batteries,acorrectly designed com-events just described. So long as the bination of certain components was battery has energy available the switch required. This combination consisted will continue to operate at a regular of a low -voltage DC source, such as rate, this depending upon the rate of a storage battery, an inverter, a transformer, arectifier, and afilter.The inverter was the only unusual com- VI BRATOR ponent in this group, and was required becausethetransformercouldnot II 1 50 function on the DC from the battery. Thus, a device must be inserted be- o

tween the battery and the transformer to change the character of the DC so 6 V. thatitwould appeartothetrans- former to be AC. The vibrator is to III be the inverter in the combination of VIBRATOR POINTS OPEN components listed abode. 15

Lc) i VIBRATOR WAVE Our previousdiscussionalsode- J 10 (Er) veloped the necessary interdependence o of the vibrator, transformer, and the "buffer" capacitor, (where the vibrator had progressed as far as the pulsating VIBRATOR key in Figure 7), in the correct elec- POINTS CLOSE WAVE IF VIBRATOR trical operation of the power unit. We POINTS WERE KEPT were at the point where we were ready CLOSED LONGER to convert the manual key into an auto- matically -actuated vibrating switch, or Fig. 8. vibrator, and discuss its performance in the circuit. build-up of current in the circuit and Now refer to Figure 8. The circuit upon the mechanical characteristics of shown here is somewhat different from the switch. Thus the VIBRATOR be- that in Figure 7. The key of Figure 7came a reality, although the similarity has been replaced by a switch con- to the bell -buzzer of Figure 3 is readily trolled by the magnetic coil in series noted. with the battery and transformer pri- Another change shown in the circuit mary.When thebatterycircuitis of Figure 8isthe moving ofthe closed,themagnetizing currentfor Capacitor "C" from its former location thetransformerflowsthroughthe across the primary terminals to a new

AUGUST, 1949 Page 3 location across the secondary terminals direct current to a load connected to of the transformer.Because the pri- theterminalsmarked"B+"and mary and secondary coils are usually "B-". If the rectifier tube is properly closelycoupled,theeffectofthe polarized for the primary battery con- capacitance across the secondary willnections, it will conduct current dur- be almost perfectly reflected into theing the portion of the cycle when the primary.However, since the tuningvibratorcontactsareclosed,(the effect of the secondary coil as com- square -toppedpulse),and afairly pared to the primary coil is dependent good efficiency will be realized.If upon the square ofthe number ofthe battery polarity is reversed, how- turns for eachcoil,(square of the ever,thepolarityofthesecondary turn ratio), the value of capacitancevoltage will be reversed and the recti- needed for proper equivalent tuningfier tube will now conduct only dur- usually is much smaller for connection ing the portion of the cycle when the in the secondary than for in the pri- vibratorcontactsareo p e n,(the mary circuit. For instance, if the turn -rounded pulse), and the only energy ratio is 50, the square of this numberavailable will be that storedinthe is2500,andthesizeofcapacitor core of the transformer andinthe neededforthesecondarywillbe buffer condenser. This results in low 1/2500 of that needed in the primary. output capabilities and poor efficien- The waveform resulting from the cies. circuit shown in Figure 8 is illustrated Several manufacturers produced "B" in the accompanying graph. The vi-eliminators ofthistype, which met brator characteristics of frequency and with rather wide acceptance and gave time efficiency can be so matched toreasonably good life and performance. the transformer characteristics and the One radio manufacturer produced a capacitance of "C" that the contacts open before the transformer core be- receiver in which he built in the power gins to saturate and close with theunit and thus made the forerunner tuned -circuit oscillation voltage prac- of the present type of set. There were tically equal tothe battery voltage. several inherent drawbacks to such a This circuit characteristic protects thedesign of power -unit, however, and it vibrator contacts from excessive spark- is desirable to outline these in order ing and electrical wear. If we connect to see the reasons for future develop- a rectifier tube and filter to the second- ments.The first,and possibly most ary of the transformer, as shown inobvious, difficulty lay in the method the circuit of Figure 9, we can supply ofdrivingthevibrator.Sincethe

Es VOLTAGE ACROSS SEC. WINDING VOLTS

VIBRATOR Ir111.ef CURRENT IN SEC. WINDING r i I i I I I I I I m t.. J 1=

T y' T To PR I. 8 -

Fig. 9.

Page 4 THE C -D CAPACITOR driving -coilwasinserieswiththe After considerable thought, a simple primary circuit, all of the magnetizing change in the design of the vibrator and load current passed through theenabled the engineers to correct the coil and thus produced the magneticdifficulty encountered in driving the pullaffecting the movement ofthe vibrator.If we did not want the unit reed.Therefore,ifthe load currentto be sensitivetoload current, we changed, the magnetic pull changed should make its driving power depend- anddirectlyaffectedtheoperating ent upon the battery voltage instead, characteristics of the vibrator. Underwhich remains substantially constant. a no-load condition, the pull would beBy supplying a high -resistance voltage slightandthereedwouldmerely coil instead of the low -resistance cur- flutter.Under an overload condition, rent coil, and connecting this across the pull would be great and the reed thevibratorcontactsinsteadofin amplitude would be excessive. Underseries with them, we can make the both conditions the tuning of the cir-unit drive independently of the load cuit would be bad and severe sparking current.InFigure10 we seethis would result.With excessive ampli- arrangement, where the coilis ener- tude, reed breakage would probably occur.Thus, for a given design of power -unit, only a narrow range of loads could be handled.This was I I I partially met by the introduction of a o series of units with different values of outputloads,each having avi- brator with a coil designed for that load.These varied from a low of 1 about 135 volts at15 ma to a high I1 of 180 volts at 40 ma. The no-load SERIES COIL condition was sometimes taken care of by the use of a "phantom load", which was a resistor connected across the output until the set load became o large enough to operate a relay having a coil in series with the output circuit. o The fact that the system operated "half -wave" was anothersourceof 1 difficulty.The transformer core was SHUNT COIL subjected to pulses of DC load current, with the result thatinefficient Fig. 10. transformer action occurred, the core having a large residual magnetization in one direction.Thisfactlimited gized when the contacts are open, and the amount of energy that could be is shorted out when the contacts close. transferredtotheloadcircuit.In One other major differenceis now addition, it necessitated the use of an involved.At rest,the vibrator con- exceptionally large transformer in or- tacts must be open in order to start der to operate at low flux -densities. the vibrator with the shunt coil, while The other problem has already beenthey must be closed in order to start discussedina preceding paragraph, the vibrator with the series coil. where the relation between the polar- the To correct the inherent difficulties ityofthebattery andthatof thecircuithalf -wave, rectifiertubeaffectstheunit'seffi- ofoperating ciency.A method of providing for however,meantthatsomemeans this difficulty had to be arranged for,would have to be developed to change suchasswitchingtheinputleads, tofull -wave operationifallof the switchingoftransformerterminals, desirable features were to be secured. etc. If we wind the transformer coils in

AUGUST, 1949 Page 5 duplicate and place them on the samenected to the transformer, which can iron core, we can cancel the residualbe so selected that the rate of oscilla- magnetism caused by the pulsating DC tion on the break of each half -cycle if we pass the current through onewill permit filling in this gap with a set of coils in one direction on onevoltage reversal. Thus the trace shown half -cycle and through the other setin the graph of Figure11has the of coils in the opposite direction onvoltage wave with slanting lines con- the other half -cycle. Thus the energynecting the horizontal portions. When that can be transferred is greatly in- theinducedcounter -voltageinthe creased,thesize of the transformertransformer primary is as indicated by can be reduced by operating at muchthe voltage graph, the current pulses higher flux -densities, and a full -wavepassed by the rectifier tube will be as rectifier can be used which will operateshown. Naturally, after going through equally well regardless of the batterythe tube the pulseswillbeallof polarity. To operate such a transform- thesame polarity.Thus we have er,however, required two vibrators arrivedatthe basic vibrator circuit of the type we have just considered,still used today in the large majority mechanically synchronized 180 degrees of auto radioreceivers,aswellas out of phase. One set of contacts hadmany other applications. Without the to be closed while the other set wasrectifier, and with a few refinements, open. Naturally, the next step was tothis is the basic arrangement for the combine the two vibrators into one,power converters made by Cornell- having sets of contacts on both sidesDubilierforproviding AC power of the moving reed which engaged on from a DC source.The vibratoris opposite half -cycles of operation. Thiscommonly called the "INTERRUPTER arrangement isillustratedin Figure TYPE",thefull -wavefeature now 11.As thereis an appreciable per-being taken for granted. When cor- centage of the total time of each half -rectly designed, and when used with cycle required to switch the contacts properlymatchedcomponents,this from one sideto the otherinthe vibratorstructurehas worked very circuit, the on -contact time for eachsatisfactorilyandprovidesexcellent cycle is always less than 100% of thelife characteristics. total time. The actual percentage of Earlyinthehistoryofvibrator contacting time is referred to as thepower suppliesforautosetsthere time -efficiency,or in some instanceswas adesiretoreduce the overall as the time -constant, of the vibrator.size and weight as well as cost.Be- cause theearlyrectifiertubes were Because the time -efficiencyisless gas -filledhalf -wave types, and were than 100%, there will be gaps in thelarge and costly, this appeared to be horizontal voltage trace between suc-one logical place to start in achieving cessive half -cycles. However, we have the reductions.Additional insulated the timing, or buffer capacitor con- setsof contacts were added tothe

Fig. 11.

Page 6 THE C -D CAPACITOR vibrator structure which were operatedcommon vibrating reed as a switch. in synchronism with the already pres-Usually B- isconnectedtothe entinterruptercontacts.Thiswas grounded terminal of the battery, and first done on the half -wave structure, this may be positive or negative, de- and resulted in a synchronized half -pending upon the car manufacturer's wave rectifier of a mechanical type re- choice.This isoflittle moment at the present, since cathode -bias is com- mon practiceinreceivers and indi- rectly -heatedcathode -typetubesare used. However, the fact that the recti- R+ ficationis done mechanically results

in a reversal of the output polarity ---o-i when the battery ground is reversed.

Sincereceiverswon'toperatewith NON -SYNCHRONOUS the plates negative, and otherdiffi- cultiessuchaspolarizedcapacitors arise, it is obvious that this condition must be corrected where receivers are B+ manufactured for use in any make of o car.Of course, where custom-built B - original equipment is considered, this reversed condition need never occur. Figure 13illustratesthe effect of SYNCHRONOUS the reversal of battery polarity on a power unit using the Non -Synchronous Fig. 12. type and on another using the Syn- chronous type of vibrator. On the left placing the tube.Decided disadvan- of the illustration we see that the rec- tages resulted from this arrangement tifier tube acts as an automatic valve, in addition to those already describedso that, regardless of the battery po- for the half -wave interrupter.How- larity (and therefore the transformer ever, the feasibility of the synchronoussecondary polarity), the output circuit rectifierwas demonstrated, andthe is always polarized correctly. On the same principle was then appliedto right we have substituted a mechanical the full -wave unit after its introduc-selector switch for the tube for the tion.This arrangement is shown inpurpose of rectification.In the upper Figure 12, where the Non -Synchronous circuit we see that, regardless of the (or Interrupter) and the Synchronousposition of the vibrator reed, the out- (Self -Rectifying) types are compared.put circuit is always positive at the This structure permits the elimina-secondary center -tap because when the tion of the tube rectifier for a costcurrent throughthe primaryisre- andspacereduction,givesslightly versed, the connection to the second- higher efficiency because of the elimi- ary winding is reversed also.In the nationoftubelosses(bothplate lower circuit, the connections to the voltagedropandfilamentcurrent vibratorandtransformerhavere-. must be considered), and in generalmained the same, but the battery po- gives a longer vibrator life. The uselarity has been reversed. As a result, ofthistypeofself -rectifyingunit, the polarity of the output circuit is however, introduces several disadvan-now the opposite ofthat formerly tages.First,the output DC circuitprevailing, with the center -tapcon- must be electrically connected to the nectionbeingmaintainednegative. input DC circuit,asbothusethe (Continued on page 10)

AUGUST, 1949 Page 7

NOW! from C -D... P

a complete line of

CONVERTERS for all purposes

MODEL 32 RU15 ft.ODEl110R10:

MC DEL 11ORT15

Think of the new sales opportunitiesoper b you rcw hat you hn+e .he dependable name of C -D in back ofa :on -Flete o= converter:. More TV installations! More work on farmpowe- supplies! Marine work! And always you work with confidence in the cual-y, depeid,ility and -rouble- free performance of these converters, bcniusa they'dtyFical C -D products.

Page 8 THE C -D CAPACITOR SEND FOR FREE CATALOG FOR DETAILS ON THESE C -D POWERCON CONVERTERS

MODEL 6R5: For 50 -watt radio equipment. 110 -volt 60 -cycle AC output from 6 -volt battery.

MODEL 12R8: Operates radio equipment up to 80 -watts. For 110 -volt 60 -cycle AC output from 12 -volt battery.

MODEL 6R10: For mobile, portable and stationary operation up to 100 watts. 110 -volt 60 -cycle AC output from 6 -volt battery. MODEL 12RÚ15: For marine, truck, trailer, bus, aircraft, etc. Rated at 150 watts. For 110 -volt 60 -cycle AC output from 12 -volt battery.

MODEL 32R8: For farm and marine power-up to 80 watts. 110 -volt 60 -cycle AC output from 32 -volt DC power source. MODEL 110R10: Adjustable to 40, 70 and 100 watt loads. For 110 -volt 60 -cycle AC output from 110 -volt DC power supply. MODEL 32 RU 15: For quick, easy conversion of farm and marine power.

110 -volt 60 -cycle AC output from 32 -volt DC power source. MODEL 11ORT15: For television receivers and other radio applications. 110 -volt 60 -cycle AC adjustable output in 110 -volt DC areas

MODEL 110RT25: For television and radio uses. Rated at 250 watts.

110 -volt 60 -cycle AC adjustable output in 110 -volt DC areas MODEL 11ORT35: For television, radio, small power tools, food mixers. 350 watt output. For 110 -volt 60 -cycle AC output in110 -volt DC areas. MODEL 11OPA5: For automatic and manual record players.

1101285: Supplies 110 -volt 60 -cycle AC power from 110 -volt DC source. MODEL 1105A6: Multi -use AC -to -DC power supply for auto -radio demonstrating, servicing and battery charging. To supply 6 volts DC from 110 -volt 60 -cycle AC source. MODEL 110óAl2: For servicing, testing, demonstrating auto, truck and small boat radio equipment and appliances. Supplies 6 or 12 volts DC from 110 -volt 60 -cycle AC source. C -D POWERCON Convertersare Honestly Rated for Dependable Trouble -Free Long Life

If the Cornell-Dubilier line of POWERCON convertersis not available at your local jobber send your order to us here in South Plainfield, N. J., and we will fillit through

the nearest Cornell-Dubilier jobber carrying a converter stock.

B/L/fR CORNELL-DU DEPENDABLE 1910 1949 CONSISTENTLY *CAPACITORS *VIBRATORS *ANTENNAS *CONVERTERS

AUGUST, 1949 Page 9 POSITIVE OUTPUT POSITIVE OUTPUT

POSITIVE OUTPUT, NON -SYNCHRONOUS NEGATIVE OUTPUT, SYNCHRONOUS POLARITY OF BATTERY POLARITY OF BATTERY MUST BE DOES NOT MATTER, CORRECT TO GIVE POSITIVE OUTPUT OUTPUT IS STILL POSITIVE FROM THIS CIRCUIT

Fíg. 13.

Thus it would be desirable to incorpo- two positions, 180 degrees apart. By rate in the receiver some easy method connectingthetransformertothe of interchanging the connections ofsocket as shown, provision is made to either the primary or the secondary of reverse the secondary or rectifier side - the transformer to the vibrator whenreeds when the vibratorisreversed the receiver is to be installed in cars in its position, but the cross -connection with opposite battery polarities. Early provides no reversal of the primary, models incorporated a terminal board (or interrupter), side -reeds; therefore, to which transformer leads were connected.Laterthevibratorbasingoutput reversal can be corrected by shown at the left in Figure 14 was vibratorpositioning.Thistypeof developed in order to use the vibrator vibrator has been highly successful, itself as a reversing switch.This isand permits the full realization of the usedwith asymetricallyarranged real advantages of the self -rectifying socket, as shown at the right, whichvibrator withoutits most important will receive the vibrator in either of disadvantage.

REVERSIBLE SYNCHRONOUS VIBRATOR AND SOCKET WIRING

Fig. 14.

Page 10 THE C -D CAPACITOR THE RADI

7 ,t!..-r.r A Free Market -Place for Buyers, Sellers, and Swappers. These advertisements are listed FREE of charge to C -D readers so if there is any- thing you would like to buy or sell,if you wish to obtain a position or if you have a position to offer to C -D readers, just send in your ad. These columns are open only to those who have a legitimate WANTED, SELL, or SWAP proposition tooffer.The Cornell-Dubilier Electric Corp. resP-ves th' rightto edit advertisements submitted, and to refuse to run any which may be considered un- suitable. We shall endeavor to restrict the ads to legitimate offers but cannot assume any responsibility for the transaction involved. Please limit your ad to a maximum of 40 words, including name and address. Advertisements will be run as promptly as space limitations permit.

WANTED -2 speed recording unit or sys- SWAP-New 4X Hensoldt Wetzler scope tem,G.I.R90orequiv.Also want withleatherlenscovers,mount and Humphrey's spinningreel.Will trade base plate for attachment to receiver, new Heddon deluxe tubular casting rod, (valuedat$85); new Luxor spinning new Ashaway spinning reel and other fishing reel; also one pair Peals English fishing tackle.What have you?Frank boots, 91/,D, with trees, in good condi- E. Popma, Orange City, Iowa. tion; all for Riders' Manuals. G. T. Mac- kenzie, University of Kentucky, Lexing- SELL OR SWAP-Gonset 10 meter con- ton, Kentucky. verter with noise clipper; Jackson audio oscillator, model 652; Sprague Tel-omike FOR SALE-Approvedsig.gen.,model condenser analyzer, model16. Harper A 200,$30. Willship COD.Reed's K. Richards, East St., Argyle, New York. Radio Service, P.O. Box 264, Lansford, North Dakota. WANTED-Prewar 5"televisionchassis, such as RCA TT5, Garod 100,or any TRADE-Complete set of Coynes Applied prewar TV chassis converted ornot. Practical Electricity, seven vols., never With or without tubes or cabinet. Send used. Want a complete course in radio. detailsandprice. RobertFlory,29 Stanley March, 1019 N. Liberty St., New Harold Ave.,Princeton, N.J. Castle, Pa. FOR SALE -5" oscilloscope, sensitivity 2" FOR SALE-Thriving radio and television per rms volt,$60; A10 bubble sextant, business in Ionia, Michigan. Located on $30; 410 Stevens shotgun, $15.Edward main highway M21 east of Ionia.Stage Matthews, 171-35 Courtney Ave., Flush- setfortelevisionsalesandservice. ing, New York. Floyd E. Colley, North St., Ionia, Mich. WANTED-Collins 310A-1or310B-1ex- FOR SALE-Antenna, AN/128-A,partof citer; Philco CR -10 auto radio; late mod- radarunit RC -48-C,$30fob Chicago. el television console; RMEDB20, VHF152; Also several 7C5 at 2 for a $1 and one 4-125A, 4-250A, 4-65A, 100TH's, 35T, 2A3, RCP VOM model 447,excellent condi- Tubes.Pasquale, 9421 Thornhill Road, tion,$13. Edward Tanrath,3151W. Silver Spring, Md. Monroe St., Chicago 12,Ill. SWAP-Auto radio;"A"eliminator;50 FOR SALE-Model 10 semi-professional watt CW xmitter; bat. charger; PA sys- Wilcox -Gay recorder, 40 watt capacity, tem (phono on top);100 QST and 100 play or cuts 12" records.Also one 16 - Radio Craft magazines; 10" TV lenses. mm Keystone movie camera.Both in Want 501bs No. 5 SCC enam. wire, port. excellent condition.Or will tradefor typewriter, welder, printing press, movie Wire recorder or printing press.D. W. camera and projector,or what have Harper,117 W. MainSt.,Albertville, you?Stanley, 2748 Meade St.,Detroit Alabama. 12, Mich.

AUGUST, 1949 Page 11 TRADE-We will develop ideas and inven- FOR SALE-Dumont 164 3" scope; RCA tions and make patent searches in ex- Chanalyst. Bothingoodcondition. changeforelectricaltestinstruments. Make offer. H.G.Lutz,BoltonRd., InventionsUnlimited,3509 Hyde Park New Hartford, N. Y. Blvd., Los Angeles 43,Calif. SWAP-Fourteen books on radio and ma- WANTED-Riders' Manuals, vols.1, 3, and chinework, nearlynewcondition. 9. Write givingcondition and price. Want radio tubes.Charles C. Butler, Also have Schick Colonel electric razor, 16108,S. Main, Gardena, Calif. like new, for sale or trade. What have you?E.Yeager, 5302 West 57thSt., WANTED-Voltohmmeter with more than Mission, Kansas. 2000 ohm/volt meter and both ac and dc ranges. P.C. Yu, 472511th Ave., TRADE-Ham radio items for photographic N. E., Seattle 5, Wash. items.Have parts,transformers, complete sets, etc. Want any 35mm camera, FOR SALE OR TRADE-Hammarlund HQ - 4x5 press, dark room items, or movie. 120X in very good condition; Philco re- W. T. Golson, 502 Lakeland Drive, Baton cording arm unitforPhilco combina- Rouge, La. tions.Will trade for photographic equip. R. A. West, I11 Waddell Pl., Oak Ridge, TRADE-Hallicrafter Ultra Skyrider, bands Tenn. 11.-5.5mc, 20.-llmc, 38.-20mc, 79.-38.mc, excellent condition. Want SX28 and will WANTED-Precision EV-10 VTVM and 912 pay some cash.A. H. Dreesen, Mans- tube tester.Also used communication field Centre, Conn. type receiver, condition not important. Will exchange lists or pay cash. Glenn FOR SALE-Transmittingtubes,slightly Watt, Chanute, Kansas. used: one 813, $8; two RK-20's, $5 ea.; two 807's, $1 ea.Also 25 receiving type WANTED -4" or 5"lens,f1.9or better. tubes,allfor$5 and Cooke's Radio Willtrade any surplus radio,phono, Slide Rule,$5. Justin M. Walker, 1000 or television part I have for what have College, Canton, Mo. you?. Louis DuRaun, 1128 Wagner Ave., Philadelphia41,Pa. URGENTLY NEED -3" DC milliameters allranges. PreferWesternElectric FOR SALE OR TRADE-Approved elec- types.Ed Howell, Box 441, Gastonia, tronic model A-200 sig.gen., $25; NRI N. C. service manual, $10; 522 2 meter transmitter, $10.Want FM tuner, television SWAP-Radio parts,communicationrec. set or what have you? Mathew J. Duni- forlate model magnetic tape recorder phin, Box1091, Wewoka, Okla. in operating condition.Also can use televisionreceiverunits.Radio Com- SELL OR TRADE-Motorola FM receiver; munication Service, 4475 Myrtle St., San Schickand Remingtonelectricrazor; Diego 5, California. Kodak f1.9 16mm magazine movie camera; Vokar slideprojector.Want test FOR SALE-All standard makes offine Equip.D. Buck, 32 Ardmore Ter., Col- used radios, power packs, transformers. lingswood, N.J. Sendstampforbulletin. Goldstone Radio,1279 Sheridan Ave.,Bronx56, SELL-Kodak Duo-620IIwith everyready N. Y. case, chrome finish,f3.5lens, compur rapid shutter 1 sec.to1/500 sec.,ex- SELL OR TRADE-Radio and photographic cellent condition.Worth $65, best offer. equip.,35mmsilentprojector.Want LouisFialkoff,143-4841Ave.,Flush- Bubble orMarinesextant,binoculars ing, L.I.,N. Y. ortelescope. WilliamHansen, 165 Silverbrook, Niles, Mich. FOR SALE-Crystaliner, fine condition, $10. Howard Clewett, Rt.1, Box 261A, Ripon, WANTED-Philco oscillator coil,part No. Calif. 06620,formodel89or 19 radio,or model 89chassis.Joseph A.Spalla, SALE-16mm Pathe sound projector, with Plaza,N.Dak. push-pull 6F6's and 10" dynamic speaker,allin carrying case, used butin FOR SALE -6 tube Motorola auto set, fits goodcondition. Bestoffertakesit. any 1940 to 1948 Dodge, Ply., Chrys., or Henry Lulli, 2352-27 St., Long Island DeSoto.Perfect condition and complete, City 5,N. Y. $20.C. Wm. Haberstroh, 1521 Larrabee St., Chicago 10,Ill. FOR SALE-Over 1,000 radio tubes, condensers,resistors, and Alnico 4" and WANTED-Altec Lansing speaker in good 5" speakers. Very reasonable, send for condition. H.A.Rollins, 113Central listprice.Knight Radio, 9418 Ave. A, Park Drive, Brownsville, Texas. Brooklyn, N. Y.

Page 12 THE C -D CAPACITOR WANTED -0-25voltMilliontubetester FOR SALE-450mc oscillators.Basic unit chart. E.Reeser, Benedict, Kansas. ofthe BC -645,uses a 955tube.Less tube, $1each.Wagner Radio Service, FOR SALE-Model458ac -dcohm-volt- 5904 S. Princeton, Chicago,I11. milliammeter(ChicagoIndustrialCo. manufacturer). Best cash offer takesit. TRADE-$30 foreign stamp collectionfor Higgins Radio Service, Mineral, Ark. used ham gear.Includes the Modern Stamp Album.Herb Ridderbusch, Box FOR SALE-Brand new Philco model 7050 902, Rainier, Oregon. tubetester. First$34.95 money order takes it. WilliamsonRadioService, FOR SALE-New No.88 NRIsig.gen., Cooper, Texas. $38; New Crossman single shot 22 air pistol, $14; Brook dc to ac 50 watt con- WANTED-Alignmentandservicedata verter 110V, $7; Everybody'sRadio on army surplus FM receiver BC -683-A Manual,75cents.Shippostpaid. L. or B.Will pay reasonable price.F.E. John Moy, Box 169, Canal St. Sta., New Francisco, Canal Winchester, Ohio. York 13, N. Y. FOR SALE-Highvoltagepowerpack, FOR SALE-SW3 receiver, has extra stage 110V ac in and 1000 - 750V dc at 225ma of audio builtin,fine condition, with out., choke input filter, ruggedly built, 80 and 40 meter coils, $15, or will swap $16. Simon Dresner,322 W.72St., for 10 meter converter. Steward Ringler, N. Y. 23, N. Y. 121S.11thSt.,Reading, Pa. FOR SALE OR TRADE-One 5CP1 cathode FOR SALE-Brand newSupreme543S ray tube and socket and one 2AP1 cath- 5000 ohm per volt multimeter, $12; new ode ray tube and socket.New Radio GE unimeter,$29.95. Wagner Radio, Clinic, 603 SW Road, Shenandoah, Iowa. 5904 S.Princeton, Chicago, Illinois. FOR SALE-Model 920 Precision tube test- TRADE-Chemicals,chemicalapparatus, er,inperfectcondition,$60. Sgt.E. chemistry books, list on request.Want DePrisco, Apt D92, Baldwin Manor, Aber- radio books or apparatus. Gerald Spec- deen Md. tor,158 Chestnut St., Lakewood, N.J. WANTED- One 2AP1A cathode ray tube FOR SALE-Complete radio repair shop, as used in Philco 022 oscilloscope.State tools, instruments, parts, manuals, Rid- price.L. R. Van Sickle, 2915 Allen, St. ers' 1 to13, Sam's 1 to Will trade Louis 4,Mo. for HO gauge electric train equip. Write forlist. Stan'sRadioRepair,E-6051 FOR SALE-S-38 Hallicrafters receiver, ex- Myrtle Court,Flint7,Mich. cellent condition, complete with instruc- tions and service bulletin.Need cash FOR SALE-Rider Chanalyst,practically badly,Bestoffertakesit. John R. new, $85.K. D. Boyd, 4300 W. Central Grimm, 52 Conway St., Carlisle, Pa. Albuquerque, N. Mex. FOR SALE-Series 920, 1000 ohm per volt, REWARD-Large reward for locating the combination VOM by Precision:E-200 following stolen meters: One Voltohmyst, Precision sig. gen.Both like new, $75. RCA model 195-A, serial No.10593 and Charles W. Kern, Sherman,Ill. two Simpson model 260, serial No. 19195. A. L. McNealus, 90-15 138thPlace, FOR SALE-Brand new Hallicrafters7" Jamaica 2, N. Y. televisionset;10" magneticspeaker; used Packard electric razor; back issues SWAP-Sound equip.(microphones, am- ofQST and RadioCraftmagazines. plifiers, speakers, etc.)for pair of good Want folding camera, binoculars and a binoculars,6 x 30 or 7 x 50 either Ger- small electric refrigerator.Charles Hol- man or American.Longer Radio and stein, 246 E.148, Bronx 51, N. Y. Sound, 43N.HazelSt.,Danville,Ill. SELL OR SWAP-Sunkraft cold quartz mer- FOR SALE -4' x 5'electric neon signfor cury vapor lamp, used as a tanning or radioserviceshops,practicallynew, sterilamp, built-in timer, wood carrying will sell very cheap.Write for details. case,cost$69.50new,hardlyused. Reinisch Radio Service, New Rockford, Want camera and test equip.Emanuel N. Dak. Batler, 46 W. 76 St.,N. Y. 23,N. Y. WANTED -3"or5"televisionkitless FOR SALE-Complete radio equip. to start sound channel, complete.Will trade a your own radioshop,includingtest BC -654 radio and transmitter with high equip.,parts,diagrams,andwork andlowvoltagesupplys,mikeand bench.Willsellallor partforone- key and speaker or will trade for sur- third less than cost.Alfred A. Johnson, plus oscilloscope BC -412.John Arnold, 5604 N. Western Ave., Chicago 45,Ill. P.O. Box 84,Bluffs,Ill.

AUGUST, 1949 Page 13 FOR SALE-Vomax900, $45; Precision TRADE -63 vols.Popular Science maga- model 612-C tube checker,$60. Both zine,Oct.,1938 thru Dec.,1945. Also testers as new.J. W. Landon, Box 6425, 17 vols. Science and Mechanics, Aug., Pittsburgh, Pa. 1939tosummer edition1943. Allin goodconditionandclean. A.Paul FOR SALE-Model 33 NRI professional sig. Rabito,2835 Paris Ave., New Orleans tracer,nearly new,perfectcondition, 19, La. originalcost$52,will take $40.Paul Cutting, 21 Ranger Rd.,East Green- FOR SALE OR TRADE-Colored sea -shell wich, R.I. brooch and earring sets,$2; preserved seahorses, 50 cents; 100 yrs. old Ameri- FOR SALE OR TRADE -2000 I.R.C. BTA can newspaper, $1. Missouri land, $3.75 1 watt resistors, brand new; Supreme per acre.Want Riders' Manuals, small No.85 tubetester,with adaptersfor oscilloscope.Your tradelistfor mine. octaltubes;dual chargingratebat. George Calvert,Rt.2,Winter Haven, charger, 6V at2A, 4V at1A. Make Florida. offer. Want typewriter.Stubby, 140 So. 4th St., Reading, Pa. WANTED-Philco 84radioinany condition, but coils must be good; also Rid- SELL OR TRADE-Airplane engines-Ohls- ers'5 and 14.For sale, Utah record son23's, $7; MerlinsuperB's,$6; player on a Zenith display case. Saxton's G.H.Q.'s, $9; coils,condensers,and Radio and ElectricService,Route 1, spark plugs for same. Want multitester, Pontiac, Illinois. small oscilloscope or what have you? Allan Morrell, 78 Stephen Place, Valley FOR SALE OR TRADE-Speco sig. tracer; Stream, N. Y. Heath sig. gen. Want Hickok 156 trace- o -meterorwhat haveyou? W.F. FOR SALE-Latest radio books in good Daniels, 1123 Central, Harper Kansas. condition, very reasonably priced. Send forlist.Leon Medler, 2109 Daly Ave., FOR SALE-Riders' vols. 7 and 3, perfect Bronx 60,N.Y. condition, $11, plus code for both vols. Also 6-2D-21 Thyratron tubes, best offer. POSITION WANTED-Can repair any make Augustine Mayer, 561 So. Sandusky St., radio.Recent graduate of Philco Tele- Tiffin, Ohio. visionTraining Course.Want jobin vicinity, full or part time. M. Maultasch, FOR SALE-RadioPhysicscourseby 535 Grand St., Brooklyn 11,N. Y. Ghirardi, new, $4; Mathematics for Elec- tricians and Radiomen by Cooke, new, FOR SALE-First quality radio tubes. Nos. $4. Both received asduplicategifts. 3S4, 12SQ7G/GT, 50L6G/GT, 12SG7GT/G Louis G. Ousborne, 915 Wildwood Park- and 70L7, 69 cents each postpaid.No way, Baltimore 29, Maryland. order tosmall.Jones Radio Co., Box 93, Douglassville Pa. WANTED-One 25D8 tube.Masline Radio Parts,192 No. Clinton Ave., Rochester, FOR SALE-G.E. television set, model 171. N. Y. Will sell cheap. H. Latko, 1922, Dickens, Chicago,Ill. FOR SALE -3 channel Transvisiontele- vision set,less cathode ray tube, $50, SALE OR TRADE-Hickok 4955-S, 4" face, or will swap for good sweep gen.C. V.O.Ma.meter,0-10meg. 4 ranges, Witter, 28 Elizabeth Av., Newark 8, N. J. 0-500 ma. 3ranges,0-1000 ac or dc volts,5 ranges, separate output jack. FOR SALE-Used Detrola record changer; $25 plus postage, or what? C. Elgasser, mounted 1,000kc xtal; 838, R14 high re- Jr.,1920 Fern St., San Diego, Calif. sistance phone units.E. W. Barth, 333 Washington, Chelsea, Mich. SWAP-Equal amount of tubes for 0-150 FOR SALE-Model 505 Hickok 5" oscillo- micro -ammeter.State price andI will graph, $179; model 156 Hickok indicating send equal costof tubes wanted. P. traceometer, $195; model 909 McMurdo Shavel, 941 Grand St., Brooklyn 6, N. Y. Silver TV sweep sig. gen., $48.50.Will sell all for $325.William J. Madigan, 56 WANTED -25B8 tube, will pay your price, Lincoln Ave., Brooklyn 8,N. Y. new or used. Also manual for Precision meter,series40. Stateprice. Paul FOR SALE-Pontiac superdeluxeauto Quayle, West Main St., Madison, Ohio. radio, 8 tubes, for 1948 car.Also tubes forsale.LincolnEstatesRadioCo., FOR SALE -400' RG-8/U coax cable,4 Rt.1,Frankfort,Ill. cents per ft.; 3 wire telephone, weather- proof,2cents perft.;25B8GT tubes, FOR SALE-Riders' vols.6,7,8,9,10, while they last, $4.80 each.Everything $62. A-1condition and we meanit. new. Oler Radio Service, New Madison, Carrs Radio Center, 17 Kelley Sq. Wor- Ohio. cester 4, Mass.

Page 14 THE C -D CAPACITOR why they all flock to *servicemen, that is

C -D SKYHAWK construction Qterproo AUTO AERIALS ioo°/°

J section all se 60.. chrome-plated meal topspacer

e spring fingerplug exclusive

lead -In You use this C -D auto aerial with full full 36"Polyethlene confidence.It won't rust - all stainless. It's the most popular model on the market.Completely protectedagainstthe elements, fully shielded lead - so dur- able it will outlast the car you install it on.Fits any cowl or fender contour. $;95 MODEL 8B each

CORNELL-DUBILIERcan now supply you with a full line of AUTO, TV and FM aerials. If your jobber does not stock them, send your order directly to us. We will ship to you through the CD jobber nearest your shop. Write: CORNELL-DUBILIER ELECTRIC CORPORATION Dept. HOS, South Plainfield,N. J.

1910

AUGUST, 1949 Page 15 a complete capacitor department

WITH THIS METAL CABINET HERE'S WHAT YOU GET: FREE CAPACITORS IN ASSORTMENT (LIST $50) YOUR COST $2999 YOU BUY Tilt CAPACITORS ONLYI íalra3 DRAWER METAL CABINET FREE an assortment of your most popular capacitors, 1 UP -2045 10 PTE -651 list price $50 1 UP -1145 5 PTE -652 1 UP -2245 10 PTE -655 20 different types of capacitors in the quantities you need 1 EDL-4215 5 PTE -6P1 them for day-to-day servicing, 1 EDL-5315 1 BR -252A a 3 -drawer metal cabinet with separate compartments for 1 EDL-2215 5BR-2015 each type of capacitor and free space for additional stock, 5 PTE -6D1 S BR -845 cabinet can be hung on wall or kept near work bench 5 PTE -6D2 5 BR -1645 without cluttering work area, 5 PTE -6D3 3 BR -1045 5 PTE -605 2 BR -2045 convenient ... time -saving.

ORDER FROMYOUR JOBBER NOW! 4 If your jobber cannot supply you with this *CAP S,s;.Ol/BjjcíQD¡°fNO,etf C -D capacitor kit, write us: Cornell-Dubilier Al". Electric Corporation, Dept. HO 99, South * 198R4TOR5 4 Plainfield, N. J., and we willship, your * 4NTEHN45 O order through your nearest C -D distributor. 1910 1949 * CONVERTERS Other plants in New Bedford, Brookline and Worcester,Mass.;Providence,R.I.;In- e u SPe, OM. dianapolis, Ind.; and subsidiary, The Radian Corporation, Cleveland, Ohio.

Printed in U.S.A.