WillsWa~ - · PDF fileTRU-FIX Dials are made of selected sheet brass .023 of ... Corrects loss of tuning adjustments, such as fading, ... down the lead-in wire. So, if a thunder

April 15, 1924

IN THIS ISSUE :

Why is a Lightning Arrester?Special Article by Horace V. S. Taylor

Building a Five -Tube Neutrodyne

Non -Squealing Regenerative Radio

The Popular Loop AerialWinner of Prize Liar Contest

YOU WILL UNDERSTAND THISMAGAZINE -AND WILL LIKE IT

This Issue 15,000 CopiesNe~iillW\a"W-4,0d\WillsWa~

PUBLISHED TWICE' A MONTH

42 MAVERICK SQUARE

RADIO PRODUCTS

THE AL 1311E LUXE,,

40 50 11114-0)60

4 inch DialIn designing the TRU-I'IX the manufacturer has goneinto every detail relative to requirements of Dials usedon Radio Instruments, and after many experiments withsprings, etc., adopted the last word in Dials-the spring -less TRU-FIX Dial.

21/2 inch DialTRU-FIX Dials are made of selected sheet brass .023 ofan inch thick. The edge is very thin with a gradualcontour to meet the panel and is finished in bright nickelwith 100 division scale running from left to right, etchedin the surface, inlaid with black enamel, thereby makingTRU-FIX DIAL easily read at all times.The Knob, highly finished, is made of Bakelite PA incheshigh with bevel edge at base and is attached to dial witha flat spring device made into the dial itself.

EAST BOSTON, MASS.

DISTINCTIVE AND SELECTIVEThe patented spring feature under the knob is one of thesuperior points of this dial. You are always sure of atrue running dial, as it keeps the dial in perfect align-ment-always flush with panel, ensures perfect settingsas the dial is not disturbed by jars or other causes. Thisgives you a dial that is different and one that alwaysinsures a inure selective tuning. Perfect control onportable sots. Other dials cannot accomplish this feature.Replaces the Vernier, as it can be moved forward orbackward to within one thousandth of an inch, withoutbacklash, and stays put.

Cross Section Tru-Fix Dials

WHY TRU-FIX IS A SUPERIOR DIAL1. Corrects out -of -alignment of shaft with panel byspring feature made into the dial.2. Corrects looseness of end play in any units used, suchas Variocouplers, Condensers, Rheostats, etc., by slightfriction on panel to take up this end play.3. Corrects overbalanced units where there is a loss offriction caused by poor assembly in their manufactureand incorrect balancing of weights and metals.4. Corrects loss of tuning adjustments, such as fading,etc., due to slight jars or vibrations, which allows thecondenser or variocoupler to rotate out of position, there-by losing the station being tuned.5. Corrects body capacity, as the metal of the dial actsas a shield when grounded. This can be done by settinga plug flush with panel and allowing the dial to touch itlightly, having the plug grounded.These Dials, on account of the above listed features, arethe only !Oats to use on portable sets.

LIST PRICES

100-3 inch Dial102-4 inch Dial104-21/2 inch Dial

Silver Gold$1.00 $2.00

1.25 2.501.00 2.00

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If Your Dealer Cannot Supply You, Send $1.25 to

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RADIO PROGRESSHORACE V. S. TAYLOR, EDITOR

Volume 1Number 3

Contents for

APRIL 15, 1924

PAGE

WHY IS A LIGHTNING ARRESTER?

AMERICAN RADIO RELAY LEAGUES

CONSTRUCTING A FIVE -TUBE NEUTRODYNE 9

A GOOD PRIZE CONTEST12

TUBE POPULARITY CAUSES SHORTAGE 13

LETTERS FROM OUR READERS' 14

TAKING THE CAP OFF CAPACITY 15

NON -SQUEALING REGENERATIVE RADIO 17

BROADCASTING HAS ITS DANGERS 19

EDITOR'S LOUD SPEAKER:HISSES AND CLAPS

THE BROADCASTING BATTLE

21

21

SO DOES THE SODA CLERK 22

LINES FOR LADY LISTENERS 23

RADIO DOING ITS OWN BROADCASTING 24

THE POPULAR LOOP AERIAL 2i

DR. RADIO PRESCRIBES29

RADIO PROGRESS is issued on the 1st and 15th of each month by the Oxford Press at 8 Temple Street,

Providence, Rhode Island. John F. O'Hara, Publisher. Gordon B. Ewing, Advertising Manager. Yearly

subscription in U. S. A., $3.00. Outside U. S. A., $3.50. Single copies, 15 cents. Application pendmg

for entry as second-class matter at the Post Office, Providence, R. I. Address all communications to RADIO

PROGRESS, 8 Temple Street (P. 0. Box 728), Providence, R. I.

The publishers of this magazine disclaim all responsibility for opinions or statements of contributors

which may at any time become subjects of controversy.

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The Best in Design, Finish and Workmanship

Good Wiring Means Heavy WireYou can easily connect heavy wire

to the special loop terminals on

MAR -CO SURE -GRIP JACKSNine styles-all with sterling silver contacts

Micarta insulation and heavy springs. $ .60 to $1.25

Balancing Condenser(left)

$1.25

Variable Grid Leak

A new neutralizing condenser. Bake-lite insulation. Nickel -plated workingparts. Easy to mount. Easy to adjust.

(right)

$1.50

A new Grid Leak, ranging in smootheasy adjustment from 1/5 to 5 megohms.Bakelite insulation. Entirely enclosedweather-proof construction.

Send for CircularsShowing Over Thirty Radio Accessories

MARTIN-COPELAND COMPANY

PROVIDENCE,

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If your dealer buyshis Radio merchandisefrom us

What he sells you is 0. K.We are Rhode Island distributors for

All leading manufacturers ofsets and parts

UNION ELECTRIC SUPPLY CO.60 PINE ST., PROVIDENCE, R. I.

Wholesale only. Positively no merchandise sold at retail.

Are you Building a

RADIO SET?

If not, are you planning to build one?

We will give you whatever parts you need,-or we willgive you a Complete Set,-if you will get a few of yourfriends to subscribe to RADIO PROGRESS.

Write to -day to Subscription Manager, RADIO PROGRESS, 8 Temple Street,

P. O. Box 728, Providence, R. I., and tell him what set or parts you want.

RADIO PROGRESS" ALWAYS ABREAST OF THE TIMES

Vol. I, No. 3 APRIL 15, 1924 15c. PER COPY, $3 PER YEAR

Why is a Lightning Arrester ?If Yours is Wrong Perhaps the FireEngine Will Call at Your House

By HORACE V. S. TAYLOR

THE most abused part of the usualradio installation is the lightning

arrester. Most radio fans do not knowwhat the arrester is and are rather hazyabout what it does. Some think it neces-sary and some omit it. This article isintended to clear up some of the ques-tions which are being asked about thissubject.

The theory of a lightning arrester isquite simple. We have an aerial ex-tending up into the air like a lightningrod. This aerial gathers the electricalenergy of a radio message out of theair, and conducts it down through theset to the ground. But the aerial canhardly be called intelligent. It will notpick up the electricity of a radio con-cert and the next day refuse to pick upthe lightning stroke, which is perhapsseveral million times more powerful. Infact, it can not pick and chose at all,but sends all the electricity it can gatherdown the lead-in wire. So, if a thundercloud, in a playful mood, hands a boltof lightning to your aerial, it is a signthat some one will pull the fire alarmbox in your neighborhood. That is, un-less you have an efficient lightning ar-rester connected to your aerial. In thisevent the arrester will conduct the boltof lightning directly and harmlessly tothe ground and your house will be pro-tected from fire.

What the Arrester DoesFrom this you will see that a light-

ning arrester is a piece of electrical ap-paratus which does not disturb the smallvoltages caused by the radio waves (if

it did, it would disturb the broadcast-ing), but which will short circuit largevoltages direct to ground. Refer toFigure 1 to see how this result is accom-plished.

Fig. 1. X -Ray View of YourLightning Arrester

NE is a thin mica disk. On each sideof this disk are blocks of carbon C.These two blocks of carbon are pressedup tight against the mica by the twosprings S. The springs are fastened atlie lower end by the binding posts B.

The whole apparatus is mounted on aporcelain base P. The mica diaphragmM has one or more small holes cut rightthrough it. Remember now that micais a very good insulator, but that theholes in the mica will allow electricityto pass from one carbon block C to itsmate. The blocks do not quite toucheach other; as a matter of fact, they areheld a small distance apart-just equalo the thickness of the mica diaphragm.

This completes the description of thearrester itself.

Connecting the ArresterTo connect this apparatus either bind-

ing post is attached to the aerial aidthe other one to the ground wire. Whena radio wave comes along it runs directto its carbon block, but it cannot getacross to the other block because of themica and air space, so nothing hap-pens-it cannot get through and thewave goes direct to your radio set andmakes music. From this you will seethat the arrester does absolutely noth-ing whatever to the broadcasting whichyou receive. But now suppose a thunderstorm comes up. The lightning comesnearer and nearer and finally a directstroke or a secondary stroke of light-ning hits the aerial. This will give apressure of several thousand up to sev-eral million volts on the wire. Imme-diately the little film of air in the holethrough the mica diaphragm breaksdown and the bolt of lightning jumpsacross from one carbon block to theother, and so goes clown the ground wiredirect to earth. The house is saved andthe fire bell does not ring.

Most types of lightning arresters onthe market are built on this principle.There is one other scheme also usedwhich is quite similar, except that thetwo disks C are placed inside a glasstube and then 'the air is pumped out,leaving a partial vacuum. Lightning canjump through such a partial vacuumquicker than through the air and so thearrester will work at a somewhat lowervoltage. The advantage of such an ar-rester is that it offers protection at alittle less electrical pressure. The dis-

-

6 RADIO PROGRESS APRIL 15, 1924

advantage is that if the glass tube getscracked and so lets in the air, thus kill-ing the vacuum, the efficiency of opera-tion is much reduced and you do notknow about it until the next lightningstroke sets the house on fire.

AERIAL

00°0 0 0SET

G110 UN p

Fig. 2. Puzzle-Find the LightningArrester

Errors in InstallingFigure 2 shows the commonest light-

ning arrester error. Or, perhaps, weshould say, doesn't show it, because thelightning arrester isn't there. This ap-plies only to an outside aerial wherethere is danger of a lightning stroke. Aninside aerial is just as safe as any otherpart of your house, and so no arresteris required by the Underwriters.

Your Insurance Won't be PaidIf you have an outside aerial and you

do not install a lightning arrester, thenyou might just as well stop paying yourinsurance premiums. The fire insurancepeople won't pay your insurance whenyour house burns down if you haven'tan arrester. But perhaps you can provethat the fire started from lighting thekitchen stove with kerosene. That willnot help you a bit. Your insurance pol-icy demands that you use approved elec-trical fittings as required by the Under-writers, or else you don't get yourMoney. So by all means make sure thatyou have a lightning arrester.

Figure 3 shows another form of light-ning protection. Here we have a singlepole double throw switch. (This meansthat there is only a single bar in theswitch, but that you can throw it eitherup or down.) When the switch is thrownup, you will see it connects the aerialto the set. This is the position for re-ceiving the music. At eleven o'clock (ormaybe one or two o'clock) when you getthrough listening you throw the switch

to the down position. This youwill notice disconnects the set fromthe aerial, but connects the aerialdirect to ground. Such a systemaffords very good lightning protec-tion, except that one night you were sosleepy you forgot to throw the switchdown, and unfortunately a thundershower came up, and so set the houseon fire. It happens that the fire insur-ance companies do not like to pay firelosses very well and so they are very ex-plicit in requiring you to put on a light-ning arrester anyway, even if you arealso using a grounding switch as shown.This arrester must be so good that itwill protect against thunder storms evenwhen you do forget to throw the switch.Since it is as good as that and will workwhen you forget the switch, why use theswitch at all? As a matter of fact, theUnderwriters do not require the switch,but recommend it if you want to use it.

Another common mistake is shownin Figure 4. This shows the aeriallead-in coming through the topof the window. From there thewire runs down -to the bottomof the window where the lightning ar-rester is installed. This is contrary tothe rules of the Underwriters. They say,"each lead-in wire shall be provided withan approved protective device located asnear as practicable to the point where

i

Fig. 3, Grounding Switch is NotEnough Protection

the wire enters the building." They donot interpret it as being close enoughto the entrance, if the arrester is severalfeet away. In this picture the arrestershould be up at the top of the window,within a foot or so of the entrance. The

idea is that when the lightning entersthrough the building it should be con-ducted to ground just as soon as pos-sible, in order to give the least chanceof causing any damage.

On the other hand, don't make themistake shown in Figure 5. Here wehave an arrester installed up at the topof the window, but unfortunately thecurtains cover it. This is dangerous, asthe Underwriters state "the protectorshall not be placed in the immediatevicinity of easily ignitible stuff, or

<::;:3:..:41EIR IA I-

ARR --->

ASET

GROUND

Fig. 4. This Location of Arresteris Not Allowed

where exposed to inflammable gasesor dust or combustible materials."When a lightning stroke does occur itsometimes happens that a flash of firewill be thrown out from the arresteritself, and naturally if ignitible curtainsare in its vicinity, there is a pretty goodchance that they may catch fire, and sothe arrester would be a source of danger,rather than safety. In such a location,two possible ways of remedying thetrouble are open. Either the arrestercan be mounted directly above the cur-tain and six inches away from it, orelse it can be moved out to the side ofthe window and installed on a boardfastened to the wall.

If either of these plans are objection-able, then it is allowable to take a pieceof heavy asbestos board and fasten it be-tween the arrester and the curtain.

Outside InstallationsOf course, another way out of this

difficulty is to put the arrester outsidethe window as shown in Figure 6. Here

APRIL 15, 1924 RADIO PROGRESS 7

it is located a foot above the entrancethrough the window. This is allowed bythe Underwriters. However, it is notusually done for the following reasons:An arrester suited for outside installa-tion has to be made waterproof and sousually it costs considerably more thanone which is satisfactory for insidework. Another trouble is that, whereas,when in your' rooms it will be kept rea-sonably clean, if left outside it is likelyto get covered with dirt and grime. Insuch a ease perhaps it will not work as

ARRESTER

Fig. 5. Arrester is Behind LaceCurtain

well as it otherwise might when light-ning strikes the aerial. Besides this itwill never get any inspection if you can-not see it from the window, and if theground wire should drop off you probablywould not know about it. Of course,such an occurrence would be seen rightaway if it were inside. For these rea-sons, we recommend the inside installa-tion, if it is possible.

What Kind of a Ground?In grounding an arrester you must be

careful to follow the Underwriters' rule.They recommend grounding on a water -pipe, but if that cannot be done groundon a pipe driven into the earth, but donot do it like Figure 7. The pipe isshown entering the ground only a coupleof feet. This is not enough to makegood contact. As explained in the lastissue of RADIO PROGR.ISS the pipe shouldenter permanently moist ground to adepth of at least four feet. Since thepermanent moisture is usually two orthree feet down, it means that some sixor eight feet of pipe should be used to

get good results. Other grounds al-

lowed by the Underwriters are groundedsteel frames of buildings, or othergrounded metallic work in the building,and artificial grounds, such as buriedplates, cones, etc.

Two Grounds UnnecessaryWe have two separate grounds shown

in Figure 8, one for the arrester andone for the radio set. While this is quitelegal it is an unnecessary waste of timeand money. Unless the ground for thearrester is good enough to be passed bythe Underwriters, it will not make asatisfactory connection for the radio set.And once you put in a first-class groundfor the arrester, why not use it for theset? This is particularly mentioned inthe fire insurance rules and is allowedby them. So the best method is to con-nect up your arrester first, and aftercomplying with the requirements of theUnderwriters, run the ground wire fromthe arrester over to the radio and youwill cut the work of installing a groundin two.

A Very Common MistakeAnother mistake made very often is

that of using a protective device whichis not approved by the Underwriters.All the approved arresters carry thenotice of approval either on the deviceitself, or else on the container. Thelabel will usually give the serial num-ber of the approval and the date. Whenyou see such a notice you will knowthat it is safe to use the apparatus andif it is missing you are running a seri-ous risk if you depend upon it. As

Fig. 6. This Shows an OutsideInstallation

pointed out above, this risk is not somuch that your house may be set on fireas that the fire insurance company will

not pay the policy if the house burnsdown from any cause at all. You can-not blame the fire insurance people fornot holding up their end of the contractif you yourself break the contract atfirst by using apparatus that you havepromised not to.

What Kind of Wire?The kind of wire to use on your light-

ning arrester has been the subject of

ARRESTER

0000 0

S F- T

jfk__.

;;

Fig. 7. The Ground on This Ar-rester Not Approved

considerable discussion and argument.Up to about a year or two ago it wasrequired that you use No. 10 insulatedwire for grounding the arrester, but inMay, 1922, this was changed. Since that

ARREST ER

WATER

<Fig.S. Too Much of a G----;:c119:'hing

One Ground Enoughtime you must use either copper orcopper -covered steel wire at least as bigas No. 14 if the former, or No. 17 if thelatter. It need not be insulated. As amatter of fact, there is no advantage atall in insulating the ground wire, as itadds considerably to the expense andnothing at all to the safety. Since youraerial will he constructed of No. 14 barecopper wire, you might just as well usethe same kind for a ground for arresterand set.

Continued on Page 8

RADIO PROGRESS APRIL 15, 1924

American Radio Relay LeagueUnusual Boomerang Prize Contest is Offered

You often speak about something youhave done being a boomerang when itcomes back and hits you. Here is achance to get a real boomerang importeddirect from Australia. This is the na-tive weapon used by the aborigines, andwhen thrown into the air it will performthe most astounding tricks. It can bemade to rise to a surprising height, thensuddenly swerve and come back to thefeet of the thrower.

Must Get Answer BackSuch a boomerang is offered as a

prize by the American Radio RelayLeague of Hartford, Conn. It will bepresented to the first radio amateur inthis country or Canada who estab-lishes two-way communication withan amateur in Australia or NewZealand. This is, the winner musttalk back and forth with one of the coun-tries named. Already one-way messageshave been received, but so far no one hasbeen able to get back an answer.

A number of foreign countries, re-garded heretofore as backward in the de-velopment of radio communication, arenow showing an increasing interest inamateur transmission. New Zealandfans have been for some time a highlyappreciative and little known audience ofAmerican broadcast stations. While lis-tening to transmissions from this coun-try they have heard amateurs in thevarious districts talking with one an-other by radio telegraph and many havelearned the code so that they are ableto understand some of these communica-tions.

As Far as KansasThey desire now to make themselves

heard in the States and several haveinstalled code transmitters for that pur-pose. Already amateurs in Eureka,Kansas, and Bridgewater, Mass., havereported hearing a New Zealand trans-mitting station. Rev. Chapman, a mis-sionary at Anvik, Alaska, claims to haveheard a New Zealand call.

As New Zealand and the Philippinesare about equally distant from the cen-ter of the United States, it is expectedthat communication with the islands will

be possible in the near future. However,the local receiving conditions are by nomeans as good as they are in New Zea-land, where atmospherics are at a mini-mum. Fred Elser, operator of thePhilippine station IZA, is making an ef-fort to communicate with the UnitedStates with two 50 -watt tubes.

RELAY LEAGUE ANNOUNCESA NOVEL DOUBLE COUN-

TERPOISEAn unusual form of counterpoise has

been announced by the American RadioLeague. This has been designed byAdrian() Ducati of Italy. An ordinaryaerial is used, but no ground. Instead theground connection of the sending set Ishooked up to a counterpoise about eightfeet above the ground level. So far this;s standard practice, but in addition to`his counterpoise there is a second seriesof wires spaced just as far above thiaerial as it is above the lower counter-poise. You might almost call it anaerial sandwich; that is, an aerial forthe meat and a counterpoise above and

f`' my like slices of bread.

It Sounds Like a Sandwich, but inSpite of That-it Works

This sounds like a rather peculiar ar--angement, but the proof of the pudding,etc., and with it Signor Ducati has com-municated very successfully with ama-teurs in this country. He is easily theforemost amateur in Italy, inasmuch ashe was the first to establish two-wayconnection with this country. Being un-familiar with all of the methods em-ployed by American radio men, he didnot place any special stress on his novelaerial. The technical department of theA. R. R. L., however, is interested inthe use of an additional counterpoiseover the antenna, and experiments willbe made shortly to determine its specialadvantages.

In other respects Signor Ducati'sequipment is similar to the better classof amateur stations in this country. andthe results are regarded as remarkableconsidering that an interest in amateur

radio is just beginning in Italy. liestates that the broadcast bug is bitingand conditions as regards reception ofprograms are about the same as theywere in the United States two yearsago.

Europe Squeals, TooEvery one wants radio sets, but the

ready-made apparatus is far from beingstandardized. The fan who is startingin radio is in doubt as to what kind ofa set he should get, and interferenceconditions are likely to be troublesomefor some time to come. Strange to say,most of the interference on short wavescome from stations in Holland, France,England, Switzerland, Belgium and otherplaces.

WHY IS A LIGHTNINGARRESTER?

Continued from Page 7Some people have taken great pains

to run the ground wire out through aconvenient window and along the out-side wall of the house down to thecellar, then into the cellar window toground on the waterpipe. Such a ramb-ling route is undesirable. It is not re-quired that the ground wire be run out-side of the house. It is preferable in-deed, since the arrester and the water -

pipe are both indoors, to have the wireconnecting them inside the building.Nor is it demanded that this wire mustbe carried on porcelain insulators. Itmust, however, be protected from me-chanical injury.

After you have looked over your ar-rester and made sure you have not madeany mistakes mentioned above, then thebest thing to do is to tell your fire in-surance agent that everything is O. K.and get him to issue to you a policyrider to be pasted on your fire insur-ance policy. He will be glad to do thiswithout making any charge for it. Thisis not required, but it is a good thingto do because then there will be no con-troversy at all about paying your fireinsurance if you have the bad luck ofhaving your house burn.

APRIL 15, 1924 RADIO PROGRESS

Constructing a Five -Tube NeutrodyneConstruction, Assembly, Wiring andTuning Information for Home Building

By KIMBALL HOUTON STARK

EDITOR'S NOTE:: 01 all the differentradio sets which lately come on the mar-ket, probably the most popular is theNeutrodyne. The reason is found in thefact that it combines exceptional sharp-ness of tuning with remarkable ease of

operation. The dial positions for any

Chief Engineer F. A. D. Andrea, In-.

given station can be logged, that is, re-corded in permanent form at anytime that the station can be broughtin again by setting the dials to the sameposition. Mr. K. IL Stark is the ChiefEngineer of the F. A. D. Andrea Co., In-corporated, who manufacture the FADAline of radio material.

This article appears in two parts.The first installment below describesthe theory of a neutrodyne and the de-tails of construction. The second halfoutlines the hook-up and gives the meth-ods of operating the set. We can recom-mend this as being one of the best radioswe have ever tested.

BREATHES there a man with soul es-Li dead that he has not enthusiasticallytold his neighbors with ready speech andbeaming eye of his marvelous DX (dis-tance) records the night before?

A rather funny statement was madeto me the other day. The thought waspresented that radio is certainly mak-ing us a nation of liars. A couple ofrabid radio hounds meet at any radiostore and imm*diately begin the discus-sion, infinite in detail and yet alwaysending with that universal topic ot,"How far did you get last night?" Oneman hears signals, 1,500 miles on a two -tube super; another chap gets Los An-geles on a one -tube set; somebody elsehappens to think of the old days whensomeone told him about hearing a com-mercial ship station three thousandmiles west of San Francisco, from NewYork City, using a crystal detector-and so it goes.

Romantic RadioIt seems to me the craze for distance

will never die out. I don't want it to.Of all the romance, mystery and mythsthat we encounter in this life and thatwe are told about, where can we getromance that will compare with listen-ing -in to concerts and music andspeeches from stations hundreds of milesaway, from invisible cities, as it were,from an empire not of radio receivers,or equipment, not of listeners or radiofans or experimenters, but a vast em-pire of pleasure and entertainment, ofmusic and of all the good things thatthis world has in store for us.

There are thousands and thousandsof radio fans that struggle along withtheir one -tube sets, or their two -tubeiets, who are just wishing night and dayhey could add a fourth tube or a fifthube in order to hear that station a fewMndred miles beyond the limit of theirreceivers today. Some of these radiopans can afford to buy complete receiv-ers, but the majority must build, orwould rather build, their own.

Sled or Radio? '

In past years, before radio came intopeople's homes, a man would build amission table, a sled for the kiddies, orpossibly a model engine; and, after plan-ning for days, what a thrill he would get-hen the thing was actually finished andmade to "work" or serve some usefulpurpose! Where in the world is theretnything that can compare in givingto such people more thrills and pleas-ures, with the everyday use of radio re-ceiver, built by their own hands, thatworks?

To give radio experimenters depend-able, authorized constructional informa-tion concerning the neutrodyne circuitreceiver is the purpose of this article.

In March of 1923, Professor L. A.

Hazeltine revealed his developed workand introduced the neutrodyne circuitradio receiver. About July of 192.3, alimited number of companies licensedunder Professor Hazeltine's patentswere building completed receivers, utiliz-ing the neutrodyne principle and in ad-dition were supplying complete sets ofparts, suitable for neutrodyne-receiverconstruction.

Painstaking Care NecessaryBeing in intimate touch with many

people who have built neutrodyne-cir-cuit receivers using such parts, I canassure you that to build such a receivercalls for reasonable care in construc-tion in order to obtain maximum broad-cast signal reception, but for thousandswho would be painstaking, the results inthe end certainly justify the expense andthe pains necessary.

List of Materials Necessary to Con-struct a Five -Tube Neutrodyne

The five -tube neutrodyne-circuit re-ceiver to be described gives two stagesof tuned radio -frequency amplification,a vacuum -late Bete: Lor and two stagesof and io-fregite n :1iplification. Sucha receiver will cost approximately $65.00for parts, and if one purchases all theadditional equipment, the total cost willbe approximately $150.00, including thefive vacuum tubes, storage battery, "B"battery, phones and antenna material.

The following list of materials for re-ceiver construction must be acquired:

ApproximatePrices

1 Panel, bakelite, 26" x 7" x3/16", drilled, machinedand engraved $ 8.00

1 Base board, oak, 26" x 6"x 34 II 1.00

1 Triple socket 2.70

2 Single sockets 2.00

3 Neutroformers (tuned sec-

ondary R. F. transformers) 22.502 Neutrodons (neutraliz i n g

condensers) 2.50

2 Audio transformers 12.00


A

41

ci

A battery switch .753 Dials (verniers are unneces-

sary) 3.601 Power rheotsat (2 ohms) 1.201 Detector tube rheostat (6

ohms) 1.257 Binding posts .841 Radio jack, closed circuit .751 Radio jack, three spring

automatic 1.0027 ft. Insulated tubing 2.2627 ft. Wire No. 14, tinned copper .25

2 Condensers, .006 mfd 1.501 Grid leak, megohms .751 Grid leak, condenser, .00025

mfd. .65screws, nuts, terminals, etc

b

Total $65.00

Great care should be taken in pur-chasing these parts and one should ob-tain only the special neutrodyne partsmade by authorized licensees underProfessor Hazeltine's patents.

Drilling Your PanelFor the panel, either bakelite, formica,

condensite or radion may be used. Adetailed panel drilling layout is shownin Figure 1, all dimensions being given.

If you do not purchase the completeset of parts but only the necessary spe-cial neutrodyne parts, you will need tolay out your own panel for drilling. Indoing this it will be found convenientto use dividers and a combination squarein order to get all dimensions, etc., ac-curately. It is suggested that you pur-chase the complete set of parts, whichincludes the panel with all holes drilledand the proper engraving done. Byusing such a finished panel in construct-ing your receiver, it presents a mightygood appearance when finished. How-ever, if you do drill your own panel, verygreat care must be taken in laying outthe position of the Neutroformer mount-ing holes as the relationship of the Neu-troformers to one another is eery im-portant.

As shown on the drawing, Figure 1,the Neutroformers are mounted at anangle of 54.7 degrees from the horizontaland should this vary even one or twodegrees, trouble will be experienced inproperly balancing out the receiver. Onthe diagram, the marking is also shownfor the binding posts and telephonejacks. All holes not marked with spe-cial dimensions are to be drilled clear-

APRIL 13, 1924 RADIO PROGRESS :11

ance for 6-32 machine screws. This re-quires the use of a No. 26 drill.

Assembling the Parts on the PanelWith our panel drilled and engraved,

the next step is to assemble the variousunits on the panel. The rear view of thecompleted five -tube neutrodyne receiveris shown in Figure 2, and from this pie-

ki117771 I

very carefully. Note in particular thepolarity of the Neutroformer windings,audio -frequency transformers, and es-pecially the connections of the Neutro-dons and telephone jacks. All high -potential plate and grid leads should bekept as widely separated as possibleand all wiring separated at least one-half inch with as few leads running

11111,111.7,;iikug liviA011

Fig. 2. Rear View of Completed Neutrodyneture one can get an idea of the generalarrangement of the parts on the panel.

It will be noted that two of thesockets are placed between the Neutro-formers, and that the triple -tube socketis placed on the left-hand end of thepanel looking from the back. The rheo-stat at the extreme left end is a powerrheostat controlling the filament cur-rent of the amplifier tubes and the rheo-stat closest to the left-hand Neutro-former controls the filament current ofthe detector tube. In the hole on thepanel drilling layout marked. "phones"is mounted a two spring closed-circuittelephone jack. This is directly underthe knob of the vernier rheostat. In theother or "horn" jack is mounted a three -spring automatic filament -control jack.The filament switch, binding posts andsockets are easily assembled in theirproper position. The Neutroformersshould be very securely screwed to thepanel in their proper position as theoperation of the set would be affected ifthey were even slightly moved out ofposition during assembly and wiring.

Wiring Up the Five -Tube NeutrodyneSet

The wiring of a receiver is usually thestumbling block for most of the experi-menters. I have seen some of the mosthorrible looking jobs on neutrodyne re-ceivers, yet when the job was properlybalanced out, at worked 0. K. Thisshould not be taken as a criterion, how-ever, and the experimenter is advised totake particular pains in wiring up hisset.

parallel to one another as possible.In assembling the receiver, it is usu-

ally best to fasten the base board to thepanel, and to fasten the audio -frequencytransformers and Neutrodons to thebase board. Before wiring up the re-ceiver, however, one should unfasten thebase board from the panel, as thismakes it much easier to wire all theparts mounted on the panel. Thenfasten the base board with its Neutro-dons and audio -frequency transformers

connections can be made and the wir-ing of the detector tube rheostat, powerrheostat, battery switch and batterybinding posts completed.

Connections to the Neutroformerscome next. It will be noted that allthe Neutroformer secondary windingshave a small loop or tap. On the wiringdiagram no connection is made to thetap of the first or left hand Neutro-former looking from the panel front. Alead is connected, however, from thetap of the second and third Neutro-formers going directly to one terminalrespectively of the second and thirdNeutrodon condenser.

The fixed condensers with capacitiesas shown on the wiring diagram arewired into position and need not befastened either to the panel or baseboard, as the stiff No. 14 copper wirewill hold them in position. After youhave completed wiring up your receiveror preferably step by step as you fasteneach wire in position check off with aheavy pencil on the wiring diagram theconnection that you have just made.When the wiring is completed, all wireswill have been checked and in additionby doing the job this way, you aredoubly checking yourself for mistakes.

On the wiring diagram, no wire is

RO

(PULNGCAzurROPOP PROTI

5,1 -

PLA91op Pc, PLATES

-48

razsr 0.10,0tREOvExc oar(PrurRpre'RPf

®`SECONDRADIO

P,EQI,PCY uptr0,-,ROPORMER)

0,ECIOR roe/OCTELIVR

0 X00

0.-AcrOV PREQUENCY0 TRANSPOR,CR.50 00 0P P

O

se

0 64,422i +POK

.8" BATTERY

"LAMENT5wrrGif

PHONES MORN

Fig. 3. Hook-up for Five -tube Set

again into place to complete the wiringof these units.

It is usually best to begin wiring byconnecting all the negative vacuum -tubesocket terminals and then extending thissame wire to the ground binding posts.

Study the wiring diagram in Fig. 3 In like manner, the positive filament

shown jumping another one with a loopsymbol. The plan shows each wire pass-ing across the others and only connect-ing to cross wires when represented bya solid black dot. Check this carefully,with your own wiring.

In the last article of this series, de-


A Good Prize ContestResults of Our Liars' Contest Show a Plentiful Crop

WE certainly got some pretty tallstories entered in the competition

for the biggest lie. After reading them,we came to the conclusion that by com-parison we must be pretty truthful. Itwas hard to select a winner. But aftercarefully considering all the manu-scripts, the judges unanimously decidedon a single one as showing the greatestoriginality. We take pleasure in awarding a year's subscription to RADIO

PROGRESS to Mr. William J. Cummings,42 Glenwood Avenue, Eden Park, R. I.We also wish to thank all our con-tributors for the interest they displayedin the contest. Mr. Cummings' story isas follows:

THE WAVE TRAP

By Wm. J. CUMMINGS

A wave trap, as most of us know, isa device for eliminating local interfer-ence and enabling one to get that elusivedistant station. After having read aseries of articles on wave traps I finallydecided to build one.

The trap I decided to build was oneof the ordinary non -degenerative type,with a Continental motor, Fisher body,Timpkin axles, Apco shock absorbers,four wheel brakes, balloon cords, self-starter and stopper, and a number ofother extras.

The wave trap when finished workedfine. WJAR, WEAN, and WSAD (allthree local stations) , were trapped againand again. In fact everything workedperfectly, but the strange, weird, hair-raising, soul -stirring and dramatic partof it I have yet to narrate.

One evening I came home and some-how or other mixed the A and B bat-teries. The three tubes in the set ofcourse-need I repeat the sad story?Well there I was without a set andbroke, so I turned back to the "mosscovered" crystal. Now it happened tobe rather dark when I started to hookup the crystal set and again I made anerror. Mistaking the wave trap for thacrystal set I hooked it up to air, ground,and phones.

Then as I slowly turned the dial, agreat shout greeted my ears. My pal-pitating heart stood still and quavered.What great invention had I stumbledon? I listened to an entire programof one of the local stations I hadtrapped a few days before. By turningthe dial back a bit I could get the pro-gram of the previous day. I turned thedial around about an inch or so and allwas silent, but on rotating it a littlemore I tuned in another local trappedstation playing a program a week oldand succeeded by rotating the dial ofthe trap to bring the program up to thatof the previous evening.

Realizing that I had really foundsomething of real value, I looked thetrap over carefully and proceeded totake notes, while the trap percolatedwith the volume of the three tube setthat it had been used on. The antennaand ground were connected on une sideof the trap and the phones on the other,one tip in one post and one in the other,or the reverse, as I found it made nodifference.

Since making that first test and hav-ing bought new tubes for my set I haveexperimented a great deal with the trapand have stored up programs up to twoweeks old. The programs will keep in-definitely if the trap dial is kept at zero.On account of the small dimensions ofthe trap programs for over two weekscould not be stored but this could easilybe remedied by making a larger trap.

As mentioned before, the programscan be kept indefinitely if the dial iskept at zero, but if on rotating the dialyou tune in a trapped station, then likethe art of Chiropractic you adjust thevertebrae of the trap and release the im-prisoned impulse.

That is all there is to it. If there areany who doubt the truth of this articlelet them make a wave trap and be con-vinced. Any type of trap may be usedand all I have found give the same won-derful results.

5 -TUBE NEUTRODYNE

Continued from Page 11

tailed instructions will be given forbalancing out, the inherent capacity ofthe vacuum tubes as well as the stray -circuit capacities, thereby eliminatingparasitic and' distorting oscillations andregeneration.

The Need for Balancing -Out orNeutralizing the Circuit

Many people who have constructedneutrodyne receivers have possiblyfound the adjusting or "balancing out"of the set before it is ready for use,

a difficult task. In most cases, it hasbeen difficult, not because the processitself is complicated but because of amisunderstanding of the results to beobtained and the methods of obtainingthem.

It may be well at this time to con-sider the function of the neutrodyne cir-cuit in order to understand just whatis accomplished when we balance out oradjust it for capacity neutralization.

Professor Hazeltine devised a methodof neutralizing both the stray circuitcapacities and the inherent capacity ofthe vacuum tube, i.e., the capacity exist-ing between the filament or cathode andplate or anode of the tube. It is thepresence of these coupling capacities in

an ordinary tuned radio -frequency am-plifier circuit that causes the circuit toregenerate and oscillate when the tunedamplifier circuits are in resonance, un-less some means is provided for controll-ing the grid potential of the tubes,which usually results in a loss of effi-ciency.

Kill the ParasitesSuch parasitic oscillations make it im-

possible to secure pure radio -frequencyamplification and in addition cause verydecided signal and speech distortion.Every listener -in knows the disadvan-tages of tuning -in to a local concert andhearing all sorts of "birdies."

Concluded in Next Issue


Tube Popularity Causes ShortageHarder to Get 201-A TubesThan to Pick Up the Coast

T N some parts of the country the build-ers of amateur sets have found a

great deal of difficulty in completingtheir radios because of the scarcity of201-A tubes. This style is one of themost popular ones made for several rea-sons. In the first place, it will amplifyfora loud speaker more than any othertube on the market. In this respect it isin a class by itself. It also consumes asmall current, only a quarter of an am-pere, from the "A" battery, so that on apinch it can be run by an ordinary hot-shot battery, such as is used by theold style ignition of a Ford automobile.

Another decided advantage of the201-A tube is that it "has nine lives."By this is meant that if the tube is ac-cidentally burned at too high a bril-liancy it is not necessarily entirelywrecked. Such high operation might becaused, for instance, by accidentallydropping the wire on the"A" terminal, and so putting 221/2 voltsor more on the filament designed forfive volts. Naturally, if this high volt-age lasts very long the filament willactually burn in two, and then it is toolate to repair it. Another cause of ex-cessive brilliance is an improper adjust-ment of the rheostat. Some fans turnthe rheostat way on to the "full -on"position, thinking that by so doingthey can get music in louder. This isa mistake. The music will not be anylouder, but the life of the tube will bevery much shorter.

Turning on Another LifeIf the 201-A tube has been operated

at such a high voltage that it no longerworks, its life may be restored againby special treatment. The way to do itis this: Light the filament by turningthe rheostat around to the normal posi-tion to give about five volts at thesocket. Then disconnect the "B" bat-tery entirely. This will naturally killthe music. Burn the tube this way withthe "A" battery on and the "B" bat-tery disconnected for about one-half anhour. At the end of this time recon-nect the "B" battery, and if the fila-

ment has not been damaged too muchyou will find it will be restored so thatthe music will sound as good as it didWhen the tube was new. The action cannot be repeated indefinitely, so that itis better to see to it that the tubes arenot burned too brightly in the firstplace.

Rumors About 201-A TubeThere have been .persisent rumors in

the last month or so that the shortageof 201-A tubes was artificially causedby the Radio Corporation in order topush the sale of their other tubes. Thisis a mistake. The only way the RadioCorporation makes its money is by sell-ing supplies, and since the tubes are allthe same price ($5.00) and cost approx-imately the same to build, there is noreason why they should want to sell anytype to the exclusion of the other.

Radio Corp. ExplainsThis matter was taken up with the

Radio Corporation of America, and Mr.E. B. Bucher, manager of the sales de-partment, released the following state-ment:

"Rumors to the effect that we havebeen holding back on our tube sales areLbsolutely false, and I wish to deny thatthis is the ease. Only 10 to 15 per cent.Df our total monthly tube production isrequired for our merchandise, the re-mainder going to purchasers using setsand parts manufactured by others.

"There are general facts in the vacuumtube situation which we are glad to giveand which, no doubt, will tend to curbmy feeling that the Radio Corporationof America is not giving this subject theclose attention that it deserves.

"(1) We maintained a day-by-day in-ventory of from 450,000 to 600,000 tubesof five different types (UV -199, UV -200,UV -201A, WD11 and WD12) up to Jan-uary 1 of this year, and steps weretaken many weeks past with the en-deavor to build this inventory to stilllarger figures.

"(2) 768.816 Radiotrons were deliv-ered to the trade in January this year;

825;186 in February, and March deliv-eries exceeded 900,000.

"(3) Seventy per cent. of our month-ly production schedule is composed ofRadiotrons UV -200 and 201-A.

"(4) 'Stocks of dry battery tubes havebeen in excess of the trade demands fromMay, 1923, to date, and current pro-duction is keeping apace of the demand.

"(5) current production on the stor-age battery types of tubes is actually inexcess of new orders booked for theseparticular types, but present productionschedules should produce an excess bythe first week in April.

"There is no desire on the part of theRadio Corporation to do anything otherthan produce tubes in, sufficient quanti-ties to meet every possible requirementof the trade. We are in the businessto sell and not to withhold. However,the circumstances under which the man-ufacturer works in meeting the require-ments of the market must be given duemnsideration.

"Briefly, the industry is too young toenable either the dealer or the dis-tributor to place orders with the manu-facturer sufficiently in advance to meetthe fluctuating demands for the specifictypes of tubes. As the factories, on theother hand, must prepare their produc-tion and procure new material from 90to 1120 days in advance of actual deliv-eries, it becomes necessary for us to-'ndeavor to predict at least four monthsin advance what the trade requirementsmay possibly be. To this end the RadioCorporation maintains a staff of expertAatisticians whose time and energies'Ire devoted solely to a study of this-ituation. Frequent conferences are heldvith the manufacturers and productionchedules are revamped to meet the

`!actuating demands of the market.

Are Not Mind Readers"During the latter part of November,

1923, a largely increased demand for thestorage battery types of tubes becameevident, but no prior notification of thispossible increase was given to the Radio

Continued on Page 14

14 RADIO PROGRESS APRIL 15, 1N4

Letters from Our ReadersOne of the Aces is One of the

GracesIn the article appearing in the March

15 issue, entitled "Three of a Kind, AllAces," we inadvertently interchangedthe names of two of the "Aces." As aresult we got a very bright letter fromMr. Thomas A. McNally of StationWBZ, which we are reproducing. Wemight say that Mr. McNally's lettersare as interesting and as snappy as hisvoice over the radio, and that is sayinga good deal. Here is his letter:The Editor-DEAR SIR:

I have at hand your young publica-tion, Vol. 1, No. 1. It immediately at-tracted my attention. After turning overa few pages, I came upon the picture of'The Three Graces," Faith, Hope, andCharity.

There was a slight error in the initialsof the announcers. I am "Hope"-butI could stand a lot of charity. You had"MCN" under Bill Tilton and "WST"under me.

My hosts of friends in Providenceand surrounding cities would recog-nize the "Irish map" as soon as they sawthe mistake. There is no mistaking mefor anybody else. I am individual! dis-tinctive! This is not egotism, just thebare, cruel truth. That is one of thereasons why I need charity as a substitu-tion for sympathy. I was born in Cen-tral Falls many years ago and migratedfrom said village at a very tender age.Like the wandering troubador, I flittedhere and there, gathering no moss, un-

til the cruel fates sat me down in thiscity of queer traffic regulations and thehome of Republicans.

Perhaps you are wondering why orhow come all this disconnected chatter.I want to thank you, on behalf of Mr.Tilton, Mr. Bach and myself for thewrite-up in your first edition. I canreadily understand why you chose ourpicture for your "premier." Good stuff!Your magazine should increase to about120,000 on the next edition.

I have so many relatives in ProvidenceI would like them all to have a copy ofyour RADIO PROGRESS, but I have onlybeen able to secure two copies.

Best of success to you and your publi-cation. It made me feel great to thinkthat the face of one of Little Rhody's"clam diggers" graced the first pages ofyour endeavors.

Respectfully,THOMAS H. MONALLY,

MCN OF WBZ.

Crosley Radio Predicts Success forRadio Progress

We felt rather flattered to receive thefollowing congratulatory letter from theCrosley Radio Corporation of Cincinnati.As our readers are aware, this companymanufactures radio sets which show anunusual amount of engineering ability,and whatever they say about radio ispretty apt to be right. The idea of de-voting a page or two to the new thingsin radio is a good one. With Mr.Plough's permission we are reproducinghis letter:

March 24, 1924.Mr. Horace V. S. Taylor,Editor RADIO PROGRESS,

Providence, Rhode Island.Dear Sir:-

You are to be complimented on select-ing an attractive color for your cover.The design of the cover is excellent. Thetitle of your magazine, RADIO PROGRESS,always abreast of the times, is very good,but I would like to suggest, inasmuchas you have asked me for my criticism,that you devote the first few pages ofyour book, or at least one page, to atabulation of the radio progress sincethe last issue of your publication. Inother words, for your copy for May tellwhat progress has been made up to thetime of publication. This would bearout the title of your magazine.

I fully realize that a new magazine is aproblem. It is hard to find out just whatthe public wants and yet be different fromthe other publications, but you are solv-ing this, and as your magazine pro-gresses you will find it much easier tosupply this want. The idea of makingevery reader a contributing editor is anexcellent one, and as a reader I shallfeel privileged in the future to send youmaterial.

With all the success that is due youfor your efforts in bringing radio to th

attention of the public, I amMost sincerely,

THE ,CROSLEY RADIO CORPORATION.

A. R. PLOUGH,

Publicity Director.

TUBE POPULARITYContinued from Page 13

Corporation by the trade channels.Major steps were then taken in our fac-tories to increase production on thattype, such as the building of additionalplant facilities, the installation of newmachinery, the training of additionalpersonnel, etc., etc. Between the firstweek of December and February, produc-tion on the storage battery types oftubes was actually doubled and stillfurther increases are obtained week byweek.

"Production schedules have been laidclown in the factories for the remainder

of this year, which it is confidently be-lieved will be largely in excess of thetrade requirements, for it is the avowedpolicy of this company to keep its pro-duction ahead of the demand.

"A temporary tube shortage may de-velop in any particular locality not byreason of insufficient factory production,but because of the difficulties of obtain-ing uniform distribution. The RadioCorporation sells its tubes to distrib-utors; from that point on it has nocontrol over distribution to the dealers.We are aware, however, that distributorsare making every effort to serve dealersin all localities, but the actual quantities

distributed in any particular territoryare also governed by the amount ofdealers' orders, dealers' credits, inabilityof some dealers to sense the public de-mand sufficiently in advance to enablethem to serve customers promptly, andnumerous other factors, all of whichhave bearing on the situation.

"As further evidence of our desire tomeet all possible trade demands, it isimportant to point out that only 10 to15 per cent. of our total tube productionis required for our own merchandise, andall that we need is more concise advancenotification of what the trade wants,thus enabling 'us to prevent shortages."


Taking the Cap Off CapacityInductance and Capacity SoundHard, but Are Easy to Understand

YOU cannot go very far in radio-I- without running across the terms

inductance and capacity. They seemlike rather mysterious qualities, but arenot so difficult when you get to knowwhat they really mean. Take the wordinductance. Inductance means weight.When you speak about the inductanceof a coil, you mean the weight of acoil. This refers to the electrical weightand not avoirdupois. When you wantto send a coil through the mail by parcelpost, you put it on a pair of scales andget the weight in pounds.

Electrical Weight is MeantBut when you want to weigh the coil

electrically to get the inductance, youdo not use scales. The laboratory inmeasuring a coil puts it in an electriccircuit and uses a couple of meters tosee how heavy it is, ordinarily a voltmeter and an ammeter. The answer doesnot come out in pounds, but in milli -henries. This term, by the way, is de-rived from the famous electrician, Henry,who discovered many of the propertiesof electrical circuits. When the read-ings of the meters have been obtained,by substituting in the proper formula theelectrical weight of the cod in millihen-ries can readily be found. If you havetwo coils, and one is long and narrowand the other is short and fat, they canstill be used interchangeably, providedthey have the same iriuctance. In read-ing the diagrams of radio circuits youwill notice that the coils are frequentlyspecified as having so many millihenries.It is better to call them by their in-ductance than by any other way. Thisis because if they were specified as somany turns of such a size of wire, woundon a given diameter of tube, it wouldtake a little longer to say it, and then,besides, if you happened to have a coil ofdifferent size of wire wound on a differ-ent diameter, you would not knowwhether you could use it or not. Bygiving the proper value of the induct-ance it enables you to pick out yourown coil.

By VANCE

How Many Henries Per Pound?It has been stated that when you

weigh the coil electrically the answer isthe inductance in millihenries, and whenyou weigh it mechanically you get theresult in pounds. It is logical to ask,How many millihenries to the pound?Unfortunately you cannot get the an-swer in any such way. One pound equalssixteen ounces, to be sure, and if weweigh the coil in ounces we can convertthat to pounds by simple division. Butthe electrical weight of a coil dependson other things besides mechanicalweight.

For one thing, it is very greatlyaffected by the number of turns woundaround the tube. If you have two coilseach weighing five pounds, one a finewire with a lot of turns, and the othera few turns of coarse wire, then theinductance of the first, with the largenumber of turns, will be very muchgreater than that of the second. An-other thing that affects the electricalweight is the spacing of the wire. Ifyou have a lot of turns wound closetogether, the coil will have greater elec-trical weight or inductance than if thesame coil is pulled out so that theturns lie far apart. Other things thataffect the number of millihenries are thesize of the wire and the dimensions ofthe spool or tube on which the coil :swound.

How Many Nuts to the Pound?Since all these factors enter into the

electrical weight of the coil, it is im-practicable to put it on ordinary scalesto get its inductance. You have to usesome kind of an electrical measuringinstrument instead, as described above.But do not think it is peculiar thatthese factors all affect electrical weight.A similar thing happens in avoirdupoisweight. For instance, suppose you havea quart of nuts. How much do theyweigh? Well, in the first place, it de-pends on what kind of nuts they are.Another thing is, Are they thick shelledor thin shelled? Another factor is the

way they are compressed into the quartmeasure. If they are packed down tightthey naturally weigh a lot more thanif they are thrown in loosely. But allthese variations do not bother us at allbecause we are used to putting them onthe scales and getting the exact weight.What we can say is that the bigger thequantity of anything we have, the tighterpacked it is, and the denser the material,the heavier it will be, and in the sameway the more wire we have, the closerit is spaced, and the greater the num-ber of turns, the more the inductance orelectrical weight expressed in millhenrieswill be.

Effects of Two CoilsWhen we get two coils close together

the effect is different from anything wehave in ordinary weight. If each of twocoils weigh five pounds, then the twocoils will weigh 10 pounds, no matterhow they are spaced. But notice this:The electrical weight of the two coilsconnected together will depend a greatdeal on how they are placed relative toeach other. If each coil is five millihen-ries, then the two will be 10 millihenries,provided one does not affect the other.They will not affect each other if theyare spaced very far apart. Also, if theyare placed close together, exactly atright angles, they will not affect eachother. Either way the two together willweigh 10 millihenries. But now supposeyou bring the coils closer together orelse turn them so they are not anylonger at right angles, and immediatelythe electrical weight changes from 10millihenries. It may go up and it maygo down, depending on the direction ofthe windings of the coil. Suppose youlook at both windings endwise. If thewire in both of them goes around in thesame direction, that is, both right handor both left hand, then the inductancewill be increased by bringing them closetogether. On the other hand, if the wirein one goes around right hand whilethe other is left hand, then the two willoppose each other and you will get leisthan 10,millihenries.


LiLc Playing BaseballDoes this idea seem hard to grasp?

It is just exactly like playing baseball.Here we have a team of nine men. Eachman is a star. If they play entirelyindependently, then the team is ninetimes as good as each individual man.But suppose now they all pull togetherwith wonderful team work, then theresult will be a lot better than ninetimes as good as a single man. But, onthe other hand, suppose they are eachjealous of the other, and instead of pull-ing together they pull apart and eachone blocks the action of his teammates.Then the whole team will not be worthmore than two or three individual play-ers. The same things happen with thecoil. When they act individually (along distance apart or at right angles)then the two add up as you would ex-pect. But when near together, if theyuse team work, the total weight of thetwo coils may be as much as four timesthe weight of each individual coil. Turnone of the coils around so they arejealous of each other (wound in oppositedirections), and they get in each other'sway, so that the weight may be reducednearly to zero.

Team Work in a VariometerThis is just what happens in a vario-

meter. Here we have two coils woundup with the same number of turns andarranged so that one can turn insidethe other. Suppose each coil taken aloneweighs five millihenries; then when youturn the variometer so that the twocoils are at right angles the combinedweight will be 10 millihenries. Turnthem so they are both wound alike andthe inductance jumps to 20 millihenries.Now turn the rotating coil or roter rightupside down, so they are bucking eachother, and the inductance drops nearlyto zero.

You will notice it is nearly to zero.It does not go quite down to nothingbecause the two coils are not quite alike.Since the roter has to turn inside thestator (the stationary part), of courseit has to be wound on a smaller formor else it would interfere. This makesthe two coils of slightly unequalstrength, and so when you subtract thesmaller from the larger, the strongerone has a little bit of inductance leftover. That is why you cannot get azero inductance with a variometer.

Variocoupler Has TapsWhen we come to a variocoupler we

change its weight not by adding or SIM-tracting another coil, but by varying theconnection from one tap to another. Inwinding up the variocoupler a lead ortap is brought out every six or eightturns. An ordinary variocoupler willhave about 60 turns. When you wanta large inductance you use all 60. Butif you want a smaller inductance tomake this connection to one of the tapsyou use, say, 15 or 20 turns. If youwant a very small inductance, connect tothe first tap, and only six turns will bein. use. This makes a very convenientmethod of varying the electrical weightin your circuit, but, of course, there isthe disadvantage of being adjustableonly in big steps instead of smoothly andcontinuously, as you do in turning a

variometer.

Consider a Variable CondenserWe come now to condensers. These

are of two kinds, the fixed and the varia-ble. The fixed condensers are made ofalternating layers of tin foil or copperfoil, which is separated from each otherby layers of treated paper or mica.Once the condenser is built its capacitycannot be changed. So it is called a

fixed condenser. The variable con-densers, on the other hand, are made oftwo sets of plates. One set can oe

turned so that it meshes or dove -tailsinto the other set. The two are in-sulated from each other by the small airspaces left between the leaves. Whenthe rotor (movable plates) is turnedso that they mesh completely with thestator, the condenser action is greatest.and when the rotor is turned half wayaround, so that it does not mesh at all.then the condenser action is least.

Just Like a Spiral SpringThis 'condenser action that we speak

about really means the springiness of thecircuit. A big condenser is just exactlylike a big spring. If you have a weightattached to a spring you know howeasily it will vibrate up and down. Thesame thing applies to an electrical cir-cuit with an inductance (weight) con-nected to a condenser (spring). If youwant to slow up the vibration of theweight and spring you can do it bymaking the spring quite long. Con-versely a short stiff spring speeds upthe vibration. This is what happens in

your radio. A large condenser, since itis a large electrical spring, causes aslow vibration. As the variable con-denser is adjusted by turning the rotorso that the plates do not mesh so

deeply, this cuts down the electricalspring to a short length, and that speedsup the frequence of vibration. That isthe way you tune your radio. If youwant to get a short wave length, whichmeans a fast speed of vibration, likeKDKA (East Pittsburg) , which runs at326 meters, you use a small capacity togive the high speed of vibration. Whenyou want to pull in WGY (Schenec-tady), you have to turn in a lot morecapacity, because, since it is a longerwave length, 380 meters, and a slowervibration, you have to have a longerspring. But suppose you decide to tuneto WEAP, New York. You have to usepractically all your condenser becausethe long wave length, 492 meters, meansa very slow oscillation, and this requiresa very long spring to cut the speeddown.

TAKING MOVIE PICTURES BYRADIO

The wonders of radio are increasingat such great rate that it is hard to tellhow much we can believe of the wonder-ful stories we hear. A recent illustrationof this was furnished by Station WJAZ,the Edgewater Beach Hotel, Chicago. Ashort time ago they announced over theair that they were going to try to takemotion pictures of their listening audi-ence through the microphone, and ifradio fans would listen closely theywould hear the click of the motion pic-ture camera. Of course, this was a joke,and it was supposed by the hotel that itwould be understood as such. The movie -man put a camera up close to the micro-phone and gave the crank a few turns,and sure enough, the clicking of thecamera was heard life-size away acrossthe continent.

That was all there was to it as far asWJAZ was concerned. Imagine theirsurprise when letters began coming inthe next day, and continuing for a week,from listeners all over the country, ask-ing whether the group picture they hadtaken turned out well, and whether itwould be shown in their local moving -picture theatres. "Did I take a goodpicture?" was the usual question.


on-Squealing Regenerative Radio"Teledyne" Circuit is One of the RecentDevelopments in the Non -radiating Sets

H. S. WILLIAMS, Radio Engineer

Ell:TOR'S NOTE: This is the second ofa series of articles by H. S. Williams,radio engineer, on operation and featuresof the Cutting & 'Washington "Teledyne,"the new non-reradiating circuit. To -day'sarticle deals with antenna and groundconstruction and the best ways of tun-ing. The first article appeared in theApril 1 issue.

UPthrough the various stages of

rapid progress in the science ofradio reception, from the early commer-cial application by Marconi to present-day "radio in the home," the importanceof the aerial, as a collector of feebleradio impulses has been of supreme im-portance to the results Obtained.

Ant.

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the, window, across the room or under energy is to be brought into the receiv-the carpet, the results are always greater ing set.if the antenna is carefully built. The The ideal antenna is one well out inmost authoritative radio engineers agree the open having a minimum of resist -that there is no substitute for a goodantenna and ground. For this reasonthe Teledyne is designed to operate onan aerial in conjunction with a goodground instead of many of the more orless inferior devices put forth as substi-tutes. Although it will operate surpris-ingly well on small and poor antennas,the Teledyne's sensitivity increases enor-mously when connected with the aver-age good antenna.

An analysis of the radio wave easilyexplains this. The energy emitted from

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Too often the radio fan depends on anantenna that he thinks is "good enough."There is the "freak" aerial. A freakaerial is a thing in the category ofeverything else notional and freakish.It soon passes.

Granted, that there is a certain thrillin "getting so and so" with a wire out

ance and the best of insulation. Thelead-in should he short and direct, wellinsulated, and clear of the Sides

of buildings. Space and convenienceconsiderations are very important limit-ing factors in the erection of a suitableantenna. Thus, since we can only ap-proach the ideal the greatest care shouldbe exercised in planning and construct-ing.

The average antenna has an effectiveheight of about twenty feet, although itsactual height may be somewhat greater.

AUTOMATIC SNITCHES ON RhiE03TAT5

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Shows the Hook-up of the 4 -Tube Teledyne

a transmitting station, as is commonlyknown, is radiated in ever wideningcircles, becoming weaker and weaker asthe distances it travels increases. Theimpulses picked up by the distant re-ceiving station are so very minute thatthe most efficient collective device shouldbe utilized if the maximum amount of

The effective height may be called itselectrical height, and it is this thatlargely determines the antenna's effi-

ciency as a collector of radio energy.The greater the effective height, thebetter the signal strength.

In contrast with the ordinary antenna,the average loop has an effective height


of about three inches. Thus the usualantenna compared with the average loopcollects, roughly, about eighty times asmuch energy. Obviously, such an initialadvantage is not one to be ignored.

For the best results under ordinarymetropolitan conditions, an aerial withbetween 60 and 100 feet between theset and the far end should be used.The antenna may be longer if there areno stations within 50 miles.

The receiving set is ordinarily connectedto water pipes, radiators, rods driven inthe ground, pumps, or gas pipes. Thegreater the resistance of the radio"ground," the less the signal strength,hence the importance of securing a low -resistance ground connection.

Hooking Up the SetThe diagram shows the method of

hooking up the various parts describedin the last issue of Remo PROGRESS.The first tube is a radio frequency am-plifier. Control is obtained in coarsesteps by the switch, while fine tuning isaccomplished by the eleven plate(.00025 mfd) condenser. The outputfrom the plate of this tube goes to theprimary of the air cored radio fre-quency transformer, which you have al-ready wound. You will notice a con-denser, .04 mfd, which connects acrossthe 90 volt "B" battery. This may beomitted or a smaller condenser, say.002, substituted. The reason for its useis to allow the radio frequency to avoidthe necessity of going through the "B"battery.

The Tickler is ImportantThe tickler coil running from the

plate of the second tube or detector iscoupled to this same air cored trans-former. After the audio frequencywaves leave the tickler coil they goeither direct to the phones or to the firstor second audio amplifier, depending onthe position of the automatic switcheson the rheostat. For these switchesmay be substituted ordinary filamentcontrol jacks, or, if desired, regularfour contact jacks may be used and thetubes turned on and off by the rheostat.As a matter of fact, everything in thehook-up diagram to the right of thetickler coil is just like any ordinarytwo -tube amplifier.

The rheostats shown are of 20 and 30ohms for use with the UV 199 tube. Ifstorage battery tubes or WD11 or 12

tubes are to be used, then six ohm rheo-stats should be substituted. The twoterminals for the horn are to be used ifthe loud speaker cord has no plug at-tached, but if a plug is used these ter-minals may be omitted, and the loudspeaker plugged into the telephone jackin the usual manner.

Ready to Tune InThere are two general methods

of tuning the Teledyne. Both are ex-tremely simple and therefore quite rapid.Each method has its advantages, andevery user of the Teledyne probablyswears by his favorite method. The im-portant feature of the Teledyne receiver,however, is the fact that, regardless ofthe method of tuning employed, or ofthe degree of skill or lack of it in theoperator, the Teledyne will not emit thehowls and squeals peculiar to other re-generative receivers, and thus cannotpossibly annoy or interefere with neigh-boring reception.

The Teledyne receiver has thus at onestroke eliminated the only objectionablefeature of regenerative receivers, andhas at the same time achieved a remark-able sensitivity.

The first way of tuning is the fa-miliar beat method. This consists incausing the detector tube to oscillate byincreasing the regeneration, and thenslowly varying the secondary condensercontrol. As this control is moved overthe scale, innumerable beat notes, knownvariously as "chirps," "squeals," "val-leys," etc., are heard.

The second step is to bring the pri-mary into tune with the secondary. Oneof the beat -notes heard while moving thesecondary control should be tuned to the"valley" or zero -beat position as is cus-tomary in single circuit tuners. The pri-mary control is then slowly varied overits range. One position will be foundwhere the beat -note is made very muchlouder, thus indicating that this is thetune position. Leaving the primary atthis adjustment, the regeneration is thendecreased until the beat -note disappearsand the signals are clear and distinct.Re -adjustments of primary and second-ary controls will often help in bringingthe signals in much louder, as in anyother receiver. The chief advantage ofthe beat method of tuning is its rapid-ity, and the ease with which weak ornew stations may be picked up and tuned

in. Its chief disadvantage lies in thepresence of the beat -note squeal whileengaged in the tuning -in process. Forthose who object to this latter feature,the second method of tuning will prob-ably offer greater appeal.

The second method of tuning the Tele-dyne may be called the Hunt method.It is characteristic of the Neutrodyne,and similar receivers, but in the Tele-dyne, only two controls are used, onefor each hand, thus greatly simplifyingthe tuning process.

The regeneration control is set at alow value, well below the oscillatingpoint. With the primary control in onehand, and the secondary control in theother, the entire range is slowly andcarefully covered, maintaining the pri-mary in tune with the secondary. Thein -tune position may be readily deter-mined by the sudden increase in atmos-pheric and extraneous noises as the pri-mary is slowly varied. A little practicemakes this process quite easy and rapid.Any stations operating and within rangeof the set will be heard as the receivercomes into tune with them. Once a sta-tion is heard, the regeneration may beincreased, and minor readjustments madeuntil the intensity is a maximum.

This method may be satisfactorilyused on the louder stations, but for tun-ing in the weaker and extremely distantstations, the beat method is preferable.

The dial scale readings on the Tele-dyne may be recorded on a chart afterthey are once found, and thus a stationonce heard, may be immediately tunedin again at any time by setting the dialsin accordance with the charted scalereadings. It is only necessary to recordthe primary and secondary readings, asthe regeneration control serves only toadjust the intensity of the signals.

$350,000,000 FOR RADIO IS THEPREDICTION OF MR. BABSONAccording to Mr. Roger W. Babson,

the eminent statistician and businessauthority, America will spend $350,000,-000 for radio this year. Vacuum tubesalone will take $50,000.000. This is, athird as much as the entire furniturebusiness of the United States, and twiceas great as the carpet and rug business.Be careful not to let any of your moneygo to the replacing of carelessly burntout tubes.


Broadcasting Has Its DangersFalling Radio Tower NearlyWrecks the Montreal Express

ONE of the popular stations which isheard in Eastern United States is

Amrad, with the call letters WGI, lo-cated at Medford Hillside, a little wayout from Boston. To listen to its pro-grams as given out to -day, no one wouldimagine that it was once a strugglingstation and was having its troubles ingetting started.

From its lofty tower close by the routeof Paul Revere's historic ride, the AmradCorporation was one of the first tobroadcast speech and music across theland. "Sowing seeds in the air" seemedin those early days of radio but the odddreams of a fanciful visionary. Howwell these "seeds" took root is evidencedby the remarkable growth of the radioindustry.

It was in the summer of 1915 thatWGI was first erected, due to the per-sistence and foresight of Harold J.Power, one of the leaders in the RadioArt. These were the days before present-day broadcasting licenses were issued bythe Government. Amrad WGI was thendesignated as IXE, an experimental sta-tion call letters. It was during 1916and 1917 that the newspapers of NewEngland frequently printed stories aboutradio music and speech, being heard inisolated communities and by ships at sea-stories which seemed almost incredibleto the reading public.

Express Train Rushes OnIn connection with the erection of the

tower over eight years ago, there is aninteresting story: On a Saturday noon,the workmen erecting the tower, thefirst and highest of its kind, had almostfinished their job. However, the sup-porting guide wires were not in place.This almost criminal negligence on thepart of the workmen nearly resulted ina serious fatality. A gentle breezesprang up, rocking from side to side the320 -foot perpendicular structure whichwas entirely unsupported. An extradraft, and over the tower toppled, fall-ing across the trolley wires of an adja-cent thoroughfare, and also across thetracks of the Boston & Maine Rail-road. The Montreal Express was ap-

proaching at 60 miles an hour, but for-tunately, the engineer saw the towerfalling, and was able to bring the trainto a standstill by applying the emer-gency without crashing into the debris.

lie safety. The proposition even wentbefore the State Commissioners, whofortunately were broad -gauged enough toappreciate the far-reaching possibilitiesof radio broadcasting and to recognize

This Tower Measured Its LengthAt once work was started to re -erect that the engineering construction of the

the tower, but this was delayed due toprotests from the trolley company, rail-road and nearby residents, who fearedthe tower a mysterious menace to pub -

tower was basically sound. Their judg-ment has been adequately justified bythe intervening years.

20 RADIO. PROGRESS APRIL 15, 1924

The picture shows the rather unusualconstruction of the broadcasting tower.While most structures are rigid at thebase, and depend on the foundations forholding some of the side pressure, thistower is quite different. No reliance atall is placed on the masonry base toprevent the tower tipping over. Instead,an elaborate series of guy wires is used.The tower is divided into lour parts andat the top of each section the guy wiresare attached. This large number must beused to prevent the tower buckling undera heavy wind storm. Although the steelwork looks rather frail, it has stood thetest of nearly ten years' storms.

Started Once in Two MonthsOf course, the early broadcasting ef-

forts were periodic, first hi -monthly andthen weekly, and then twice a week. Overtwo years ago, May 20, 1921, regulardaily and nightly broadcasting wasscheduled, and has continued without in-termission ever since. The first Directorof Broadcasting was H. M. Taylor. Thefirst studio was a comparatively primi-tive affair in marked contrast to the

Harold J. Power

richly furnished and conveniently ar-ranged studios of to -day. Three timeshas the studio been entirely remodeledto keep pace with the increasing im-provements of the broadcasting art-inorder to keep this oldest broadcastingstation on a par with the best of therecent stations.

v hue using comparatively low power,100 watts, the station has been heardfrom coast to coast, in Canada, and theWest Indies. Noted persons of thiscountry and Europe have been attractedto the station. The present Director ofBroadcasting is H. D. Miller.

The First Radio SchoolThe executive head of this sta-

tion is Harold . J. Power. Hisstory is as romantic as the indus-try he has helped to shape. He startedin radio as a young grammar school boyand became so enthusiastic that he gotpermission to be let out of school inEverett early each day so he could runhome and get the Navy Yard time sig-nals at noon. He used at this time ahome-made set with which he had experi-mented for a year, first in his mother's veniently holding small bolts and thekitchen, then in a shack called the like."Laboratory," before he received hisinitial message. In 1910 he conductedwhat is believed to have been the firstradio school in the East-a night classat the Everett High School.

J. P. Morgan InterestedAfter he finished school Mr. Power, as

a result of his unremitting work withradio, was able to get a wireless opera-tor's berth on a Boston -New York pas-senger steamer. Later he was operatoron the late John Jacob Astor's yacht.His next move was to the "Corsair," thefamous yacht of Pierpont Morgan. Whileoperator on the "Corsair," Mr. Power,though even then hardly more than alad, interested Mr. Morgan in the pos-sibilities, then little recognized, of radioas a commercial proposition. The re-sult was the establishment in 1915 ofthe first Amrad plant at Medford Hill--dde, with Morgan financial backing.After several years of struggle and per-sistent research work, the concern wasplaced on its present sound basis.

Invents the "S" TubeIn its model manufacturing plant, the

American Radio and Research Corpora-tion, the largest among the independents,produces the highest class type of mod-ern radio equipment. Production facili-ties are 1,000 sets per day under normalconditions. Research, so important inthe development of any art, has not beenneglected. One of the startling scientificachievements of the research end of thebusiness-one that has attracted consid-erable attention-is the "S" Tube-aRectifier without a filament.

ODDS AND ENDS TRAYHaim- A. N VRSON

All the 6-32 and 8-31 screws, nuts andbolts and all the thousand and onesmall parts that seem indispensable forbuilding a radio set have to go some-where. The slack worker puts them allin one tin can. But the methodical onewho saves time in the end provides sep-arate trays for the principal items. Iftime is no object, a tray about 12 inchessquare divided into six or more com-partments can be made. But an equal-ly desirable tray already divided intocompartments is found in the shallowtin muffin pans used in every kitchen.These can be purchased for 10 cents ora little more, all shiny and new, andwill save many times their cost in con-

"MAHOGANITE" IS COPY-RIGHTED

Perhaps you are using a radio panelwhich is grained like mahogany woodwith streaks of red and black in it. Suchan appearance is very attractive on a setand adds considerably to the neatness ofthe design. But it may or not be ma-hoganized. This name can be used onlyif the product is manufactured by theAmerican Hard Rubber Company as theywere the first to use this name and havecopyrighted it as applying only to theirown product.

A good many people in the past haveused "mahoganite" as the name for thiskind of material, although made by com-peting companies, and while by law theAmerican Hard Rubber Company has thelegal right to sue for copyright infringe-ment, they have taken the broad standthat it is undoubtedly inadvertanee thathas caused this theft of name. However,they have served notice that in the futureany one infringing will be prosecuted.

RADIO VOTE AGAINST CAPI-TAL PUNISHMENT

An analysis of several thousand of theletters received from WEAF's audienceas a result of the debate held before itsmicrophone at the Hotel Astor betweenWarden Lewis E. Lawes of Sing Singand Senator William Love of Brooklynon March 25, showed that 48 per cent.of the audience favored capital punish-ment and 52 per cent. were against it.

HISSES AND CLAPSWHEN you tune in to -night

and you hear a sopranosinging some wonderful solo, like"At Dawning," for instance, whatwill you do? Undoubtedly youwill be thrilled and perhaps re-mark, "What a wonderful voiceshe has." But do you let the mat-ter drop there? If you do, youwill not have done your duty.

You will often hear that cour-tesy requires that you send ap-plause cards to the broadcastingstations when you are particular-ly pleased with some program,and no doubt most people agreethat this is the polite thing to do;but have you ever acted on thisprompting and expressed your ap-preciation by filling out andmailing an applause card? Per-haps it is not generally knownthat most of the talent gives itsservice free to the broadcastingstation. Even such a big companyas the General Electric Companydoes not pay its artists anythingfor their performances before themicrophone at WGY, Schenec-tady. All their services are do-nated free of charge. And whatdo they get out of it? Only twothings. First, the advertisementof themselves, and, second, themental satisfaction which theyget from knowing that they arehelping to make the world apleasanter place in which to live.But how can they know they aresucceeding in this laudable pur-pose if no one tells them about it?

Like Talking to YourselfDid you ever talk into a tele-

phone and find that it was out oforder? Would you be so foolishas to continue to speak your mes-sage into it when you got no re-sponse from the party wno wascut off at the other end? Proba-bly any remarks you did make

were of rather a choice nature.Well, when a person talks into amicrophone in broadcasting itseems just like talking into a deadtelephone. Absolutely nothinghappens. Perhaps the instrumentis even out of order; you do notknow. You talk for perhaps fiveminutes, maybe for an hour, andnothing but silence reaches yourear in reply. And if that silenceis repeated when the mail comesin the next day and on succeedingdays, nothing is heard from youraudience, you naturally are dis-couraged from ever repeating theperformance.

Two Dollars or One CentAnother point to consider is the

effect on the broadcasting directorat the studio. The only way beknows what the public wants isby reading over the applausecards coming in. And so if youdo like a certain piece of musicor a certain singer, the only wayyou can be sure that you can getan encore is by letting the direc-tor know about it. Then, too,you sometimes hear somethingthat is very disagreeable. Per.haps the soprano flats badly andit grates on your ears. This mayhappen every night if you do notsend in a few hisses. You spendtwo dollars to see a show andthen "give a hand" to the perform-ers besides. By all means to-night, after you have heard theconcert, spend a cent for a postalcard and write a few hisses orclaps and send it in.

THE BROADCASTING BATTLEAt the present time t'le news-

papers are full of the fight be-tween the Radio Corporation ofAmerica and its allied organiza-tions, the Westinghouse ElectricCo., the General Electric Com-pany, the Western Electric, on

Due hand, and the Government onthe other. The claim is made bythe latter that an attempt is be-ing made to monopolize broad-casting. This is denied by thecorporation,

This situation was broughtabout by the recent action of theWestern Electric Company inbringing suit against severalbroadcasting stations for in-fringement of their patents. Aword here might be said as to howthe various patent rights were ac-quired. As we all know, radiois a very new science, and it un-doubtedly has the great popularappeal of any science. There aremultitudes of people working onits improvement all the time.Quite possibly you, yourself, havebeen experimenting somewhat inthe last month, using one hook-up and then another, which youmay have read of, then combiningthem with your own ideas to seeif you cannot get even better re-sults; and if you are successfulyou very likely take out a patent.When you multiply your effortsaloncr, these lines by the hundredsof thousands of other experiment-ers you will realize that the rapidgrowth of the industry must haveresulted from the large numberof patents covering the entirefield.

Beating the Patent GameAccording to patent law, if you

make an improvement on some-body's invention which he haspatented, you can make and usethe improvement, but not the un-derlying patent which you haveimproved. On the other hand, theoriginal patentee can not useyour improvement.

So you each block the other.Neither one can make or use theimproved article. Owing to Vieoperation of this law, no com-pany could make a good radio set..


One could make some parts andanother other parts. But com-plete sets were out of the ques-tion. What was more natural,under the circumstances, thanthat the big companies should gettogether and agree to pool theirpatents? As a matter of fact, thesame thing happened a good manyyears ago in the automobile in-dustry. Before that combinationone company could make an en-gine, another a steering gear, anaa third a transmission. But noone company could make a com-plete automobile.

Uncle Sam Takes a HandDuring the war the Government

asked the three biggest electricalmanufacturing companies in theUnited States to get together andpool their patents. This they didby a cross licensing agreement,under which each company coulduse the other companies patents.Since that time they have beenable to make complete sets with-out infringement. They alsogranted licenses for use of theirpatents to several independentcompanies, who are now makingcomplete sets.

The position of the Radio Cor-poration in the discussion is thatthey have spent millions of dol-lars in all in developing radio toits present success. The only waythey can get a return on themoney invested is by selling theirapparatus. If anyone can manu-facture and sell the patented arti-cles without giving any return tothe patentee, then what use is thepatent? To quote from Mr. H. B.Thayer, President of the RadioCorporation

"Broadcasting is made possible by in-ventions that have cost their ownerslarge sums not only in acquiring patents,but also in experimental and develop-ment expense. We have recognized thefact that many broadcasters, in makingwrongful use of our inventions, havebeen ignorant of their infringement. Wehave, therefore, established reasonablelicense fees, the payment of which,coupled with an agreement to refrainfrom further infringement, would liqui-date any claims for infringement andwould give the broadcaster a legal rightto the use of the patent during their

life. The fees are so moderate as torepresent a return far below the cus-tomary profits on unpatented electricalapparatus.

"With approximately 400 stations inthe United States using our inventionswithout a license from us, it became amatter of ordinary prudence for use toinstitute legal proceedings that wouldestablish our ownership of patents andour rights as owners. Not to protectthem would be sheer neglect of duty."

This gives the position of theCorporation. On the other hand,the Government thinks that thereis danger of a monopoly beingcreated in radio, which will bevery detrimental to the art. Ifone company is able to dictate atwill who shall do broadcastingand who shall not, there is con-siderable danger that an attemptwill sooner or later be made toput out propaganda of one kindor another. Just imagine at elec-tion time if one company can dic-tate the sort of political speecheswhich are allowed to go on the air,what a tremendous power thiswould be. Or even, in the matterof religion, suppose notice wereserved on the broadcasting sta-tions that hereafter only churchservices of certain denominationsshould be broadcast. Granting acomplete legal monopoly, there isno limit to the censorship whichthe one company might not beable to establish.

Secretary Hoover SpeaksMr. Herbert C. Hoover, Secre-

tary of Commerce, is the cham-pion of the people's rights in thematter. He says :

"I am in receipt of many requests formy views as to issues now before thecourts bearing on the control of radiobroadcasting. * * * I can state emphati-cally that it would be most unfortunatefor the people of this country to whombroadcasting has become an importantincident of life if its control shouldcome into the hands of any single cor-poration, individual, or combination. rtwould be in principle the same asthough the entire press of the countrywas so controlled. * * *

"In the licensing system put in forceby this Department the life of broad-casting licenses is limited to three

months, so that no vested right can beobtained either in a wave length or a li-cense. I believe it is safe to say irrespective of claims under patent rightson apparatus that broadcasting will notcease and neither will our public policyallow it to become monopolized."

We Become a ProphetIf we may assume the role of a

prophet we predict the followingoutcome of the controversy :The case will be carried eventu-ally to the Supreme Court andwill be dragged out over a longperiod of time. Eventually it willsimmer down to this situation :The Radio Corporation, which isthe legal owner of the patents(and quite properly-it has paidvast sums of money for them-),will allow any responsible organi-zation to broadcast. This will re-move the muzzle from the air. Butthey will charge license fees forthe use of their patents, and willfix these fees at an amount whichgive them an adequate return onthe time and money which theyhave invested.

SO DOES THE SODA CLERKIn previous issues of this maga-

zine, we have invited you., whoare now reading this article, tosend in comments and criticisms,and if you are one of the largenumber who have done so, wewant to thank you for yourinterest.

The attempt is being made toconduct RADIO PROGRESS a littledifferently from the way otherpapers are run. Of course, eachpublication tries to please you,but we are making an unusualeffort togive you what you want.It is like a drug store. A manwalks in and tells the soda jerkerwhat he will have. He does notexpect the man behind thecounter to serve what he wants,and he knows he is not gifted asa mind reader, so he condescendsto tell the soda server that hewill take coffee ice cream withhot nut fudge poured over it.

So once more we ask you to letus know what kind of ice creamyou prefer we should serve you inthis magazine.


Lines for Lady ListenersEdited by Miss Opal A. Mowry

Contributions for This Department Will be Accepted if They Are of Special Interest to Women

First Music Then LooksMOW that the first thrill of listen--I- ing to entertainments from the airby merely turning a few dials has wornoff, people are beginning to give morethought to the selectivity of the radioset, and also to distances which the setwill receive. The day is past when weshall be satisfied with just being ableto receive music, lectures, etc., with nothought to clearness. We have to hearevery word of the lecture and every noteof the music or we immediately knowthat our set is not what it ought to be.We now realize that radio is not onlya luxury, but it is becoming more andmore educational and important, and wewill not be satisfied until we have themost selective receiver which we can get,as well as one that will bring in the dis-tances in our home. The ,programsfrom local stations may be just as goodas those from distant stations, but be-cause we know that we are receivingfrom many miles away it makes it seemall the more wonderful and entertain-ing. It is remarkable to listen to localstations, ' but the greater the distancereceived the more thrilling it is.

When buying or building a radio set,then, we must give more thought tothe selectivity and distance which itwill receive than to the appearance. Ofcourse we all like to have a nice look-ing set in our home, but which is moreimportant, the way it looks or the wayit works? After we have procured aset which receives great distances andis also selective it is then time to givethought to appearance, and this will bedone.

Then What?Mother: "Jessie, the next time you

hurt that kitty, I am going to do thesame thing to you. If you slap it, Pllslap you. If you pull its ears, I'll pullyours. 'If you pinch it, I'll pinch you.There now."

Jessie (after a moment's thought) :"Mamma, what'll you do if I pull itstail r-Croqlev Radio Weekly.

THIS IS W -E -E --PThe shades of night were falling fast,When through the air we heard at last,

My Radio.Then Pa begins to try and tuneAnd gets as crazy as a loon

On Radio.We dare not speak nor dare to thinkWhen Pa is on the ragged brink

Of Radio.If papers rustle he gets mad,"Shut up!" he cries in tones not glad,

"Oh-Radio!"Then music sweet it fills the airAnd things come in from everywhere

By Radio.Pa raves and swears and tears his hair-Mixed organ peals and squeals are there-

Bum Radio.Was ever such a craze as this,That takes the joys from wedded bliss

Like Radio.-W. W. Harris, in Universal Winding..

WHICH ONE DO YOU LIKE?In this store it is not only possible

for the customer to see the loud speak-er he wants, but also to hear it byplugging in on the one which best suitshis taste. The horns do not have tobe removed from the shelf, but are keptin place, which keeps them in bettercondition, as it is not necessary forthem to be handled so much. This isthe very newest and practical methodadopted for demonstrating loud speak-ers, since it is possible to listen to theone of your choice by merely pluggingin. A pilot light placed at the base ofeach horn indicates the loud speaker inoperation. The originator of this novelidea is Harold Herbert.

ie.1181111 r Koh

Top Shelf is for Horns and Belles

TIMING THE CURFEW BELLIn some cities it is customary to ring

the fire bell at 9 o'clock every eveningfor the double purpose of testing theelectrical system of the fire alarm andalso for giving the correct time to theitizens. Nowadays the hour has been

changed until 10 o'clock in the evening.This insures getting the correct time

exact to the second. The radio receiveris either tuned direct to Arlington, whichgives the standard time for the wholeUnited States, or if found desirable oneof the relaying stations, like KDKA(East Pittsburg), is tuned in. By thismeans the radio fans who may be listen-ing to a concert from some other stationcan still get the correct time from thebooming of the fire bell.

RADIO PROGRESS APRIL. 15,- 1924

Radio Doing Its Own BroadcastingNew Sending Station Does WithoutSingers and Speakers and Talks Itself

Tx these days you frequently hear ofi trouble as to what should be broadcast,and there is discussion as to what tal-ent to employ. The performers are be-ginning to think they should get paidfor singing. But the latest in the art isto do away with the performer and let

the radio do its own broadcasting. Dr.Harvey Fletcher, of the Western Elec-tric Company, is the inventor of a new

type of apparatus which can be made totalk itself, not merely reproducingwhat someone else has said.

Dr. Fletcher, who received his degreefrom the University of Chicago, uses avacuum tube oscillator and amplifierand with his special tube circuits ba

can make a loud speaker say A, E, I,0, U. The vacuum tube oscillator isconnected up to an overloaded amplifier

which causes bad distortion. It is thisdistortion which produces the har-monics, which distinguishes a spokenword from a mere tone. Two separatecircuits are used, which allow twogroups of harmonics to be controlled.It is these that determine the characterof the sound, instead of just the pitch.

Will be in Big DemandWhen this invention is perfected so

that any. one's voice can be duplicatedat will, the imagination hesitates as tohow far it may be used. Maybe thebusiness man will have one set up inhis office and tuned so that when anundesirable visitor steps in the office

boy by pressing a button can make abellow "Throw him out," in a tout

that will strike fear in the visitor, or.again, the love-sick youth will send aninstrument to his sweetie to put on herdresser beside his photograph, which

will continually remind her in his owntone of voice how much he loves her.

They Tune the ToneOur picture shows Mr. John ti".

berg at the left helping Mr. HarveyFletcher to get just the tone of voicewhich they are aiming for.

TESTING THE "KICK" OFTRANSFORMERSThum. A. NICKERSON

It is always advisable before placinga transformer in a radio set to test theprimary and secondary windings forcontinuity. This may be done in themore usual way by placing a small bat-tery and pair of phones in series witheach winding to be tested. Each timethe circuit is completed, there should bea click registered by the phones.

Here's a very simple but effectivemethod of testing both primary and sec-ondary with one test. Touch the ter-minals of a three to six -volt battery

source to the primary terminals and atthe same time touch a moistened fingerto each of the secondary terminals. Asmall electric "shock" is a sure index ofproper winding. In the case of audiotransformers, the strength of the shockreceived is to a considerable extent anindex of the voltage step-up caused bythe transformer.

RADIO THE RULING RAGEAn inventory of the radio craze was

recently compiled by an interested au-thority. This is what he found:

Twenty-five thousand retail dealers.One hundred and seventy-five million

dollars estimated expenditure by the

American public during 1923 for radiomaterial.

Two hundred and fifty books on radio.Seven radio trade papers.Fifty. magazines carrying radio sec-

tions.Thirty radio periodicals.Three thousand weeklies with radio

sections.One thousand newspapers which carry

radio news.One thousand wholesale distributers

and jobbers.Three thousand manufacturers of ra-

dio supplies.Two hundred and fifty thousand per-

sons connected with the industry.


The Popular Loop AerialMany Fans Are Discarding TheirOutside Aerial for a Loop Antenna

An Interview with R. H. Langley, RadioEngineer, General Electric Company

MANN- of the modern sets have oneor two novel appliances. Some

have a big wooden cross built into thecover of the radio and on this cross iswound ten to fifty turns of wire, thusforming a. loop aerial. In other sets isfound a jack labelled "loop" and a loopaerial, as just described is plugged intothis jack by means of a flexible coil.What are the advantages of such a pieceof apparatus over the usually used out-door aerial?

The loop antenna is a very interestingdevice. It is quite different in its methodof operation from the outdoor aerial.The outdoor antenna is in effect nothingmore nor less than a condenser. It is avery large condenser to be sure so faras its physical dimensions are concerned,but electrically it is a relatively smallone. The loop, on the other hand,is an inductance. This fundamental dif-ference between the two is the reasonwhy it is necessary to use differentmethods of tuning in the two cases.

Like Automobile GeneratorThere is a very close parallel between

the ordinary direct current generator ordynamo and the loop antenna exposed topassing radio waves. In the generatora number of coils corresponding to theloop aerial are rotated in front' of thepoles of a powerful magnet. The pur-pose of rotating them is in order thatthey may move with respect to the mag-netism, and thus have a voltage or elec-trical pressure generated in them. Theamount of this voltage depends ofcourse, upon the strength of the fieldand the speed at which the wires areswept through it.

In the radio case, the coil stands still,but the field moves swiftly past the coil,thus accomplishing the same result. Thespeed at which the field moves naturallycannot be varied and is always the speedof light, that is 156,000 miles persecond.

Let us see now what form of loopwould have the greatest voltage gener-ated in it by a passing radio wave. Let

is think of this radio wave as verymuch like great smooth waves on theocean, which of course, also move for-ward with a very definite speed. Theturns of wire on our loop antenna arenecessarily in series with each other,that is to say, they form a continuouswinding. See Figure 1. If the maxi-mum voltage is to be generated in the

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loop, then the voltage induced in thetwo sides of each turn must be in thedirection so that they may add and notoppose each other. If the voltage gen-erated in both sides of the loop were inthe upward direction at any one in-stant, then these two voltages wouldcancel each other, but if the voltage onone side of the turn were up and on theother side of turn it were down, thenthey would add. When such a loop isconnected to your set, a current willflow around the turns of the loop. Thisis exactly what we wish to have happen.

Up and Downs of LoopNow in order to have the voltage gen-

erated up on one side of the loop whileit is down on the other side, the loopwould have to be one-half a wave lengthong, that is to say it would have to be

long enough in the horizontal directionso that one side was in the crest of thewave when the other side was in thetrough of the wave as shown in Figure2. Since the distance between the crestsis called the wave length, then the dis-tance from the crest to the trough isone-half the wave length.

The higher the sides of the loop are,that is, the longer the vertical wires are,the greater will be the voltage generated,and of course the voltage generated ineach turn is added to all the others.

As Big as a BattleshipBut a loop one-half a wave length

long is quite out of the question. Themost popular wave length is 360 meters,and you remember that a meter is a littleover a yard. Some of the popular stations,like KYW in Chicago, radiate at 5'36

meters, which is nearly three -eights at

a mile. A loop of this length would benearly as long as a ,steamship, and al-most as difficult to handle.

The loops which we are using everyday are of quite reasonable dimensions,say, two to four feet long. This is onlya few thousandths of a wave lengthlong. How do they work? In order toanswer this question let us see how wewould build a coil of wire in order thatabsolutely no voltage should be gener-ated in it by the passing wave. Theonly way in which this could be accom-plished would be so to build the coil thatthe same voltage would be generated inboth sides of it and that the voltagesgenerated in the two sides would be op-posed to each other. This would give acomplete cancellation and no voltage atall at the terminals of the loop or coil.It is obvious that the only way in whichthis could be done would be by so :u-

ranging the loop that it had no lengthat all. That is to say, arranging it so

that the two sides were exactly in thesame place. This would mean that thehorizontal wires across the top and bot-tom of the loop would cease to exist andthe loop would become nothing but a

wire laced up and down between pegs onthe plain surface of a board.

If there is any distance at all betweenthe two sides of the loop, then therewill be some difference not in theamount of voltage generated in the twosides, but in the time at which this voltage is generated and there will conse-


quently be some voltage at the terminalsof the loop since complete cancellationof voltages cannot occur.

Another way of putting this would bethat while the pressure in the left handend of the coil is the same as in theright hand end, the fluctuations up anddown in the two ends do not keep stepand so do not exactly cancel each other.If two men are walking along, one di-rectly behind the other, and they keepexactly in step, they do not interferewith each other, but when the man be-hind gets a little out of step with theman in front, then the man in frontknows about it.

Suppresses SignalIf the loop is rotated so that its

horizontal wires are at right angles tothe direction in which the signal is com-ing, then the loop has no length so faras those signals are concerned. The pass-ing wave strikes both sides of each turnin the loop at exactly the same instance,and the voltages generated are there-fore, equal and opposed, and there is noterminal voltage, as Figure 3 shows.This is of course the fact which givesthe loop antenna its very useful direc-tional property. It is to be noted, how-ever, that if the loop is turned ever soslightly from this zero position, then thevoltages no longer cancel, and there isa voltage at the terminal. This meansthat the zero position of the loop is verysharp, but the maximum position is not.

To get ChicagoIn applying the loop antenna to an

actual radio receiver, it is necessary thatprovision be made to tune it to resonancewith the desired signal. This is accom-plished by means of a variable air con-denser. The coil aerial must be large

ONE WAVE. LENGTH

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enough so that when the variable con-denser is turned to give the greatestcapacity the combination of coil andcondenser will pick up the longest wavelength that you want to receive. This

will be probably around 536 meters,KYW Chicago. The specification for thebest loop antenna therefore, is that itshall have just as many turns as pos-sible, each turn being just as long aspassible and just as high as possible,and still have no more than the requiredmaximum inductance. The higher the

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Fig. 3. Directional Effectloop is, the greater will be the voltagegenerated in each side of each turn, andthe longer it is the greater will be thedifference in time at which these volt-ages are generated in the two sides ofthe loop and 'consequently the greaterwill be the voltage at the terminals, butit must not have an inductance valuegreater than that required for tuning.

Wind Coil on CylinderNow the inductance of a coil of wire

increases very rapidly as the turns arewound closer together. The maximuminductance is obtained with the mini-mum number of turns when they arewound close together. In order to getthe maximum number of turns for agiven inductance, which is what ourloop requires, the turns should be woundjust as far apart as possible. It isfound that this spacing is best accom-plished by winding the loop on a framewhich has the form of a vertical cylin-der. The wire goes up one side of thecylinder across the top and down theother side and across the bottom, andthe turns are spaced around the circum-ference of the cylinder so that the com-plete winding covers an arc of about 120degrees on each side of the cylinder.

As a loop aerial of this form is rathermore difficult to build and operate, themore usual construction is that shown inour diagram. It sacrifices something inefficiency, but is easier to construct.It also takes up less room and is moreportable. But for those that want theultimate volume and selectivity, thecylindrical form is the one to adopt.

LEARNING TO DANCEIt is easy to dance if your set can

pick music from WJY and WJZ in NewYork. Just recently these two stations,which together make up Broadcast Cen-tral in New York City, have completedarrangements so they can transmittwelve different orchestras. These in-clude some ' of the best known in thedistrict. To mention a few of them,there are the orchestras of Hotel Com-modore, The Waldorf-Astoria, Hotel Ala -mac, Trocadero Club, Moulin Rouge,Hotel Ambassador and Hotel MeAlpin.

Direct wires are run to each of

these stations. That is because it is im-practical to transport entire orchestrasto the broadcasting studio. The schemealso enables the radio audiences to hearthese famous dance orchestras just asthey play in their respective accustomedsurroundings, with the inspiration of at-mosphere and the dancers right beforethem. Many of the orchestras could notleave to reach a broadcasting stationstudio during the most popular radiodance hour, ten -thirty to eleven -thirty,and without the direct -wire system sucha succession of leading orchestras wouldbe impossible.

HEAVENLY MUSICMusic, which is literally heavenly, has

recently been dropped from the clouds.This remarkable occurrence has comeabout in this way: Same enterprisingairplane men have equipped their planeswith powerful radio receiving sets andinstalled loud speakers with the hornpointing straight down. As they flitfrom city to city, the whole country-side as they pass is delighted with thestrains of jazz music coming from oneof the popular broadcasting stations.As a matter of fact, one old farmer re-cently heard "It Ain't Gonna Rain NoMo," corning apparently from the depthsof a bad thunder cloud, and he concludedit must be some new form of weatherreport sent out by the Weather Bureau.

In receiving broadcasting from an air-plane a long wire with a weight attachedis dropped from the machine, and, ofcourse, the rush of the wind as the planegoes at a speed of 100 miles an hourcauses this wire to trail away out be-hind. This forms an aerial. The groundis connected to the metallic frameworkof the airplane itself.


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curves (plotted from careful experiment) show you that fixedtransformers do not give satisfactory amplification for manyof the important stations. Why? Because the fixed windingsare out of tune.With Ballantine instruments you can accurately tune every-thing from 200 to 600 meters-by merely turning the knob.This adjusts the windings to the wave length of the stationwanted.

Adds to Your List of StationsPerfect shielding and pig -tail connections assure clear tones.Then, by keeping amplification uniformly high throughout thebroadcast range, you get all there is within reach of your set.

Send for This Booklet"Radio Frequency Amplification with the Ballantine Vario-transformer," 25 pages of practical interest. Mailed to Radioexperimenters upon request.

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NOVEL LOUD SPEAKERSMost loud speakers may be called

glorified telephones with a horn. Nat-urally a factory designed and built loudspeaker will be better than a home-made one, but if you are interested innovelties it will be possible to get prettygood results with some everyday ap-paratus. The most important part is agood telephone unit. There are severalgood ones on the market. Perhaps themost popular is the type using a micaor aluminum diaphram instead of theusual steel disk.

With this loud -speaking ear phone itis possible to build a large variety ofhorns. One of the attractive ones ismade by taking a rather large vase andmounting the phone in the bottom. Thisis rather surprising to your visitors whohear the music, but are unable to findwhere it is coming from. Another typeof horn which works pretty well is thatmade from a good size flower pot. Onecorrespondent reports the use of a largegoldfish bowl for the horn. He hastensto add that you must first remove thegoldfish. The largest horn that has beenreported is one moulded out of rein-forced concrete.

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ARE YOU OUT OF WORK?If you have a radio set and are out

of work, then be sure you tune in toStation NAA, Arlington, 435 meters, nextWednesday night at 7:30. The govern-

ment is giving a regular broadcastingservice every Wednesday from this sta-tion. They are sending out the news of

various governmental positions whichare open in Washington and elsewherewith the expectation of reaching inter-ested persons very much quicker thanthrough the ordinary department bu-reaus. These positions range all theway from laborers to linemen and fromclerks to chiefs. You may land just thejob you may have been looking for.

RADIO PROGRESS8 Temple St. (P. 0. Box 728)

Providence, R. I. Date

You may enter my subscription to RADIO PROGRESS

year $3.002 years $5.50year

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28 RADIO PROGRESS APRIL 15, -1924

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HEARD AND SAW BY RADIOThe chap that said he saw by radio

was perhaps not lying, for he undoubt-edly referred to the saw he heard cut-ting a girl in two, as broadcast by iSta-tion WLW, Cincinnati, last week. It wascarried out by Mr. George Stark, thewell-known magician. A young and(needless to say) pretty girl is tieddown on a wooden platform by a num-ber of ropes. Men are selected from theaudience to hold the ends .of the ropewhile a barrel is slipped over her feetand up to her waist. You can still seeher feet projecting through a hole in

the other end of the barrel. Then a

heavy cross -cut saw, such as is used forfelling trees, is brought out, and rightbefore the eyes of the audience is usedto cut the barrel with the girl inside intwo. After both her legs have beenamputated, the halves of the barrel areremoved and there she appears stillCori up as before.

Unfortunately, all this could not beseen over the radio, but Mr. Stark in apreliminary speech described what wasgoing to happen, and then you could

This Looks Like

hear the various sounds broadcast fromthe Crosley Station. The noise of thesaw hacking into the barrel was quite

Quite a "Feet"

plainly heard. Our picture shows Mr.Stark, the magician, assisted by Mr.Powell Crosley, Jr., of Station WLW.

NOTE: In this section the Technical Editor will answerquestions of general interest on any radio matters. Any ofour readers may ask not more than two questions, and ifthe subjects are of importance to most radio fans they will

be answered free of charge in the magazine. If they are

Question. What is meant by a D. I..75 coil?

Answer. This is the standard abbre-viation for a duo-laterial coil with 75turns in it. This is one of the popularhoneycomb coils. In general there aretwo styles of honeycomb, and they lookalike except on close inspection. In onestyle the wires of each layer cross eachother every eighth of an inch or so, butthe wires of one layer lie directly overthe wires of the layer underneath. Look-ing at the coil from the side, you cansee small diamond -shaped holes runningway in to the tube on which the coil iswound.

The duo-laterial coil, on the othe.hand, is wound so that each layer is

staggered, compared to the layer below.so the diamond -shaped holes mentionedabove cannot be seen. As a matter offact, the inductance of the two forms ofcoil is almost exactly the same if theyare wound with the same number ofturns.

Question. Why is an indoor aerial notso good as an outdoor one?

Answer. The indoor aerial is usuallybut not necessarily inferior to the out-door aerial. There are two reasons forthis. The first is a matter of size. Yonthink nothing of using an aerial 30 or40 feet high and 100 feet long, but wherewill you find a dwelling of this tre-mendous size to cover such an aerial ?The ordinary house is only 30 or 40 feetlong, and to get a hundred foot aerial in-side it requires that the wire be doubledback on itself two or three times. Thisnecessarily sacrifices efficiency. The sec-ond objection to the inside aerial is thatit is usually shielded by various pipesand wires in the walls and ceilings ofthe house. You must remember that any

of special interest to the questioner alone, or if a personalanswer is desired, a charge of fifty cents will be made foreach answer. This will entitle the questioner to a personalanswer by letter. However, if the question requires consid-erable experimental or development work, higher rates willbe charged. which may be obtained upon application.

piece of metal which is connected tothe ground thinks that it is an aerialand takes out of the air all the radioenergy it can get. So you will see thatif you have around your aerial a net-work of hot and cold water pipes, steampipes, electric light wire, telephone wire,gas pipes, bell and enunciator wires, theywill rob the air of nine -tenths of all theradio energy coming into the room whereyour aerial is installed. These are thereasons why the outdoor aerial is usuallyto be preferred, and not the fact thatyour wire is covered by a roof.

Question. How can the squeal ba

eliminated from an amplifier?Answer. Most squeals these days are

caused by regenerative receivers in theneighborhood being improperly operated.If this is your trouble, there is nothingyou can do to cure it. If, however, thesqueal does not appear in the phoneswhen using the detector only, it cannotbe from this cause. If the latter case,the most likely reason is that there issome feedback of energy from one step tomother. Such feedback is the result ofoo close spacing of either the trans-

former or the tubes. If your transform-ers are shielded, it is well to groundthe metal covering, and, in that casetwo or three transformers can be in-

stalled, even touching each other with-out bad effects; but if you have ordinaryaudio transformers, it is well to spacethem at least two or three inches apart.As a further precaution it is sometime sdesirable to turn them at right anglesto each other. This will prevent feedingback of energy. Another point to belooked after is to make the grid leadsjust as short as possible and keep themaway from the vicinity of the plate.

Question. I have a single tube regen-erative set and wish to add one or two

Is it better to use audio oradio amplification?Answer. Audio amplification is what

ou will need. A single audio amplifieradded to your set will enaible you toget loud -speaker operation on local sta-tions and head -set operation on stations1000 to 1500 miles away. A secondaudio amplifier will extend the range ofyour loud speaker to 1000 or more mile3.The advantages of the audio amplifierare that the parts are relatively cheapand easily hooked up. No controls areused at all except a rheostat for thefilament. Even this may be omitted andthe filament connected directly in

parallel with the detector tube. As amatter of fact, such a modification isusually recommended at the presenttime. On the other hand, the radioamplifier is rather difficult to adjustproperly and requires further controls,which are hard to regulate. The averageamateur makes a failure of radio am-plification.

Question. What causes a blue glowin a vacuum tube?

Answer. A blue glow will be seen Ina vacuum tube when it is improperlyoperated by putting too much "B" bat-tery voltage on it. It will occur onlyin a soft tube, such as the UV 200.These tubes in general are used only indetectors and not in amplifiers. Suchtubes are called soft when they containa small amount of air, but if the vacuumis pumped as perfectly as possible theamplifier is called hard. When a softdetector tube is worked with 18 to 22volts "B" battery the little particles ofnegative electricity (electrons) shot offfrom the white hot filament are attractedacross to the plate and cause a current inthe telephone. They encounter numerous

Continued on Page 32


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In building a set many an amateurwho wants to save money does so byomitting the cabinet. This in generalis a mistake. Of course, if it is a choicebetween having a cabinet or a tube,you can do without the former; but itis the experience of radio repair menthat the omission of the cabinet has arather bad effect on the finished set.This is because it is difficult to hook upthe parts when assembled on an openboard and keep the wires short anddirect.

To get efficient operation it is verydesirable that the leads, particularly thegrid and plate leads, be run as shortand direct as possible. The "A" bat-tery wires are not important and maybe fastened to the back and sides of thecabinet to get them out of the way.By disposing of them in this mannerthe undersirable capacity action betweenwires is avoided. A further advantageof properly housing a set lies in themental attitude of the builder. If heknows he is working on a good lookingjob, he usually takes a good deal morepains in laying out the parts, than if hethrows them together on a board.

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1 ir tt taw at minvit

DR. RADIO PRESCRIBESContinued from Page 29

molecules of air on the way across, butdo not affect them, as the speed atwhich they travel is relatively lowowing to the low attraction of the "B"battery voltage. But suppose now thata 45 volts or more "B" battery is usedon the detector plate. This high voltagecauses such a powerful attraction thatthe electrons are speeded up to a veryhigh velocity. As they rush across fromthe filaments to the plate they en-counter the little particles of air left inthe tube and literally knock the stuf-fing out of them. That is, in collidingwith a molecule of air the electronactually breaks it up and releases oneor more other electrons out of the airmolecule. This causes a fearful shockin the ether, which is manifested to theeye by a bluish haze or glow. As mightnaturally be expected, such a conditionof irregularity is bad for the radio set.When listening in on a detector adjust-ed in this way a constant wheezing willbe heard, which breaks up the music. Asthere is no advantage at all in suchoperation, the remedy is to reduce the"B" battery voltage until the blue hazedisappears.

Question. Which is better for a "B"battery, two 22% volt blocks or one 45volt block?

Answer. Each has its advantages. Ifyou use a 45 volt block you do not haveto make any connections across, and sothis bother is saved. Therie is lesschance of interchanging the "A" and"B" battery leaves and so burning outyour tubes. Sometimes the price of the45 volts is slightly less, if it is obtainedin one block, rather than in two. On

the other hand, a 45 volt block is usedas a unit and when part of it wearsout the whole block must be scrapped.For this reason most people prefer thesmaller units. Suppose, for instance,you bought a set of automobile tires andthe tire dealer stipulated that when onetire wore out the other three must bethrown away at once. This would seemlike a rather foolish contract to make.But that is what you do when you buya 45 volt "B" battery. The detectortakes a small voltage and so uses only apart of the 45 volt "B" battery. Theamplifiers take the full 45 to 90 volts.So you see that part of the battery isworking harder than the rest of it, andwhen this wears out it means scrappingthe whole thing.

RADIO APPARATUS

The Giblin Broadcast ReceiverTHE Giblin Radio Frequency Broadcast

Receiver makes it possible to obtainradio entertainment without the necessityof erecting outside antenna wires or usinga troublesome ground wire. A small, loopaerial placed near the set will pick up sig-nals, which, though they have come longdistances, and are weakened by hills, val-leys, trees and buildings, will be clear andof great volume. Many families, living inapartments where it is undesirable or im-possible to erect antenna wires, can nowhear enjoyable, ever-changing programsthrough the day and evening by "listening -in" with a Giblin Broad-

cast Receiver.

The Giblin Audio -FrequencyAmplifying Transformer

Price $4.50

.\ \ .GIBLINDITADIOEAR

\ SMAIDAIRD RADIO LELECrRIC CO.PAwrOCNV-1,1.1.

STANSTABILIZERC)0IZERDETECTOR "A'SWEECII

AMPLIFIER

IS T.STIP

\ 0

2N0 STEP

The set comprises two stages of radio frequency ampli-fication, a detector and three stages of audio frequencyamplification. The parts are mounted on a sub -base towhich a Bakelite panel is attached. It is enclosed in ahandsome solid mahogany cabinet.

The Giblin Radio -FrequencyAmplifying Transformer

Price $5.00

Buy Giblin Products from your dealerWrite for descriptive circulars

STANDARD RADIO SELECT i'rIC CO.PAWTUCISE HOUR ISIAND

TONEADJUSTER

WARREN

HEAD SET

WARREN Jr.

SPEAKER

$8.50The tone quality, volume and faithful reproductionare almost unbelievable. Non -resonant aluminumhorn, adjustable diaphragm unit, scientifically ad-justed, well packed. The ideal speaker for yourportable set when you go camping this summer.

All Warren head sets are thoroughly testedand toned alike. They are electrically andmechanically efficient-and sell by prefer-ence, not persuasion. If your dealer doesnot carry Warren products, send us hisname, and we will see that you are supplied

Warren Radio PhoneManufacturing Co., Inc.

WARREN, R. I.

Specialists in Head Sets and Loud Speakers

JobbersDealersWrite forproposition

The FamousWarrenHead Set

$6.00

Documents

WillsWa~ - · PDF fileTRU-FIX Dials are made of selected sheet brass .023 of ... Corrects loss of tuning adjustments, such as fading, ... down the lead-in wire. So, if a thunder