Radio Digest (July 1924-Apr 1925)

July 12, 1924 RADIO DIGES T— Illustrated Summertime Operating and Trouble Shootin Hints Covering All Makes of Sets By Harry J. Marx DURING these warmer months when the aerial artillery seems to be continually in action, the problem of successful operation of a receiving set assumes decidedly greater importance than ever before. There are however, quite a few little kinks in operation and tuning, which, when properly applied, will be of considerable value in obtaining very satisfactory reception. The Antenna If during the winter months you found that your long antenna gave you lots of volume and permitted the best long distance reception, better get acquainted with the fact that in the summer time that same antenna makes a decidedly efficient collector of interference. Fans have already discovered that 25 to 50 feet gives good results in warmer weather with a decided reduction in the interference that accompanies all out of town stations. If, however, you decide to put up an extra wire of shorter length for summer time use, don't run it close to and parallel to your long distance antenna. Why? well your long antenna will pick up signal and interference as before and pass it on to the small antenna by induction unless the wires are sufficiently far apart and not parallel. Likewise don't keep two lead-ins close together coining down into the room where the set is located because exactly the same thing may happen there. Unless you have enough stages of Radio frequency don't try loop aerial reception. The chances are against your getting much reception. A loop aerial necessitates two stages of Radio frequency amplification for satisfactory operation on any out of town stations. Static Eliminators The so-called static eliminators seem to sound good in news stories but somehow or other a real practical one hasn't appeared on the market up to the present time. It is peculiar how their merits are extolled during the winter weather but as soon as summer is with us the static eliminator has vanished. The best type of static eliminator is the fan who carefully watches all those little points in the proper operation of his set and who therefore gets the best possible signals. His results always make the other fellow think there's a nigger in the woodpile! A little less volume without noise is better than a street corner bellow with a machine gun background. Efficiency of Receiving Set In cold weather, when volume is good and reception is clear, little attention is paid to a number of little noises in the receiving set, such as battery noises, tube noises, audio amplifier whistles, ground hum, scratching and crackling from poor connections and even loud speaker troubles. But during warmer weather all these help to build up the level of interference to the detriment of good reception. Bun Sown Batteries Both plate and filament batteries when run down develop additional resistances in the circuit which is also the cause of crackling discharges in reception. For this reason more care should be taken during hot weather to see that these sources of current are always in the best of condition. Poor joints in the wiring of your set, especially due to careless soldering, are the causes of poor electrical connections which are often indicated by irregular and very noisy reception. Careful attention to each soldered joint would improve the efficiency of many a condemned Radio set. The elimination of noisy tubes is of more importance now than ever before. Soft tubes appear to have a larger proportionate number of offenders than the hard amplifiers. Many of the A type tubes have a bad habit of softening under continued use or high plate voltages and then soon become very noisy in operation. Just borrow a few tubes some time and find out a iittle more about the tubes in your set. ' Ground Hum Ground hum is an especially annoying source of discomfort nowadays. It may be due to a number of things such as run down A batteries, wrong rheostat adjustments, poor grid leak, improper tuning, interference from power line, proximity to some form of generator of electrical oscillations, flashing signs or Jsn t it wonderful that^ (9/£ no. 7/iere is not/iiny co Oi?e one control makes it £, ■!■< f» I ==... V7 r ■ ■ 9. . .j?^-* • V \ * < Bristol Complicated combinations are eliminated when Single Control tuning in with Bristol Single Control Radio p jj p • Receiver — every station is on the one dial. It ivaaio receiver gives the joy!r of radio wJth technicalities left out. The well-known Grimes Inverse Duplex System (non reradiating) is utilized in this Receiving Set. Because of the reflex, only four tubes are required to give power equivalent to six. The price, without accessories, $190.00. Audiophone You forget the radio equipment when listening Loud Speaker i^lTU tne Audiophone Loud Speaker. The tone is full, clear and pleasing. It gives a true reproduction of the original. Made in three models— Senior $30.00, Junior $22.50, and Baby $12.50. Ask for Bulletins Nos.'3014 and Ay-3015 Made and Sold by THE BRISTOL COMPANY Waterbury, Connecticut imperfections in the tuning apparatus. It requires considerable patience to trace down the sources of trouble but it can be done. Cheap or defective audio frequency transformers will often introduce a whistle in reception. Occasionally it is quite distinct and piercing while often it is just audible in the background of reception. There are two or three methods of combating this trouble outside of replacing the transformers. Grounding the metal cores or shields of the transformers; connecting a small fixed condenser (.00025 to .002 mfd.) across various terminals of the transformer, or across the variable grid leak. One of these methods will usually eliminate the trouble. Filament control jacks and even the other types of jacks occassionally start trouble due to imperfect contact between springs. It may be necessary to sandpaper the contact points or possibly to slightly bend the springs so as to increase the contact pressure. Trouble With Phone Plugs Phone plugs sometimes become wet or dirty and cause trouble in reception. Loud speakers sometimes go on a strike and it is often that diaphragms develop cracks that produce cracking sounds when in operation. Occasionally the writer has to take apart the loud speaker because some thoughtless friend thought the horn was an ash receptacle. Fixed condensers are big factors in improving a reception, but with the inaccuracy and poor quality of the numerous cheaper grades on the market they do much toward spoiling your set. Be wise and buy the best. Grid Leaks Poor quality grid leaks or improper adjustment of variable grid leaks will develop anything from a shrill pitched whistle to intermittent choking of reception. Fixed grid leaks vary considerably from the marked ratings, especially during warm and moist weather conditions. Moisture collecting on grid leaks reduces the resistance to a marked degree. Watch your grid leaks. Very few people realize the importance of good contact in tube sockets. This problem of contact of springs with the tube prongs is of especial importance in Radio frequency stages. Checking this over in your set will help solve some of your troubles. WD11 Radiotron WD-11 is famous as the tube that really made possible the swift growth of radio in the home, as we know it today. Inexpensive to operate — using but one 1^2-volt dry cell — doing away with the need for storage batteries — it has lowered the cost of Radio. Radio Corporation of America Sales Offices — Dept. 317 233 Broadway, New York 10 South LaSalle St., 433 California St. Chicago, 111. San Francisco, Cal. $5.00 This symbol of quality is your protection. Be sure that every vacuum tube you buy is marked RADIOTRON. Radiotron REG. U. S. PAT. OFP. No. 23 of a Series Featuring Experiences of "ALL-AMERICAN" Users All -Americans Improved My Set 1 "As I am a radio fan Radio Digest every we it that a fellow from umbia — u sing AllAmerican Transformers — got Kansas City, about 1700 miles. "I had been unable to get more than about 500 miles on my three-tube set, so last Saturday I bought two AllAmerican Transformers, 10:1 and 3:1 and put them in, in place of two I had. "Monday I picked up WKY, Oklahoma City, Okla. Tuesday, March 18th, at 10 p. m. — just as KYW, WDAP and WJAZ By Hans Erbs, Chicago and get the (now WEBH) the powerful local ek, I saw in stations at Chicago came on — British Col I picked up EGO, Oakland, Cal., on the loud speaker and held them 'til they signed off at 12:10, Chicago time. "I think that is a little better than the other fellow. AllAmericans improved my set one hundred per cent." All-American Audio Frequency Transformers. Come in three ratios: 3:1, $4.50; 5:1, 10:1, $4.75. The best — no necessity to pay more. SPECIAL OFFER Just out I New All -American "Radio Key Book" — 48 pages of up-to-the minute radio information. Tells you how to hear farther and better. Send lOo, coin or stamps. Worth a dollar. All the better dealers sell the "ALL-AMERICAN" RAULAND MFG. CO., 2640 Coyne St., CHICAGO PIONEERS IN THE INDUSTRY Audio and Radio Frequency; Power Amplifying (input and output) Over three-quarter million in use. 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