March, 1925 25 Cents
Total Page：16
File Type：pdf, Size：1020Kb
MARCH, 1925 25 CENTS I ;, This Issue: HOW TO MAKE A SUIT -CASE RECEIVER REMARKABLE PICTURES OF RADIO IN CANADA. NEW REFINEMENTS IN BEST'S 45,000 CYCLE SUPER -HETERODYNE. SIMPLE THEORY OF BALANCED TUNED RADIO FREQUENCY AMPLIFICATION. Selections from Carmen says the broadcasting announcer, and in a mo- ment you are transport- ed to old romantic Spain, 4" to enticing, sunny Se- ville. That is but one of the endless joys of radio owning. For the full enjoyment of modern life, radio has become a necessity. For full enjoy- ment of radio, you will find Cunning- ham Tubes essential. Since 1915- Standard for all sets Types C -301A C -299 C -300 C -11 C -12 In the orange and blue carton RADIO TUBES Homo Offi ce CHICAGO 1 8 2 Second Street, NEW YORKYOR SAN FRANCISCO ;#E Patent Notice: Cunningham tubes are covered by patents dated 2- 18 -08, 2- 18 -12, 12- 30 -13, 10- 23 -17, 10- 23 -17, and others issued and pending. Cunningham 40 -page data book fully explaining care and operation of Radio Tubes now available by sending 10e in stamps to San Francisco Office. Ta, "//y//// r ,, % taP%«ic,!a.s A í i t 1 1 Scientfi' s .5 t had to be the BEST We could have manufactured a loud speaker two years ago, but we wouldn't ! We have waited- studying, planning, continually striv- ing for perfection and now at last! WE HAVE IT-In the new TOWER'S LOUD SPEAKER. Surely a Wonderful TOWER Triumph. The many features include, mag- nets that lift 2 lbs. 10 oz. dia- phragm of specially constructed material, perfect, non -vibrating horn, 10" bell. TOWER'S phones are tested by Government Licensed Radio Opera- tors. Weight only 81 oz. On sale at all good deal- ers from coast to coast. THE TOWER MFG. CORPORATION 98 BROOKLINE AVE. Dept. E, BOSTON, MASS. 7.= The U.S. Custom House Tower at Boston is 500 feet high and is situated in the business district overlooking Boston Harbor. It is the tallest Government building in America. Worlds Greatest Loud Speaker Value Tell them that you saw it In RADIO Forecast of Contributions for April Issue RADIO A recent development in tuned radio fre- Established 1917 quency transformers, with their application in Published Monthly by the Pacific Radio Publishing Co. the Browning -Drake circuit is fully described ARTHUR H. HALLORAN, Editor by Volney D. Hurd. The article is illustrated by photographs, circuit diagrams and a picture LAWRENCE MOTT, H. W. DICKOW, circuit, enabling anyone to duplicate his re- dissociate Editor Advertising Manager sults. Branch Offices: Correct Addresses: New York City -17 W. 42nd St. Instructions for change of ad- Chicago -157 E. Ontario St. dress should be sent to the C. Nichols describes three circuits based Boston-52 Irving St. publisher two weeks before E. Kansas City, Mo. -1102 Repub- the date they are to go into on experiments with the single tube reflex. These lie Bldg. effect. Both old and new ad- simplify controls and apply the latest develop- Hates: dresses must always be given. ments in tuned radio frequency amplification. Issued Monthly, 25c a copy. Advertising: Subscription price $2.50 per year Advertising Forms Close on the in the U. S., $3.00 per year First of the Month Preceding elsewhere. Date of Issue. Entered as second -class matter at the Post Office at San Francisco, Calif. Frank C. Jones presents the results of some Copyright 1925, by the Pacific Radio Publishing Co. actual load tests of electrolytic and kenotron rectifiers. Address all communications to Pacific Radio Publishing Company As a fitting follow -up to his articles on har- Pacific Building, San Francisco, California monic transmission F. Dawson Bliley presents "A Transmitter That's Different." VOLUME VII. MARCH, 1925 NUMBER 3 Paul B. Findlay describes the Army's high power radio station at Fort Leavenworth, illus- trating his story with some excellent pictures. CONTENTS RADIOTORIAL COMMENT 9 C. H. Campbell gives the details for a prac- RADIO IN THE ICEFIELDS OF THE CANADIAN ROCKIES 10 tical remote control system which is in successful By Lewis R. Freeman use at 1 B M. RADIO ACTIVITIES ON THE CANADIAN NATIONAL RAILWAYS 13 By W. H. Swift A SELF -CONTAINED PORTABLE RECEIVER 15 Alexander Maxwell tells how to build a one - By Brainard Foote tube short -wave loop receiver. BALANCED TUNED CIRCUIT RADIO FREQUENCY . AMPLIFIERS 17 By C. M. Jansky, Jr. AN INEXPENSIVE HIGH -SPEED CHEMICAL CODE In the April issue will be published the first series on -frequency RECORDER 20 article in a remarkable audio By Harry W. Minnermann transformers, constituting the most complete an- published. A SECOND STEP OF RADIO FREQUENCY FOR THE alysis of the subject ever TWO -TUBE REFLEX 21 By E. C. Nichols A KISS IN THE DARK 23 Humphreys illustrates and describes the By Oliver B. Scott Ferd LOOP construction of "An- A- Batteryless Audio Am- EXPERIMENTING WITH A 24 A. C. as the primary By Harry A. Nickerson plifier" utilizing 110 volt source of supply. AN IMPROVED LOOP ANTENNA 25 current By A. H. Vance A LOW -LOSS, LOW -WAVE HELIX 26 By G. F. Lampkin D. B. McGown discusses "Harmonic Inter- AUTOMATIC RADIO TELEGRAPHIC RELAYING 27 By Jack Bront ference," its meaning, effect, and elimination in radiocast reception. SHORT WAVE COUNTERPOISES 29 By Gaston B. Ashe MEXICAN RADIOCAST STATIONS 30 RADIOPHONE MODULATION CIRCUITS FOR THE Harry A. Nickerson has some helpful ideas in RADIO NOVICE 31 his article on "Building Sets to Make Money," By L. R. Felder where time is the essence of success. ELIMINATING THE CW -PHONE SWITCH 33 By Chas. F. Felstead MEASUREMENT OF ULTRA -RADIO FREQUENCIES 35 By Frank C. Jones The new 20 K. W. tube set operated by the MODIFICATION OF BEST'S 45,000 CYCLE SUPER- Army at Annapolis, Md., is illustrated and HETERODYNE 37 described by S. R. Winters. By Thomas L. Kennon REBUILDING THE CR -9 FOR SHORT -WAVE RECEPTION 38 By R. McGinnis James A. Ramsey has written an interesting QUERIES AND REPLIES 39 account of the part radio is playing in educa- WITH THE AMATEUR OPERATORS 41 tion. CALLS HEARD 41 FROM THE RADIO MANUFACTURERS 42 RADIO GLOSSARY 74 By Jack Bront The fiction feature is "The Ether Garblers," CONSTRUCTION HINTS 84 a radio mystery story by Volney G. Mathison. 2 Tell them that you saw it in RADIO life in EVEREADY HOUR / There's more EVERY TUESDAY AT 9 P. M. For real radio enjoyment, tune in the "Eveready Group." Broadcast through .Eveready Batteries stations W E A F New York W F I Philadelphia BUY Eveready "B" Batteries and you get elec- W J A R Providence W C A E Pittsburgh W E E I Boston W G R Buffalo tricity in its surest, safest and most compact form. They reduce your operating expense. New de- velopments in the Union Carbide and Carbon Re- search Laboratories, Inc., have been converted into new manufacturing processes in the Ever- eady factories. Good as they always have been, Eveready "B" Batteries are much better today. The Eveready achievement of giving you more hours of "B" Battery service for less money has cut the cost of running receivers in half, and in some cases the new Evereadys make "B" Battery expense only a third of what it used to be. There is an Eveready Radio Battery for every radio use. Manufactured and guaranteed by NATIONAL CARBON COMPANY, INC. Headquarters for Radio Battery Information New York San Francisco Canadian National Carbon Co., Limited, Toronto, Ontario EVEREADY Radio Batteries No. 7111. -they last longer 1%-volt Dry Cell "A" Battery jor all dry cell tubes .. No. 770. 45 -volt Extra Large Vertical for heavy duty Price $4.75 No. 772. 4S -volt Large Vertical No. 771. Price 4% -volt $3.75 "C" Battery improves quality, saves "B" Batteries 60e Tell them that you saw it in RADIO 3 When the "Daughter of the Stars" talks with the children of earth YOU remember the dramatic -in fact, many government and com- price. Exide Batteries are made by night last winter when the giant mercial radio plants -were equipped the largest manufacturers of storage Navy dirigible Shenandoah went with Exide Batteries. batteries in the world. adrift in a raging gale. You can get Exides at Radio "You are over Newark," said For your own set Dealers and at all Exide Service Stations. If your dealer should be radio station WOR. "What can we When you use Exide Radio Batter- do to help you?" out of booklets describing Exide ies in your home you get the clearest Radio Batteries, send us your name Thousands of people sitting by reception, for Exides give uniform and we will mail them to you. radio sets in their cozy homes heard current through a long period of the plucky lieutenant - commander discharge. THE ELECTRIC STORAGE BATTERY COMPANY on the Shenandoah send yf There is an Exide type Philadelphia back the reply : " Thanks, for every tube and a size old man, everything's Exide Batteries of Canada, Limited for every set: "A" bat- 153 Dufferin St.. Toronto O. K." teries for 2 -volt, 4 -volt In the air, as on the and 6 -volt tubes; "B" sea, radio equipment batteries, 24 and 48 volt, must be the most reliable of 6000 milliampere hour it is possible to get. That capacity. They are effi- is why the Shenandoah, cient, dependable, long - The new Exide 6 volt "A" xiôe the huge ship Leviathan Battery in one¢iece case. lasting - and right in RADIO BATTERIES FOR BETTER RADIO RECEPTION USE STORAGE BATTERIES 4 Tell them that you saw it in RADIO They Cost More But They Do More Super- Zenith VIII - the ideal radio set for the fine home Super- Zenith X The complete Zenith line ranges in price from $95 to $550.