Radio mirror (Jan-Oct 1923)

.Vov /-', /0-\ RADIO DIGEST WIRE DIRECTED AIR WAVES MAKE GOOD TESTS MADE ON PACIFIC COAST BETWEEN CITIES 500-Watt Transmitters Work over Power Lines for 200 Miles — Use High Waves SAN FRANCISCO. — The "directed Radio system of dispatching." a new method of broadcasting, has recently been put into operation near this city by engineers of the Pacific Gas and Electric Company. Messages were successfully transmitted a distance of 200 miles, between the Vaca Dixon substation, near Vacaville, Calif., and the Pitt river power house. Specially constructed 500-watt transmitters and standard receivers were used. In explaining the experiments, Roy Wilkins, Radio engineer, stated that the electromagnetic waves were transmitted to the high voltage power lines at the point ofsending and picked off at the receiving end. High Wave Lengths Used These waves followed the course of the steel tower lines in a straight line due north 120 miles from Vaca-Dixon to Cottonwood, then on a right angle turn going 80 miles into the Pitt region. Mr. Wilkins said tests were made using wave lengths of from 10.300 to 23,000 meters. Under this system of directed Radio, the energy or sound wave is not broadcast, but travels in the vicinity of the high power transmission lines and will not interfere with other sending or receiving stations. The system will be used for transmitting messages between power houses in the mountains and large centers of distribution. This system will be especially valuable in maintaining a continuity of service during heavy storms when telephone lines and other systems of communication are unavailable. FAN WORKS COPP SET SANS AID OF PHONES "Loud Speaking Transformers with Five-Fo.ot Cord"— Next! CLEVELAND, O. — Why worry about a little thing like telephone receivers? Just listen to J. T. Curtis, 7221 Dellenbaugh avenue. "Just recentlj-, after using my Copp set, detector and two stages of amplification, I removed the phones, put them away, and detached the batteries without turning down the rheostats. I had been listening in on most all of the United States. "The next evening I hooked on the batteries preparatory to the nightly seance but did not hook on the phones. I stepped out of the room for a moment and when I returned I was surprised to hear music. PA AND MA RADIOTRON AND A GROWING FAMILY .. ...... W^W" — — "S -~~r~ From the smallest to the largest Radio vacuum tube on the market. Left to right are: UV-199, UV-200, UV-M1-A, UV-20Z (S watt). UV-20J (SO watt), UV-2M (2SS watt). UV-206 (1 kilowatt), UV-Z04 (S kilowatt) and UV-207 (20 kilowatt). An idea of size may be gained from the fact that the UV-204 or ZSO-watt tube, which is in the center of the picture, is 14% inches in height Photo by General Electric Co. w*.. i n p--~ '-~»tt~ w-i '■""' — ~ .. i I found that it was coming from the set, but couldn't tell from just what part. When I turned off the amplifier rheostats the music ceased, so I think that in some way the music came from one of the transformers. Sounds fishy, doesn't it? But it sure is true." From the foregoing we may expect to see advertisements reading like this: "Loud speaking transformers complete with headband and five foot cord." Mathematical Broadcast First Given by Station WOR NEWARK, N. J. — During the next few weeks Radio Station WOR will conduct an educational experiment very possibly the first of its kind. This station has secured the services of Mr. William W. Strader to give several talks under the general topic of "Some Tools of Algebra." Mr. Strader is a teacher of mathematics of considerable experience, not only in the school room, but also as a lecturer before classes held in industrial plants. These talks will be from fifteen to twenty minutes long. They will no doubt interest many groups of listeners-in. ftecctocft. COMPLETE BLUE PRINTS for the construction of a Reinartz Receiving Unit and two step amplifier. INSTRUCTIONS FOR ASSEMBLY Description of apparatus and accessories and details of tuning. WINDING A REINARTZ COIL Cabinet Dimensions Panel Layouts List of Parts Send only money orders — no checks or stamps. Coins at your own risk. Book Department RADIO DIGEST 123 W. Madison Street CHICAGO, ILL. Q A lightning arrester is not needed with I Beware of the "bootleggers" who an indoor aerial. | imitations of patented articles. sell DOBBINS KAMODESK •PATENT APPLIES TOR An attractive piece of furniture designed and so constructed to accommodate the Radio set and its entire equipment. With it you make a neat installation of Radio in the home. Its many advantages and moderate cost make it almost indispensable. For sale by first class Radio and Furniture Dealers or write Robbins Woodworking Co. Dept. C. LIBERTYVILLE, ILLINOIS PREMIER "MICROMETER" VARIOCOUPLERS Satisfy The Most Critical $5.00 COMPLETE WITH DIAL. A HIGHLY SELECTIVE VARIOCOTJPLEE having 180-degree orientation and 20 Antenna taps which facilitate very sharp tuning. Wound with No. 21 single silk or black enameled pure copper wire Eishty turns on stator— fifty-five on rotor. All metal parts ranjre from 150 to 750 meters. All metal parts brass — contacts positive — stays "Put" at any angle. Adaptable for either single circuit or loose coupled tuned plate hook-ups. Bakelite button on each tap wire permitting easy and safe soldering. Our Complete Parts Bulletin on request. DISTRIBUTORS — We make a most complete line of Radio parts. Some territory open for live, responsible concerns. PREMIER ELECTRIC COMPANY Manufacturers Est. 1905. 3810 Ravenswood Avenue, CHICAGO. ILL. Kellogg Radio Equipment j For Better Results The Kellogg Variometer The stator and rotor are of Kellogg Bakelite, with properly proportioned windings of well insulated copper wire. Two terminals are provided for the rotor and three of the stator, permitting the variometer to be used in all known variometer circuits. Kellogg variometers have no sliding contacts; _ nothing to wear or short. A spring takes up all play and allows the rotor to turn with a smooth even motion. No. 501 Each $8.00 KELLOGG SWITCHBOARD & SUPPLY COMPANY CHICAGO ARTHUR PUDLIN'S Variable High Resistance Leak Used and endorsed by all leading Radio Engineers of the country. Price 75c-with .002S condenser, $1 Just Completed our Artmica Condenser All Capacities, 25 Cents If you cannot buy our products at your local dealer, send orders and remittance direct to us. Send 2c stamp for blue print of Rosenblum's wonder circuit. Hear 3000 miles on 1 tube. We absolutely guarantee this with the Arthur Pudlin high resistance. ARTHUR PUDLIN Engineering Co. 1S40 Broadway New York, N. Y.