Radio Broadcast (May 1928-Apr 1929)

RADIO BROADCAST ADVERTISER 139 Letters from Readers (Continued from page 137) reasons I am a subscriber to Radio Broadcast is because of its clear, complete, concise articles of real developments in radio backed by a fearless conservative editorial policy. H. H. Horning, Pottsville, Pa. To the Editor: I wish to express my earnest appreciation of your new feature, the " Home-Study Sheets." The neatness with which they are printed and the useful information they contain are certainly a great aid to your publication. What we want is experimental and physics side of radio, not the program discussion side. Vincent V. Garzia, Jr., Elmhurst, L. I. The Sea-Going Tube Again SOME time ago we published an interesting account of the travels of a sea-going vacuum tube. The article, it will be remembered, stated that the vacuum tube passed from one ocean to the other through the Panama Canal, which resulted in considerable discussion among our readers. In this department in our August issue R. S. Fulton, radio operator on the S. S. Hecbelega, tried to show how it would be impossible for a small object to pass through the Canal. Now we print another letter which takes the affirmative side of the controversy. You take your choice ! To the Editor: It is quite possible for any small article to pass from one ocean to the other through the Canal, as I shall endeavor to demonstrate. A vessel in passing from the Atlantic to the Pacific approaches and enters the lock at sea level, floating in salt water. The gates are closed behind her, water from the lake is allowed to enter the lock until the vessel has been raised to the level of the lake. Any small article, such as a vacuum tube, which happened to be near the outer gates of the lock at the time the vessel entered would be drawn along into the lock by the slight following current always created by the movement of a vessel, and would be raised to the lake level along with the vessel, and likewise probably would be drawn along with her into the lake when the inner gates were opened for her passage. Once in the lake, the tube's course would be determined by the number of vessels passing through the canal. If south-bound vessels predominated, the currents in the lake would be stronger in the direction of the locks on the Pacific side, whereas if more north-bound vessels passed through, the tube probably would be carried out to the Atlantic again, through the lock through which it entered. Of course, most of the water used in raising and lowering vessels in the locks comes from the lake, but every time a vessel passes from sea level to lake level some sea water enters the lake. If Mr. Fulton doubts this let him taste the water in Gatun Lake, which is fed by fresh-water streams, and he will find that it has a distinct brackish flavor, due to the sea water entering through the locks. It is almost a case of water flowing up hill. E. D. Prey, Ellendale, Del. Short-Wave Hints from the Tropics To the Editor: As a point of interest to short-wave receiver constructors, the following data has been used in avoiding the usual obstreperous "body capacity" found in most regenerative short-wave receivers. When building, use a heavy metal sub-panel bracket — or rather, a pair of them. Use the positive or negative filament to "ground them out," and the body capacity becomes a thing of the past as far as causing the set to go into oscillation is concerned. This point has made the building of short-wave receivers in this part of the Americas a. success where otherwise it was a failure. For all-year reception, short waves are the only answer here. The standard receiver is a {Concluded on page 141) Will Be Different in 1929 The Only Handbook Prepared for the Change Is THE RADIO MANUAL 16 Chapters Cover Elementary Electricity and Magnetism; Motors and Generators; Storage Batteries and Charging Circuits; The Vacuum Tube; Circuits Employed in Vacuum Tube Transmitters; Modulating Systems; Wavemeters; PiezoElectric Oscillators; Wave Traps; Marine Vacuum Tube Transmitters; Radio Broadcasting Equipment; Arc Transmitters; Spark Transmitters; Commercial Radio Receivers; Radio Beacons and Direction Finders; Radio Laws and Regulations; Handling and Abstracting Traffic. Here is the most complete, most up-to-date handbook in the radio field. It deals with every problem of principle, method, or apparatus involved in radio transmitting and receiving. It meets every need of student, amateur, operator and inspector. It presents in a single volume, a complete course in radio operation developed simply and clearly, yet in complete technical detail. The beginner with no knowledge of electricity will find all he needs either for amateur operation or to qualify for government license. The professional operator or inspector will use it as a daily reference guide. A Wealth oS Information Never Before Made Available The accepted practise as adopted by the International Radio Telegraphic Convention effective January I, 1928, is completely recorded— the New International "Q" signals; procedure for obtaining a radio compass bearing; procedure when SOS call is transmitted or when the spoken expression Mayday is heard from a radio telephone station; etc., etc. There is also presented for the first time a complete description of the Western Electric 5 Kilowatt Broadcasting Transmitter; description and circuit diagram of Western Electric Superheterodyne Radio Receiving Outfit type 6004-C; Navy standard 2-Kilowatt Spark Transmitter, etc., etc. Every detail up to the minute. Prepared by Official Examining Officer The author, G. E. STERLING, is Radio Inspector and Examining Officer, Radio Division, U. S. Dept. of Commerce. The book has been edited in detail by ROBERT S. KRUSE, for five years Technical Editor of QST., the Magazine of the Radio Relay League. Many other experts assisted them. Special subjects such as Radio Control operating have been contributed to by Carl Dreher of the National Broadcasting Co., and the treatment of the stabilization of radio frequency amplifiers is by Dr. Lewis M. Hull, the wellknown authority. The Whole Subject in One Volume Never before has so complete a treatment of radio theory and operation been compressed into a single volume. Here is information that otherwise you could secure only by consulting many different books. And every detail is vouched for by authorities of the first rank. The Manual is profusely illustrated with photographs and diagrams. There are 700 pages, bound in flexible fabrikoid that is extremely durable. The immediate demand for so valuable a handbook has already nearly exhausted the second large edition. To be sure of receiving your copy without delay, order at once. FREE EXAMINATION Use This Coupon D. VAN NOSTRAND CO., Inc., 8 Warren St., New York Send me THE RADIO MANUAL for examination. Within ten days after receipt I will either return the volume or send you $6.00 — the price in full. (Radio Broadcast 12 Name St. &No City and State.