Page:April 1916 QST.djvu/16

MONTHLY MEETING OF THE INSTITUTE OF RADIO ENGINEERS

 On Wednesday, March 1st, in the Engineering Societies’ Building, 33 West 39th Street, New York City, the Institute of Radio Engineers held their monthly meeting. A paper on “Recent Standard Radio Sets” was presented by Harry Shoemaker, the research engineer of the Marconi Company. Mr. Shoemaker described in detail the sets which the Marconi Wireless Telegraph Company of America have recently placed in several hundred ship stations.

THE RADIO CLUB OF AMERICA

 On Friday evening, March 17th, at Columbia University, New York City, Mr. Fritz Lowenstein presented a paper on “The Efficiency of Radio Sets.” Mr. Lowenstein discussed the design, installation and operation of various sizes of transmitting and receiving sets. Special consideration was given to the correct methods of tuning open spark and quenched spark transmitters. The Radio Club of America is progressing rapidly and each month has a paper similar to this. Anyone who is interested in the Association may obtain information from D. S. Browne, Corresponding Secretary, 206 West 86th St., New York City, N. Y.

SOS

 Wichita, Kans.—On January 4th, about three o’clock in the morning, Don I. Shepherd, a member of The American Radio Relay League was listening in and distinctly heard ...---..., ...---... Then the call letters of a Greek ship Thessaloniki which was some 500 miles off New York City several days before. Mr. Shepherd heard all the stations along the coast getting in their signals once in awhile and the Brooklyn Navy Yard telling NRE about the call. This is quite a record.

SOMETHING FOR EVERYONE

A Device Used by the Marconi Company

While visiting a friend learned the following simple method of increasing radia-

tion, reducing the safety gap sparking, and also preventing the puncturing of transformer secondaries: For a quarter to one kilowatt sets, wind two coils of No. 4 to

12 copper wire around a tube one inch in diameter, consisting of about ten turns each. Place these air choke coils on each terminal of the transformer secondary and connect to the high frequency condenser so that each is in series with one side of the charging circuit. This air choke prevents the charged condenser from backing its current into the transformer, provided that the choking effect is greater in the coils than in the closed oscillatory circuit. The coils should he air spaced and about ¾ of an inch in turn.

To prove there is no backward discharge at the transformer, leave a small gap at the terminals of the transformer secondary and an arc will be formed instead of a crashing spark. This simple device by directing all the energy to the close circuit, increases radiation but does not effect the wave length. For a 2½ Kw. set, the writer uses two coils of No. 4 aluminum wire consisting of ten turns, two inches in diameter, and spaced one inch.

Contributed by

ROY C. BURR.  

HIGH NOTE — LOW NOTE

W. A. Parks, Washington, D. C. Writes:

I noticed in the February issue of “QST” that 1VN states that 75% of the stations that he hears have a high pitch (amateurs), and that on that account they are very much easier to read. I believe that the natural period of the diaphragm of the telephones has a great deal to do with this. I am using mica diaphragm phones and find that amateurs who have a low note, in fact the very ones mentioned by 1VN are much easier to read than those having a high note. I have heard 1VN fairly loud, (using galena detector altogether), and also 8YC, 8YI, and others having a high note, and who come in fine, and I am not blind to the certain well known advantages of the high note, in a properly designed set. Personally, I prefer to read the low musical note, about 120 cycles.

I have made what I think is pretty close to the record for a crystal detector and amateur sending and receiving apparatus. At 11:42 P. M.—February 29, (my time), I copied several sentences from 9OQ, Mr. Charles Coultas. 950 Beach Avenue, St. Louis, Mo. I have written to him and received his verification of the same. He was not loud but easily readable. NAA had their arc going at the time and when an arc set is going in the vicinity of a receiving station the signals from all spark stations are very noticeably weakened.

A picture of 9OQ’s set appears on page 6 of the December “QST” under the title