Page:March 1916 QST.djvu/14
MARCH, 1916 53
terruptions per second, an oscillation transformer, glass insulator, of my own make, and wound with edgewise copper strip, and
an aerial only 75 feet high and 200 feet long, input to transformer, as when heard by above named party, three amperes.
This is one of the best records I have so far heard of, as the distance from Athens, Georgia, to Philadelphia. Pa., is between 700 and 800 miles. This was at 9:10 P. M. or there abouts and when conditions for wireless were not the best.
To the Editor “QST.”
In the various Armstrong circuits, is the increase in the strength of signals due entirely to the beat or heterodyne effect, or are there any other effects noticeable which cause added response in the phones?If there were another type of generator, for undamped waves, as efficient as the audion, and if the beat effect produced by the generator were utilized on an ordinary detector circuit as sensitive as the ordinary
audion receiver circuit. would this circuit be as sensitive and satisfactory as an Armstrong circuit?
What is meant by “increase in audibility”—an amplifier concern claims to have an instrument that increases the audibility 1500 times. Does this mean that the sound wave produced has 1500 times the amplitude and what relation has it to the number of times the signal strength is increased?
(Signed) EDGAR FELIX,
New York City.
In the various Armstrong circuits, the increase in strength of signals is due to amplifying effect as in the ordinary amplifier rather than the heterodyne principle. Of course, in the Armstrong circuit, these two effects are combined, but the real increase is due to amplification.
It is the writer’s opinion that another type of generator such as you mention would not he as efficient as the Armstrong circuit. This is due to the peculiar repeating action which is obtained between the inductance coils.
“Increase in audibility” means that the instruments amplifies a given sound a certain number of times when a given factor of loudness is taken as the audibility unit. That is, a certain strength of signal may be taken with an audibility of one, then the amplification or increase in signal strength is a given number times the audibility.
A more complete discussion of these questions will he found in Armstrong’s article in “The Proceedings of The Institute of Radio Engineers,” Volume 3, No. 3.
This station has done a great deal of successful relaying which is probably due to its well-constructed apparatus. Mr. Mathews of Chicago, Ill. is the owner of the station. He has spent a great deal of time in getting everything about his set “just right.” Do you do the same?