Page:Popular Science Monthly Volume 88.djvu/183

 What Radio Readers Want to Know

��Increasing an Umbrella Aerial.

C. A. P., Fresno, Cal., asks :

Q. 1. Would it be advisable to add 2,000' of wire to my umbrella aerial ?

A. 1. If you add the wire so as to make the length of the antenna greater it will be ad- visable to add the amount of v>rire you men- tion. It would be better if you could ar- range so as to have this wire extend 300 or 400 feet out from the pole. This would give you a longer fundamental wavelength, which is necessary when receiving from stations using verj' long wavelights for transmission.

Q. 2. Can I hear Arlington with a silicon detector?

A. 2. It is possible that you could hear NAA. Stations along the Atlantic coast with aerials no larger than yours have heard the high power stations of the Pacific coast. Very recently we had occasion to note the recep- tion of Berlin by an amateur station in Massa- chusetts. The operator used an oscillating audion in connection with a home-made re- ceiving set. His aerial was about 150 feet long and 50 feet high, although 300 feet above sea level and in sight of the ocean. Very ex- cellent work is being done by well informed amateurs who are using oscillating audions.

Q. 3. What is the best receiver for long distances?

A. 3. We would advise you to equip your station with an oscillating audion. For in- formation regarding audions, oscillating au- dions, radio telegraphic transmitting and re- ceiving apparatus write to the DeForest Radio Telegraph & Telephone Co., 101 Park Avenue, New York City. Be sure to mention the fact that you desire the instruments for amateur experimental work, as the price is very much lower for this kind of work than when sold for commercial operation. They will supply you with bulletins covering the subject on request.

Q. 4. What station uses call 2GN?

A. 4. We have no record of these letters being assigned as yet.

Radio Receiver Information.

M. H., Wilmette, 111., a.sks :

Q. 1. What is the natural wavelength of an inverted L aerial of total length 85 ft., 5 wires on 9 ft. spreader, and 55 feet high ?

A. 1. About 200 meters.

Q. 2. What size wire is most efficient for a loose coupler to receive 600 meter wave- lengths?

A. 2. It makes very little difference what

��size wire is used. In general the useful sizes run from about No. 22 to No. 28 B. & S. gauge.

Q. 3. What would be the dimension and size of wire necessary to make a loading coil from 10,000 meter wavelengths?

A. 3. Wind No. 28 S. C. C. magnet wire on a cylinder 5" in diameter and about 30" long.

Q. 4. Does the secondary circuit also need loading?

A. 4. Yes, or the two circuits would not be tuned to the same wavelength. The second- ary circuit is usually increased in period by shunting the secondary of the tuner with a variable condenser of large capacity. Load- ing inductance is also used the same as for the primary.

Receiving Set For Amateurs.

J. A. Strossman, Mt. Sterling, asks :

Q. 1. I have a four-wire aerial 90 feet long, 50 feet high at one end and 30 feet high at the other. Is this a fairly good aerial for ama- teur use?

A. 1. We should consider it quite satisfac- tory.

Q. 2. What is the natural wavelength of this aerial ?

A. 2. About 225 meters.

Q. 3. How many miles should I receive with this aerial, using a double slide tuner, galena detector, and 1,000 ohm receivers?

A. 3. Local conditions so affect the receiv- ing range that it is even worse than guessing to try to give any distance. For this reason we do not publish receiving distances in this column.

Q. 4. What is the best all around detector for amateur use?

A. 4. Galena is usually considered the most sensitive of the single minerals. Silicon will keep its adjustment better but is not as sen- sitive as galena.

Radio Abbreviations.

A. R. L., Pittsburgh, Pa., asks :

Q. 1. Will you please feive me the meaning of the following abbreviations used in sending radio messages? CK, HR, SRNS.

A. 1. CK is the abbreviation for check used to state the number of words in the message. HR stands for here and is used to indicate that a station has a message there for transmission. It is sometimes used to acknowledge the reception of a message. We can find no reference to your third abbrevia-

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