Page:Popular Science Monthly Volume 88.djvu/641

 Experimental Electricity

��Practical Hints for the Amateur

���Wireless Communication

��An Undamped Wave Receiver

By W. Ross McKnight

some spark signals by certain critical ad- justments of the lighting and high vol- tage batteries. When in this state, the audion is a perfect generator of high- frequency oscillations. Not every bulb, however, can be made to "oscillate" merely by adjusting either or both of the battery systems. Also, this condition, when obtained by these means, is not stable and reliable, nor is it flexible enough to accommodate itself to tuning to various wavelengths and to various

��YOU are missing much enjoyment, if your wireless set is not equipped to receive signals from stations employing undamped ("continuous") waves. Arlington transacts considerable business with a Poulsen arc transmitter. Tuckerton and Sayville, working with Germany, use undamped waves, as well as a new government station, NAJ, on the great lakes. A number of other stations which use arc sets are located on the Pacific Coast and in the Southwest. Notable among them is the new Navy station at Darien, Pan- a m a Canal Zone with call letters UBA. It is expected that others will be established from time to time. Again, Wiring diagram of the

it is not impossible for the advanced ex- perimenter to "get" the Nauen and Eilvese stations in Germany, if he be in position to erect an aerial some six hun- dred or more feet long.

Persons who have experimented with the audion detector have found that it may be rendered extremely sensitive to

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��spark -frequen- cies, both of which are im- portant con- siderations.

Consequent- ly, instruments and manipula- tions are want- ed that will enable one to undamped wave receiver turn his audion

into a high-frequency generator with the certainty and reliability that water may be turned from a faucet.

The following information will enable any amateur having an audion, to receive signals from undamped wave stations located within, say, looo to 1500 miles, and, under favorable conditions of

��CASH PRIZES FOR RADIO ARTICLES

The POPULAR SCIENCE MONTHLY is offering cash prizes for radio ar- ticles. See page 481 of this issue for details.

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