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 



I ^ AWWW\_AWkWA 



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 



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