140 



THE WORLD'S ADVANCE 



with fair degree of accuracy during 

 specified hours. In fact, at the present 

 time, these two stations are only in com- 

 munication between 5 p. m., Eastern 

 Standard Time, and 2 130 a. m., Eastern 

 Standard Time, which are, of course, the 

 more favorable hours during the day for 

 long-distance radio telegraphic communi- 

 cation in this portion of the universe. 



The traffic from the Tuckerton station 

 is sent in series of groups of messages 

 which are acknowledged at the Eilvese 

 station at the end of each group. The 

 Eilvese station then replies, requesting 

 repetitions of lost words, which is fol- 

 lowed by the dispatch of traffic that has 

 meanwhile accumulated at Eilvese. 



The service 

 between these 

 two stations is 

 handled in an 

 accurate man- 

 ner, but at a 

 slow speed, 

 con sequent- 

 ly only a lim- 

 ited amount of 

 business can 

 be handled. 



As mention- 

 ed before, the 

 Goldschmidt 

 h i g h - f r e- 

 quency altern- 

 ator is unique 

 in that a very 

 high frequency 



is obtained from a low initial generator 

 speed of about 3,000 revolutions per min- 

 ute. The generator itself comprises a 

 stator and rotor, the stator being mag- 

 netized by a direct current source of 

 supply. The number of field poles and 

 the design of the rotor are such that the 

 initial frequency of the machine is 15,000 

 cycles per second. The rotor is then 

 shunted by coils of inductance and a con- 

 denser constituting an oscillatory circuit, 

 which has a natural frequency of 15,000 

 cycles per second. Due to the rotating 

 magnetic field produced, the rotor induces 

 currents in the stator having a frequency 

 of just double the value, viz., 30,000 

 cycles per second. The rotation of the 

 rotor in the magnetic field produced by 

 the 30,000 cvcles in the stator induces 



Looking Toward the Top of the Tallest Steel Mast of the 

 Arlington Station. 



in it (the rotor) currents at a frequency 

 of 45,000 cycles per second. A second 

 circuit is now joined across the rotor, 

 which has a natural frequency of 45,000 

 cycles and the reaction of this magnetic 

 field on the stator produces in it a fre- 

 quency of 60,000 cycles per second. The 

 terminals of the stator are in turn con- 

 nected to the aerial and earth connec- 

 tions, the aerial being so adjusted by tun- 

 ing inductances to give it a natural fre- 

 quency of 60,000 cycles. In other words, 

 the antenna and earth connections are 

 joined across the original direct current 

 field magnets, which also have alternat- 

 ing currents of high frequency flowing 

 through them. The antenna is in turn 



attuned to the 

 high-frequency 

 energy. 



Signalling is 

 a c cpmplish- 

 ed by the in- 

 sertion of a 

 telegraph key 

 in the direct 

 current circuit 

 to the field 

 coils, the field 

 windings being 

 thus magnet- 

 ized and de- 

 magnetized to 

 produce the 

 dots and 

 dashes of the 

 telegraph code. 



The high-frequency alternating current 

 super-imposed upon the direct current 

 circuit is prevented from flowing back 

 into that circuit by specially designed 

 choke coils. 



-It is extremely important that the 

 speed of a high-frequency alternator 

 be maintained constant in order to keep 

 the aerial in resonance. Arrangements 

 are therefore made whereby the field of 

 the motor driving the generator is weak- 

 ened just previous to the pressing of the 

 key. Thus the speed of the generator is 

 kept fairly constant. 



A transmitting station of this type is 

 indeed novel, since the customary high 

 potential condensers, noisy spark gap and 

 oscillation transformer are absent. It is 

 rather awesome to see this machine in 



