Popular Science Monthly 



459 



of the ringing musical tone which is so 

 desirable. At one time it was tliought 

 that the increase in damping of spark 

 signals, as compared to those of sus- 

 tained-wave transmitters, was responsible 

 for this change of note, but more recent- 

 ly it has been found that the difficulty 

 arose through the constant changes of 

 phase from group to group. If the train 

 of waves produced by a single spark dis- 

 charge continued until the next spark 

 passed, and if the second spark occurred 

 at just the right instant and in the right 

 direction to keep its waves in exact phase 

 (or so to speak, hand in hand) with 

 those which were dying away, the beats- 

 receiver would pro- 

 duce a musical 

 tone instead of a 

 hiss. The method 

 of the present pat- 

 ent is directed to- 

 w a r d producing 

 this result. 



Referring to the 

 figure, the closed 

 primary circuit /, 

 including the con- 

 denser / and 

 quenched spark- 

 gap 2, coupled to 

 the antenna circuit 



Fig. 7. 



//, is charged by 

 power from the alternator I2 through 

 lead wires 4 and 5. A portion of the 

 spark-gap is shunted by the closed cir- 

 cuit ///, which comprises the secondary 

 of transformer 8, condenser 7, and 

 spark-gap p, with shunting-switch ij. 

 Transformer 8 serves to couple the con- 

 trolling circuit IV with the ignition cir- 

 cuit ///; IV includes one coil of trans- 

 former i^, coupling it to the antenna. 

 Primary and secondary of 75 may be 

 short-circuited by switches 16 and //. 

 Associated with the antenna is a closed 

 pick-up circuit VI, which has coupled to 

 it a rectifying-detector combination VIII 

 and a local high-frequency-generator 

 circuit VII. 



The operation of circuits / and // is 

 in accordance with the ordinary quenched 

 spark-gap practice. Controlling circuit 

 IV, however, acting through ignition cir- 

 cuit ///, (and being of high persistence 

 compared to the antenna), tends to reg- 

 ulate the recurrence of si)ark in the 

 main gap 2. With transformer 75 in 



operation, by opening switches 16 and 

 //, the antenna // reacts upon and gov- 

 erns the controlling circuit IV; the con- 

 joint operation of these various systems 

 keeps the successive wave groups of the 

 same phase and therefore, by continual 

 reinforcement of the oscillations in the 

 persistent receiver-circuit, results in a 

 pure signal note in the heterodyne tele- 

 phone. Thus it becomes possible to take 

 advantage of the musical note for read- 

 ing through static, in addition to the am- 

 plifying properties 

 of the beats-receiv- 

 er and the compar- 

 ative simplicity of 

 quenched-gap op- 

 eration. The cir- 

 c u i t s VI, VII, 

 VIII, form a 

 beats-receiver used 

 as a tone-tester at 

 the transmitting 

 station ; when the 

 outgoing wave- 

 trains are held ex- 

 actly in step by the 

 controlling circuits, 

 the telephone of 

 VIII gives off a 

 musical tone of the 

 distant receiving 



A modified form of quenched-gap sender 



the 



sort heard 

 station. 



at 



ANNOUNCEMENT 



The time which must neces- 

 sarily elapse before the pub- 

 lication in a monthly maga- 

 zine of neics of any sort has 

 forced us to discontinue the 

 department of "Radio Club 

 Neivs.'* The editor will, 

 hoivever, be interested to re- 

 ceive communications from 

 Radio Club secretaries, and 

 suggestions from them con- 

 cerning the magazine and 

 future articles. 



