236 



ANKALS NEW YORK ACADEMY OF 8CIEXCES 



aiidion until the appearance of the local oscillations indicates that the 

 limit of amplification has been reached. By careful adjustment about a 

 thousand times amplification and very sharp tuning can be obtained with 

 two steps. 



For continuous wave reception^ there are several methods of operating 

 cascade systems. It is possible to have either system generate oscilla- 

 tions, the other system acting simply as an amplifier or both systems may 

 be made to generate in synchronism. It will generally be found that 

 when both systems produce oscillations, beats will be produced, so that a 

 continuous note is heard in the telephones ; but by adjusting the fre- 

 quency of one of the systems the pitch of this note will be reduced as the 

 two systems approach synchronism, until finally at one or two hundred 



Fig. 29 



beats per second the two systems pull xito step in much the same Avay as 

 two alternators. The ability of the two systems to keep in step depends 

 mainly on the value of the coupling between them, and the closer this is 

 the better the two hold together. There is still another Avay of working 

 this combination, and that is asynchronously. In this case beats are 

 continuously produced in the system so that a continuous note is heard 

 in the telephone, but the circuits may be so adjusted that the note is not 

 loud enough to be troublesome, or it may be tuned out of the telephone 

 in the manner previously described. Incoming oscillations are combined 

 in the system to produce beats with the beats already present, so that a 

 rather curious note is heard. Yery good amplification is secured by this 

 method, though naturally the system is troublesome to operate. 



It may be noted here that whenever a signal is too weak to read with 

 one audion system, and cascade operation becomes necessary, it is always 

 better practice to use the cascade circuits for the radio frequencies, even 

 if the regenerative circuits are not employed with each individual audion 



