502 BELL SYSTEM TECHNICAL JOURNAL 



corresponding to a total possible adjustment of about one part in 

 100,000. This condenser is shown at C in the circuit drawing. 



The oscillator circuit, showing the tubes and transformers, the 

 plate tuning elements, the filament and plate current meters, and the 

 frequency adjusting condenser is shown in Fig. 12. The adjusting 

 condenser is mounted between the meters and is controlled by the 

 large knob and dial. 



One complete oscillator unit, consisting of a 100,000-cycle crystal 

 controlled oscillator with three independent 100,000-cycle outputs, 



Fig. 12 — Standard frequency oscillator without shield. 



having a self-contained temperature and pressure controlled crystal, 

 and having a temperature controlled, electrically shielded circuit, is 

 shown in Fig. 13. 



The submultiple generator circuit that is used to obtain outputs at 

 10,000 cycles and 1,000 cycles is shown in Fig. 14. It consists of an 

 inherently unstable vacuum tube oscillator with the tube operating 

 on the curved part of its characteristic. The frequency of this 

 oscillator may be controlled readily by any frequency which is a 

 small multiple or submultiple of it. In this instance the oscillator is 

 controlled by an input having the frequency of its tenth harmonic, 

 the controlling high-frequency input being resistance coupled into the 



