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BELL SYSTEM TECHNICAL JOURNAL 



jL- This means that if elements of the same accuracy were used, the 

 heterodyne oscillator would be somewhat more accurate. Its total 

 error would be represented by jca + Jco -\- Jl- Since ^CajCa and 

 ACo/Co will be both positive and of about the same order of magnitude 

 partial compensation will obtain and the error will be of the order of 



0.20 



0.12 



0.08 



0.04 



-0.04 

 -0.08 

 -0.12 

 -0.16 

 -0.20 

 -0.24 

 -0.28 

 -0.32 

 -0.36 



0.08 



0.12 0.16 



X 



0.24 0.28 



Fig. 1 — The frequency errors in a heterodyne oscillator at a frequency F = xfo 

 + Fo after the low frequency check had been made can be obtained from the plot as 



follows: For a variation ACq in the fixed capacitance Co, ^Fc^ = yco-p^fo] for a 



Co 



variation in the air condenser capacitance Ca, AFc^ = yc^ -y^ fo] for a variation in the 

 inductance L, AFl = yL-j-fo. 



magnitude of AFl. In the case of the ordinary type of oscillator the 

 errors due to the capacitance and inductance variations will be equal 

 and of the same sign so that the error will be of the order of magnitude 

 of 2AFl- For audio frequency applications this accuracy has been 

 found to be adequate given sufificient care in the construction of the 

 circuit elements. 



