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reliability are enhanced  and  the  experimental  readjustment  often  re-
quired in electronic circuit design is minimized.

  In brief, the circuit design technique presented here is  based  on  the
fundamental equations of vacuum  tube  circuits.  The  small-signal  para-
meters such as g_m and g_p, which appear in  these  equations  are  obtained
directly from the G-Curves included in  this  Manual.  Quantities  of  in-
terest, such as output voltage, gain,  distortion,  etc.,  may  be  obtained
explicitly for use with the fundamental equations because  of  the  addi-
tional data available with  the  G-Curve  technique.  In  most  treatments
of vacuum tube fundamentals,  the  circuit  equations  are  developed  and
the concept of small-signal parameters, although well explained,  are  not
used as a basis for circuit design.

  The use of these curves and the equations listed  in  Chapter  2  enable
the designer to  understand  more  clearly  in  what  manner  circuit  per-
formance changes whenever any circuit  parameters  are  varied.  Also,  it
becomes evident that  when  a  required  performance  cannot  be  obtained
without operating the tube at or near its peak rating, another  tube  type
with greater power-handling capability should be chosen.

  The selection of a different tube type is relatively simple in terms  of
the tables of power-handling  ability  included  in  this  Manual.  First,
amplifier distortion and tube dissipation are calculated.  If  the  distor-
tion is larger than desired and/or the dissipation is high, a tube  having
a larger nominal value of g_p or G_m2 should be selected.  If  on  the  other
hand the distortion is lower and/or the  dissipation  is  much  less  than
permissible, then a tube having a lower g_p or G_m2 may be selected.

  Tube reliability is one of  the  major  problems  confronting  designers
of specialized equipment.  It may be attained by the  design  of  conserva-
tively rated circuits where the selection of tubes  and  operating  condi-
tions is such that circuit performance is  accomplished  with  the  lowest
possible element dissipation.  The G-Curve  technique  is  well  suited  to
the design of conservatively rated circuits since it provides  the  design
information required.

  The author wishes to thank Mr. W. E. Babcock  of  RCA  for  his  tech-
nical review and comments on this Manual.  He  wishes  also  to  note  the
assistance of H.G.McGuire and T.Turner  in  the  preparation  of  some
of the material.

Kingsville, Md.                         Keats A. Pullen, Jr., Eng.D.
March 1958
 
 
 
 
 
 
 

viii

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Copyright 2008 for Phyllis K. Pullen, M.D.,
by Robert J. Legg