PRESENT STATUS OF TRANSISTOR DEVELOPMENT 



423 



since /•(, appears as a positive lecdback olomoiit. ll\c cuinc in Fiji;. 14 is 

 a plot of the short-circuit stabiUty contour when r, and /v have the 

 nominal values of 700 and 20,000 ohms. Transistors haviiifi; (i and /•,, 

 sufficiently large to place their representative points al)ove this contour 

 will l)e short-circuit unstable, i.e., they will oscillate when short-cir- 

 cuited. Those having an a — rt, point below the stability contour will 

 be unconditionally stable under any termination conditions. The large 

 unshaded rectangle bounds those values of a and vo , which were repre- 



Tf = 250 OHMS 

 rZ = 250 OHMS 



r^ - 20,000 OHMS 



a= 2 



Fig. 11^ — Equivalent circuit and average element values of the type A transistor. 



Fig. 12 — Reproducibilitj' of point-contact linear characteristics. 



Fig. 13 — Average characteristics of the M1729 and typical characteristics of 

 tlie M1752 transistors. 



