Load Carrying Capacity of Amplifiers

T h i s p a p e r describes t h e a d a p t a t i o n o f t h e c a t h o d e r a y oscillog r a p h t o t h e d e t e r m i n a t i o n o f t h e o v e r l o a d p o i n t o f v a c u u m t u b e amplifiers. U s i n g t h e i n p u t v o l t a g e t o p r o d u c e a h o r i z o n t a l deflection, a n d t h e o u t p u t v o l t a g e or c u r r e n t to p r o d u c e a v e r t i c a l deflection, t h e a m p l i f i e r p e r f o r m a n c e is readily determined by noting the resulting figure on the fluorescent screen. So l o n g as t h e figure is v i r t u a l l y a s t r a i g h t line or an o b v i o u s l y u n d i s t o r t e d ellipse, i t w a s f o u n d t h a t t h e a m p l i f i e r o u t p u t i s free f r o m harmonics. A s soon a s o v e r l o a d i n g begins, t h e oscillogram shows e i t h e r a s h a r p b e n d at e i t h e r or b o t h e x t r e m i t i e s of t h e line or a p p a r e n t d i s t o r t i o n o f t h e ellipse. T h e m e t h o d has t h e a d v a n t a g e o f b e i n g q u i c k .