6. A P P L I C A T I O N S
The basic use of your V T - 1 7 1 [ " V T - 1 7 1 E J is to measure
sinusoidal wave voltages a s an A C v o l t m e t e r . In addition,
it provides a wide v a r i e t y of applications a s described
below.
(1) Amplifier Gain Measurement
Y o u r V T - 1 7 1 [ " V T - 1 7 1 E J is capable of measuring an
a m p l i f i e r g a i n , which is a signal m a g n i f i c a t i o n f r o m
point A to B in F i g u r e 5 w i t h a signal generator
connected to the a m p l i f i e r input. If the measured
signal levels a t points A and B are a and b d B ,
respectively, then the g a i n is ( b - a ) d B .
A l s o , the method is applicable to negative-feedback
a m p l i f i e r s ; t h a t i s , it is a v a i l a b l e f o r measuring a n
open loop gain of each a m p l i f i e r c i r c u i t w i t h the
negative-feedback signal leaves applied.
F u r t h e r , the method can be used f o r measuring the
frequency responses of given c i r c u i t s by changing the
signal generator frequency.
A s an example, let us calculate the open loop gain
( f r o m point A to B ) of the negative-feedback a m p l i f i e r
shown in F i g u r e 6 . A s s u m e t h a t the measured level a t
point A b e + 1 . 5 d B in the - 6 0 d B range and t h a t of
point B - 4 d B in the +10dB range. The gain f r o m point
A to B is
( + l 0 d B - 4 d B ) - ( - 6 0 d B + 1.5dB) = 6 4 . 5 d B .
S I G N A L
G E N E R A T O R
Figure 5 - Amplifier Gain Measurement.
S I G N A L
G E N E R A T O R
Figure 6 - Negatve Feedback Amplifier Gain Measurement.
®