6. A P P L I C A T I O N S
The basic use of your V T - 1 7 3 is to measure sinusoidal
w a v e voltages as an A C voltmeter. 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 3 is capable of measuring an a m p l i f i e r
g a i n , which is a signal magnification f r o m point A to
B in F i g u r e 6 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 at points
A and B are a and b d B , respectively, then the gain 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 is, it is a v a i l a b l e for measuring an
open loop gain of each a m p l i f i e r circuit w i t h the
negative-feedback signal leaves applied.
F u r t h e r , the method can be used for 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 7 . Assume t h a t the measured level a t
point A be+ 1.5dB in the - 6 0 d B range and t h a t of
S I G N A L
G E N E R A T O R
Figure
6 - Amplifier Gain Measurement.
S I G N A L
G E N E R A T O R
Figure
7 - Negatve Feedback Amplifier Gain Measurement.
- 1 1 -
point B - 4 d B in the
+TQdB
range. The gain f r o m point
A to B is
( + 1 0 d B - 4 d B ) - ( - 6 0 d B + 1.5dB) = 64.5dB.
