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I
apter^
3
Teclitiical
description
0
—
—
Impedincp
Arrplifi*!
0
—
—
rioT)
QIOt/102
QI03/I06
LEVEL
METER
Ratio
Circuit
_c>-/
OAt03-)05
nd
QA106
D
METER
Arr^liliw
AC-DC
Q110-I!3
QA506/I07
Fig.
3. 1
Block
Diagram
TF
2337A
3.1
PRINCIPLES
OF OPERATION
The method
of distortion
measurement
is
carried
out
in
the
usual
way
by
filtering
out the
fundamental
component and comparing
the
amplitude
of the
residual with
that of the total signal.
Distortion analysis
-
Distortion factor
is
defined
by
the equation
-
DISTORTION
-FACTOR
V
V
....
V
2
3
n
where
V,
V.
X
100%
amplitude
of
fundamental
Vg*
Vg
= amplitude
of
2nd,
3rd
nth
harmonic
N
= amplitude
of
noise
and
hum
harmonics.
The method employed
by
the
TF
2337A Automatic
Distortion
Meter
is
based on
the
following
approximation which,
assuming
a
distortion factor
of
less than
15%, introduces no appreciable
error
DISTORTION
FACTOR
-V2'
.
V3'
2
2
V
+
N
n
.
...
X
100%
12
TF
2337A
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