I.C.E Supertester 680 R - Page 20

squa.red,
Z
-
output
impedance
(from
4000 to 7000
ohms
approximately, t0 the
primary
of the transformer
according to the
type of transformer
and final valve
in use);
frorir 3 t6
7 ohms in the moving
coil of the loudspeaker,
beariflg
in mind that
this figure may
yary
/
according to the type
of loudspeaker.
I
For further
details, consider
few examples illustrating
also
this system of measuring
the
output in watts:
The measured output
voltage at the
primary
terminals
of the output
transformer is 100
volts;
j
knowing the impedance
valle gf the
primary
0f the transformer
in
question,
usually
around
"'
5000 ohms, we
get
the
following:
Simplified
Circuit
for
output
metel.
100,
100 x 100 1
0,000
w=_:_
_2watts.
5000
5000 5000
lf the
above mentioned impedance
instead
of 5000 ohms is 7000
ohms, we have:
100, I00 x 100
1 0,000
W= :1.42
watts.
7000
7000
7000
If 0n the
other hand we measure
the voliage
at
the
terminals of
the secondary of
the output
transformer, that
is
in
parallel
with
the moving coil
of the loudspeaker,
we find
for examilie
an output
voltage of 3 volts;
as we know that
the impedance
of the moving
coil of ihe
loudspeaker to
be tested is
for example 5 ohms, we
get
the fotlowing:
32 3x3
I
*=--=
5
:l-=1.8watts
0n the other hand,
of the impedance
of the moving
coil is
for exanrcle 3.2 ohms,
we have
the following:
32 3x3 I
W:-
:2.81watts.
OU TPIJT
Diagram
showing
how
to
use the
SuPerlester
680 R. {or
output
mea-
surements.
m5noTl rooov
250v.
sov
10v
I
MAx
I
2ooov
5oov
loov
20v
+
*
*
R1+ R2=
1600r1
-\'+
\
Rr
/
,
dB<
y''de
ooooo
34
3.2 3.2
3.2