Heathkit SB-10 - Page 6

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RF
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Figure
3
A
balanced
modulator
is normally
employed
to suppress
the carrier.
A sinEle
balanced mod-
ulator
can
be designed
to balance
out either
or
both input
signals
but canno.-t
balance out
one
sideband
and not
the other. Hence,
the
necessity
for
two balanced
modulators,
as
used
here,
v/ith
output
circuits
connected in
push-pull
-parallel.
With
the RF
inputs
to V1 and
V2
in
parallel
and
the outputs
of V1 and V^2
in
push-pull,
the carrier
is split
into
two
components in the output
circuit'
each
equal but 180" out
of
phase
with
each other.
Since
the same
configuration
exists
in
V3
and
V4,
the carrier
is balanced out in
each
modulator.
Thus,
with
all conditions satis-
fied
(9@ phase
difference
between
both RF
and audio
inputs
to each of
the balanced modulators
and the
carrier suppressed),
the result is
a
single
sideband
output signal.
Page
6
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AUDIO
PHASE
SHIFT
NETWORK
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