L
=
R:
both
channels
are
driven
in
phase
with
the
same
level.
L
=
-R:
both
channels
are
driven
out
of
phase
with
the
same
level.
The
amplitude
is
stabilized
with
the
control
loop
3105
II
and
T107.
After
peak
rectification
with
G1
101,
R191
feeds
amplifier
BIOS
II.
The
reference
is
a
constant
current
flowing
in
the
opposite
direction
Via
R192.
G1
102
temperature-compensates
G1
101.
The
field—effect
transistor
T109
in
series
with
R185
is
connected
in
parallel
with
R184.
The
output
voltage
of
B105
II
acts
on
the
feedback
circuit
R185/R184
until
the
nominal
value
of
the
oscillator
voltage
is
achieved.
4.6
Indication
See
circuit
diagram
230.8518,
sheet
1.
The
checkpoint
selector
8106
selects
the
signal
to
be
indicated
and
can
be
set
to
the
positions
L
and
R
for
the
AF
input
signal,
L
+
R
for
the
sum
signal,
MPXl
and
MPX2
for
the
multiplex
signal
and
PILOT
for
indication
of
the
pilot
component
in
the
multiplex
signal.
The
indication
sensitivity
can
be
increased
by
disconnecting
the
lO-dB
attenuator
R225/R226
with
820.
The
halfwave
peak
rectifier
circuit
using
T117
to
T120
evaluates
the
negative
halfwaves
of
the
input
signals
L
or
R.
The
differential
amplifier
Tll9/T120
delivers
the
signal
for
the
transistor
T118
which
operates
as
a
rectifier.
Capacitor
C143
is
charged
to
the
peak
value.
The
FET
impedance
transformer
T117
delivers
the
indicating
voltage
for
meter
J10
while
offering
a
minimal
load
for
the
charging
circuit.
The
feedback
Via
R216
adjusts
the
operating
point
of
the
differential
amplifier
so
that
only
the
peaks
exceed
the
ad-
justed
level
(for
a
constant-level
input
it
is
exceeded
for
only
short
periods)
and
recharge
the
capacitor
immediately.The
discharge
time
constant
is
fixed
by
R219
and
is
around
10
seconds.
4.7
Selection
of
L
or
R
Channel
for
Mono
See
circuit
diagram
230.8518
S,
sheet
3.
For
monaural
transmissions
the
signal
on
the
left
or
right
channel,
depending
on
the
setting
of
link
E8103,
is
switched
through
to
the
outputs
instead
of
the
coded
signal.
The
selected
mode
is
stored—
irrespective
of
power
failure
—
in
the
bipolar
relays
R5101
and
R5102
whose
windings
are
connected
in
parallel.
A
contact
of
relay
R5101
switches
the
signal
path.
A
contact
of
relay
R5102
feeds
the
R
38122
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21