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OCUBIC·
COMMUNICATIONS
S"AItI
DIVIBICN
Ril'
CI07
CRI02
CIOS
ALe TO
.>-4"'VV"",,"OO 111Tilt
RI04
.C_R.... IOSt-<)
:~~':IN
WIPER
~CIOI
RIII
ALe AMPLIFIERS
CRIO.
TO
>.-.........
-0
QIOI
.,L.
RIOS
CIO.
+IO.IY
WATTMETER /
~""',..
RI02
SWR
DETECTOR
CI04
RIOI
nOl
TO LP'
R
LINI
CIIt08
!'Wo.
ALC
RUL
ALe
AUTOMATIC LEVEL CONTROL
any signal reflected from the antenna due
to mismatch, etc., while CRI02 provides a
voltage proportional to the power sent to
the antenna.
These signals
are smoothed
by the
CI04-RI03-CI06 and CI05-RI04-CI07
combinations.
These
signals
are then
used
in the ALC, SWR, and wattmeter cir-
cuitry to provide front panel indications
and protective functions for
the trans-
mitter power amplifier.
The
FWD and
REFL signals from the
wattmeter board are coupled to the pre-
selector board where they are adjusted by
RI04 and RIO?
respectively.
CI02 and C-
10) bypass the lines
as they
come into
the board. CRI04 and CRI05 act as an "or"
gate,
allowing the largest of the
two signals to pass to the invert-
ing input
of ALC amplifier UlOlA.
Feedback for this amplifier is ·via
RIOJ,
while RI02 and RI05 estab-
lish a bias at the
non-inverting
input which sets the quiescent op-
erating
point
of
the output of
this
stage.
RIOI and CRIOI pro-
vide a regulated
voltage for this
bias network and for UIOI, as weIl
as for the
ALe
ZERO adjustment.
If
the
REFLected ALC signaJ.
should exceed a given amount,
or
if the
FWD ALC signal should ex-
ceed that produced at themaximum
safe
output of
the PA,
CRIOS or
CRI04 will
conduct,
causing the
output
of UIOlA to go more negat-
ive.
This
output will
be
passed through CRl02, and on to mOl in the pre-
selector, where
it is used to
reduce the gain
of the stage,
and thus the
output of
the transmitter.
Manual
RF GAIN
control is accomplished by in-
serting a voltage to QIOl via CRIOJ to the ALC line when in the receive con-
dition.
The "R" line, through CRl06 and Rl08, biases the inverting input of
UlOIA in such a manner as to disable it in receive.
The output of
UIOIA is also coupled via Rl06 to the inverting input of
UlOlB.
The ratio of feedback resistor Rlll to
input resistor RI06 deter-
mines the gain of the ·stage, and the output is coupled through limiting res-
istor Rl12 to the meter switch,
where it may be selected by the operator to
give a front panel
ALC indication if he so desires.
RIIO, connected to the
non-inverting input
of UIOIB,
provides a zero set
calibration control for
the meter reading.
When in the receive condition, UIOIB is also disabled by
the "R" line, through CRIO?, in the same manner as UlOlA.
6-5
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