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TRANSMIT PREAMP
CI~8~
TX OUT
~
JI34
R139
"T"
LIIIE
RI41
C167
+IO.5V r.....A~'/\-~~
+-IO.5V
FROM
~flI!jl-4k1'-A.."-+-{
QIOI
o
~~M~!~ATIDNS
S . , . N
DIVISION
the ratio
of Rl40
to the im-
pedance of the
RIJS-Cl?l com-
bination.
Bias
is
applied
only in the transmit condition,
from the "T" line, via voltage
divider
R14l-R142.
The emit-
ter
circuii
is
composed
of
R14J bypassed by Cl?2.
Ouipui
is iaken
from a
tap
on autotransformer Ll04
and coupled ihrough cl6S, pro-
viding a low
impedance signal
that can be coupled through a
coaxial
cable
to
the power
amplifier board
with minimum
loss.
C16?
and
RlJ9
form a
supply line
decoupling
net-
work.
POWER AMPLIFIER
RIOt
PA
PREORIVER
RI'
CI04
IN
~ J-..J'-A........ l-+~
RI02
RI04
1'1102
+14V
DRIVER
AMPLIFIER
FROM
BIAS LII«
RI07
From the preselector,
the transmit signal
is applied
io
PA predriver
QJ.Ol on ihe
power amplifier board via coupling capacitor Cl04.
Since QJ.Ol
is a feedback stage, 'its gainis sei
by
the ratio of feedback resistor RIOJ
io
inpui
resisior
m02, while bias
is
+-14V
iaken from the
PA bias line via voltage
divider mOl-Rl04.
The
emiiter circuit
is conveniional, and the ouiput is taken
via TlOl,
which provides
a
push-pull
signal for ihe folYowing
driver siages.
CIOS and ferrite bead FBlOl provide de-
coupling for the collector supply line.
4-6
IJ
LIOI
11111
ClOg
Ril!
0102
CIII
e-.........
QIO!
CliO
11112
CI2
ïi§
The driver amplifiers, fed
.by
iransformer
TIOl,
are sup-
plied
bias via the
cenier tap
of that
transformer and RF ch-
oke LlÛl.
RIO? and CRlOl form
a forward-biased diode regulat-
or circuit
to control
the am-
ount
of
bias
supplied.
cI06,
ClO? and CIOS are bypasses.
The
C12J,
Rl09, RllO and
Rlll network
assures the
cor-
rect load impedance on the sec-
ondary of TlOl.
The
RIIJ-CI09
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