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_CUBIC
COMMUNICATIONS
S""AIfI
DIVISIDN
to
~ro~erly
align the filter re-
s~onse.
Cl)5 acts
as an
out~ut
cou~ling ca~acitor,
and carries
the signal
to the base of Qlll.
Power for Qlll is taken from the
CWN line,
and bias is
~rovided
by
R14j
and R146.
Out~ut
is
taken
across
emitter resistor
R147 and
cou~led
to the second
~assband
tuning mixer Qll) th-
rough C141 and R148.
"'H
01011
CI
ï1
ZII
Cl 1
Cl33
C13!!
"1311
YIt;;;I:,~
Cl!
-=-
J:
I.
--:r:
fc
134
-=
-=-=":'
Cl32
+-'O.llV
TOOll3
Old'
RI4
CI41
RI47
MAIN I.F. AMPLIFIER
NARROW CW
FILTER
TI04
10.llV
CI56
~
~""""""""""-r._...-_~_C_I!!_7.r
: IÇ
oWo
MAIN t.F. AMPLIFIER
RIllII
FROM
CI!!I
0113
c>--l
The signal from
Qll),
now
again at the
9 MHz I.F., is co-
u~led
through
C151
to the main I.F. amplifier, UlOl.
This integrated cir-
cuit is composed of two
am~lifier
seetions,
with the
out~ut
of the first
section developed across the R16o-LI05
load combination.
C154 re sonates with
LI05, while R160 broadens
the
res~onse
by
"swamping" the tuned circuit.
C152
couples the
out~ut
thus
develo~ed
from
the first
amplifier seetion of UlOl to
the second section of the same IC. Out-
~ut
of the second seetion is
cou~led
to
push-~ull
Tl04, which is
resonated
by
C156.
C157 is a bypass.
The output of
Tl04 is coupled to the product detector,
Q120.
AGC control
is
a~plied
through
voltage
divider R158--R159.
Overall
gain of UIOl is up to 70 dB.
PROruCT DErECTOR!AUDIO MUTE
+IV
PRODUCT DETECTOR
AND MUTE
Carrier oscillator en-
ergy is
cou~led
via C186 to
the base of Ql21, which for-
ms an
emitter-coupled pair
with Ql20.
Bias is
develo~
ed
by
R200 and R198,
acting
as
a
voltage divider,
and
R201 and R20) serve as isol-
ating resistors,
while Cl84
is a
bypass.
Ql20 and Ql21
act
as
a
mixer, combining
the I.F. input from Tl04 and
the carrier oscillator
sig-
nals to
reeover the
audio
frequency
of the
ineoming
signal.
Output
is
coupled
via
C182
to an
RC network
eomposed of
R218 and C208,
1'1191
R
11111
1'1200
CI1I2
cillT
R202
b
'=
FROM
CARRIER OSC.
CZIO
TO
.....+-~-+--l
r-o
NOTCH
FILTER
CRIII
C201l~
"1'1"
LlHE
-8
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