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OCUBIC
COMMUNICATIONS
5""11,,, DIVIBIDN
L.O. BUFFERS
8 SWITCHING
R17~
RI66
~
el63
R164
0
JI15
To
COUNTER
+ev
I.
C162
CI66
~ ~-----4It---""--v'\I'I""'"
CI74
~ T O
'-Rili>
- 0111
which will be covered later.
Local oscillator
energy is coupled to the base of the other driver, Q-
118.
The gain of this stage is determined by the ratio of feedback resistor
R190 to input resistor R187; C174 and C176 are merely DG blocking capacitors.
The emitter of the stage is bypassed conventionally.
Output
is
taken fr om
the collector through a winding of the transmit mixer, Zl02, a doubly balan-
ced mixer assembly identical to thatused for AIOl.
L.O. drive is connected to Zl02
through an
amplifier/buffer network
contained on the exciter board also.
Signal from
the
local
oscillator
board is applied to buffer Ql14 via
c164.
Output is taken from the R165
portion of
the emitter resistance,
and coupled through R166 and C163 to
the
counter board,
to provide
the
L.O.
el64
signal 'for
the front
panel digital
JIO~ o-;l-4~-+-r
dial ,while the remainder of the em-
itter resistance,
R164, is bypassed
by c162.
Signal
is also
taken from the
collector of Ql14,
coupled. through
C165,
and
applied
to the
base of
Ql15.
The emitter resistor of this
stage is
unbypassed,
creating some
degree of degenerative feedback, and
the output is taken via C174 and R187 to the mixer driver, Ql18.
PRESELEeTOR--INPUT SWITCHING
0------4......
- - ( >
TO 0106
TX PREAMP
Output from transmit mixer Zl02
which is now at the desired operat-
ing frequency,
is
coupled
to
the
same preselector board
used.
in the
receive portion
of the transceiver.
Tt is coupled via CI08
and ClIO to
the input
of the band
preamplifier
filters
when the "T"
line is high,
biasing switch CRI09 on through LI02
and Rl13.
Since the "R" line is low
under transmit conditions, the volt-
age
dropped
across
Rl13
reverse
biases receive switch CRI08, discon-
necting the
receiver input Îrom the
preselector.
TO ALe
"R"
RX IN
CI07
JI32
0--11-................,
cloe
TX IN
o--t
E-.-.....
...J
J13~
"T"
o----4I~-_o
*C109
CliO
RI13
RII4
PRESELECTOR
BOARD
INPUT
SWITCHING
TO
lAND
PMAMPS
PRESELECTOR--BANDPASS FILTERS
8ince operation of all
of
the
individual
band filters
is
identi-
cal, only one,
the 80 meter version,
is discussed here.
These filters are
selected by the EAND switch on the front panel of the transceiver, utilizing
the control lines from Sl03 on the Eandswitch/Low Pass Filter board.
4-4
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