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OCUBIC
COMMUNICATIONS
S . . .",
DIVISION
IUI5
ft
.,1
SIDETONE LEVEL
RI24
"=
CIOS
TO ..Fo--!
p.... +
RIII
CRllr
CRI2S
CIOS
Rl20
SIDETONE OSCILLATOR
T
CW
RII6
feedback path, Rl21 , CR125 , CRlll and R120; with the diodes providing a lev-
eling action for the oscillator
output.
The output
is applied
to sidetone level control R124,
and thence to the
audio freq-
uency power amplifier via coup-
ling capacitor CIOS.
Keying
of
the
sidetone
oscillator
is
accomplished by
Ql02
and QlOJ.
When in the CW
mode,
CRIIO is reverse biased,
but the
base
of Ql02
is held
low
by
the "T"
line, maintain-
ing Ql02 in a conducting state.
When the key is closed, the "T"
line
goes high,
allowing
the
base of Ql02 to rise,
and cut-
ting off conduction in Rl16 in
the collector circuit
Thus, when the key is closed, and the MODE switch is in the CW position
the base of Ql03 is low due to the fact that QI02 is not conducting,
and it
does not conduct.
This allows
UIOIB to oscillate.
When the key is opened,
the "T" line goes low, CRl09 conduets , and the base of QI02 is grounded.
It
thus conducts, creating a voltage drop across Rl16, and biases QI03 on. This
prevents UIOIB from oscillating.
=2
VOLT OSCILLATOR/REGULATOR
CII4
CRII'
R14.
+ ~ - e v
CR"
CIIII
~+
Ira
!Ic...
-=
-
"="-=
-SY OSCILLATOR
AND REGULATOR
UIOI
+I4V
RI44
RI41
CIIZ
~
The negative five volts DG required
by
various portions
of the
transceiver
circuitry
is provided
by
oscillator U-
103, a timer IC connected in the astable
mode.
The frequency
of
oscillation is
set
by
the
R143,
Rl44 and Cl12 combin-
ation.
Output is taken
through
capac-
itor Cl14,
and applied
to a
voltage
doubler composed of
CRllS and CRl19.
Cl14 and Cl15
are an
integral part of
the doubler circuit, charging alternate-
lyon different
half-cycles of the osc-
illator output.
Their
individual vol-
tages
add during discharge,
providing
the required voltage doubler action.
The negative voltage
thus generated is regulated
by
the combination of
dropping resistor Rl46 and zener diode CR120,
in a conventional zener reg-
ulator circuit.
Output is filtered
by
Cl16.
5-8
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