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o
~~M~~~ATIDNS
S ....",
DIVIBION
charged to 2/3 of the supply voltage
after theinput has returned high, the
output of UIOl is high.
When this condition prevails,
Ql14
is
turned
on
through R129 and R130.
This in turn satur?-tes QllS, which keys an
external
relay (such as for a linear amplifier,
etc.) through protective diode CR1Il
and resistor Rl32.
Should FULL
breakin be selected by the operator,
the base of Ql13 is
grounded and the control input of the timer is never allowed to go low. Key-
ing is then controlled by the key line,
connected to the
junction
of R129
and R130.
When the transmitter is keyed,
this line goes high, and Ql14 and
QllS are again saturated,
groundingthe external relay line.
Note that few
external amplifiers
are capable
of operating at full breakin,
due to the
slownessof the switching of the various relays, etc.
Only those amplifiers
especially built,
or modified,
forQSK operation
should be used when full
breakin is desired.
NOISE BLANKER
+NI
RIII
FROM
0103
RIZ4
CI04
CI05
+NIl
.I
CIOZ
RI07
RIIO
"--H-JV"V'v~'-i>~~O
4
CRIOI
RIOG
RI09
RI05
CIII
2ND
a
3RD STAGES,
JII2
NOISE BLANKER
CI13
CRIOZ
~11~TOAlor
.-...·ff..........
-f-{
~TO
0108
CRI03
0107
+NI
FIRST STAGE,
NOISE BLANKER
RIOI
A NT()...I'V'V\r-j
CIOI
The noise blanker signal input
is taken directly from the receiver
antenna input,
and is coupled
th-
rough
isolation resistor-capacitor
combination
RIOI-CIOl to the
base
of
compound stage
QlOl and
Ql02.
Bias for
that pair is derived from
Rl08 andRI03,
with supply decoup-
ling provided by RI09 and CI02.
Frequency
compensation is ac-
complished
by RI06-CI04 and
RIOS-
CIOS networks.
Output is taken th-
rough
CI03,
RIIO, and CI08 to the
base of the second
compound stage.
That stage, Ql04 and QlO
S,
operates
in the same manner as the first one.
In turn,
this
output is
taken to
yet
a third
compound stage,
Qlo6
and
Ql07.
This
pair
utilizes
a
conventional
emitter
network
and
untuned transformer TlOl
in
its
output.
Note that the
entire cir-
cuit is broadbanded--no selectivity
is built 'in,
so that noise pulses,
no matter
what frequency,
will be
accepted.
The
use
of
three com-
pound stage
amplifiers
in cascade
realizes a very high gain, for good
sensitivity to the noise pulses.
The upper half
of the second-
ary of TIOl drives detector
CRI02,
and after
filtering
by the
CllS-
Cl16-Rl26 network, the resultant DC
signal is
applied to
operational
amplifier UI01.
The gain of this device is set
by
the ratio of R128 to
R129
and its input threshold point is
determined
by
voltage divider R127 and R-
129 on the
non-inverting input.
The DC
output of
AIOl is applied through
6-9
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