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_CUBIC
COMMUNICATIONS
S.,IIIII
DIVISION
BAND LOOP PHASE
COMPARATOR
R233
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FROM
DIVIDE:R
U10l, a dual
J
-K flip flop,
is used
a's a divide- by-four prescaler for
the divider
chain.
lts output is coupled
to the
clock inputs of U102 and
U103 in parallel.
The outputs of U102 and Vl03
are gated through U104A to
produce an output pulse
when the counter has completed its
count~ng
cycle;
this pulse is then inverted through U104B,
and used
to drive the phase de-
tector driver, Ql23.
+.v
+sv
Programming
of counters U102 and
U103 is accomplished
by
the diode ma-
trix composed
of CR121 through CR129,
and memory U105.
For 160 meter
oper-
ation,
all
five
input lines to U105
are low,
or
binary 00000; for 80 me-
ters,
the
coding
is 00001;
for 40,
00010;
for 20, 00011;
for 15, 00100;
for 10A,
00101;
for lOB, 00110;
for
lOC, 01000;
and for 10D, 10000.
Band
program memoryUlOS
decodes these ad-
dresses into the bit combinations nec-
essary to
set
the
required division
ratios into counters U102 and U103, as
shown in
the accompanying
memory map
of VlOS,
Additional diodes
(CR130 through
CR133)
are connected to the 10 meter
control lines
which provide
a common
10 meter bus, regardless of which seg-
ment of the
band is
selected
by
the
BAND switch,
and is used
to energize
the 10
meter VCO
and 10 meter L.O.
filter.
The output
of
the
programmable
divider is coupled through
R232
to the
base
of driver
Ql23.
lts output
is
coupled to the phase comparator, U109.
The other input
to the phase compara-
tor is the 125 kHz signal
from U101B,
the loop
reference oscillator and di-
vider.
YlOl controls the frequency of
the oscillator
at
2 MHz,
with C246
providing
a
means
of
adjusting the
calibration.
Output of
the phase
comparator,
U109, is coupled
thr~ugh
R233
to the
inputs
of two amplifier stages, UllOA
and UllOB.
Capacitor
and resistor
combinations
C24S-R233
and R239-C249
form the loop filter.
For 160 through
15 meter
operation,
UllOA is used as
the error
amplifier, with
its output
driving
the
varicaps
in
those band
oscillators;
for the 10 meter
band,
Vl01B,
with higher
gain,
is used to
drive the varicap of that band's
osc-
illator.
More
gain
is
required be-
-2
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