
5.
The
dierence
frequency
(1st
IF)
from
the
A4
sampler
is
compared
to
a
reference.
The
1st
IF
feedbac
k
signal
from
the
A4
is
ltered
and
applied
to
a
phase
comparator
circuit
in
the
A11
phase
lo
c
k
assem
bly
.
The
other
input
to
the
phase
comparator
is
a
crystal
con
trolled
1
MHz
signal
from
the
A12
reference
assem
bly
.
An
y
frequency
dierence
b et
w
een
these
t
w
o
signals
pro duces
a
prop ortional
error
v
oltage.
6.
A
tuning
signal
(YO
DRIVE)
tunes
the
source
and
phase
lo
c
k
is
ac
hiev
ed.
The
error
v
oltage
is
used
to
driv
e
the
A3
source
YIG
oscillator,
in
order
to
bring
it
closer
to
the
required
frequency
.
The
lo
op
pro cess
con
tinues
un
til
the
1st
IF
feedbac
k
signal
to
the
phase
comparator
is
equal
to
the
1
MHzreference
signal,
and
phase
lo
c
k
is
ac
hiev
ed.
7.
A
syn
thesized
subsw
eep
is
generated
b
y
A13/A14.
The
A3
source
trac
ks
the
syn
thesizer.
When
the
source
is
phase
lo
c
k
ed
to
the
syn
thesizer
at
the
start
frequency
,
the
syn
thesizer
starts
to
sw
eep.
The
phase
lo
c
k
ed
lo
op
forces
the
source
to
track
the
syn
thesizer,
maintaining
a
constan
t
1
MHz
1st
IF
signal
.
The
full
high
band
sw
eep
is
generated
in
a
series
of
subsw
eeps,
b
y
phase
lo
c
king
the
A3
source
signal
to
harmonic
m
ultiples
of
the
fractional-N
V
CO.
The
16
to
31
MHz
subsw
eep
is
pro duced
b
y
a
one
half
harmonic,
using
the
divide-b
y-2
circuit
on
the
A14
assem
bly
.
A
t
the
transitions
b et
w
een
subsw
eeps,
the
source
is
pretuned
and
then
relo
c
ks.
T
able
12-3
lists
the
high
band
subsw
eep
frequencies
from
the
fractional-N
V
CO
and
the
RF
output.
Figure
HBBLK12
here.
Figure
12-5.
High
Band
Operation
of
the
Source
12-14
Theory
of
Operation
DRAFT
3/21/106
15:14
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