
Source
High
Band
Operation
The
high
band
frequency
range
is
16
MHz
to
3.O
GHz
or
16
MHz
to
6.0
GHz
with
Option
006.
These
frequencies
are
generated
in
subsw
eeps
b
y
phase-lo c
king
the
A3
source
signal
to
harmonic
m
ultiples
of
the
fractional-N
V
CO.
The
high
band
subsw
eep
sequence,
illustrated
in
Figure
12-5 ,
follo ws
these
steps:
1.
A
signal
(HI
OUT)
is
generated
b
y
the
fractional-NV
CO.
The
V
CO
in
the
A14
fractional-N
assem
bly
generates
a
CW
or
sw
ept
signal
in
the
range
of
30
to
60
MHz.
This
signal
is
syn
thesized
and
phase
lo
c
k
ed
to
a
100
kHz
reference
signal
from
the
A12
reference
assem
bly
.
The
signal
from
the
fractional-N
V
CO
is
divided
b
y
1
or
2,
and
go
es
to
the
pulse
generator.
2.
A
com
b
of
harmonics
(1st
LO)
is
pro duced
in
the
A7
pulse
generator.
The
divided
do
wn
signal
from
the
fractional-N
V
CO
driv
es
a
step
reco
v
ery
dio
de
(SRD)
in
the
A7
pulse
generator
assem
bly
.
The
SRD
m
ultiplies
the
fundamen
tal
signal
from
the
fractional-N
in
to
a
com
b
of
harmonic
frequencies.
The
harmonics
are
used
as
the
1st
LO
(lo
cal
oscillator)
signal
to
the
samplers.
One
of
the
harmonic
signals
is
1
MHz
b elow
the
start
signal
set
from
the
fron
t
panel.
3.
The
A3
source
is
pretuned.
The
source
RF
OUT
is
fed
to
the
A4
sampler.
The
pretune
D
A
C
in
the
A11
phase
lo
c
k
assem
bly
sets
the
A3
source
to
a
rst
appro
ximation
frequency
(1
to
6
MHz
higher
than
the
start
frequency).
This
signal
(RF
OUT)
go
es
to
the
A4
R
input
sampler/mixer
assem
bly
.
4.
The
syn
thesizer
signal
and
the
source
signal
are
com
bined
b
y
the
sampler.
A
dierence
frequency
is
generated.
In
the
A4
sampler,
the
1st
LO
signal
from
the
pulse
generator
is
com
bined
with
the
RF
OUT
signal.
The
IF
(intermediate
frequency)
pro duced
is
a
rst
appro
ximation
of
1
MHz.
This
signal
(1st
IF)
is
routed
bac
k
to
the
A11
phase
lo
c
k
assem
bly
.
DRAFT
3/21/106
15:14
Theory
of
Operation
12-13
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