HP 8340b User Manual

20-30
LOOP
CHARACTERISTICS
20-30
Loop
assemblies
form
a
frequency
synthesizer
with
the
following
performance characteristics:
•
Fixed
frequency
output
range
from
20
to
30
MHz
(required
by
the
YO loop)
•
Analog
sweep
widths
between
100
Hz and
5
MHz
•
CW
frequency
resolution
as
low
as
1
Hz
The 20-30
Loops contain three
phase
locked
loops
that
are
used
in
three
different
configurations
to
achieve
the
required
CW
resolution and
sweep
range.
The
loops
are
referred
to
as
PLL1,
PLL2
and
PLL3.
PLL2
is
used
in all
modes
of
operation.
PLL1
and
PLL3
are
only
used
during
narrow
sweeps
or
in
CW
mode,
and
are
designed
to
be
phase-locked
to
the
output
of
PLL2.
The
purpose
of
PLL3
and
PLL1
are
explained
below.
PLL2
THEORY
OF
OPERATION
PLL2
Assemblies
•
A40 PLL2
VCO
(voltage
controlled
oscillator)
•
A41
PLL2
phase
detector
•
A42
PLL2
divider
•
A43
PLL2
discriminator
PLL2 VCO
The
PLL2
phase
lock
loop
is
the
primary phase
lock
loop
in
the
20-30
synthesizer,
and
is
used
in
all
modes
of
operation.
Refer
to
Figure
C-1.
PLL2
phase-locks
to
a
10
MHz
signal
from
the
reference
loop.
The 20-30
loops
must
sweep
the
YO
directly
during
YO
sweeps
of
100
Hz
to
5
Mhz,
but
the
20-30
loops
output
has
to
be
divided
down
in
steps
to allow
this.
The
three
divided
outputs each
cover
a
portion
of
the
100
Hz
to
5
MHz
range:
YO
Sweep
width
is
between
100
Hz
and
5
kHz.
The
75
to
150
MHz
VCO
signal
is
divided
by 500
to
provide
the
necessary resolution,
However,
the
output signal
can
not
be
used
directly
by
the
YO
loop.
The
PLL3
and
PLL1
loops
convert
this
high-resolution, low-frequency
signal
to
a
frequency
range
that
is
usable
by
the
YO
loop
(20
to
30
MHz).
YO
Sweep
width
is
Between
>5
kHz
and
100
kHz.
The
75
to
150
MHz
VCO
signal
is
divided
by
25
(divided
by
five
twice).
The
output
is 3
to
6
MHz,
and
can
not
be
used
directly
by
the
YO
loop.
The
PLL3
and
PLL1
loops
convert
this
high-resolution,
low-frequency
signal
to
a
frequency range
that
is
usable
by
the
YO
loop
(20
to
30
MHz).
YO
Sweep
width
is
Between
>100
kHz
and
5
MHz.
The
75
to
150
MHz
VCO
signal
is
divided
by
five
to
produce
a
15
to
30
MHz
output.
This
signal
is
sent
directly
to
the
YO
loop.
HP
8340B/41B
20-30
Loops
Overall
Theory
of
Operation
C-3

HP 8340b Specifications

General

Brand	HP
Model	8340b
Category	Inverter
Language	English