HP 8340b User Manual

Type
B,
caused
by
the
20/30
mixing
with
the
Ith
harmonic
of
10
MHz
in
the
reference
phase detector.
Type
B,
crossing frequency
whenever:
10*Flf/10
=
I
or
Fit
=
I
where
FIf
=
20/30
loop
output frequency
ORDER
of the
spur
=
10
Type
C1
and
C3
are
both
due
to the
20/30
output
and
its
harmonics
mixing
with
the
M/N
VCO.
Given:
Fmn
=
M/N
Output frequency
=
200
-
10*M/N
(MHz)
Fit
=
20/30
Output
Frequency
=
20
to
30
(MHz)
M,
N
are
the
divider
numbers
for the
M/N
Loop
I,
J,
K
are
integers
Type C1, crossing frequency
when:
Fmn/Flf
=
1/2
or
Fit
=
20
•
(20-M/N)/!
ORDER
of Spur
=
1/2
This
type
of
spur
can
be
caused
by
several
factors,
such
as
the
A48
sampler
assembly
70
MHz
low
pass
filter,
or
the
A46
low
pass
filter
assembly.
Type
C3,
crossing frequency when:
Fmn/Flf
=
20*1
±
J/(2*K)
or
Fit
=
20
•
K
•
(20-M/N)/20*1
±
J
ORDER
of
spur
=
20*1
±
J/(2*K)
This
type
is
caused
by
the
Ith
harmonic
of
the
PLL1
VCO
sampled
by
the
Kth
harmonic
of
the
M/N
VCO.
For
any
CW
frequency,
selecting
the
appropriate
SHIFT
functions
displays
the M/N
frequency,
20/30
frequency,
and
YO
frequency.
A
synthesized
spurious
response
must
be
a
function
of
these
signals.
Any coupling
from
one
signal
path into
another
can
result
in
a
spurious response
(i.e.,
loose
connec¬
tors,
poor
shielding, cable
routing,
etc.).
Low
band
spurs
are
caused
by
mixing
products
in
the
low
band
mixer.
Because
these
are
not
crossing
spurs
(they
are
not
YO
loop
sidebands),
they
are
added
to
the
output
as
part
of the
down-conversion
process.
The
YO
output
should
mix
with
the
3.7
GHz oscillator
output
and
produce
a
single
mixer
output
at
Fyo
—
3.7
GHz,
but,
harmonics
of
both
oscillators
are
present,
or are
generated
in
the
mixer.
These
mix
to
form
spurs
on
the
output.
Troubleshooting synthesized
spurs.
1.
To
eliminate
various
RF
paths,
determine the
YO
frequency
at which the
spur occurs
and
select
a
CW
frequency
in
both
low
band
and
band
1
that
uses
that
YO
frequency.
If
the
spur
occurs
only
in
low
band,
troubleshoot
the
low
band
RF
path.
If
the
spur
occurs
only
in
band
1,
troubleshoot the
high
band
RF
path.
2.
Using
the
equations
above,
change
the
CW
frequency
so
that the
M/N
output remains
constant
and
only
the
20/30
output
changes.
A-48
Assembly-Level
Service
Overall
Instrument
Troubleshooting
HP 8340B/41B

HP 8340b Specifications

General

Brand	HP
Model	8340b
Category	Inverter
Language	English