HP 8340b - Page 475

3.
Determine
the
order
of
the
spur
(i.e.
ratio
of
YO
frequency change
to
spur
frequency
change).
If
the
spur
is
a
crossing
spur,
at
some
point
the
spur
will
be
on
top
of
the
YO
frequency
and at
some
point
(50
kHz
away
from
the
YO
frequency)
the
spur
amplitude
will
decrease.
If
the
spur
is
a
crossing
spur,
refer
to the
appropriate
spur
family
type
above.
4.
To determine
which internal
frequency
source(s)
is
generating
the
spur:
a.
Change
the
CW
frequency
while
monitoring
the
SHIFT
function
diagnostics,
looking
for
a
sudden change
in
spur frequency
and/or amplitude.
For
example,
press
[SHIFT]
[M1],
then
change
the
CW
frequency.
Look
for
a
correlation
between
any
sudden
change
in
spur
fre¬
quency
and/or
amplitude
with
a
change
in
M/N
output
frequency or
20/30
output
frequency.
If
a
sudden
change
in
the
spur occurs
at
the
same
time
the M/N
or
20/30
makes
a
large
change,
the
internal
frequency
source
that
changed
is
probably
one
of
the
signals
generating
the
spur.
b.
If
you suspect
the
20/30,
press
[SHIFT]
[M3]
to
display
the
PLL2 VCO
frequency
and
PLL3
up
converter
frequency
and
repeat
the
above
test.
NOTE:
For
more
information
on
the
diagnostic
modes,
refer
to
the
Frequency
Range
and
CW
Mode
Accuracy
test
in
Section
IV,
Performance
Tests.
I/O CONNECTORS
(19)
To determine
source
or
destination
of
input
or
output
connector
signals,
and
for
troubleshooting
information,
refer
to
the
front
panel
—
rear
panel functional
group.
REMOTE
OPERATION
(20)
Section
IV, Performance
Tests, contains an
HP-IB
Operation
Verification
Program
Listing.
This
pro¬
gram
verifies
the
ability
of the
instrument
to
respond
to
a
remote
input (complete
HP-IB
handshake).
The
program
tests each
data
bit
and
reads
the
instrument
status
bytes.
If
the
instrument
exhibits
a
problem
while
running
this
test,
refer
to
the
controller
section
functional
group.
If
you
do
not
see
a
problem
while
running
this
program,
and
the
instrument
does not respond
properly
to
other
remote
commands,
refer to
the
computer
documentation
to
read
the
computer
HP-IB
I/O
card
status.
By
outputting the
I/O
card
status,
the
source
of
the
problem can
be
determined.
HP
8340B/41B
Assembly-Level
Service
Overall
Instrument Troubleshooting
A-49