HP 8753D - Page 381

Receiver
and Source
Requirements.
Refer to
Chapter
7,
\Specications
and
Measurement
Uncertainties
."
IF
Input: R
always;
and
port
1
or
port
2
for
a
ratio
measurement.
Display
Annotations.
The
analyzer
shows
the
annotation
ofs
when
the
frequency
oset
mode
is
on. The
annotation
of?
indicates
that
the
source
frequency
is
approximately
10
MHz
away
from
the
sum
of
the
IF
and
LO
frequencies
that
you
requested.
This
is
most likely
caused by
the
LO
frequency
being
outside
the
0
1
to
+5
MHz
accuracy
requirement.
Error
Message
.
If
you
connect
your
test
device
before
you
switch
on
the
frequency
oset
function,
the
error
message
PHASE
LOCK
CAL
FAILED
appears
on
the
screen.
This
is
normal,
and
will
disappear
when
you
press
the
NN
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
NN
NN
NN
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
N
NN
NN
FREQ
OFFS
on
OFF
softkey
.
Spurious
Signal
Passband
Frequencies.
Unwanted mixing
products (or
spurious
LO
signals)
at
specic
frequencies can
cause measurement
inaccuracy,
because of
the
characteristics
of
a
sampler
. These
specic frequencies
can be
calculated. Y
ou
can
reduce
unwanted
mixing
products
going
to the
sampler by
inserting a
low pass
lter
at
your
test
device's
IF
output.
6-114 Application and Operation Concepts