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HP
5343A/
5344A
SWP lNTFC
A
SWP lNTFC
"T"
Con
nector
Figure 4. Co
nn
ect ions
fo
r
counting
sweeper
markers
using sweeper int erfa
ce.
Suppose you analyze the
display of
the
HP 8756A in
the LK
/R
measurement we
have set
up,
and see
an
anomaly
in the trace.
You
want
to
determine
the
frequency
of
the
anomaly.
To
use
the
sweeper
interface
function to do this
,
you
would
follow these
instructions
:
1.
Connect
the
sweeper
interface
cables as
shown
in figure
4
.
2
.
Make sure
that the HP
53445 is
not
trying to
lock
.
Both
[MANUAL
LOCK)
and
[AUTO LOCK)
keys
should be off.
3
.
If
you
are
in
the NORM locking
mode,
activate
the
sweeper
interface
function
by pressing
[SWP
M)
on
the
HP
5343A.
This
function
is
activated
automatically
in
SUBHMNC lock
.
Relock
the
system by
pressing
[MANUAL LOCK
).
4. To activate marker 1, press
[M
I]
on
the
HP 8350B, and use
the
knob
to
position the marker
to the
anomaly
on the trace
.
Then
press
[
SHIFT]
[M2
)
on the
HP
8350B to cause the
counter to count the
marker
instead
of
the
lock frequency
.
The counter
will
count the active
marker
,
indicated
by
a
blinking
light in the corresponding marker
key of the
HP
8350B.
The
active
marker
can be
anyone
of the five
markers
,
MI-M5.
In the
example
we
activated
marker
one
(MI)
,
and
moved it
t
o
the anomaly
.
We
can
now
read
the frequency of interest from
the counter
.
The
system will stop
counting
when
you
press
[
SHIFT]
[M3
)
on the HP 8350B
.
Using
the
[MANUAL LOCK
)
key
on
the
HP 5344A,
unlock and then
relock
the source
,
and
the
counter
will once again
display the start frequency.
QUESTIONS
/
ANSWERS
Q:
In
LK
/
R,
counting
the
sweeper' s
markers with the HP 5343A takes a long
time
and
the
knob that adjusts
the
7
A
:
Q:
A:
Q:
A:
marker
frequency
on the HP
8350B seems
slow in
responding.
Is
there an
y
thing
I
can do about
this?
When the HP 53445 comes to a marker
frequency, it stops the sweeper
from
sweeping,
and counts the frequency
.
This
measurement
takes
time
.
High
resolution measurements take
more time
than
low resolution
measurements,
so
the counting
can be speeded up
if
lower
resolution
is used
.
Use the shift key
and the blue resolution settings
o
n
the
counter.
Make sure
that you are
not
trying
to
lock
when you
enter anything
on the counter
.
The counter's keys
are
disabled
if the [
MANUAL
LOC
K)
o
r
[AUTO LOCK)
keys are active
.
Why
does
the
counter
reading
jump
around so
much while
counting marker
frequencies?
The sweeper is
sweeping
unlocked
over a
wide
band
,
and
because
of
its
limitations
in
residual FM
,
resolu-
tions
greater
than
about
100
kHz
produce
unrealistically
precise
counter measurements
.
How
can
I count the
stop frequency?
The HP
5344S
manual
says
that I can
count the stop frequency
by
preSSing
[STOP
)
[SHIFT)
[M2)
on
the HP
8350B
.
But this does not work.
Because the 8756
System
Interface
is
operating
,
this
particular
function
will be
disabled.
To
count the stop
frequency
set the
active
marker to the
same
frequency
as the HP
8350B stop
frequency and press
[SHIFT
]
[M2
).
SOBBARMONIC/OFFSET
LOCKING
The instructions so
far
have
detailed
operation
in
no
r
mal
locking
mode.
This
section
contains
a
description
of
subharmonic/offset
locking,
its advantages
and
disadvantages,
and instructions on how
to use it.
The MODE
switch on the rear
panel
of
the
HP 5344A
determines
whether
the
HP
5344S
will
operate
in
normal
(NORM)
or
subhar-
mon
i
c
/o
ffset
(
SUBHMNC
)
locking.
There
is a
complete description
of
these
modes in
the
HP
53448 Operating
and
Service Manual; a brief
description
is
provided
here
.
In
the
normal mode,
the
counter
samples
the
plug-
in's
RF
ootput directly, and no offsets or
harmonics
are
used by
the
HP 53448.
Figure
3
shows
a
basic
transmission
measurement
configuration in
the normal
locking mode.
Note that
a power splitter or coupler is
required
to
sample
the
RF
output,
and
external
27.8 kHz modulation
is required so
that
the
counter
samples an
unmodulated
signal
.
If
the sweeper
plug-in
has a
re
ar
panel
AUX OUTPUT
(H
P 83590
series and HP 86290
series
RF
plug
-
ins)
,
then
the
HP
53445
subharmonic
/
offset locking mode can be used
(see figure 5).
In this mode
the counter
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