HP 8508A - Page 35

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:
Operation
Where
a
function
is
accessed
using
the
alternative
function
of
a
key,
the
function
is
described
by
showing
[SHIFT]
then
the
function
name
(which
appears
in
blue
on
the
front
panel)
-
for
example,
to
obtain
[SHIFT
REF!
this
would
be
described
as
press
[SHIFT]
then
[SAVE
REF].
1. PRESET
Before
beginning
a
new
measurement,
press
[PRESET]
to
return
the
HP
8508A
to
a
known
state.
The
following
list
shows
the
preset
condition:
=
MEASUREMENTS
FUNCTIONS
MEASUREMENTS
A...
-
-
-OW
REF
sce.
do)
ES
es
OFF
DISPLAY
1...
226.
UNITS
FORMAT
.
2
6
oe
2 +
©
«OFF
REFL
MEAS.
»
22-2
-
+
OFF
DISPLAYS
REF
SELECT
....->
OFF
METER
SELECT
.....-
OFF
POWER
MEAS.
2.2.
ee
es
OFF
LOCK
RANGE
..----
AUTO
*
SYSTEM
IMPD
.
. .
.
-
-
-OFF
MAG
RANGE
1...
--
>
AUTO
HOLD
VALUE
.....
-
-OFF
DISPLAY
7
...----
mv
DISPLAY2
....-
blank
2.
UNLOCKED
INDICATOR
Check
that
there
is
no
input
to
the
probes.
With
no
input
signal,
the
A
UNLOCKED
indicator
should
be
ON
and
DISPLAY
1
(the
left
display)
should
indicate
under-range
(
--.-).
NOTE:
If
there
are
high
level
radiated
signals
present,
DISPLAY
1
may
give
a
reading.
This
reading
is
caused
by
the
un-terminated
probe
acting
as
an
antenna.
It
will
not
affect
the
instrument’s
ability
to
make
measurements
on
your
circuit.
:
3,
SINGLE-CHANNEL
MEASUREMENT
-
CHANNEL
A
The
A
probe
is
used
as
a
reference
by
the
HP
8508A,
and
must
be
connected
for
the
instrument
to
function.
The
signal
level
should
be
in
the
range
300uV
to
1V.
Connect
the
A
probe
to
the
source
and
turn
on
the
output.
The
A
UNLOCKED
indicator
should
go
OFF
and
DISPLAY
1
should
show
the
source
output
voltage.
4. VOLTAGE UNITS
Select
[DISPLAY]
dB
to
have
the
HP
8508A
compute
and
display
the
voltage
in
dBuV.
5.
POWER
MEASUREMENT
Press
[POWER
MEAS]
to
display
power
in
dBm
in
a
50ohm
system.
The
conversion
of
voltage
to
power
uses
the
value
set
with
the
[SYSTEM
IMPD]
key,
the
default
value
being
50
ohms.
£4
Press
[POWER
MEAS]
again
to
return
to
the
voltage
measurement
mode.
|
6.
SINGLE-CHANNEL
MEASUREMENT
-
B
CHANNEL
Most
measurements
with
the
HP
8508A
will
be
done
using
the
B
probe,
leaving
the
A
probe
in
place
as
a
reference.
The
B
channel
is
much
more
sensitive
since
the
A
channel
already
provides
the
signal
to
which
the
instrument
is
locked.
Press
[B]
to
display
the
B
input
voltage
in
Display
2.
(The
A
reading
remains
in
Display
1
unless
you
turn
it
off
by
pressing
the
[A]
key.
The
A
probe
must
still
be
connected
in
order
to
keep
the
instrument
locked.)
Display
2
shows
E1089
3-11