HP 8508A - Page 39

Operation
Measurement details
1,
Connect
the
equipment
as
shown
below.
Press
[PRESET]
to
get
the
instrument
to
a
known
state,
then
[B]
to
measure
the
filter
output.
Le
a
To
frequency
counter
(optional)
HP8508A
"A"
Input
(50
ohms)
Power Splitter
Low Pass Filter
HP8508A "B" Input
(50 ohms)
Figure 3-9. Test Setup
2.
Select
[METER
SELECT]
DISP2
to
activate
the
meter
on
the
B
voltage,
then
tune
the
source
frequency
for
a
maximum
to
set
the
source
in
the
filter
passband.
Tuning
is
achieved
using
the
trend
indicators
(LED’s).
An
increasing
level
is
highlighted
by
the
top
LED
being
illuminated.
A
decreasing
level
is
highlighted
by
the
bottom
LED
being
illuminated.
A
null
is
indicated
by
both
LEDs
being
extinguished.
oooolooo
Figure
3-10.
Meter
Display
3.
Press
[B/A
MAG]
to
measure
the
amplitude
ratio,
and
select
[DISPLAY]
dB
to
display
a
log
ratio.
4.
Press
[SHIFT]
then
[SAVE
REF]
to
store
the
current
reading,
zero
the
magnitude
reading
and
refer
future
measurements
to
the
filter
passband.
3-15