HP 339A - Page 22

Section
III
d.
Set
the
FILTER
switches
off
(out).
e.
Connect
the
signal
to be
measured
to
the
DISTORTION
ANALYZER
input
connectors.
f.
Adjust
the
INPUT
RANGE
control
in
the
direction
indicated
by
the
INPUT
RANGE
indicator
lights
until
an
“on-scale”
meter
indication,
as
near
full-scale
as
possible,
is
obtained.
(Both
indicator
lights
will be
off.)
3-26.
RELATIVE
LEVEL
OPERATION.
3-27. The
RELATIVE
LEVEL
FUNCTION
permits
the
user
to
adjust
the
meter
gain
of
the
339A to
set a
convenient
reference
level on
the
meter
(usually 0
dB).
This
function
is
convenient
for
measuring
signal
levels
relative
to
a
reference
level.
To
use the
RELative
LEVEL
FUNCTION,
proceed
as
follows:
a.
Set
the
FUNCTION
switch to
RELative
LEVEL.
b.
Set
the
METER
RESPONSE
switch
to
NORMal.
c.
Set
the
INPUT,/
G ND
SELECT
switch
to
Distortion
ANalyzer.
(Low
input
connected
to
chassis
ground
or
floating
as
desired.)
d.
Set
the
FILTER
switches
off (out).
e.
Connect
the
reference
signal
to
the
DISTORTION
ANALYZER
input
connectors.
f.
Adjust
the
INPUT
RANGE
control
in
the
direction
indicated
by
the
INPUT
RANGE
indicator
lights
until
an
“on-scale"
meter
indication
is
obtained.
g.
Use
the
RELATIVE
ADJUST
control
to
set
the
meter
to
the
desired
reference
level.
h.
Measure
other
input
levels
relative
to
the
reference
just
established.
Do
not
change
the
RELATIVE
ADJUST
control.
3-28.
Oscillator
Level
Operation.
3-29.
In
the
OSCillator
LEVEL
function,
the
analyzer
inputs and
the
MONITOR
output
is
disabled
and
the
339 A
meter
circuit is
used
to
monitor
the
output
level of
the
oscillator.
To
measure
the
oscillator
output
level,
perform
the
following:
a.
Set
the
FUNCTION
switch
to
OSCillator
LEVEL.
b.
Set
the
METER
RESPONSE
switch to
NOR-
MAL.
c.
Set the
FILTER
switches
to
off
(out).
d.
Adjust
the
INPUT
RANGE
control
as
necessary
to
obtain an
“on-scale”
meter
indication
as
near
full-scale
as
possible.
Model 339A
e. The
meter
reading,
relative
to
the meter
range
selected by
the
INPUT RANGE
control indicates
the
output
level of the
oscillator.
3-30.
To adjust
the
oscillator
output
to
a
particular level,
perform
the
following:
a.
Set
the
FUNCTION
switch to
OSCillator LEVEL.
b.
Set the
METER
RESPONSE
switch to
NOR-
MAL.
c. Set
the
FILTER
switches
to off
(out).
d.
Set
the
INPUT
RANGE
control to
the
appropriate
meter
range
for
the
oscillator
output
level
desired.
e.
Adjust
the
OSCILLATOR
LEVEL
control and
LEVEL
vernier until
the
desired
output
level is
indicated
on
the
meter.
3-31.
VU
MEASUREMENTS.
3-32. To
measure
volume
units
(VU), the
meter
response
characteristics
are
changed
to
those of a
VU meter by
switching
the
METER
RESPONSE
switch to
the
VU
position.
VU
measurements
can
be
made in
the INPUT
LEVEL
or
RELative
LEVEL
functions.
Measurement
results
are
normally
read
on the
dBm 600
ohms
meter
scale.
Operating
procedures
for
making
VU
measure-
ments
are
the
same as
those
listed for
Normal
Voltmeter
Operation
or
Relative
Level
Operation.
3-33.
Filters.
3-34. Three 60
dB/decade
active filters,
one
high-pass
and
two
low-pass,
are
included
to
permit the user
to
eliminate
unwanted
frequencies and
noise.
These
filters
may
be
selected
individually
or in any
combination by
means
of the
front
panel
FILTER
switch. The
frequencies
labeled
beside
each
switch
indicate the 3 dB
“roll-off’
point of
that
particular
filter.
3-35. Input
Ground
Select.
3-36.
The
ANALYZER
Low
input reference is
selected
by
the
INPUT/
GND
SELECT
switch.
When using
the
DISTORTION
ANALYZER
input,
the
input
low is
connected to
chassis
ground
(center
switch
position)
or
allowed
to
float
(right
switch
position). When using
the
AM
DETECTOR
input (left
switch
position)
the
input
low is
connected
to
chassis
ground.
To
prevent
damage
to
the
analzyer input
circuits,
do
not float
the
low input
terminal
more
than
±30
V
dc
relative
to
earth ground.
3-4