Advertisement
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
Advertisement
