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1.
Meter
indicates
voltage
level,
distortion
in
dB
or
percent,
or
VU
(volume
units)
in
dB.
2.
Filters
permit the user
to
eliminate
unwanted
frequencies
and
noise
from
the
measurement. The
filters
include a
400
Hz
high-pass
filter
which
is
normally used
to
reject
power-line
related noise, a
30 kHz
low-pass
filter
for
use
in
making
"proof
of
performance"
measurements
at
AM
broadcast
stations,
and
an
80
kHz low-pass
filter
to
eliminate high
frequency
noise.
3
DISTORTION
RANGE
control selects the gain
of
the
distortion
measurement
circuits to
the
proper
sensitivity for
measuring
the applied
signal.
4.
INPUT
RANGE
control
sets
the
input
range
of
the
distortion
and meter
circuits
to
the
proper
sensitivity
for
measuring
the applied
signal.
5.
Input
Range
indicators indicate the direction the
INPUT
RANGE
control
must
be turned
to
select
the correct
range
for
the signal applied.
6.
FREQUENCY
controls
determine
the
fundamental
reiection
frequency
of
the analyzer
and
the output
frequency
of
the
oscillator.
Figure
3-1.
Control.
Connector and
Indicator
Descriptions.
7.
Frequency
indicators
indicate
the
direction
the
FREQUENCY
controls
must
be turned
to
bring the analyzer
circuits
within
"pull-in
range"
of
the
fundamental
frequency
of
the applied
signal.
This applies only
when
using
an
external
signal
source.
8.
OSCILLATOR
OUTPUT
terminals.
Output impedance
is
600
O.
9.
OSCILLATOR LEVEL
control
changes
the output
level
in
10
dB
V
steps
from
3
mV
rms
to
3
V
rms
into
600
n.
The
LEVEL
control also
includes an
OFF
position
which
disconnects
the
oscillator
output
and
terminates
the
output terminals with
a
600
0
resistive
load.
10.
Oscillator
LEVEL
Vernier permits the output
level to
be
varied
below
the
level
selected by the
LEVEL
control.
This
makes
the
oscillator
output
level
continuously
variable
from
less
than
1
mV
to
greater-than 3
rms
into
600
fl.
1
1
.
OSCILLATOR FREQUENCY
VERNIER.
Frequency
range
of
the vernier
permits
the
oscillator
output frequency
to
be
in-
creased
above
the
frequency
selected
by
the
FREQUENCY
controls.
Frequency
range
of
the
vernier
is
approximately equal
to
one
step
on
the center
frequency
control.
3-0
12.
DISTORTION
ANALY2ER
(and
voltmeter)
terminals
provide
connection
for
analyzer
and
voltmeter
inputs.
1
3.
ANALYZER
(and voltmeter)
INPUT/GND SELECT
switch
selects Distortion
ANalyzer
input
with
either
circuit
or
chassis
ground
or
AM
DETECTOR
input
with chassis
ground
only.
14
.
AM
DETECTOR
input terminal provides
connection
for
amplitude
modulated RF
signals.
1
5.
Ground
Terminal provides connection
to
339A
Chassis.
1
6.
METER RESPONSE
switch
selects
normal
or
VU
(volume
units)
meter
response.
1
7.
RELATIVE
ADJUST
permits
the user
to
set a
convenient
reference
level
on
the
meter
when
using the voltmeter
RELative
LEVEL FUNCTION.
18.
FUNCTION
control
selects
analyzer
or
voltmeter
functions.
19.
MONITOR
terminals permit the
signal
applied
to
the
meter
circuitry to
be monitored.
The
MONITOR
output
is
1
V
rms
for a full-scale
meter
deflection.
With an
audio
signal
applied
to
the
DISTORTION
ANALYZER
input
the
MONITOR
output
will
be:
DISTORTION FUNCTION
-
Distortion
products
of
the applied
signal after the
fundamental has been removed.
INPUT LEVEL
-
And
RELative
LEVEL FUNCTIONS.
Scaled
presentation
of
the applied
signal.
With
a
modulated RF
signal applied
to
the
AM
DETECTOR
input
the
MONITOR
output
will
provide:
DISTORTION FUNCTION
-
Scaled
presentation
of
the
demodulated
input signal
with the
fundamental removed.
INPUT LEVEL
and
RELative
LEVEL FUNCTIONS
-
Scaled
presentation
of
the
demodulated
input
signal.
The
MONITOR
terminals
are
disabled
when
using
the
OSCillator
LEVEL FUNCTION.
20.
LINE
switch
applies ac
power
to
the instrument.
21
.
AC
LINE connector provides connection
for
ac power.
22.
AC VOLTAGE SELECTOR
switches setthe instrument
to
operate from
100
V,
1
20
V,
220
V, or
240
V
ac
power
source.
23.
FUSE
protects the
instrument
circuits
from
excessive
current.
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