HP 339A - Page 18

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.