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Model
339A
Section
I
SECTION
I
GENERAL INFORMATION
1-1.
INTRODUCTION.
1-2,
This
Operating
and
Service
Manual
contains
information necessary
to
install,
operate,
test,
adjust,
and
service
the
Hewlett-Packard
Model 339A
Distortion
Measurement
Set.
1
-3
This
section of the
manual
contains
the
performance
specifications
and
general
operating
characteristics
of
the
Model
339 A.
Also
listed
are available options
and
accessories,
and
instrument
and manual
identification
information.
1-4.
SPECiFiCATiONS.
1-5.
Operating
Specifications for the
Model 339A
are
listed
in
Table
1-1.
These
specifications
are
the
performance standards
or
limits
against
which
the
instrument
is
tested.
Table
1-2
lists
general
operating
characteristics
of the instrument.
These
characteristics
are
not
specifications
but
are
typical
operating
characteristics
included
as
additional information
for the
user.
1-6.
INSTRUMENT
AND MANUAL
IDENTIFI-
CATION.
1-7.
Instrument
identification
by
serial
number
is
located
on
the rear panel.
Hewlett-Packard
uses a
two-
section
serial
number
consisting of a
four-digit prefix
and
a
five-digit
suffix
separated
by
a
letter
designating the
country
in
which
the
instrument
was
manufactured.
(
A
=
U.S.A.;
G
=
West Germany;
J
=
Japan;
U
=
United
Kingdom.) The
prefix
is
the
same
for
all
identical
instruments
and
changes only
when
a
major
instrument
change
is
made.
The
suffix,
however,
is
assigned
sequentially
and
is
unique
to
each
instrument.
1-8.
This
manual
applies to
instruments with
serial
numbers
indicated
on
the
title
page.
If
changes have been
made
in
the
instrument
since
the
manual was
printed,
a
yellow
"Manual
Changes" supplement
supplied with
the
manual
will
define these
changes and
explain
how
to
adapt
the
manual
to the
newer
instruments.
In
addition,
backdating information contained
in
Section VII
adapts
the
manual
to
instruments with
serial
numbers
lower
than
those
listed
on
the
title
page.
1-9.
Part
numbers
for the
manual
and
the
microfiche
copy
of the
manual
are also
listed
on
the
title
page.
1-10.
DESCRIPTION.
1-11.
The Model
339A
Distortion
Measurement
Set
combines
a
low
distortion signal source, a
high
resolu-
tion distortion
analyzer,
an
rms
responding
voltmeter
and
a
VU
(volume
units)
meter
in
one
unit.
1-12.
The
signal
source used
in
the
Model 339A
is
a
"bridged-T"
oscillator
which
provides a
low
distortion
sine-wave
signal
from
10
Hz
to
110
kHz.
The
output
amplitude
is
variable
from
1
mV
rms
to 3
V
rms
into a
600
ohm
load
and
is
maintained by an amplitude
control
circuit
which minimizes amplitude
variations
even
when
fraonan
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1-13.
The
distortion
analyzer
section
of the
339A
contains
a
tracking
notch
filter
which
is
tuned
to the
oscillator
frequency.
The
analyzer
measures
total
harmonic
distortion
(THD)
from
100%
full-scale
to
.01%
full-scale in
nine
ranges
and
features
both automatic
"Set
Level"
and automatic
"Nulling"
to
greatly simplify
operation.
The Auto
Set Level feature automatically
sets
the reference
level
over
a
10
dB
range.
If
the input signal
is
outside
this
range, a
LED
on
the front
panel
indicates
whether
the
INPUT
RANGE
control
setting
must
be
increased or
decreased
to
be within the
"pull-in"
range
of
the
Auto
Set Level.
The Auto
Nulling
feature
is
fully
automatic
when
the
339
A
internal oscillator
is
used
as the
signal source.
When
an
external
oscillator
is
used
as the
signal source,
an
LED
on
the front
panel
indicates
which
direction the
FREQUENCY
controls
must
be
set
to
be
within
the
Auto
Nulling
range. Distortion
characteristics
of the input
signal
can
be
monitored
at
the
MONITOR
OUTPUT
terminals with external
equipment
(oscillo-
scope, voltmeter,
spectrum
analyzer,
etc.)
to
provide
additional analysis of the distortion products.
1-14.
The Model
339
A
is
equippped
with
an amplitude
modulation
(AM)
detector
which
has
a
frequency
response
from
550
kHz
to
1.6
MHz.
The
AM
detector
permits
the
measurement
of
modulation
distortion.
1-15.
The 339A
contains
three active
filters,
one
high-
pass
and two
low-pass,
which
enables
the
user
to
eliminate
unwanted
frequencies
and
noise
to
permit
higher resolution
measurements.
1-16.
The
ac
voltmeter
section
of
the
339A
measures
the
rms
value of input voltage
from
1
mV
full-scale
to
300
V
full-scale
in
twelve ranges.
In the
VU
meter
mode,
the
1-1
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