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CHAPTER
1
G_E_NER AL_
D_E_S_C
ILLPJJiiy
INTRODUCTION
1
.1
The 9081 and 9082
are synthesized
signal
generators designed primarily
for
the
testing
of radio
communications equipment.
Although
providing
the precision of
a
synthesizer system
locked
to
a high-stability
frequency standard they
retain the
versatility
of
analogue-type
tuning.
RF
TUNING
1
.2
A
major
feature of the instruments
is
their
'single-knob' tuning allied
to
a
channelized
mode
of operation.
This
enables
the instruments
to
be tuned
in
steps
according
to
the
channel spacing
required.
The
r.f.
tuning automatically
locks
into
the
centre
frequency
of the particular
channel.
Selection of the
HOLD
position
on
the front
panel switch then electronically disconnects the
spin
wheel.
1
.3
A
fine
tune
facility
provides
for
interpolation
between
channels,
and
this
can
also
be
carried
out by
an
external slow
sweep
voltage
if
desired.
The
carrier
frequency
is
displayed on an 8-digit
LED
readout
in
which
the resolution
is
varied
to
suit
the particular
tuning
mode
(Fast,
Slow
or
Hold)
in
use.
1
.4
The
Channel Spacing
switch provides ten
different
frequency
spacings
which conform
to
the internationally
agreed
requirements
of different authorities.
A
continuous
tuning
facility
(Z\f)
is
provided
in
which
the
frequency increments
are
reduced
to
a
minimum
value
when
using
SLOW
tune
mode.
RF
OUTPUT
1
.5
Automatic
levelling
maintains
the
output typically within
±0.5dB
over
the entire
frequency range.
A
switched attenuator
and
vernier control provide an output
range from
-130dBm
to
+3dBm,
(+13dBm
for
models
9081H
and 9082H),
calibrated
in
both
dBm
and
voltage
units.
An
output switch provides a
multiply-by-two
facility
which
permits
a doubling
of the
normal output
levels
in
CW, FM
and
Phase
Modulation modes.
MODULATION
FACILITIES
1.6
AM, FM
and
Phase
Modulation
(0M)
facilities
are provided.
Three
spot
modulation
frequencies
(400Hz,
1kHz and
5kHz)
are available
from
an
internal oscillator.
External
modulation can
also
be
used, the
maximum
frequencies permitted being
100kHz
for
FM, 5kHz
for
$M,
100kHz
for
AM
on
Model
9081
and
20kHz
for
AM
on
Model
9082.
1-1
.
9081 and 9082 Vol
.
2
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