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Model
339A
Section VIII
8-46.
Output
Buffer
and
Attenuator.
The
oscillator
signal
is
applied
to
the
output
buffer amplifier
(A1U3)
through theoutput
LEVEL
VERNIERcontrol. The
level
vernier varies the
output
level
of the buffer amplifier
from
approximately
6.5
V
rms
to
1.8
V
rms.
The
output
of the
buffer amplifier
is
divided
by
the
output attenuator
in
10
dB V
steps
from
3
V
rms
full-scale to 3
mV
rms
full-scale
into a
600
ohm
load.
The
attenuator
also includes
an
OFF
position
which
disables the
oscillator
output
and
terminates
the
OUTPUT
terminals with
a
600
ohm
resistive
load.
The
combination
of the
output
attenuator
and
level
vernier
permit
the selection
of output
levels
from
1
mV
rms
to
greater-than
3
V
rms
into
600 ohms.
The
oscillator
output
level
may
be
monitored on
the
meter
when
the
OSCillator
LEVEL
function
is
selected.
A
zener diode protection
circuit
protects the
oscillator
circuitry
from
the accidental application
of voltage
to
the
oscillator
OUTPUT
terminals.
8-9
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