NOTE: For low leve! applications, pull the AMPL knob for -20 dB (10-to-1 reduction)
attenuation
of
the output signal.
E.
If
required, pull and ad
just
the OFFSET knob
for
a DC offset in the output signal at the
OUTPUT jack.
F.
Pull the SWEEP WIDTH knob out
to
turn on the modulation.
G.
Pull the MODULATION CARRIER knob out for FM modulation, otherwise leave it
pushed in for AM modulation.
H.
For external modulation
of
the carrier, push the MOD button in, or leave
it
released to use
the internai
400Hz modulation signal.
I. Ad
just
the MODULATION CARRIER knob
for
the desired modulation leve!.
5.8
Application Note: Amplifier Response Testing
A typical use for the Mode! FG3B Sweep/Function Generator is evaluating the performance
of
audio power arnplifiers. Sweep testing an amplifier permits the user
to
see at a glanee the overall quality
of
the unit. Problems such as limited bandwidth or instability due
to
comp<ment failure become apparent
by variations
in
the output leve!.
If
the amplifier has tone con trois, sweep testing will readily show their operation. The boost-
and-cut effects
of
treble and bass con trois will appear as peaks and dips in the output, respective!
y,
during the sweep. Otherwise set the tone con trois
to
the flat position during testing to avoid confusion.
17
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