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HEAD CONSTANT
DISPLACEMENT LIMIT
CURRENT LIMIT
OUTPUT IMPEDANCE
POWER
This provides a lockable setting from 0 to
10 inches/V-sec.
on a ten-turn control. The
proper setting depends on the shaker head
being used, and is stamped on a label by the
connector on each B & K Exciter Head. This
must be properly set to ensure accurate
settings of the DISPLACEMENT LIMIT.
The setting controls the displacement level
above which the DISPLACEMENT trigger
circuit fires and removes the input signal. The
limit can be set anywhere between 0.1 to 2.0
inches (2.5 to 50 mm) peak to peak displace-
ment.
The setting controls the RMS output current
level, including the DC component, above
which the CURRENT trigger circuit will fire
and remove the input signal. An averaging
time-constant
of 50 sec. is used, matching
the minimum thermal time-constant of mov-
ing coils typically used with the 2707.
This time-constant can be reduced to 2.5 sec.
as in section 3.4. The maximum current for
each B & K Exciter Head is shown on a label
by the connector on each head.
A two-position switch to select the feedback
mode of the amplifier. The "Low" impedance
position selects voltage feedback and the
"High" impedance position selects current
feedback.
A three-position, high-current
~witch
which
first connects mains power to the amplifier
and exciter and then connects the amplifier to
the exciter moving coil. In the "Off" position,
power and shaker load are disconnected from
the amplifier. In the "Power On" position
only the AC power is applied energizing the
Amplifier and Exciter Body (via the AC
POWER EXCITER cable entry), and lighting
7
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