Atec Bruel-Kajaer-2706 - Manual (Page 2)

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variable gain control and a preampli-
fier. The preamplifier is capacitively
coupled to the driver stage, which is
equipped with a clipping detector. Ex-
cessive signal levels at the input will
saturate the amplifier and cause clip-
ping of the output waveform. This
will trigger the clipping detector,
which then lights the yellow clipping
warning light on the front panel. The
instrument remains in operation dur-
ing clipping.
The power stage employs an output
current limiter, which limits the in-
stantaneous positive and negative
peaks of the output current. The pow-
er output stage is protected by a tem-
perature sensing device. Abnormal
load conditions, high ambient tem-
peratures or an output short-circuit
could result in output transistor tem-
peratures well in excess of design
limits. To prevent any subsequent
damage, the temperature protective
circuitry blocks the amplifier input
signal. When the heat-sink tempera-
ture reverts to the normal level the
power amplifier will automaticially
regain operation.
Example Of Set-Up
A typical frequency response test set-
up for vibration testing is shown in
Fig. 2.
An input forcing signal is taken
directly from the Signal Analyzer
Type 2032 and is fed to the power
amplifier which drives the Vibration
Exciter Type 4809. The signal ana-
lyzer measures the input forcing sig-
nal and the structural response
signal and uses them to produce a
representation of frequency response
function of the structure under test.
Power Amplifier
2706
Dual Channel Signal
2032
Charge Amplifier
2635
Charge Amplifier
2635
Accelerometer
4384
Force Transducer
8200
850792/1e
Fig.2 Typical frequency response test set-up