Atec Bruel-Kajaer-2706 - Manual

Product Data
Brüel & Kjær
B K
Power Amplifier — Type 2706
USES:
❍ To drive the Vibration Exciter Type 4809
❍ To drive the Mini-Shaker Type 4810 safely to full
rating
❍ General purpose power amplifier, supplying for
example 75 W into a 3
Ω
loudspeaker for
reverberation measurements
FEATURES:
❍ 75 VA power output capability
❍ Switchable 5 A or 1.8 A max. current limiting
❍ 40 dB voltage gain
❍ Built-in attenuator and continuously variable gain
control
❍ Low distortion over wide frequency range
❍ Built-in protection against short-circuit and excess
heat sink temperature
❍ Front panel indicator light showing clipped output
signal
The Power Amplifier Type 2706 has
been designed to drive small vibration
exciters, particularly the Brüel & Kjær
Vibration Exciter Type 4809. It can
also be used to drive the Mini-Shaker
Type 4810 to full rating. For this ap-
plication, the maximum output cur-
rent should be limited to 1.8 A.
The power amplifier has a flat fre-
quency response from 10 Hz to 20 kHz
(
±
0.5 dB). The power output capabil-
ity is 75 VA into a 3 Ω exciter or resis-
tive load and the maximum voltage
gain is 40 dB. This enables the power
amplifier to be used in acoustical
measurement set-ups, even when
third-octave narrow band noise is em-
ployed.
The use of a transformerless power
output stage and high negative feed-
back results in very low harmonic dis-
tortion. A balanced preamplifier and
rugged solid-state design results in a
stable instrument which can tolerate
temperature fluctuations and supply
line variations.
Description
The block diagram for the various cir-
cuit functions is shown in Fig. 1.
The input circuitry includes an at-
tenuator for attenuation of the input
signal in 10 dB steps from 0 to 40 dB.
This is followed by a continuously
Input
Attenuator
10 µ F
Coupling
Capacitor
Driver
Power
Amplifier
Peak
Current
Limiters
Tempera-
ture
Sensor
Preamplifier
Gain
Control
Clipping
5 A
1.8 A
Input
272084/2e
Fig.1 Block diagram of Power Amplifier Type 2706