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44
4.1.4,
4.15.
4.1.6.
S 1 to S3 in position square wave
R1 = 714, 715, 716 + 710
R2=711
R3=717
$1 = 253/5b or 253/6a
S2 = 253/5a for negative pulses ) at the
S3 = 253/6b for positive pulses
J OUTPUT
=22V
Sine shaper
The triangular signal of the oscillator is fed via WAVE FORM
switch to the sine shaper circuit 412.
The conversion from triangle to sine wave, with a distortion factor of 0.2 % typical, is achieved by non-
linear wave form shaping at a diode-resistor network in the IC. The peaks of the triangular wave form
are suppressed by a special compensating circuit in the integrated circuit.
Associated preset controls for shaping are potentiometers 808 and 812. The output on pin 1 is routed
via a low-pass filter which serves to reduce the harmonic content of the sine wave at the highest fre-
quencies. Preset 814 provides a control adjustment for the amplitude response. The output d.c. offset
is preset to zero by 816. The emitter-follower 350/351 is used for impedance matching.
The
output is fed via the wave form selector switch and front-panel AMPLITUDE control 821 to the power
amplifier.
Power amplifier
The power amplifier mainly consists of a voltage amplifier, output stage and the attenuator. Via the
AMPLITUDE
potmeter the level of the selected signal is applied to the voltage amplifier 352 - 355,
which operates as a complementary cascode stage in pull-push arrangement to drive the power output.
The
output
stage comprises 356/358 and 357/359
and operates with complementary
darlingtons.
Feedback
is done via resistor 831 with parallel capacitor 556 to the input of the voltage amplifier,
resulting in overall gain of ca. 15 dB.
The DC OFFSET
is controlled by potmeter 822 via resistor 826 to the input of the voltage amplifier.
and can be set up to £10 V ; see also note in chapter 3.2.1. Resistors 846/847, which determine the
output impedance, feed the three-stage-attenuator. The front panel ATTENUATION
pushbutton 253/
1/2/3 permits selection of 10 dB, 20 dB and 30 cB by switching resistors 849 to 855 as L-section attenu-
ator. For 600 Q output impedance the signal is connected via resistor 857 to the OUTPUT socket.
Power supply
The required two power supplies of +22 V are realized by means of four terminal adjustable voltage re-
gulator 410 and 411. Positive voltage is adjusted by 781 and negative voltage by means of 784 to an ac-
curacy of +0.1 V.
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