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permits exact frequency selection in the range
.±
500 Hz in relation to the
setting on the main scale.
By means
of
a noiseless switch on the front panel, marked OSCILLATOR
STOP, the voltage on the anode of the 1.2 MHz oscillator can be disconnected.
This arrangement is specially provided for reverberation measurements. The
identical operation can be obtained by remote control ,this can be seen from
the circuit diagram of the Oscillator.
The output voltage from the fixed oscillator is fed to the grid circuit of a
pentode, the grid bias of which is controlled by a regulating amplifier. To
obtain a high degree of regulation, the working-point of the pentode is chosen
on the non-linear portion of the Ia-Eg characteristic, near cut-off. The purpose
•
30
Full Indica-
t ing Me
t
er dB
deflection
--........
• 20
Graduation
' " [·' :
-
10
-20
-
30
- 40
0
u.:
a:i
'li
-50
0
>
::J
Q.
-60
::J
0
-70
I
I
--
--
--
-
-
~",
v
Distorted Signal
---
--
.,
\
1 - -
\\
-.......,_
\\
~
\\
\
Maximum
dynamic
1
\
range of
""'\
Compressor
OUTPUT LEVEL
~ ~
t::!:
control turned
~:n
0
dB
____.-
-----
-10
dB-
\
1\\
-30dB-
_
-
r---
~
-50
dB,
~
""'
~
~
\~1
\
r-~
\\.~
No ise
~
level
-
of
B.F.a.
7
6
5
4
3
2
1-~+1
2
3
4
L
Approx.
3V
5 d
/62261-
Relative var iation of COMPRESSOR INPUT voltage
Fig. 1.2. Regulation characteristics for different positions of the potentiometer
marked OUTPUT LEVEL.
5
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