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OUTPUT SECTION
ATTENUATOR:
READ OUT SELECTOR:
RECORDER:
Stepped attenuator ( 1 0 dB steps) for
attenuation of the signal level between
filter outputs and the output amplifier.
To ensure the best possible signal-to-
noise ratio the knob should be kept as
far clockwise as possible.
A four position switch which provides:
a) A choice between a "Lin" or "Log"
meter display, and
b) A choice between an AC signal direct
from the amplifier or a linear or loga-
rithmic DC signal from the rectifier.
Output socket for AC or DC recording.
EFFECTIVE AVERAGING TIME: For the selection of integrating time
constants to give effective averaging
times ranging from 0.1 to 100 sees. The
first two positions "Fast", "Slow" cor-
respond to the I EC standard for preci-
sion sound level meters.
2.1.2. Filter Section
MODULATOR BALANCE:
The two potentiometers balance the
first mixer to suppress the unwanted
frequency from the V.C.O
.
for low fre-
quency analysis. See section 3.1.3.
FREQUENCY DISPLAY:
A six digit Nixie display shows the
tuned in frequency in kHz.
COUNTING TIME INCREASE:
When the push button is depressed, the
frequency sampling rate of the Nixie
display is increased by 10, providing an
extra digit on the Nixie display.
A row of push buttons is situated directly below the EFFECTIVE
AVERAGING TIME switch. Their functions are as follows:
10
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