Wavetek 452, Instruction Manual

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138
MODELS 452/452-01 & 852/852-01 SIGNAL PROCESSING FILTERS
Dual HI/LO Variable Analog Filters
•
Frequency Range:
0.01 Hz
to
111 kHz
•
Resolution:
3
Digits
•
Cutoff Frequency Accuracy:
+
20/0
•
Responses: Butterworth and Flat Delay
•
Dynamic Range:
90
dB
•
Low Noise
Design
The Models 452 and 852 Dual
H
I/LO
Filters each consist of two identical
filter channels contained in a com­
mon cabinet. Each filter channel has
separate input/output terminals,
offers high pass and low pass
functions,
0
dB and 20 dB gain,
Butterworth/Flat Delay responses
and 3-digit resolution for cutoff fre­
quency selection.
Versatility
Individual channels may be readily
interconnected for series or parallel
operation, resulting in bandpass (or
doubled rolloff) and band reject
functions respectively.
Each filter channel provides switch
selectable Flat Amplitude (Butter­
worth) response for frequency
domain applications and Flat Delay
response for transient-free time
domain applications.
The Models 452 and 852 are elec­
trically and mechanically similar,
each covering the cutoff frequency
range of
0.1 Hz
to
111 kHz.
Rolloff of
the Model 452 is 24 dB/octave/
channel, while the Model 852 is 48
dB/octave/channel. The factory
installed Option
01
will extend the
cutoff frequency range and resolu­
tion on the Models 452 and 852 to
0.01 Hz.
Implementation
Frequency determining passive
elements of the filters are stable
precision metal film resistors and
close tolerance polycarbonate or
mica film capacitors. The active
elements are FET-input le operational
amplifiers which provide highly stable
gain, and very low noise and distor­
tion. This combination of active and
passive elements produces a filter
having high cutoff frequency ac­
curacy and resettability, excellent
temperature stability and long term
stability. Another result of precise
control of frequency-determining
elements is close amplitude and
phase match between channels.