BRUEL & KJAER 2121 Instruction Manual

Frequency Analyzer
Type 2121
A precision mains operated instrument with
selectable filter bandwidths of 1 %, 3%, 10%
and 23,1
%
(third octave) for constant per-
centage bandwidth analysis of sound, vibra-
tion and voltage in the frequency range from
20 Hz to 20 kHz. High Pass, Low Pass and
Band stop filters, tuneable over the same
frequency range., are also provided. Its meter
circuit contains a true RMS rectifier with
selectable "Fast" and "Slow" meter damping
for measurement of signals with crest factors
up to 5 (14 dB). With a B & K condenser
microphone and preamplifier it conforms to
IEC recommendation 179 for precision sound
level meters.
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