BRUEL & KJAER 2663, Technical Documentation Manual

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Chapter 2 — Operation
Circuit Adjustment for Acceleration Measurement
Preamplifiers Types 2663 and 2663 B
User Manual
BE 1068 – 12
13
2.5 Circuit Adjustment for Acceleration Measurement
In order to produce the most stable unit possible, the preamplifier parameter values
are adjusted by changing the appropriate circuit resistors.
Fig.2.9 shows the pream-
plifiers with the side-cover removed. It contains six resistors which are easily re-
placeable and the floating/grounded connection. These resistors are mounted on
stands from the main preamplifier circuit and the remainder of the circuit is protect-
ed by a shield. The basic formulae necessary for calculation of the resistor values
required for particular parameter values are printed on the shield. Standard, metal
film resistors should be used.
Fig.2.9 Type 2663/2663 B with side-cover removed
The following parameters are adjustable:
●
Low frequency cut-off
●
High frequency cut-off
●
Output Bias
●
Sensitivity
●
Floating/Grounded
Both section 2.5.1 and section 2.5.2 deal with the procedures needed to change the
high and low frequency cut-offs. Changing the output bias of the preamplifier is ex-
plained in
section 2.5.3 , while selection of the gain is covered in section 2.5.4 and
grounded/floating connection is covered in section 2.5.5 . If velocity measurement is
of interest, the preamplifier can be adjusted to operate as an integrator. This is dealt
with in
section 2.6 .
Note 1: Before beginning any measurement, screw the preamplifier cover back onto
the preamplifier housing so as to keep radiation pickup to a minimum.