REV C ECN 10389 09/24/13
3
OPERATION
To operate Model 3224C, it is necessary to
use an electrostatic charge amplifier to convert the
charge mode output signal from the accel. to a low
impedance voltage mode signal which may then be
fed directly to the readout instrument(s).
A recommended charge amplifier for field use
is the Dytran Series 4751B. These instruments convert
the 3224C to Low Impedance Voltage Mode (LIVM)
operation. They are mounted in-line between the
3224C and the LIVM power unit and convert the pC/G
signal to mV/G. These miniature charge amplifiers are
available in four models with fixed sensitivities of 50,
20, 10 and 1 mV/pC. This yields nominal system
sensitivities of 30, 30, 12 and 0.6 mV/G, respectively.
For laboratory use, 3224C may be used with
any vibration type laboratory charge amplifiers and
even with most electrostatic types. Consult the factory
if there is a question about compatibility with available
charge amplifiers.
The cable supplied with Model 3224C is
terminated in a jack type (male thread) 10-32 coaxial
connector. The recommended extension cables are
the Dytran low noise coaxial cables, model 6013AXX
(10-32 plug to 10-32 plug) or the model 6053 (10-32
plug to BNC plug). Both cables mate directly with the
cable attached the 3224C. Other cables are available
if either of these does not meet your requirements.
Contact the Dytran sales department for help in
selecting the best cable for your requirement.
The polarity convention of Model 3224C is
negative charge output for acceleration toward the top
of the unit. This is so because most charge amplifiers
are inverting amplifiers, hence the resultant system
signal will be positive with the above input convention.
UNMOUNTING THE ACCELEROMETER
In order to "unmount" the Model 3224C, use
the Model 6725 tool. The larger slotted end of the tool
is used for this purpose. Slip the tool over the
accelerometer body from the rounded end and gently
rotate the tool in either direction until the adhesive
shears and the instrument is released.
Do not use
pliers, wrenches and other tools to
remove the instrument, as these are certain to mar or
otherwise damage the unit.
MAINTENANCE AND REPAIR
The only maintenance necessary is to keep
cables and connections clean and free from moisture.
All charge mode systems are considered high
impedance systems and as such are susceptible to
moisture which degrades insulation resistance.
Should a problem arise with the accelerometer
or cable, contact the factory for assistance in trouble
shooting or returning the instrument for evaluation
and/or repair. Do not send the instrument back without
first calling the factory to obtain a Returned Material
Authorization (RMA) number.