Drawing Number: 21096
Revision: NR
SERIES 134A20 TOURMALINE PRESSURE BAR GENERAL OPERATION MANUAL
2
Connect the Series 134A20 Tourmaline Pressure
Bar with In-Line Amplifier to a PCB power
conditioner. Connect the output of the power
conditioner to an appropriate readout instrument.
Tie the three-inch, low-noise cable to a rigid
structure to prevent excessive motion and noise.
Allow for strain relief.
Caution
If the tourmaline pressure bar or the three-inch
cable become disconnected from the in-line
amplifier, take caution to momentarily electrically
short out the cable and tourmaline pressure bar
before reconnecting the cable to the in-line
amplifier. This prevents any unusual high charge
buildup from damaging the input stage of the in-
line amplifier.
Black vinyl tape is supplied on the sensing end of
the tourmaline bar to dampen heat transfer into the
sensing crystal. This tape can be removed and
replaced if damaged.
4.0
OPERATION
Switch on the (PCB) power conditioner and
observe the bias monitoring voltmeter (or LED) on
the front panel.
If the indicator reads proper bias (green area on the
meter, approximately 11 volts), the connections
from the Series 402A In-Line Amplifier are correct
and the in-line amplifier is operational. If the meter
reads in the red or yellow areas, the system is
shorted or open. The short or open circuit may be
in the in-line amplifier, the cable connecting the in-
line amplifier to the power conditioner, or in the
power conditioner.
Allow the system to stabilize for a minute. A signal
drift may occur when connecting the power
conditioner to the readout instrument. This should
stabilize as components in the power conditioner
and readout instrument charge.
If long cables between the Series 134A20 and the
power conditioner are used, impedance matching
of the long cable and increase of the constant
current in the power conditioner may be required
because of the high-speed response of the sensor.
Check with PCB if there are questions.
5.0
CALIBRATION
The tourmaline pressure bar must be calibrated
dynamically
. The tourmaline pressure bar does not
measure static pressures. In addition, application of
high static pressure to the tourmaline bar may cause
damage.
Two methods are used at PCB to calibrate the
Series 134A20: a shock tube and a hydraulic pulse
tester. The shock tube is used primarily to check
the sub-microsecond response of the tourmaline
pressure bar.
The hydraulic pulse tester is used to generate a
known, short-duration pressure pulse at five
different pressure levels to determine the average
sensitivity of the sensor.
Recalibration services are offered by PCB. In
addition, the shock tube and hydraulic pulse
calibrator are offered as standard products by PCB.
6.0
USE OF CHARGE MODE
TOURMALINE PRESSURE
BAR
The tourmaline pressure bar is a charge output
piezoelectric sensor that can be used without the in-
line
source
follower
amplifier for certain
applications. Calibration information is supplied
showing (charge) output sensitivity of the
tourmaline bar alone, along with its crystal
capacitance.
