ENDEVCO
www.endevco.com Tel: +1 (866) ENDEVCO [+1 (866) 363-3826]
IM 2680/5 083119
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As an example, let’s assume that we are going to use a model 2230 high-
temperature accelerometer. The room temperature resistance is 1G Ω that
would work well with the 2680, but the resistance drops to 100kΩ when
the accelerometer reaches 900°F (482°C) which is well below the minimum
source resistance requirement of the 2680.
In this instance, consider using a 2685 airborne amplifier in conjunction
with a 2771C in-line charge converter. The 2771C has a minimum
source resistance requirement of 100k, which will work over the entire
temperature range.
6.0
PERFORMANCE TESTING
It is sometimes desirable (or required) to test the integrity of a system after
installation. This section will provide both a quick test and an in-depth test
for both the 2680 and 2685. The quick test might be conducted prior to
installation to verify the unit is operational.
The most efficient way to test the performance is described in section 6.1.
If these instruments are unavailable, section 6.2 suggests methods where
standard laboratory instrumentation can be used to effectively perform
the tests. See the appropriate Endevco technical paper for further tests, if
required
6.1
Preferred method, 2680 and 2685
Using one of the Endevco test instruments discussed herein is the easiest
and most effective way to conduct a performance test on either of the
airborne amplifiers. The two instruments and their applications are
discussed below.
6.1.1
Hand-held shaker method
The Endevco model REF2520/R (figure 9) reference shaker is a highly
convenient way to test and confirm the calibration and performance of
the accelerometer, cable and amplifier with one simple test. The vibration
level is limited to 1g peak.
Figure 8: Model
2771C in-line charge
converter to be
installed between the
accelerometer and the
2685’s input connector.