16
4.5 Adjustment
It is possible to adjust the measuring amplifier MC2A either with an electrical
signal (calibration box) or directly with a well defined transducer output signal.
After the zero adjustment a defined signal is fed in with a HBM calibrator, or
the transducer is mechanically detuned by some specific amount.
The range fine adjustment facility (screw driver potentiometer P 22) is then
used to set the corresponding output voltage (" 80 mV/V or " 8 mV/V
resp.¢ " 5 V).
4.6 Reference phase
Correction of the reference phase may be necessary when the apparatus is
first used or when long cables (e.g. > 20 m) are being used (due to the capac-
itance).
Correction of the reference phase is carried out by adjusting potentiometer
P 25. Having balanced the zero point connect a transducer whose plunger
can be displaced far enough to give an output signal of 4 ... 4.5 V.
Next, set the output voltage at maximum with P 25.
A signal for the reference phase setting can be attained by taking measure-
ments between point 9 and Kl. 23/8.
A correctly set reference phase is shown in the circuit diagram, Chapter 5.
HBM
MC2A
A1974−2.4 en/de/fr