III. Calibration
1. Turn power ON by placing the rear-panel slide switch in the upward posi-
tion. With application of AC power, the front-panel red LED indicator
should light.
2. ZERO ADJUSTMENT: Establish a zero input to the 3140A by bringing the
transducer frequency to zero or by disconnecting the transducer from the
3140A I/O Connector. Then adjust the front-panel ZERO control (see Fig.
5, above) to produce an output of zero.
3. SPAN ADJUSTMENT: Press the front-panel CAL button. The input signal is
now replaced by a digitally divided, crystal-controlled frequency equal
to 80% of the full-scale value of the input ranqe selected in Step 4,
Section II, above. Now adjust the Coarse and Fine SPAN controls to
produce an output equal to 80% of the selected range. The 3140A is
4. TRIGGER LEVEL ADJUSTMENT: Turn the front-panel INPUT SENSITIVITY control
fully counterclockwise. Then, using the transducer as a frequency source,
apply the lowest-valued input signal for which a valid reading is requir-
ed. Then turn the INPUT SENSITIVITY control clockwise until a stable
output is observed.
FOR MODELS 3240A AND 3340A ONLY:
1A. POWER-UP and ZERO ADJUSTMENT: as in Steps 1 and 2, above.
2A. SCALE SELECTION: Determine the full-scale output of the transducer in
terms of the desired unit of measurement. For example, the full-scale
output for a flowmeter might be 5000 Hz, which corresponds (in units of
flow) to a measurement of, say, 728.2 cfm. Then select the full-scale
frequency ranqe, as explained in Step 4 of Section II. In our example,
this would be the 5000-Hz setting.
Now select the Digital Indicator scale that accommodates the full-scale
output of the transducer in the desired unit of measurement. In our ex-
ample, this scale would be ± 10000, with decimal point to the left of the
last zero, giving a full-scale reading of 1000.0, to accommodate a full-
scale measurement of 728.2 cfm. For the setting of scale and decimal-
point location, refer to the Model 3200/3300 Instruction Manual.
Fig. 5
Model
3140A
Front Panel
6
normally scaled for a full-scale output of +5 volts.
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General