BECKWITH ELECTRIC M-0329B, Instruction Book, Page: 28 / 35

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M-0329B Instruction Book
11.1 Calibration
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NOTE : The M-0329B has been fully calibrated
at the factory prior to shipment. There is
no need to recalibrate the unit before
initial installation. Further calibration is
only necessary if a component was
changed during a repair procedure.
Bandcenter and Bandwidth
The BANDCENTER and BANDWIDTH dials are
calibrated by adjusting the position of the knob on
the potentiometer shaft. Initially, the knob should
be turned to the full counterclockwise position and
adjusted so that the pointer is aligned with the
small dot to the left of the minimum scale setting.
Further adjustments (if necessary) should be made
at approximately half scale.
Bandcenter
1. Set the BANDCENTER control to the
maximum scale 140 V center.
2. Adjust R15 until the measured
Bandcenter is 140 V rms.
3. Set the BANDCENTER control to the
minimum scale 100 V center.
4. Adjust R17 until the measured
Bandcenter is 100 V rms.
5. Repeat Steps 1 through 4 until both the
minimum and maximum are calibrated
to within ±0.5 V rms.
6. Measure the voltage Bandcenter at the
120 V rms setting. The Bandcenter
should be 120 V rms ±0.5 V.
7. If the 120 V rms setting is not within
specifications, repeat Steps 1 through 6
at the 102 V rms setting and the 138 V
rms setting.
Bandwidth
1. Set the BANDWIDTH dial to 12 V.
2. Slowly raise the voltage input until the
BLOCK RAISE relay energizes. Note
the voltage (V
BR
).
3. Slowly lower the voltage until the
BLOCK LOWER relay energizes.Note
the voltage (V
BL
).
4. Calculate the bandwidth (V
BR
-V
BL
) by
taking the difference between the
voltage recorded in step 2 and step 3.
5. The calculated bandwidth at 12 V should
equal 12 V rms ±0.8 V rms for a 120 V
unit. If out of specification, adjust the
BANDWIDTH dial on the shaft until the
proper reading is acquired.
6. Adjust the BANDWIDTH dial to 18 V,
and measure and record the bandwidth
as in steps 2 through 3. The calculated
bandwidth should equal 18 V rms ±0.9
V rms for a 120 V unit.
7. Adjust the BANDWIDTH dial to 24 V,
and measure and record the bandwidth
as in steps 2 through 3. The calculated
bandwidth should equal 24 V rms ±1.2
V rms for a 120 V unit.
8. Adjust the BANDWIDTH dial to 6 V,
and measure and record the bandwidth
as in steps 2 through 3. The calculated
bandwidth should equal 6 V rms ±1.0 V
rms for a 120 V unit.
9. Reset the BANDWIDTH dial to desired
setting.