Operating instructions

28 YP2425F/YP4025F Table of Contents Index Great Plains Manufacturing, Inc.
403-362M Table of Contents Index 2013-03-25
Calibration Adjustment
Once a sample has been taken, two steps remain:
a. Calculate the current rate.
b. If needed, calculate and apply an adjustment to the
gearbox setting.
Calibration: Rate Calculation
30. If not already done, weigh the metered sample. This
is the gross weight.
31. Subtract the weight of the empty containers (the
tare) from the gross weight.
If your sample size was based on cranking for a full
hectare or acre, no further rate calculation is necessary.
The net weight is the per-hectare or per-acre rate. Skip
to step 33.
32. If the sample size was
1
⁄
10
th
ha (or ac), calculate the
rate for the full area.
Calibration: Gearbox Adjustment
33. If the calculated rate is within about 2% of your
target, there may be no benefit in attempting further
calibration. Resume at “Row Sample Close-Out”on
page 26 or “Meter Sample Close-Out” on page 27.
34. Calculate a gearbox scale adjustment. Divide the
target
a
rate by the sampled rate.
35. Use this factor to determine the next gearbox setting.
36. Reset the gearbox adjuster to the “Next_Setting”
value.
For corrections of 5% or more, re-calibration is
recommended.
If a Low range correction puts the “Next_Setting” above
90, start settings development over in High range.
If a High Range correction puts the “Next_Setting” below
20, start settings development over in Low range.
a. Use the desired field application rate. Do not use any “adjusted” rate used to determine the initial gearbox setting.
Example based on YP4025-1670:
The example in this column is based on a target rate:
120 kg/ha
a gearbox setting of:
80
and a row sample, using 16 containers.
When empty the collection of 16 containers weighs:
1.1 kg
Example:
The sample and all containers weighs a total of:
12.6 kg
The net weight of the sample is:
12.6 - 1.1, or:
11.5 kg
Net_Weight Gross_Weight Tare–=
Example:
Area rate for the sample is:
11.5 x 10, or:
115 kg/ha
This is just approximately 4% under the desired rate,
and is probably worth adjusting for.
Area_Rate Net_Weight 10×=
Example:
120 ÷ 115 is:
1.043 or 104.3%
Factor
Target_Rate
Area_Rate
-----------------------------
=
Example:
80 x 1.043 is:
83.5
Next_Setting Previous_Setting Factor×=
Note: The gearbox adjustment has a near-linear effect
on rates only near mid-scale or for small
adjustment changes. For corrections of 10% or
more, or near the ends of the scale, recalibration
is essential, as further adjustment is likely.