Great Plains NTA2007 Operator Manual - Manual (Page 85)

Great Plains Manufacturing, Inc. Table of Contents Index Adjustments 81
2012-01-05 Table of Contents Index 166-372M
21. Wipe all the material off the flanges around the
meter doors, on the chute, and capture that material
in the calibration bag.
22. Accurately weigh the calibration bag plus material. If
you set a “tare” on the scale, the reading is the
sample net weight, so skip step 23.
23. Subtract the empty container weight to determine
the application rate for
1 ⁄
10
hectare (or
1 ⁄
10
acre).
24. Press the Stop softkey on the monitor
and enter the sample net weight (SampleWeight).
The monitor responds with a Calibration Constant.
Push the Save softkey to accept this
value.
25. If the sample was based on
1 ⁄
10
hectare (or
1 ⁄
10
acre), multiply the sample size by 10 to
determine application rate per acre (hectare) at the
current variable rate gearbox setting.
If the calibrated rate matches the target rate, skip to
step 31. Otherwise…
26. Subtract the calibrated rate per hectare (or acre)
from the target rate to determine a correction
difference.
27. Refer to the Seed Rate Chart for gearbox setting
values for the target rate.
Manual Seeding Example; Net Weight (step 23):
TotalWeight is 20.96 kg
for bag plus sample
BagWeight is 0.91 kg
SampleWeight is 20.96 - 0.91, which is:
20.96 kg
SampleWeight TotalWeight BagWeight – =
If the calibrated rate turns out to match the desired
target rate, record the material details and final
Calibration Constant for future reference.
Manual Seeding Example; Calibrated Rate:
CalibratedRate = 20.96 x 10, which is:
209.6 kg/ha
This is 4.8% higher than our target rate of 200 kg/ha.
However, because the gearbox actuator effect is not
linear, we cannot simply adjust the control arm by 4.8%.
CalibratedRate SampleWeight 10
×
=
Metric Example:
TargetRate =
200
RateDifference =
200 - 217,
which is:
-17 kg
USc Example:
TargetRate =
67.6
RateDifference =
67.6 - 75.6,
which is:
-8 pounds
The calibration run metered too much.
You must lower the gearbox setting to compensate.
RateDifference T etR arg ate CalibratedRate – =
TargetRate
Metric Example:
Initial Variable
Rate Gearbox
Setting: 62
163.7 183.5 59 78794
169.0 189.4 60 78916
174.3 195.4 61 79050
179.6 201.3 62 79197
185.0 207.4 63 79357
190 4 213 4 64 79532