Great Plains NTA2007HD Operator Manual - Manual (Page 80)

76 Great Plains Manufacturing, Inc. Contents Index NTA607/2007HD
166-283M Contents Index 04/04/2011
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 deter-
mine application rate per acre (hectare) at the cur-
rent variable rate gearbox setting.
If the calibrated rate matches the target rate, skip to
step 31. Otherwise…
26. Subtract the calibrated rate per acre (or hectare)
from the target rate to determine a correction differ-
ence.
Null4:
27. Refer to the seed rate chart for Seed Rate gearbox
setting values for the target rate.
Null4:
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 tar-
get 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 lin-
ear, we cannot simply adjust the control arm by 4.8%.
CalibratedRate SampleWeight
10 ×
=
Null4:
USc Example:
TargetRate =
67.6
RateDifference =
67.6 - 75.6,
which is:
-8 pounds
Metric Example:
TargetRate =
200
RateDifference =
200 - 217,
which is:
-17 kg
The calibration run metered too much.
You must lower the gearbox setting to compensate.
RateDifference T etR arg ate CalibratedRate – =
TargetRate
Null4:
USc Example:
Initial Variable
Rate Gearbox
Setting: 38
56.9 63.7 35 77538
60.4 67.6 36 77591
63.9 71.7 37 77640
67.6 75.8 38 77683
71.4 80.0 39 77723
75 2 84 3 40 77760
31374