DAVIS Rain Collector with Grip Grooves and Bird Spikes (flat base) - Manual (Page 6)

Adjusting the Rain Collector
6
Extending Cable Runs
If the cable length supplied with the rain collector is not long enough for your
purposes, you may extend it. The maximum length of cable is 900 feet (274 m). To
extend the cable, purchase standard 4-Conductor Extension Cables from Davis and
connect them to the existing rain collector cable.
Adjusting the Rain Collector
The non-metric version of the rain collector is calibrated at
the factory so the spoons tip (and records rainfall) for each
0.01". The metric version is calibrated so the spoons tip for
each 0.2 mm of rain. To adjust the calibration slightly, use
a 3/16" (or 5 mm) wrench to rotate the adjustment screws
which are located underneath the tipping spoons. (See
“Rain Collector Internal Components” on page
2.) The
adjustment guide embossed in the platform shows how far
you must rotate both screws in turn to effect a 1% and a
2% change. Moving the screws in the positive (+) direction causes the spoons to tip
more times (i.e. give a larger count) for a given amount of water.
Note: Modify both adjustment screws by the same amount.
To check the accuracy of the rain collector, compare the Davis rain collector with a
tube type rain gauge. Use a rain gauge with an aperture of at least 4 inches. Any
smaller and the readings obtained may not be accurate. Place the tube type rain
gauge directly next to the Davis rain collector. Compare the totals on three storms to
determine whether your rain collector needs calibration and by how much.Adjust the
screws to fine-tune the reading for the next three storms if necessary.
Note: Avoid comparison to rainfall readings obtained from television, radio, newspapers, or
neighbors’ readings. Such readings are not an accurate measurement of the weather
conditions in your specific location. The rain collector is carefully tested at the factory to
conform to the specifications listed in the back of this manual.