[ TERC VHS-1 Sun Photometer ] [ Manual TOC ]

Maintaining the TERC VHS-1 Sun Photometer

Here are some important tips for maintaining the TERC VHS-1:

1. Store the instrument inside a sealed plastic bag to keep dust away from the LED sunlight detector.

2. The black plastic of the TERC VHS-1 case will quickly warm up in exposed sunlight. Since the light response of the LED changes slightly with temperature, keep the instrument covered or inside a backpack or box until just before you plan to use it.

3. NEVER leave the TERC VHS-1 in exposed sunlight.

4. NEVER leave the TERC VHS-1 inside a car or car trunk on a hot, sunny day.

5. The batteries should last a full year or more in normal use--unless you forget to switch the instrument off when it is not in use. If the instrument seems erratic or doesn't respond well to sunlight, use the voltmeter to check the battery voltages. Replace the batteries when their voltage falls below about 7 volts.

6. You should check the calibration of the TERC VHS-1 using the Langley method on at least one clear day every fall and spring. Keep a careful record of your calibrations to determine how much the ET constant changes.