Fluke Biomedical 07-443 - Manual (Page 7)

Operation
Zeroing the Unit
2
2-1
Section 2
Operation
2.1 Zeroing the Unit
Each time the Model 07-443 Densitometer is turned ON, and before a measurement is made, it must be
zeroed to ensure accurate measurements. Use the following procedure:
1. Press the ON/OFF push-button to turn the unit on.
2. Gently close the top section of the Densitometer until the Photo Head touches the aperture.
3. Holding the unit in the closed position, press the ZERO button once and wait until the display reads
0.00.
4. Slowly allow the top section of the unit to return to the open position.
5. Should the unit complete the Auto-Zero sequence and show a value either slightly higher or lower
than 0.00, it may be necessary to manually adjust the display to obtain a reading of 0.00. The Zero
Adjustment Pot, located along the right edge of the unit, is used for this purpose.
The zeroing procedure also allows the BASE/FOG value to be subtracted from all subsequent
measurements as follows:
1. Press the ON/OFF push-button to turn the unit on.
2. Place the BASE/FOG area over the aperture.
3. Gently close the top section of the unit until the photo head and the aperture are pressed tightly
against the film.
4. Holding the unit in the closed position, press the ZERO button and wait until the display reads 0.00.
5. Slowly open the unit.
The zero reference is now set to the BASE/FOG value. Subsequent measurements will be made
with respect to the BASE/FOG value.
2.2 Making a Measurement
1. Push the ON/OFF button to turn the unit on.
2. Zero the instrument (refer to Zeroing the Unit, step 2 through 4).
3. With a piece of film media or step wedge in hand, press the LAMP button. The lamp in the bottom
casting will turn on and stay on for about three (3) seconds.
4. Place the film media or step wedge on the light table and position the area to be measured over the
aperture (refer to Figure 2-1).
Press the LAMP Button as necessary to keep the
lamp illuminated.
NOTE